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Temporal and Spatial Distribution Characteristics of Heavy Metals in Water Level Fluctuating Zone of Zigui Section in Three Gorges Reservoir Area
CHEN tian, CHENG Rui-mei, XIAO Wen-fa, SHEN Ya-fei, ZENG Li-xiong, WANG Li-jun, SUN Peng-fei,
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Abstract:
Objective To analyze and compare the temporal and spatial differences in soil heavy metal content in the water-fluctuation zone of the Three Gorges reservoir area, study the current situation of metal pollution in this area, and put forward prevention and control measures. Methods The soils in the flooded area (elevation 145-175 m) and unflooded area (elevation 175-185 m) from the water-fluctuation zone of the Three Gorges reservoir area in the Zigui section in 2008, 2014, and 2018 were used for the study. We examined the physicochemical properties and copper (Cu), iron (Fe), manganese (Mn), and zinc (Mn) contents of these samples through the digestion method. Results The results showed that: (1) The contents of soil total nitrogen (TN), total phosphorus (TP) and organic matter (SOM) in the flooded area continued to decrease from 2008 to 2018. The soil pH increased compared with 2008 and it was close to 7 in 2018. (2) As of 2018, the contents of Cu, Fe, Mn and Zn in the soil of water level fluctuating zone have been increasing. The geological accumulation index pollution degree of Zn in the middle and lower part of water level fluctuating zone (elevation 145~165 m) and the soil in the non-flooded area was “strong”; Cu in the lower part of the water level fluctuating zone (elevation 145~165 m) and Zn in the soil in the middle and lower part of water level fluctuating zone and non-flooded area had caused slight ecological risks. (3) The correlation analysis between soil physical and chemical properties and the contents of four heavy metals in water level fluctuating zone showed that the rise of soil pH might bring the risk of increasing the accumulation of four heavy metals. The increase of soil TP might reduce the accumulation of four heavy metals in the soil, while the increase of soil TN content might cause the increase of soil Fe and Mn in the non-flooded area and the decrease of Cu and Zn in the flooded area. Conclusion In summary, the operation of the Three Gorges Dam has caused a decline in the quality of soil nutrients such as reducing nitrogen and phosphorus contents. The status of soil heavy metal pollution in water level fluctuating zone cannot be ignored, especially the ecological risks of Cu and Zn. Therefore, long-term monitoring should be continued, and artificial intervention means such as changing vegetation composition can be considered if necessary.
Correlation between Water-carbon Metabolism and Growth and Fruiting Traits of Upper, Middle and Lower Branches in the Crown of Hippophae rhamnoides subsp. sinensis Rousi
LI Hai-bo, XUE Hao, XUE Jing-ru, CAO Xi-juan, WANG Lin
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Objective To understand the relationship between water and carbon metabolism and growth and fruiting of branches at different positions in the crown of Hippophae rhamnoides for providing a certain theoretical basis for the formulation of cultivation technical measures for Hippophae rhamnoides tree shape culture. Method According to the two-year-old branches in the upper, middle and lower crown of Hippophae rhamnoides, water status, photosynthesis, non-structural carbohydrate (NSC) content, branch and leaf growth, fruiting traits and fruit nutrients were compared. Result The results showed that there was no significant difference in the pre-dawn water potential of branches in different parts of the crown, and the water potential of the bottom branches at midday was significantly higher than that of the upper and middle branches. The percentage loss of conductivity (PLC) of the middle branch in pre-dawn was significantly lower than that of upper and lower branches, and the PLC of the bottom branch at midday was significantly higher than that of top and middle branches. The stem and leaf area specific hydraulic conductivity of upper branches was significantly higher than that of middle and lower branches. The net photosynthetic rate in the top branch was the largest, followed by middle branch and bottom branch. NSC content in xylem of middle branches was significantly higher than that of upper branches, but there was no significant difference between the upper and lower branches, as well as between the middle and lower branches. There was no significant difference in NSC content in phloem among branches, and the NSC content in leaves of upper and middle branches was significantly higher than that of lower branches. The vertical and horizontal diameter of flower buds, the proportion of pure flower buds, the germination rate, the number of new shoots, the basal diameter of new shoots, the leaf area and the specific leaf mass of the bottom branches were significantly lower than those of the upper and middle branches. The fruit size, fruit setting rate and soluble solid content of the bottom branches were also significantly lower than those of the upper and middle branches. The branch length and base diameter of the upper branches are significantly higher than that of the middle branch. The fruit quality and fruit vertical and horizontal diameter of the middle branch were significantly higher than those of the upper branch. There was no significant difference in the contents of flavonoids, vitamin C and titratable acid among different branches. Conclusion The lower branches are greatly affected by shading, which significantly restricts the uptake and growth of photosynthetic products, and affects their fruiting traits. The upper branches are dominant in growth, and the middle branches are dominant in fruiting traits. Therefore, the tree-shaped cultivation of Hippophae rhamnoides should take full account of its light conditions, and timely remove the branches in the lower light area. At the same time, we should pay attention to the balance between nutritional growth and reproductive growth, and making full use of the upper and middle branches of the crownfor improving the yield and quality of Hippophae rhamnoides.
Sapling Stem Stoichiometry of Dominant Species in Three Types of Tropical Forests in Southern Yunnan
TU Jing, LI Zhong-fei, SUN Jing, ZHAO Xiao-peng
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Objective The aim this study was to explore the distribution patterns and limitation of nutrient elements in subtropical forest species in southern Yunnan, for revealing the adaptive mechanism of tree species under a changing environment. Method The dominant species in three types of tropical forests, i.e., tropical seasonal rain forests, tropical montane rain forests and montane moist evergreen broad-leaved forests, were sampled in southern Yunnan to analyze C, N, P and their stoichiometric ratios in sapling stems. Result 1) The total C of sapling stems of dominant species in the three types of tropical forests generally increased, but total N and P decreased with increasing elevation. 2) The ratios of stem C:N and C:P in montane moist evergreen broad-leaved forests were relatively high compared to other two types of forests. The ratio of stem N:P both in tropical seasonal rain forests and tropical montane rain forests were less than 14, while this value in montane moist evergreen broad-leaved forests was higher than 16. 3) The stem C and N of dominant species in upper canopy were smaller than lower canopy. However, total P contents in upper canopy was higher than those in lower canopy. The value of N:P in upper canopy was less than 14, whereas it was higher than 16 in lower canopy. These results suggested that the growth of dominant species in upper canopy was mainly limited by N. 4) The results of Redundancy analysis revealed that elevation and community had a great effect on C, N and P contents and their stoichiometric ratios in sapling stems of dominant species. Conclusion Montane moist evergreen broad-leaved forest has a relatively high nutrient efficiency, and the forest ecosystems in southern Yunnan are mainly limited by N and P contents. The difference of ecological stoichiometric characteristics in trees under different environments can reveal the coping mechanisms of species adaptating to changing environments.
Characteristics of Nutrient Resorption in Leaves of Pinus thunbergii with Different Densities in Sandy Coastal.
REN Yi-wei, YI Hua-peng, ZHONG Xiao-ying
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Objective To study the nutrient resorption characteristics of Pinus thunbergii under different densities (high density: 1150 plants·hm−2, medium density: 535 plants·hm−2, low density: 285 plants·hm−2)and the effects of leaves and soil nutrient contents and stoichiometric characteristics on the resorption efficiency, in order to provide a scientific basis for the rational management of Pinus thunbergii. Method Taking Pinus thunbergii in the shelter forest of Muping coastal zone in Yantai as the research object, by collecting mature leaves, senescing leaves and soil samples of 0-20 cm under forest of Pinus thunbergii with different stand densities, the carbon (C), nitrogen (N), phosphorus (P) of leaves and soil, nitrate nitrogen (NO3 -N), ammonium nitrogen (NH4 +-N), available phosphorus (AP) contents were determined, and researched the nutrient resorption characteristics of Pinus thunbergii at different densities, and analyzed the resorption of Pinus thunbergii leaves under different densities characteristics, leaves and soil nutrient contents, stoichiometric characteristics and their correlations. Result (1)The average nitrogen resorption rate (NRE) and phosphorus resorption rate (PRE) were 52.44% and 48.53% in Muping coastal shelter forest. The NRE was higher than the average level of global coniferous forests, and the PRE was lower than the average level of global coniferous forests. Under the three densities, the growth and development of Pinus thunbergii were more restricted by N, which was consistent with the “relative resorption hypothesis”. (2)In the medium density area, the nutrient contents and resorption rates of mature leaves were the highest, and the NRE was significantly higher than high stand densities. The contents of C, N and P in mature leaves of Pinus thunbergii increased with the increase of density and then decreased, and the contents of senescing leaves were not significantly different among different densities. At medium density, C:N of mature leaves was significantly higher than that of low and high density; C:P of senescing leaves was significantly lower at low density. (3) Soil AP content was significantly higher in low-density forests; soil TN was significantly higher in medium-density forests; soil TP in high density stands was significantly lower than that in medium and low density stands. Soil C:N and C:P were significantly higher at high density, and at medium density, N:P was significantly higher than low and high density. (4) Nutrients and stoichiometric indicators of senescing leaves had more significant effects on nutrient resorption, and the responses of NRE and PRE to leaf and soil nutrients and their stoichiometric characteristics were different under different densities. Conclusion In our experimental condition, Pinus thunbergii with medium density can relatively improve the nutrient utilization efficiency, which is more conducive to adapting to the N limitation in this area.
Optimization of Fermentation Conditions of Trichoderma songyi M75 Strain by Response Surface Methodology
Zhang Ming, NING shao-hua, Gao Qian, Xie Xian, Cheng Yuan, Liang Jun
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Objecive To improve the antibacterial activity of its sterile filtrate against the pathogen of pine shoot blight and obtain the high-efficiency antibacterial fermentation medium formula of Trichoderma songyi M75, response surface method was used to optimize the liquid fermentation culture conditions of T. songyi M75 . Method Plackett-Burman experiment, the steepest ascent method, and response surface method were used to optimize the fermentation medium of T. songyi M75, and the experiment data were analyzed using Design Expert 11.0. Result The three main influential factors were glucose, temperature and speed and the optimal fermentation culture concentrations conditions were: glucose 2.75%, tryptone 1.2%, zinc sulfate 0.2%, potato juice 1000 mL, temperature 31.0 ℃, rotation speed 195 r/min, inoculation volume 5%, liquid volume 180 mL, fermentation culture 5 d. Conclusion This study greatly improves the antibacterial activity and obtains the optimal culture conditions, which provides an effective basis for the follow-up study of T. songyi strains.
