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Intra-annual Radial Growth Dynamics of Larix principis-rupprechtii Plantations with Different Stand Densities and Its Response to Environmental Factors
WANG Guo-rui, XU Li-hong, YU Peng-tao, WANG Yan-hui, ZANG You-ting, HU Zhen-hua, LIU Ze-bin, LI Jia-mei
, Available online  , doi: 10.12403/j.1001-1498.20230193
Objective To investigate the seasonal variation characteristics of radial growth of Larix principis-rupprechtii plantations with different densities and its responses to environmental factors for providing a scientific basis for accurate assessment and prediction of the radial growth of L. principis-rupprechtii at regional scales, and achieving sustainable management and multi-functional maintenance. Method In the small watershed of Xiangshui River in the south of Liupanshan, four sample plots of L. principis-rupprechtii with different densities were set up, and the intra-annual radial growth process of L. principis-rupprechtii was monitored using a manual band dendrometer, and meteorological factors, soil temperature and humidity were monitored simultaneously. Result The results indicated that: (1) in the growing season, the radial growth of L. principis-rupprechtii showed a "S" curve. The rapid increasing stage mainly occurred from early June to late June, DOY152‒210. (2) The average cumulative radial growth of L. principis-rupprechtii decreased with the increase of stand density. In the plantations with densities of 544, 742, 999 and 1 020 N·hm−2, the average cumulative radial growth of L. principis-rupprechtii was 1 070 ± 230, 775 ± 181, 518 ± 214 and 494 ± 124 μm, respectively. With the increase of stand density, the cumulative radial growth of L. principis-rupprechtii showed a downward trend during the year, but its rapid increasing stage was shortened. (3) The results of mixed-effect model showed that the radial growth of L. principis-rupprechtii was mainly affected by soil moisture and average temperature, but stand density and growth period also had significant effects on radial growth during the year. The model including the variables of stand density, growth period, tree size and meteorological factors could explain 72.0% of the variance, but after excluding the factors of stand density and growth period, model with tree size and meteorological factors could only explain 46.4% of the variance. Conclusion More than two-thirds of the radial growth of L. principis-rupprechtii occurrs the rapid growth period. The average cumulative radial growth of L. principis-rupprechtii decreases with increasing density. Stand density, growth stage, tree size and meteorological factors jointly regulate the intra-annual radial growth of trees.
Effects of Combined Application of Organic-Inorganic Fertilizer on Soil and Leaf Nutrients in Walnut