Spatiotemporal Dynamic Characteristics of Non-structural Carbohydrates of Abies georgei var. smithii in Sygera Mountain
FAN Zhi-ying, CHEN Kang, LI Jiang-rong, WANG Han-ju, PAN Kai-wen
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Objective To verify the formation mechanism of the alpine treeline and explore the limiting factors of the upper limit of tree distribution. Methods In the low altitude coniferous and broad-leaved mixed forest (3500 m), suitable altitude area (3900 m) and high altitude treeline transition zone (4300 m) in Sygera Mountain, the contents of non-structural carbohydrates and C, N, and P in leaves, branches, stems and roots of Abies georgei var. smithii as well as were measured both in the growing season (early July) and non-growing season (end of November). Results The results showed that the non-structural carbohydrate sources and sinks of Abies georgei var. smithii were stable in different growing seasons, and there was no insufficient carbon supply. There were little effects of altitude on the non-structural carbohydrates and their components in Abies georgei var. smithii . There were significant differences in NSC content among organs, and the physiological activities and functions of leaves, branches, trunks, and roots were significantly different in different growing seasons. In the non-growing season, non-structural carbohydrates and their components were significantly higher than those in the growing season. In the non-growing season, higher soluble sugars and NSC contents enabled the vegetation to resist cold temperature and other harsh conditions. The content of NSC in Abies georgei var. smithii increased with the increase of altitude, which supported the hypothesis “growth limitation” . Conclusion The growth of Abies georgei var. smithii is more restricted by plant nutrients than by carbon.
Community composition and ecological functional analysis of the endophytic microorganisms in Eucommia ulmoides seeds
ZHANG Qing-Qing, DONG Chun-Bo, SHAO Qiu-Yu, LU Ying-Xia, DONG Xuan, LIANG Zong-Qi, HAN Yan-Feng
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Objective To reveal the microbial community composition and diversity in Eucommia ulmoides seeds and enrich the related microbial resources. Methods In this study, the diversity of endophytic microorganisms in E. ulmoides seeds was analyzed by traditional culture method and high-throughput sequencing technology, and functional annotated by FAPROTAX and FUNGuild database. Results A total of 40 fungi strains (3 phyla and 11 genera) were isolated from E. ulmoides seeds, and the dominant genus was Aspergillus (30%); 142 bacterial strains (1 phylum, 6 genera) were isolated, of which Solibacillus was the dominant genus (47.18%). Through high-throughput sequencing, 141 fungal OTUs were obtained belonging to 6 phylum and 101 genera; 442 bacterial OTUs were obtained belonging to 24 phylum and 313 genera. At the genus level, the dominant fungi were Apiotrichum (31.28%) and Debaryomyces (26.07%); The dominant bacterial genera were Pseudomonas (16.66%) and Lactobacillus (9.68%). The results of functional annotation showed that fungi mainly degraded organic matter, promoted the growth of host plants and the absorption of soil nutrients by host, improved soil microbial community structure and Pathogen community. The bacteria mainly consisted of chemoheterotrophic, heterotrophic, fermentation. and nitrogen fixation bacteria. Conclusion E. ulmoides seeds carry a variety of probiotics and potential phytopathogens, which have important effects on plant growth and development. In addition, a number of beneficial functional bacteria were isolated in this study, which will provide microbial resources for the subsequent artificial control of seed microbiome to enhance plant health.
Effects of light and N:P ratio on photosynthetic characteristics in seedlings of three typical tree species
XIANG Wang, CHENG Xiang-Rong, XU Hai-Dong, LIU Jiang-Wei
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Objective To study the response of photosynthetic characteristics of different ecological tree species to light and nutrient supply for providing a scientific basis for plantation cultivation. Method The seedlings of Quercus acutissima, Phoebe bournei, and Schima superba were used. This study included two light intensities (natural full light and 45% full light) and three N:P ratios (N:P=5, N:P=15, N:P=45). We measured the changes of Photosynthetic fluorescence parameters, and seedlings’ height, seedlings’ ground diameter to study the changes of plant photosynthetic characteristics in different environments, and analyze the relationship between seedling growth and photosynthetic parameters. Result (1) Compared with the full light treatment, the shading treatment decreased the light saturation point (LSP) and the maximum net photosynthetic rate (Pnmax) of Q. acutissima, and increased the Pnmax of S. superba. but had no significant effect on Pnmax of P. bournei. Under the two light treatments, ertilization increased the LSP and light compensation point (LCP) of P. bournei and S. superba, but the effects of fertilization on the shading LSP and LCP of Q. acutissima were less. (2) Shading significantly reduced the quantum yield of regulated energy dissipation of PSⅡ [Y(NPQ) ] of Q. acutissima, P. bournei and S. superba, and significantly increased the photosynthetic electron transport rate (ETR). Under the full light treatments, fertilization generally increased the effective quantum yield of PSⅡ [Y(II) ] and ETR of Q. acutissima, P. bournei and S. superba, but decreased Y(NPQ) . Under the shading treatments, fertilization significantly increased Y(II) and ETR of P. bournei, while Y(II) and ETR of Q. acutissima increased significantly when the N:P supply ratio was 5. Y(II) and ETR of S. superba increased significantly when the N:P supply ratio was 15. (3) Compared with the full light treatment, shading significantly increased the contents of chlorophyll a, chlorophyll b, chlorophyll a + b and carotenoid of Q. acutissima, P. bournei and S. superba. Under the two light treatments, fertilization significantly increased the photosynthetic pigment content of Q. acutissima, S. superba and P. bournei (only full light treatment). (4) Regardless of light or shading, fertilization generally increased the relative growth rates of seedling’s height and ground diameter of the three tree species, and there was a positive correlation between the growth and photosynthetic pigment. Conclusion Photosynthetic characteristics and growth of Q. acutissima, P. bournei and S. superba are affected by the interaction of light and fertilization. The effect of nitrogen and phosphorus fertilization on seedling growth under different light intensities depends on nitrogen and phosphorus supply ratio and tree species.
Diversity Analysis of Leaf Phenotypic Traits of Eucommia ulmoides Germplasm Resources
MENG Yide, DU Hong-yan, WANG Lu, LV Geng-xin, QING Jun, HE Feng, HUANG Hai-yan, DU Qing-xin
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Objective The genetic diversity of leaf phenotypic traits of 701 Eucommia ulmoides germplasm resources was investigated to provide theoretical support and materials for the breeding, development and utilization of Eucommia ulmoides. Methods Fourteen phenotypic traits of Eucommia ulmoides leaves were determined. Correlation analysis, principal component analysis and cluster analysis were used to investigate the genetic diversity of leaf phenotypic traits among different germplasm. Results There were significant differences among 14 phenotypic traits of Eucommia ulmoides leaves. The coefficient of variation of leaf area was the largest (20.68%), and the coefficient of variation of chlorophyll reference value was the smallest (4.57%). The genetic diversity index of each phenotypic trait ranged from 1.90 to 2.09, and the genetic diversity index of leaf length and petiole length was the highest with 2.09.There were 26 pairs of leaf phenotypic traits that are significantly positively correlated, and 19 pairs that are significantly negatively correlated (P<0.01). There were extremely significant positive correlations among the five traits of leaf length, leaf width, leaf area, leaf circumference and petiole length (P<0.01). The cumulative contribution rate of 6 principal components extracted by principal component analysis was 89.211%. Based on 14 phenotypic traits, 701 Eucommia ulmoides germplasm were divided into 4 categories. There were significant differences in leaf phenotypic traits among various groups. Conclusion The leaf phenotypic traits of Eucommia ulmoides germplasm resources show rich diversity, and six traits are selected as important indicators for evaluating the resources of Eucommia ulmoides germplasm resources, including leaf area, Specific leaf fresh weight, green component of leaf, chlorophyll reference value, length to width ratio of leaf, and internode length. It provides an excellent germplasm basis for the selection and comprehensive utilization of Eucommia ulmoides varieties.
Transcriptome Analysis of Sonneratia apetala Root in Response to Salt Stress
LIANG Rui-tao, HAN Wei-dong, YANG Shao-xia, CHEN Bei-bei
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Objective To lay a molecular basis for functional verification experiment and genetic breeding of tree salinity tolerance, the genetic mechanisms was explored, and salt-related genes were identified for Sonneratia apetala Buch.-Ham. Method In this study, the root tissues were collected from a 1-year-old S. apetala treated with 500 mmol•L−1 NaCl for 0 (control group) and 10 d (treatment group). Then transcriptome sequencing and bioinformatics analysis was performed based on the three-generation full-length transcriptome dataset of S. apetala. Result (1) Compared with the control group, 14401 genes were differentially expressed after salt treatment, of which 7153 were up-regulated and 7248 were down-regulated. (2) GO analysis found that a total of 11068 differential genes were annotated in 47 GO items. (3) For KEGG enrichment analysis, a total of 6189 differential expression genes were enriched to 134 pathways, of which 14 were significantly enriched (P-value <0.01, Q-value <0.05). (4) Further functional annotation analysis of the differentially expressed genes revealed a total of 89 genes was potential salt-related candidate genes. Among these, 24, 22, 19, 10 and 14 genes encoded enzymes or functional proteins referred to antioxidation, osmotic adjustment substances, plant hormones, protein kinase and transcription factors, respectively. Conclusion Genes relating to active oxygen scavenging, osmotic regulation, plant hormones, protein kinases and transcription factors participate in the regulation of salt stress adaptation in S. apetala.
Effects of PagWOX11/12a Gene on Stem Growth and Development of Populus alba × P. glandulosa
Wen Shuang-Shuang, Wang Liu-Qiang, Lu Meng-Zhu
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: Objective To analyze the effect of PagWOX11/12a gene on the growth and development of poplar for further research on the regulation mechanism of this gene in woody plants. Method Bioinformatics methods and software were used to construct phylogenetic evolutionary tree, sequence alignment and biochemical characterization analysis. Tissue-specific expression patterns were analyzed by qRT-PCR. The phenotype of poplar after specifically suppressed the expression of PagWOX11/12a was analyzed by using transgenic plant 35S::PagWOX11/12a-SRDX (DR). Result PagWOX11/12a gene could encode a protein with 255 amino acids, which was expressed in different tissues of 84K. The phenotypic analysis of DR transgenic plants showed that inhibiting the expression of this gene could reduce the length of phloem cells, pith cells and xylem fiber cells, inhibit internode elongation, and significantly reduced plant height compared with non-transgenic 84K. Conclusion PagWOX11/12a gene participates in regulating the height growth of poplar by affecting the elongation of internodes. This study provides a reference for further revealing the regulatory mechanism of PagWOX11/12a gene involved in the growth and development of poplar.
Niche Characteristics of Population in Shrub Communities in Spruce-fir Forest Burned Areas on the Northeast Margin of Qinghai-Tibetan Plateau
ZHAO An, ZHOU Xiao-lei, SHI Rui-jin, ZHOU Xu-jiao, YANG Fu-qiang, HE Wan-peng
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Objective To reveal the niche characteristics of shrub community population in the burned areas of Spruce-fir forest in different years on the northeast edge of Qinghai-Tibetan Plateau. Method Levins and Shannon Wiener niche breadth index, Pianka and Schoener niche overlap index were used to calculate the niche breadth and niche overlap degree of population, and the specialized species and generalized species of community were divided. Result The results of Levins and Shannon Wiener niche breadth index of shrub species in burned and unburned forest land were basically the same, and there were differences in the niche breadth of the same species in burned and unburned forest land. There are three specialized species in the 5-years burned area, two specialized species and 1 generalized species in the 15-years burned area and one specialized species in unburned forest land. The proportion of species logarithms with severe niche overlap among species was 15-year-burned land>5-year-burned land>unfired forest land. The species logarithm proportion of general niche overlap was 5-years-burned land>15-yearly-burned land>unfired Woodland. And the proportion of species logarithm with less niche overlap was unburned forest land > 15 years burned area > 5 years burned area. Conclusion After severe fire disturbance in the Spruce-fir forest on the northeast edge of Qinghai-Tibetan Plateau, the degree of niche overlap among species of shrub communities in burned areas of different years is constantly changing, while the degree of niche overlap among species in undergrowth of unburned forest land remains relatively low, and the community is in a positive succession stage.
Identification of MicroRNAs during Seed Germination and Its Response to PEG and NaCl Stresses
Wang Xiao-jing, Wang Tao, Yang Kai, Li Lu-bin
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Objective To identify microRNAs (miRNAs) and reveal its expressional pattern in seed coat rupture stage of Moso bamboo seeds (Phyllostachys edulis) under different drought and salt stresses. Methods Polyethylene glycol (PEG6000) and NaCl were used to simulate drought and salinity stress, respectively. Small RNA libraries were separately built for Moso bamboo seeds germinated under H2O, 10% PEG, 15% PEG, 50 mmol·L−1 NaCl and 100 mmol·L−1 NaCl, and the seeds were all sampled at seed coat rupture stage. High throughput sequencing and bioinformatics analysis were used to explore the expressional pattern of miRNA. Results A total of 246 known miRNAs and 262 novel mature miRNAs were identified in this study. The most abundant miRNAs in seed coat rupture stage of Moso bamboo was miR166, followed by miR159, miR6478, miR319, etc. According to miRNA target prediction, MIR396 family owned the largest number of target genes, and ph02gene13935 (GAMYB) could to be regulated by 28 miRNAs of MIR159, MIR319 or MIR396; A total of 123 differentially expressed miRNAs (DEmiRNA) were identified in six comparison groups; Compared with control group, in 10% PEG, 15% PEG, 50 mmol·L−1 NaCl and 100 mmol·L−1 NaCl treatments, phe-miR171e-5p, phe-miR3630-3p, phe-miR171e-5p and phe-miR159a were differentially expressed respectively with highest expressional level in known miRNAs; The target genes of DEmiRNA were significantly enriched in different GO and KEGG pathways; Ten DEmiRNAs were verified by qPCR, and the overall trend of qPCR results was consistent with the sequencing data. Conclusion In seed coat rupture stage of moso bamboo, there exhibit high accumulation of known miRNAs such as miR159, miR6478, miR319 in all control and four treatment groups, which may play a conservative regulatory role in Moso bamboo seed germination. Compared with the control group, phe-miR171e-5p, phe-miR3630-3p, phe-miR171e-5p and phe-miR159a 1 are differentially expressed in 10% PEG, 15% PEG, 50 mmol·L−1 NaCl and 100 mmol·L−1 NaCl, respectively, which can respond to PEG or NaCl stress during seed coat rupture stage of Moso bamboo.
The Variation of Stand Structure with Age and Its Hydrological Effects of Larch Plantation in Liupan Mountains
XU Xiao-qin, YU Peng-tao, WANG Yan-hui, XU Li-hong, YU Yi-peng, LIU Ze-bin
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Objective To study the change of stand structure with age and its hydrological influence, and provide a theoretical basis for forest vegetation construction and management in the semi-arid area, Liupan Mountains. Method The main plantation type -- Larix principis-rupprechtii (Larch) plantation was selected in Diediediegou small watershed in the semi-arid area, Liupan Mountains. Based on daily meteorological data from 1993—2002, both the coupled stand structure model and BROOK90, an ecohydrological model were applied to simulate the variation of stand structures (average tree height, diameter at breast height (DBH), canopy density and leaf area index (LAI)) with plantation age, and then its effects on each water balance component (interception, transpiration, soil evaporation and runoff) were obtained. Result The Larch plantation could be divided into rapid growth period (5~15 years old), slow growth period (15~40 years old) and stable period (over 40 years old) with the increase of age. During the rapid growth period, the average tree height, average DBH, canopy density and canopy LAI increased rapidly with the increase of age, with an average annual growth rate of 0.48 m·a−1, 0.54 cm·a−1, 0.03 and 0.19, respectively. During the slow growth period, the average stand tree height, DBH and canopy density increased slowly, while the LAI increased first and then decreased. But during the stable period, the stand structures did not change significantly. In the fast growth period, the average annual interception and transpiration increased rapidly with the increase of age, and the rate was 1.91 and 24.13 mm·a−1, respectively. Meanwhile, the average annual soil evaporation and water yield decreased rapidly with the increase of age, and the decrease rate was 10.58 and 14.88 mm·a−1, respectively. In the slow growth period, the change of average annual transpiration, soil evaporation and runoff with age slowed down, and tended to be stable when the age was 30 years. The average annual change rates were 0.62, −0.75 and −0.76 mm·a−1, respectively. Conclusion In the semi-arid area of Liupan Mountains, the stand structure of Larch plantations changes continuously when the stand age is less than 30 years, especially less than 15 years, which significantly affectes the eco-hydrological function. And when the stand age is over 30 years old, the stand structure is stable and the water balance components tend to be stable too, which indicates that it is no longer necessary to consider the influence of stand age in the integrated forest-water management.
Establishment of Agrobacterium Mediated Genetic Transformation System of Litsea cubeba
WANG Min-yan, YU Wen-xian, ZHAO Yun-xiao, CHEN Yi-cun, GAO Ming, WU Li-wen, WU Shan-qun, WANG Yang-dong
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Objective To screen the hormone proportion suitable for callus differentiation of Litsea cubeba and clarify its tolerance to antibiotics, and preliminarily establish the genetic transformation system of L. cubeba. Method The effects of different hormone concentrations on adventitious bud induction and adventitious bud rooting of L. cubeba callus were studied. The critical screening concentrations of hygromycin and cefotaxime were discussed, and the foreign gene was introduced into L.cubeba callus by Agrobacterium mediated method. Result The optimum medium for inducing adventitious bud differentiation of callus was MS + 2.0 mg·L−1 6-BA + 0.01 mg·L−1 IBA + 0.05 mg·L−1 TDZ, and the differentiation rate was 16.67%~36.67%; The optimum medium for adventitious bud rooting was 1/2MS + 0.5 mg·L−1 IAA, and the rooting rate was 97.33%. The initial concentration of hygromycin for resistant callus screening was 5 mg·L−1 (about 7~10 days), and then the critical screening culture was carried out by gradually increasing the hygromycin screening concentration to 30 mg·L−1. the optimum concentration of cephalosporin was 300 mg·L−1. Finally, foreign gene was transferred into the callus by Agrobacterium mediated method, and PCR primers were designed for identification. A total of 16 resistant seedlings contained the target band, indicating that the target gene had been inserted into the L. cubeba genome, with a transformation rate of 0.67%. In addition, our research group obtained the resistant calli of multiple genes through this method. Southern detection showed that the target fragment had been inserted into the calli of L. cubeba. Conclusion The regeneration and genetic transformation system of L. cubeba has been preliminarily established, and the resistant calli of multiple genes have been obtained, which provides technical support for further gene function research and genetic improvement. The next step is to optimize the genetic transformation system and improve its transformation efficiency.
Effect of Different Concentrations of Graphene on the Growth, Root Morphology and 15N Uptake and Utilization of Cunninghamia lanceolata Seedlings
PENG Ting-ting, WEI Yong-ping, ZHANG Jin-feng, ZHANG Xiao, CHEN Hong-hua, CHEN Ai-ling, ZHAO Jian-guo, HU Ya-lin, CAO Guang-qiu
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Objective To provide theoretical basis for the efficient cultivation of C. lanceolate, the effects of graphene on the growth, root morphology and nitrogen uptake and utilization of Cunninghamia lanceolata were investigated in this study. Method A pot experiment with four concentrations of graphene (0, 20, 25, 30 mg·L−1) was conducted in this study by using the superior clone of C. lanceolata seedlings ‘Yang 061’ to investigate the growth, root morphology, 15N distribution and utilization rate of C. lanceolata seedlings under various graphene treatments. Results The indexes of growth and root morphologies were maximum at 25 mg·L−1 graphene concentration except for stem weight and root volume, but no significant difference were observed among different treatments. The 15N utilization rate of seedlings was 25 mg·L−1>20 mg·L−1>30 mg·L−1>CK1, and the distribution of 15N in different organs of C. lanceolata seedlings was leaf > stems > roots. Correlation analysis results showed that a significantly positive correlation between roots 15N partition rate and seedlings 15N utilization rate with different growth indexes were observed except for root length, root volume, root 15N partition rate and root diameter. Conclusion A certain concentration of graphene is beneficial to the growth of C. lanceolata seedlings and can promote the absorption and utilization of N.
Influencing Factors on the Crown Ratio of Korean Pine Plantation in Eastern Liaoning Province
LIU Qi-feng, CHEN Dong-sheng, FENG Jian, GAO Hui-lin
, Available online  
Abstract:
Objective To study the effects of different competition levels and topography on the canopy length and compare the forest layers, the crown ratio model considering competition and topographic (slope, slope aspect and slope position) variables of Pinus koraiensis plantation in eastern area of Liaoning province was developed. Method The crown ratio model was developed by incorporating competition index and topographic variable using re-parameterization and dummy variable methods. and the specific topographic variable expressing the largest contribution was selected. The effect of competition and topographic variable on the crown ratio was simulated. Result Compared with the basic model, the R2a for the finial model incorporating competition, topographic variable and forest layer increased by 0.113, RMSE decreased by 0.012. The contributions of competition, slope aspect and forest layer to the crown ratio model were 14.14%、2.25%、0.16%, respectively. The crown ratio decreased with the increase of D and increased with the increase of forest competition. With the increase of the competition, the crown ratio turned from negative growth to positive growth with tree height increasing gradually . The F test showed that there were significant differences in crown ratio between different slope aspects and forest layers, and the change rule was shady slope > semi-sunny slope > sunny slope and upper forest layer > lower forest layer. Conclusion Topography and forest competition factors significantly affect the crown ratio, and slope aspect is the most important topographic factor affecting the crown ratio of individual tree of Pinus koraiensis plantation. The crown ratio model based on topography and forest competition has high accuracy and provides a reference for the management and growth prediction of Pinus koraiensis plantation in eastern area of Liaoning Province.
Response of Radial Growth of Larix griffithii to Temperature and Precipitation Fluctuation in Tibet Shergyla Mountain
YU De-shui, LU Jie, ZHANG Meng, ZHANG Xin-sheng
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Objective To study the response of radial growth of Larix griffithii Hoof to temperature and precipitation based on the annual ring core of L. griffithii collected in the Shergyla Mountain. Method The standard chronology was established by using the tree chronology method combined with TASP-Win and ARSTAN programs. Pearson and bootstrap calculation methods were used to analyze the correlation between ring width index and temperature and precipitation from 1961 to 2020. Result There were significant differences in radial growth before and after temperature fluctuation. Before the temperature fluctuation, the radial growth was positively correlated with the average temperature in January and June of the year and August of the previous year (P< 0.05). It was positively correlated with the average precipitation from September to October and December of the previous year and negatively correlated with that in August of the previous year. And It was significantly positively correlated with the relative humidity from January to December (P< 0.01). After the temperature fluctuation, the radial growth was negatively correlated with the average temperature from March to December and positively correlated with the precipitation in August and June of the previous year. Conclusion The climatic conditions in Southeast Tibet are extremely special. The uneven hydrothermal conditions caused by climate fluctuations is the main reason for the radial growth change of L griffithii. AThe short-term change of temperature in the non-growing season also has a significant indigenous impact on the radial growth of trees.
The Relationship Between Height-to-diameter Ratio and DBH and Tree Height in Typical Natural Broad-leaved Forests in Mid-subtropical Zone
YAN Ming-hai, WANG Jin chi, HUANG Qing-lin, ZHUANG Chong-yang, ZHENG Qun-rui, ZHUO Ming-xiu, GUAN Xiao-hui
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Abstract:
Objective To provide a typical reference in the aspect of height-to-diameter ratio of broad-leaved trees for the sustainable management of artificial broad-leaved forest, semi-natural broad-leaved forest and natural broad-leaved forest in mid-subtropical zone, the relationship between tree height-to-diameter ratio and DBH and tree height were revealed in each stratum of typical natural broad-leaved forests. Method In Jian’ou Wanmulin Provincial Nature Reserve, 50 m × 50 m plots were set up in 5 most typical natural broad-leaved forest in mid-subtropical zone respectively. Spearman rank correlation coefficient was used to analyze the correlation between tree height-to-diameter ratio and DBH and tree height in each stratum, and exponential function and hyperbola equation were chosen to fit the relationship between height-to-diameter ratio and DBH in each stratum. Results The variation range of the average value of the height-to-diameter ratio in each stratum was not large. The average height-to-diameter ratio of the stand in the 5 sample plots was 103.1. The mean height-to-diameter ratio in stratum Ⅲ(112.7) was the largest, followed by stratum Ⅱ (89.0) and stratum Ⅰ(66.9), as well as in the minimum and maximum values. The height-to-diameter ratio of each stratum showed a significant negative correlation with DHB and the correlation coefficient was high. The absolute value of correlation coefficient was the highest in stratum Ⅰ(0.896~0.961) and stratum Ⅱ(0.912~0.971), the middle in the stand(0.613~0.749), and the lowest in stratum Ⅲ(0.415~0.596).The relationship between tree height-to-diameter ratio and tree height in each stratum was complex and the absolute value of correlation coefficient was low (< 0.480). The stand showed extremely negative correlation, but the absolute value of correlation coefficient was low (0.283~0.458). The R2 of the tree height-to-diameter ratio and DBH in stratum Ⅰ and stratum Ⅱ fitted by exponential function were 0.852~0.906 and 0.830~0.914, respectively, while the R2 of the stand and stratum Ⅲ were 0.465~0.575 and 0.202~0.399, respectively. The R2 of the height-to-diameter ratio and DBH in stratum Ⅰ and stratum Ⅱ fitted by hyperbolic curve were 0.874~0.937 and 0.856~0.968, respectively, while the R2 of the stand and stratum Ⅲ were 0.387~0.536 and 0.186~0.350, respectively. Exponential function fitting stand and stratum Ⅰ relationship of DBH than height-to-diameter ratio of R2 was relatively high, and RMSE and AMR was relatively small. hyperbola from fitting relationship of DBH than height-to-diameter ratio stratum Ⅰ and stratum Ⅱ fitted by hyperbola equation had relatively high R2 and small RMSE and AMR was values. Conclusion The tree height/diameter ratio of typical natural broad-leaved forest in mid-subtropical zone varies with the stratum. The tree height/diameter ratio in the same stratum also varies with DBH. The height-to-diameter ratio and DBH in each stratum shows a very significant negative correlation and the correlation coefficient is high, and the curve fitting of the relationship is significant. Hyperbolic function can well describe the relationship between height-to-diameter ratio and DBH in the stratum Ⅰ and stratum Ⅱ, while exponential function is more suitable to describe the relationship between height-to-diameter ratio and DBH in the stand and the stratum Ⅲ. The relationship between tree height-to-diameter ratio and tree height in each stratum is complex and the correlation coefficient is low. In the typical natural broad-leaved forest of the mid-subtropical zone, the characteristics of tree height/diameter ratio can be expressed by the relationship curve between tree height to diameter and DBH of each stratum.
Soil Water Infiltration Characteristics of Four Caragana korshinskii Forests in Loess Hilly Area of Inner Mongolia
JIANG Lei, QIN Fu-cang, ZENG Lin-jian, ZHAO Qi
, Available online  
Abstract:
Objective To study the soil infiltration characteristics of four Caragana korshinskii forests in the loess hilly area of Inner Mongolia for providing a reference for reasonable local forest planting and vegetation restoration and construction. Method The cutting ring knife was used for sampling and analyzing soil physical and chemical properties in Caragana korshinskii and Populus davidiana × Caragana korshinskii, Armeniaca sibirica × Caragana korshinskii, Pinus tabuliformis × Caragana korshinskii forests. . The single ring soil column method was used to observe the undisturbed soil water infiltration, and the correlation between infiltration characteristics and soil physical and chemical properties was analyzed. Results The initial infiltration rate, steady infiltration rate, 5 h cumulative infiltration amount, and the rate of wetting front of the four forests were the largest in A. sibirica × C. korshinskii forest (8.60 mm · min−1, 1.05 mm · min−1, 279.83 mm, 2.5 mm · min−1), followed by P. davidiana × C. korshinskii (5.6 mm · min−1, 0.76 mm · min−1, 255.65 mm, 2.2 mm · min−1), P. tabuliformis × C. korshinskii (4.80 mm · min−1, 0.73 mm · min−1, 243.03 mm, 2.0 mm · min−1), C. korshinskii(3.16 mm·min−1, 0.53 mm·min−1, 178.64 mm, 3.4 mm·min−1). After infiltration, the soil saturated moisture content and field water holding capacity were shown as follows: A. sibirica × C. korshinskii > P. davidiana × C. korshinskii, P. tabuliformis × C. korshinskii > C. korshinskii. Soil bulk density and porosity were the main factors affecting the infiltration capacity and water status of the four woodlands. Conclusion Comparing with other forests, A. sibirica × C. korshinskii has better regulation and water conservation function, and can effectively reduce surface runoff and soil erosion.
Polymorphic Site-Index Model with Site Mixed Effects for Chinese fir Plantations in Hunan Hilly Plains
SONG Zhen, HUANG Lang, HU Song, ZHANG Xiong-qing, ZHU Guang-yu
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Objective To improve regional site index model, the site index model with the random effects of site factors was developed. Method Based on the 360 samples with dominant height-age of Chinese fir in the hilly and plain area of Hunan Province, the quantification method I was used to select the site factors affecting the dominant height growth (P<0.05). The 8 commonly used models were used to develop the basic site index model, as well as the models considering the random effects of site factors and their combinations. The evaluation statistics including AIC, BIC, logLik and R2 were used to select the optimal random effect model. In addition, K-means clustering was used to divide site type groups for model applications. Results 1) The site factors including altitude, slope, aspect and soil type had significant impact on dominant height growth based on the quantitative method I. And soil type was the most important factor, following by altitude, slope aspect, and Slope. 2) The fitting accuracy of the 8 candidate basic models was low (R2=0.4243~0.5644). M4 (R2=0.5644) was selected the best basic model for developing the polymorphic site index curve. 3) Considering the influence of the site effect on the site index, the nonlinear mixed effects models with different site factors and their combination of random effects were developed. The mixed effects model with the random effects of site type performed the best (R2=0.8089). 4) The site types were divided into 11 site groups. The mixed model containing the site type groups improved the modeling accuracy (R2=0.8117). Conclusion The site index model with site mixed effect can significantly improve the site modeling accuracy of regional complex site types, and provide a reference and basis for regional forest site quality evaluation.
Effects of AM Fungi and Inorganic Phosphorus on Phosphorus Uptake and Grown Soil Phosphorus Fraction of Camellia Oleifera Seedlings
HUANG Yu-xuan, LIN Yu-lan, ZHANG Lin-ping, WU Fei, YANG Ying, TAN Ming-xi
, Available online  
Abstract:
Objective To investigate the promotion of phosphorus uptake in Camellia oleifera seedlings by mycorrhizal fungi at different inorganic phosphorus levels, and provide a theoretical basis for the study of inoculation with mycorrhizal fungi to enhance phosphorus efficiency of C. oleifera seedlings. Method One-year old C. oleifera was used as the host plant, and young sets of Claroideogolmus etuicatum were inoculated with KH2PO4 (0, 10, 50, 100 mg·kg-1). The effects of inoculation with AM fungi and inorganic phosphorus on phosphorus uptake and grown soil phosphorus fraction of C. oleifera seedlings were investigated. Result Under the conditions of no (0 mg·kg-1), low (10 mg·kg-1), medium (50 mg·kg-1) and high (100 mg·kg-1) phosphorus application, the phosphorus content of mycorrhization C. oleifera seedlings was significantly higher than that of non- mycorrhization. The above-ground phosphorus content increased by 5.64%, 8.14%, 14.28% and 5.79%, respectively, and the phosphorus content of seedling root system increased by 12.85%, 20.01%, 19.63% and 18.09%, respectively. The effects of inoculation with AM fungal treatment, application of inorganic phosphorus treatment and their interaction on soil total phosphorus content, effective phosphorus content and organic phosphorus content were highly significant. Inoculation with C. etuicatum significantly reduced the content of four phosphorus forms, Al-P, Fe-P, Ca-P and O-P in the soil. Under low phosphorus conditions, inoculation of C. etuicatum significantly increased the expression of Pht1;1 gene in leaves and root systems of the seedlings; under medium and high phosphorus conditions, inoculation of C. etuicatum decreased the gene expression of Pht1;1 gene in leaves and root of C. oleifera seedlings. Conclusion AM fungi can alter phosphorus morphology in C. oleifera grown soil, promote the uptake efficiency of effective phosphorus in soil by plants, and participate in regulating the expression of Pht1;1 gene in C. oleifera. The results of this study provide a scientific basis for microbial fertilizer to improve soil phosphorus uptake efficiency of C. oleifera seedlings and reduce phosphorus fertilizer application, which promotes the healthy and sustainable development of C. oleifera industry in China.
Effects of Different Host Plants on the Growth, Reproduction and Physiological Enzyme Activity of of Dendrolimus houi Lajonquiere (Lepidoptera: Lasiocampidae)
SHEN Hai-yan, LIANG Yun, CHEN Zheng-hao, HUA Yin, LI Chang-liang, ZHANG Zhu-he, WENG Huai-feng, HUANG Biao, ZHANG Fei-ping, LIANG Guang-hong
, Available online  
Abstract:
Objective To provide insights into carrying out ecological regulation of new mixed forest, the physiological adaptation mechanism of Dendrolimus houi Lajonquiere to different host plants was analyzed based on the effects of different host plants on the growth, reproduction, detoxification enzyme and digestive enzyme activities of D. houi. Methods The developmental duration of the larvae and pupae as well as the fecundity of adult of D. houi were measured through indoor rearing in hots plants of Cryptomeria fortunei Hooibrenk, Platycladus orientalis (L.) Franco, Cupressus funebris Endl., Pinus yunnanensis Franch. and Pinus massoniana Lamb. The activities of detoxification enzymes (i. e. glutathione S-transferases (GSTs), cytochrome P450 (CYP450), and carboxylesterase (CarE)) and digestive enzymes (i. e. protease, amylase (AMS), and lipase (LPS)) in the 5th instar larvae of D. houi feeding on different host plants were also assayed. Results D. houi larvae feeding on C. fortunei, C. funebris, P. orientalis and P. yunnanensis had a complete life cycle, while the larvae feeding on P. massoniana only survived to the 5th instar and did not have a complete life cycle. At the same time, the larvae and pupae of D. houi feeding on C. fortunei and C. funebris had shorter developmental duration, heavier female pupae and more fecundity of adult compared with other host plants. The activities of GSTs and CYP450 in the 5th instar larvae of D. houi feeding on C. fortunei and C. funebris were significantly higher than those feeding on P. yunnanensis, P. orientalis and P. massoniana (P<0.05). Among the three digestive enzymes, the activities of protease in larvae of D. houi feeding on C. fortunei and C. funebris were relatively high. Conclusion Dendrolimus houi has better adaptability to Cryptomeria fortunei and Cupressus funebris than the other host plants, and detoxification enzymes and proteases within D. houi may be the key factors which affect their adaptability to Cryptomeria fortunei and Cupressus funebris.
Phenotypic Traits Variation Pattern of Elaeagnus mollis Diels.Plantation
YANG Yu-jie,  HU Xiao-yan, HUANG Yao, WANG Sheng-ji, CHENG Bao-chang, ZHANG Jian-guo, DU Shu-hui, WANG Zhao-shan
, Available online  
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Objective To excavate high-quality germplasm resources and provide solid foundation for the selection and breeding of superior and new varieties in the future, it is necessary to analyze the phenotypic traits variation pattern of E. mollis. Method 100 10-year-old seedlings were selected from the provincial nature reserve of E. mollis located in Yicheng, Shanxi Province. A trait list of E. mollis was compiled according to the quantitative classification method. Various methods were used to reveal the variation pattern of E. mollis germplasm resources. Results The phenotypic variation of E. mollis ranged from 9.72% to 37.66%, with an average coefficient variation value of 22.26%. H’ of the phenotypic traits varied between 1.056 and 2.213. Correlation analysis showed that phenotypic traits of a single organ correlated significantly with each other, phenotypic traits from different organs showed no correlation. However, the leaf length showed significant correlation with fruit traits. PCA result showed that the first 7 principal components contributed 79.053% to the total variation, and the contribution rate of each trait was scattered. Cluster analysis based on phenotypic traits of fruit showed that all the individuals can be divided into 3 groups at the coefficient distance of 10 and differences among these 3 groups were significant. PCA analysis of phenotypic traits of fruit indicated that yield and kernel related traits can be chosen as the primary target in future E. mollis breeding. Therefore, individual 10, 17, 33, 37, 56 and 74 were chosen as the primary material for future breeding of superior and new varieties of E. mollis. Conclusion The phenotypic traits variation pattern of E. mollis plantation in Shanxi Province was high, different materials can be chosen based on various breeding targets.
Tree Crown Extraction of UAV Remote Sensing High Canopy Density Stand Based on Instance Segmentation
XIE Yun-hong, JIN Xue-hui, SUN Zhao, DING Zhi-dan, LI Rui, LI Hao-wei, SUN Yu-jun
, Available online  
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Objective To obtain canopy information in high canopy density forest by remote sensing images. Method A single tree crown extraction method of UAV remote sensing image based on instance segmentation model was tested. Seven residual networks were selected for feature extraction of the model, and the single tree crowns of pure Chinese fir forests with different canopy density were extracted one by one. Result The results showed that the average boundary AP value and mask AP value of seven instance segmentation models for canopy segmentation of low canopy density forest were 55.89% and 57.29%, respectively. The average RMSE of east-west crown width, north-south crown width and crown area parameters was 0.161, 0.179 and 0.341, respectively. The R2 was 0.912, 0.918 and 0.957, respectively. The average boundary AP value of canopy segmentation and the average AP value of canopy cover of high canopy density forest were 46.00% and 44.45%, respectively. The average RMSE of east-west crown width, north-south crown width and crown area parameters was 0.479, 0.497 and 1.256, respectively. The average predicted R2 was 0.806, 0.762 and 0.936, respectively. Conclusion The extraction accuracy of each parameter is higher than the traditional survey accuracy, and this method can obtain crown information automatically, rapidly and accurately.
Investigation of Arbuscular mycorrhizal fungi (AMF) in several alpine oak understory forests in the subalpine zone of the Hengduan mountains
Li Hong-bo, Huang Yao-hua, Kang Ding-xu, Wu Jian-rong, Ma Huan-cheng, Chen Shi
, Available online  
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Objective To clarify the taxonomic status of AMF spores under the oak forest in the subalpine belt of the Hengduan Mountains. Method Six samples of alpine oak root enclosures and root systems were selected from different parts of the subalpine belt of the Hengduan Mountains, and AMF spores in the soil were selected by wet sieving sedimentation method. AMF-specific primers were used to amplify the 18SrRNA gene of the ITS region, which was identified by combining morphological and molecular biological means, and the phylogenetic relationships were constructed to infer their affinities. Result The results showed that AMF spores and root cloning consequences of alpine oak in Sichuan and Tibet were the genus Paraglomus. And the consequence of AMF cloning on the root surface and the AMF in soil of alpine oak in Shangri-La showed that AMF could exist in the inter-roots of alpine oak plants. These AMF were the genus Glomus. In addition, only one AMF was found in the root envelope and inter-root soil of alpine oak forest in different sampling sites, suggesting that AMF might have a symbiotic relationship with alpine oak. Aniline blue pigment staining result showed obvious arbuscular and vesicle structures in roots. In addition, the AMF spores under the Alpine oak forest differentiated during the evolution and were between the taxonomic status of Paraglomus and Glomus, and there were differences in AMF in Tibet, Sichuan and Shangri-La, Yunnan. Conclusion AMF generally exists in the pure understory root rhizosphere and inter-root soil of alpine oak in the subalpine belt of the Hengduan Mountains, which provides a theoretical reference for understanding the formation and evolution of AMF in the understory of alpine oak in the subalpine belt of the Hengduan Mountains
Physiological and transcriptomic analysis of Catalpa bungei seedlings in response to saline-alkali stresses
Gao Xin-qiang, Wang Xiao-yan, Jiao Wei, Wang Jing, Zheng Li-yue, Wang Dan-ning, Wang Xing-yun, Hou Li-jiang, Shang Zeng-zhen, Liu Yan-zhen
, Available online  
Abstract:
Objective To explore the physiological and molecular mechanism of saline-alkali tolerance in Catalpa bungei, we studied the influence of different saline-alkali stress on the growth, photosynthetic and physiological indicators of C. bungei seedlings combing with transcriptome sequencing. Methods Pot experiment was used to study the different responses of biomass, photosynthetic and physiological indicators of C. bungei seedlings to different saline-alkali stress. Illumina high-throughput sequence technology was used to sequence the transcriptome, and the effect of saline-alkali stress on transcriptional level was analyzed by bioinformatics. Results Under different saline-alkali stress, the damage degree of leaves was Na2CO3>mixed saline-alkali>NaCl. Net growth of plant height and stem diameter, fresh weight and dry weight of overground part and root, biomass, root-shoot ratio were all significantly suppressed with increasing saline-alkali concentration. But the growth stress index decreased with increasing concentration. Contents of MDA and relative conductivity both rose to varying degrees with increasing concentration. SOD enzymatic activity, contents of soluble sugar and Pro, contents of total chlorophyll and photosynthetic rate increased firstly and decreased then with increasing concentration. Transcriptome sequencing generated a total of 60.4Gb of raw data. Finally, we obtained 55 793 Unigenes after assembling, of which 29 534 (52.93%) Unigeneswere annotated. Through differentially expressed genes (DEGs) analysis, 1 779, 2 835 and 4 059 DEGs were screened from three comparison groups (CK vs NaCl, CK vs Na2CO3 and CK vs mixed saline-alkali) respectively. GO functional enrichment analysis of these DEGs indicated that they were significantly enriched in integral component of membrane, intrinsic component of membrane, catalytic activity, isoprenoid metabolic and biosynthetic process, oxidoreductase activity. KEGG functional enrichment analysis of these DEGs indicated that they were significantly enriched in phenylpropanoid biosynthesis, starch and sucrose metabolism, plant hormone signal transduction, terpenoid backbone biosynthesis and arginine biosynthesis. Moreover, the most abundant differentially expressed transcription factors (TFs) were bHLH, ERF, MYB-related, NAC, C2H2, WRKY, MYB and bZIP families. Conclusion C. bungei mainly resists from saline-alkali stress by accumulating contents of soluble sugars and Pro, improving SOD enzymatic activity and photosynthesis, but all of them show the phenomenon of "low promotion and high suppression", indicating that it has a certain threshold value. C. bungei common responses to saline-alkali stress by regulating biological processes and metabolic pathways including component of membrane, catalytic activity, isoprenoid metabolic and biosynthetic process, phenylpropanoid biosynthesis, starch and sucrose metabolism, plant hormone signal transduction, and interacting with TFs. This study provides a scientific theoretical basis for deeply studying the physiological and molecular mechanisms of saline-alkali tolerance in C. bungei.
Larval Behavioural Responses of Melanotus cribricollis (Coleoptera: Elateridae) to the Volatiles Emitted from Bamboo Shoot and Carbon Dioxide
ZHANG Wei, TENG Ying, HUANG Xu-jun, LI Zhi-hong, ZHANG Ya-bo, SHU Jin-ping, WANG Hao-jie
, Available online  
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Objective To understand the mechanism of food foraging below ground of Melanotus cribricollis larva which is the dominant and most destructive soil-dwelling insect of bamboo shoots in south China and provide important basic information for the development of effective monitor and control techniques. Method We tested the orientation behavior of M. cribricollis larvae towards bamboo shoot and CO2-releasing capsules by using a dual-choice olfactometer. The volatiles emitted from Phyllostachys violascens shoot were tentatively identified by solid phase micro-extraction (SPME) coupled with GC-MS, and their relative content were determined as well. Result Both bamboo shoot and CO2 source could significantly induce the directional movement of the larvae of C. There was no significant difference in the larval behavior among different weights of bamboo shoots (P>0.05), whiel larval orientation behavior was significantly correlated with CO2 concentration (P<0.05). Between bamboo and CO2-releasing capsules, wireworms preferred significantly to the bamboo shoot (P<0.05). A total of 17 compounds emitted from Ph. violascens shoot were tentatively identified. The higher relative contents were olefins (66.62%) and sesquiterpenes (27.98%), and the sesquiterpene compound with the highest content was α-humulene. Conclusion M. cribricollis larvae shows significant stronger orientation towards bamboo shoot and CO2 source, and prefers bamboo shoot significantly. Compared with CO2 source, the volatile organic compounds (VOCs) emitted from bamboo shoot show to be more effective in food foraging of bamboo shoot wireworm. In addition, 7 terpene compounds with potential attraction to wireworms are identified in this study, which provids important basic information for the development of attract-and-kill formulations for the control of wireworms.
Response of Active Organic Carbon and Carbon Pool Management Index of Karst Soil to Rocky Desertification Control Measures
LI Jin-yao, PAN Weng, WANG Jia, XUE Liang, ZHANG Xian-song, LI Sheng
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Objective To explore the responses of soil active organic carbon pool and CPMI to different control measures in rocky desertification area and provide the scientific basis for rational land use and rocky desertification ecological management in karst area. Method Three typical measures for controlling rocky desertification in karst including Nested terrace(NL), Fish scale pit(FSP), and terrace(TR) were compared with CK (natural slope soils) . The response of soil active carbon and carbon pool management index under different control measures was studied. Result The soil active organic carbon content and storage under different rocky desertification control measures showed a trend of the highest FSP, followed by the NL, and the lowest TR. The contents of EOC, DOC and pool storage showed that FSP were significantly higher than the other measures. The CPMI in FSP were all higher than NL and TR. The CPMI showed that the fish scale pit measure was greater than the other two rocky desertification control measures. The control measures improved the quality of the topsoil in the karst area.. Conclusion This study suggests that different rocky desertification control can significantly affect the active organic carbon in karst. FSP is more beneficial to the active SOC fraction accumulation and the quality of carbon pool than other measures. FSP can be used as a priority measure for the ecological restoration of karst rocky desertification.
Genome-Wide Analysis of Microsatellite Loci and Specific Monomorphism SSR Marker Development in Walnut (Juglans regia L.) Reference Genome
He Jun-xing, Ma Qing-guo, Pei Dong, Zhang Jun-pei
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Objective To identify the number and distribution of SSR loci on different chromosomes in the whole genome of walnut (Juglans regia L., 2n = 2x = 32), and to develop and validate the monomorphic SSR primers. Method In this study, walnut whole genome sequencing data were used as experimental materials, and the whole genome microsatellites were screened and analyzed by bioinformatics software MISA. Primer 3.0 was employed to design monomorphic SSR primers. SSR primers were evaluated by electronic PCR and some of the monomorphic ones were synthesized randomly to detect their usefulness and verify the effectiveness of the method. Result (1) A total of 357 629 SSR loci were identified in the walnut genome, with a distribution density of 662.28 SSRs/MB. The dominant repeat units were mainly A/T bases, showing significant base preference. These SSR sequences were mainly short sequences with a length of 10~30 bp, up to more than 95.00%. The number of SSR loci on different chromosomes varied greatly. Among them, the number of SSR loci on chr1 chromosome was the largest, and the numer of SSR loci on chromosome 16 was the least. The number and type of SSRs showed positively correlated with chromosome sequence length. Most of the 644 rare SSR units were hexa-nucleotides. (2) Based on cluster analysis, all the 16 chromosomes could be divided into 4 groups, of which the number of members in group 4 was the most (11), and there was only chromosome 10 in group 1. In general, chromosome 10 forms a main branch, indicating that it may have experienced a relatively conservative evolutionary history. (3) 303 009 pairs of SSR primers were designed by using the conservative sequence flanking the SSR locus. And then 32 pairs of monomorphic primers clarified by electronic PCR were randomly screened and synthesized for wet PCR experiments, of which 30 pairs (93.75%) were amplified in 6 walnut varieties. The PCR amplification results of 28 pairs (87.50%) were consistent with that of electronic PCR. Conclusion In this study, SSR loci in different chromosome sequences of ‘Zhongmucha-1’ walnut reference genome are identified. Their amounts and repeat types are found to be highly variable among different chromosome sequences and show a highly significant positive correlation with chromosome length. Mono-nucleotide repeat SSRs are the most common type. A novel protocol combining electronic PCR and traditional screening methods are established and validated, which provide an effective strategy for the personalized and rapid development of walnut SSR primers. The developed 28 pairs of monomorphic primers can provide scientific basis for “Illegitimacy Testing” of hybrid offspring in molecular marker assisted breeding.
The effect of Russula rosea and Russula griseocarnosa on microorganism structure of mycosphere soil
Yu Fei, Liang Jun-feng
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Objective To provide a theoretical basis for the conservation and propagation of the two species of Russula and the realization of artificial cultivation, the mycosphere soil microbial communities of Russula rosea and Russula griseocarnosa was analyzed, and the soil microorganisms that promoting the growth of the two species of Russula were screened. Method The community structure of mycosphere and bulk soil microorganisms (fungi and bacteria) of two species of Russula were analyzed by Illumina MiSeq sequencing technology, and evaluated comprehensively based on soil physicochemical property. Result The mycosphere soil microorganisms of the two species of Russula were slightly different. The dominant mycosphere soil microorganisms of R. rosea were Acidothermus, Mycobacterium, Reyranella, Ktedonobacter, Rhodanobacter and Oidiodendron, while the dominant mycosphere soil microorganisms of R. griseocarnosa were Variibacter, Bryobacter, Blastochloris, Cladophialophora, Paecilomyces and Arthrinium. Bacteria (Variibacter, Candidatus_Solibacter, Sorangium, Mycobacterium, Singulisphaera, Isosphaera, Bdellovibrio and Paenibacillus) and fungi (Trichoderma, Penicillium, and Hypomyces) were the common growth promoting microbes of Russula rosea and R. griseocarnosa. pH was the key factor affecting mycosphere soil microorganisms. Conclusion The two species of Russula can specifically select soil microorganisms that are beneficial to their growth according to their growth needs and form different microbial community structures. The mycosphere mycorrhizal auxiliary bacteria that were screened out in this study can provide theoretical basis for the preparation of special microbial fertilizer and artificial propagation promotion of Russula, which has great promotion for the sustainable utilization of Russula, the expansion of understory edible fungi scale and the improvement of economic benefits.
Study on Adaptation Strategies of Quercus variabilis, Robinia pseudoacacia and Platycladus orientalis to Drought in Taihang Mountain
Niu Cun-yang, Shou Wen-kai, Yang Xi-tian, Zhang Zhi-hua, Qiao Yong-sheng
, Available online  
Abstract:
Objective To provide theoretical basis for vegetation restoration in Taihang Mountain, the study discussed different adaptation strategies of Quercus variabilis, Robinia pseudoacacia and Platycladus orientalis to drought from perspective of hydraulic architecture. Method Based on Quercus variabilis (38-year-old), Robinia pseudoacacia (42-year-old) and Platycladus orientalis (30-year-old) in Taihang Mountain, Native sapwood specific hydraulic conductivity (Ks) and maximum specific hydraulic conductivity (Ksmax) of perennial stems were measured by using a Pipette. Percent loss of hydraulic conductivity (PLC) of Quercus variabilis and Robinia pseudoacacia were measured by flushing method, and PLC of Platycladus orientalis was measured by vacuum method. Wood anatomy was measured by using optical microscope and scanning electron microscope technology. Result (1) The mean vessel diameter (Dv), hydraulic weighted vessel diameter (Dh) and aperture fraction (Fap), number of pits per unit area of vessel wall (Np), total pit area per vessel area (Fa) of Quercus variabilis and Robinia pseudoacacia were all significant higher than those of Platycladus orientalis. Ks and PLC of the former two deciduous tree species were therefore significantly higher than those of Platycladus orientalis; (2) The Dv, Dh, surface area of inter-vessel pit membranes (Ap), area of single pit aperture (Aap), Fap, Np and Fa of Robinia pseudoacacia were significantly higher than those of Quercus variabilis. However, PLC of Robinia pseudoacacia was significantly lower than that of Quercus variabilis, which might be due to the fact that the pit chamber and pit aperture of Robinia pseudoacacia had punctate and dentate vestures, which enhanced resistance to drought induced cavitation. (3) The \begin{document}$ {A}_{\mathrm{a}\mathrm{p}} $\end{document}, Fa and Fap Increased with the increase in the diameter of the xylem vessels of the three tree species. Conclusion Quercus variabilis and Robinia pseudoacacia have high xylem water transport efficiency, which indicates that they employ fast growth strategy. While Platycladus orientalis adopts conservative resource acquisition strategy with lower xylem water transports efficiency. The xylem vessels and pit structures synergistically affect xylem water transport efficiency and resistance to drought-induced cavitation, and xylem anatomy is an important trait determining the adaptation strategies of different tree species to arid environments.
Effects of litter and nitrogen addition on carbon and nitrogen in soil leaching solution of subtropical Castanopsis fabric and Cunninghamia lanceolata forest
WANG Meng-si, MA Hong-liang, GUAN Xiao-hui, GAO Ren, YIN Yun-feng
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Abstract:
Objective Litter is the main source of carbon and nitrogen in forest soils. The effect of litter decomposition on soil carbon and nitrogen by leaching was studied through analyzing the changes of dissolved carbon and nitrogen in litter or soil leaching solution, for exploring the relationship between litter decomposition and soil carbon and nitrogen. Method Soil and litter in broad-leaved and coniferous forests were collected from subtropical forests. Six treatments were set, including litter, soil, litter + soil, nitrogen + litter, nitrogen + soil, and litter + soil + nitrogen. Three replicates were set for each treatment. The nitrogen addition amount was 120mg NH4 + -N·kg−1 soil. The amount of litter added in coniferous and broad-leaved forests was 12.1 g·kg−1 and 19.7 g·kg−1, respectively. The litter was placed on the surface of soil or quartzite, and the soil moisture was controlled at 60% water-holding capacity. An incubation experiment was carried out with nitrogen addition by leaching to simulate nitrogen deposition in a dark incubator at 25 ℃ for 220 days. During the incubation period, the nitrogen solution leached in 5 times with different nitrogen amounts, each with 110 mL of solution (80, 10, 10, 10, 10 mg NH4 + -N in sequence according to the number of leaching times), and the leaching solution was collected and measured.. In addition, the dissolved organic carbon (DOC) and nitrogen (DON), and NH4 + -N and NO3--N in the leaching solution were also measured. Result The results showed that the litter leaching solution had lower inorganic nitrogen and DON, and higher DOC. Litter addition significantly reduced the NO3--N by 22.6% and 29.9% in the coniferous forest and broad-leaved forest soil leaching solution, respectively and increased the DOC by 181.4% in the coniferous forest soil leaching solution. However, litter addition significantly decreased the DON by 39.2% in the broad-leaved forest soil leaching solution and MBN by 53.2% in the broad-leaved forest soil. Under nitrogen addition, the interception of added nitrogen by litter was less, and the interception of litter in broad-leaved forest litter was higher than that in coniferous forest. Litter input to soil by leaching decreased DOC, while DON increased. Nitrogen addition increased soil leaching inorganic nitrogen and coniferous forest soil leaching solution DON, but the effect of litter on reducing soil nitrogen leaching was not weakened by nitrogen addition. Conclusion The litter slows down the negative impact of soil NO3--N output on water environment. Nitrogen addition can affect soil nitrogen changes by altering the output of DOC and DON in broad-leaved and coniferous forest litters.
The Response of Leaf Anatomical Structure and Photosynthetic Physiology of Pinus massoniana Lamb. and Castanopsis hystrix Miq. to Throughfall Reduction
GUO Xin-wei, LIU Shi-rong, WANG Hui, CHEN Zhi-cheng, NIE Xiu-qing, ZHANG Jing-lei, MING An-gang, CHEN Lin
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Abstract:
Objective To explore the response of leaf anatomy and leaf photosynthetic physiology to long-term drought and analyze the relationship between leaf anatomy and leaf photosynthetic physiology under long-term drought conditions. Method We conducted a simulated drought experiment by reducing the throughfall in the forest and measured the leaf gas exchange, chlorophyll fluorescence, leaf nutrient (N, P) and leaf anatomy of the two typical tree species (Pinus massoniana Lamb. and Castanopsis hystrix Miq.) in subtropical China at the 8th year after rainfall reduction. Results (1) Significant differences were observed in leaf anatomy between P. massoniana and C. hystrix in response to throughfall reduction; the upper and lower epidermis, leaf thickness and stomatal density of P. massoniana needles increased significantly. However, the thickness of the upper epidermis of the leaves of C. hystrix increased significantly, and the thickness of the spongy tissue decreased significantly. (2) No significant differences were observed in the gas exchange parameters (net photosynthetic rate Pn, stomatal conductance Gs, transpiration rate Tr), chlorophyll fluorescence parameters (photosystem II maximum photochemical efficiency Fv/Fm, actual photochemical efficiency ΦPSII, apparent electron transfer rate ETR) and leaf nutrient contents of both species after 8 years of throughfall reduction. (3) Compared with P. massoniana, the stomatal limitation (Ls) of the C. hystrix was larger and thewater use efficiency (WUE) was higher, especially in the dry season. Conclusion There are differences in the strategies of P. massoniana and C. hystrix to cope with drought stress. P. massoniana responds to drought by adjusting leaf anatomy to produce xeromorphic needles, while C. hystrix is more inclined to adjust stomata (Ls) and improve water use efficiency (WUE) to adapt to drought.
Identification of MYB Family Members and Functional Verification of PdMYB2 in Paeonia delavayi
ZOU Hong-zhu, HAN Lu-lu, ZHOU Lin, LV Ji-hang, JIA Ying-hua, Wang Yan
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Objective The role of MYB transcription factor family in pigment formation of yellow Paeonia delavayi flowers was analyzed to provide candidate genes for color improvement and molecular breeding of tree peony. Method In this study, members of MYB gene family of P. delavayi were identified and classified based on the transcriptome data of petals. One member of R2R3-MYBs, PdMYB2, was selected as a candidate gene according to phylogenetic tree, homologous sequence alignment and gene differential expression analysis. The function of PdMYB2 was analyzed by subcellular localization, qRT-PCR, transient overexpression, transgenic tobacco and LC-MS/MS. Result A total of 64 MYB genes were identified, including 25 R2R3-MYBs, one R1R2R3-MYBs, two 4R-MYBs and 36 members of MYB-related. The PdMYB2 was found to express in the nucleus and cytoplasm. Overexpression of PdMYB2 in tobacco increased anthocyanin accumulation and up-regulated the expression of anthocyanin-related structural genes NtCHS and NtCHI in petals and leaves. Conclusion PdMYB2 plays a positive regulatory role in the flavonoid biosynthesis pathway, which can promote the accumulation of anthocyanins and increase the expression of structural genes in the flavonoid pathway.
Mass loss of mixed leaf litter with Pinus massoniana and native broad-leaved species
Zhang Yan, Li Xun, Song Si-meng, Zhang Jian
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Objective To understand the mixed litters decomposition characteristics of Pinus massoniana and native broad-leaved trees, and the relationship between the mass loss rate of mixed litter with the species and proportion of broad-leaved litter. Method Based on the leaf litter of Pinus massoniana Lamb.(P), Cinnamomum camphora Presl.(C), Sassafras tzumu Hemsl.(S) and Toona sinensis Roem.(T), we conducted a two-year field needle-width mixed decomposition experiment of litter bags to study the mass loss of the pure litter of the above four tree species and their mixed litter, i.e., combining needles of one conifer with leaves of one, two or three broad-leaved species (i.e., PC, PS, PT, PSC, PST, PCT and PSCT, respectively), as well as including various ratios of these mixed litters in each treatment. There was a total of 35 treatments, including 31 mixed and 4 pure litter treatments. Result After two years of decomposition, the combinations of PT, PC, PCT, PST and PSCT had higher mass loss rates of than PS and PSC. The mass loss rate of leaf litters generally showed a synergistic effect and it increased from the 6th to 18th month, and then declined thereafter. It was the highest (67.74%) at the 18th month of decomposition. Compared with other mixed litters, the mass loss rate of PT64, PCT721 and PSCT7111 showed a strong synergistic effect in 4 incubation periods. The results of regression analysis showed that the decomposition coefficient k and mixing effect were negatively correlated with the initial contents of total phenolic, lignin, cellulose, the ratios of C/N, C/P, lignin/N, and lignin/P. In contrast, they were positively correlated with the initial contents of N and P. Conclusion Our results show that mixed litters with 30%-40% broad-leaved species, especially with the litter of T. sinensis, may benefit the litter mass loss of P. massoniana and promote the nutrient return to forest soils.
Response of the suitable distribution areas of Prunus pedunculata to climate change
Zhang Jun-Ming, Bian Lei, Zhou Fei-Mei, Wang Xing-Mei, Yang Tao, Zhang Sheng-Ping, Wang Wei, Song Min-Li, Xv Xin-Qiao
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Objective To reveal the response of suitable distribution of Prunus pedunculata to climate change. Method Based on the field investigation, MaxEnt and ArcGIS software were used to predict the change of suitable distribution area of Prunus pedunculata in the future climate scenario. Results The suitable distribution region of Prunus pedunculata was mainly concentrated in China, Mongolia and Russia, and the distribution area located in 97.23°~122.62° E and 35.49°~54.91° N. Under the reference climate (1970−2000) scenario, the medium and high suitable distribution area are mainly located in China. Seasonality Precipitation (bio15, Coefficient of Variation) was the climate variable with the highest score in the prediction process. Under the four future(2021−2100)climate scenarios (SSP1-2.6, SSP2-4.5, SSP3-7.0 and SSP5-8.5), the geometric center of the suitable distribution area would move to the northwest. In the scenario of increased emissions, the average migration rate of geometric centers increased. Conclusion Seasonality Precipitation (bio15) is the most critical variable to limit the distribution of Prunus pedunculata. The suitable distribution area of Prunus pedunculata trends to migrate to the northwest. Under the high emission scenario, the change of the suitable distribution region is more active than the low emission scenario.
Evaluation on Germplasm Resources of Cyclocarya paliurus and Its Oriented Selection of Superior Families and Trees
LAN Li-xia, XU Zhan-hong, SUN Cao-wen, FANG Sheng-zuo
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Objective In order to select superior families and individual plants which is suitable for planting in Nanjing and surrounding areas for providing a theoretical basis for the oriented silviculture of Cyclocarya paliurus plantations. Method The 3.5-year old germplasm resources of C. paliurus trees were comprehensively evaluated in this study. The 31 families of C. paliurus trees were used as test materials to determine the traits of growth and the leaf contents of total flavonoid, triterpenoid, and polyphenol. And cluster analysis and entropy method were used to screen superior families and individual trees based on the variations in traits. Results Significant variations were observed in tree height, diameter at the base, and the leaf contents of total flavonoid, triterpenoid and polyphenol among different families. Hierarchical cluster analysis showed that the 31 families of C. paliurus were classified into four distinct groups. The C. paliurus families in cluster 1, cluster 2 and cluster 3 could be recommended as the families for high accumulation of total triterpenoid, total polyphenol, and total flavonoid, respectively. In contrast, the families in cluster 4 showed poor performance in all measured metabolites. Seven superior families (GXJZS7#、GZSQ12#、GXLS26#、HNYS2#、AHQLF13#、SCMC31# and GXJZS1#) of C. paliurus were preliminary selected for the accumulation of target secondary metabolites using entropy method. Within the seven superior families, all the trees were further assessed, and eleven superior individuals were selected. Conclusion There are significant variations in growth and leaf secondary metabolites among the tested germplasm resources, showing a great potential for the selecting and breeding of C. paliurus. Based on the comprehensive assessment, seven superior families and eleven excellent individuals are selected for further test and future application.
Genetic Variation Analysis of Phenotypic Traits of Xanthoceras sorbifolium Germplasm Resources
Wang Ya-li, Gu Zhi-jie, Jia Qiao-xia
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Abstract:
Objective To analyze the phenotypic variation of X. sorbifolium, and provide useful information for genetic improvement. Method Thirty-five phenotypic traits among 37 germplasms were analyzed by variance analysis, principal component analysis (PCA), and cluster analysis. Result Large variation and rich phenotypic diversity were found among and within germplasms of X. sorbifolium. The average coefficient of variation for 35 traits of 37 germplasm resources was 25.49%, and the variation range was12.80% to 63.25%. the variation of branch traits was the largest (45.51%) , followed by inflorescence traits (31.01%) , fruit traits (24.67%), flower traits (24.35%), seed traits (21.82%), and leaf traits (21.45%). The mean phenotypic differentiation coefficient was 80.52%, indicating that the variation among germplasm resources was the main source of phenotypic variation. The cumulative contribution rate of the first nine main principal components reached 80.333%. The 37 germplasms were classified into two main groups and six subgroups according to their characteristics by Ward’s method and reasonable utilization of each subgroup were suggested. Conclusion The genetic variation of phenotypic traits of X. sorbifolium is abundant, among which the variation range of inflorescence, fruit and flower traits is larger than that of leaves and seeds. It provides useful information for the genetic improvement, preservation, and evaluation of X. sorbifolium germplasms.
Develop Annual Stand Volume Growth Model of Chinese fir Including Different Stand Density Indices
JIANG Li, ZHANG Xiong-qing, Duan Ai-guo, ZHANG Jian-guo
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Objective Stand density is an important index to reflect the number and competition in a stand. It plays a critical role in stand growth models. It is of great significance to analyze the application value of stand density index in stand volume growth model for accurate prediction. Method Based on the 28 years continuous observation data of the spacing trials of Chinese fir (Cunninghamia lanceolata) plantation in Shaowu, Fujian Province, the annual growth model of stand volume of Chinese fir including five different density indices respectively were developed based on the variable rate method, as well as the model without stand density index. Result The R2 values of the models including density indices were all larger than 0.979, and the model performance was higher than that of the model without density index. Among the five models including stand density indices, the model including living number of trees per ha (N) had the largest value of R2, followed by the model with RS density. However, the two models are not feasible because of the parameter estimates of stand density index were not significant. The R2 values of all models from high to low were: stand volume model including N (0.979 9), relative spacing RS (0.979 9), stand density index SDI (0.979 4), dominant high nutrient area ratio Z (0.979 3), Nilson density index model (0.979 0) and without density index (0.972 8). Conclusion Accounting for significance of the parameter estimate, the model with stand density index SDI performed the best in the stand volume model of Chinese fir. In addition, stand volume in stands of planting density (1 667 ~ 3 333 trees·hm-2) was larger than the denser stands (5 000 ~ 10 000 trees·hm-2).
Investigation and Analysis on Host Species and Their Resistance Substances to Bacterial Bark Canker of Populus × euramericana
LI Yong, CHANG Ju-pu, GUO Li-min, SUN Shang, YANG Xu-qi, PIAO Chun-gen
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Abstract:
Objective To investigate and analyze the host species of bacterial canker of Populus × euramericana, the disease-resistant varieties and the possible disease-resistant substances they contain. Method The host of the pathogen and the resistant varieties were determined by field investigation and inoculation tests. The content of active substances in the bark of disease-resistant and susceptible varieties was analyzed by HPLC. Result The hosts of bacterial pathogen of P. × euramericana canker are P. deltoides, P. × euramericana and Salix matsudana. P. × euramericana cl. 'Zhonglin 46', P. deltoides cl. '2025', P. × euramericana cv. '2001', P. deltoides cl '313', P. deltoides 'Zhonghe-1' and P. deltoides '16-09' were highly susceptible to the bark canker disease; P. × euramericana 'Yukang 1' and P. deltoides '16-10' were highly resistant varieties, P. deltoides '131', P. deltoides '03-59', P. deltoides '02-212' and P. deltoides '03-34' were resistant varieties. Hybrid willows and Salix babylonica are resistant to the pathogen, and Salix × aureo-pendula can be affected, but do not cause serious disease. The HPLC analysis showed that the contents of catechol, benzoic acid and chlorogenic acid in the bark of resistant and highly susceptible poplar varieties were significantly different. The catechol and catechin increased when the hosts were infected by Lonsdalea populi. Conclusion In this study, the host species of bacterial canker of P. × euramericana are determined, and resistant and highly susceptible poplar varieties are screened. It is showed the catechol and catechin are important compound for host to defense the pathogen infection. The results will be helpful to the control of the bacterial disease of poplar.
Effects of Castanopsis kawakamii Forest Litter on Seed Germination of Pinus massoniana
JIA Mei-hua, WANG Zhe, LIU Jin-fu, JIN Meng-ran, HE Zhong-sheng, XING Cong, SHI You-wen, SHEN Cai-xia
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Abstract:
Objective To understand the effect of litter of Castanopsis kawakamii natural forest on the competitive intensity of regeneration of Pinus massoniana. Method The allelopathic effects of litter extract of natural forest with different concentration and decomposition degree on seed germination and radicle growth of P. massoniana were studied. Result (1) The main factor affecting the germination of P. massoniana seeds was the degree of litter decomposition. Compared with the blank control, the litter of undecomposed layer and fully decomposed layer had no significant effect on the germination of P. massoniana seeds; the semi-decomposed layer inhibited the germination rate and germination index and promoted the germination potential. (2) The main factors affecting the growth of radicle were the concentration and action time of litter extract, and the effect of undecomposed layer on the whole radicle growth period of P. massoniana seeds was enhanced with the decrease of concentration, but increased with the decrease of concentration, and the promoting effect was the strongest at the concentration of 1 ≤ 100, and the effect of semi-decomposition layer was promoted by low concentration and high concentration, and the intermediate concentration was inhibited by the undecomposed layer. The fully decomposition layer showed promoting effect as a whole, and the promoting effect decreased with the decrease of concentration. (3) Correspondence analysis showed that different decomposition degree-concentration had no significant effect on seed germination of P. massoniana, but had significant correlation with radicle growth. Conclusion The result proves that the litter extract of different decomposition degree has a weak promoting or inhibiting effect on the seed germination of P. massoniana, promotes the growth of radicle at low concentration, and promotes the regeneration of P. massoniana, which will intensify the interspecific competition in the forest, and lead to the inhibition of the natural regeneration of C. kawakamii.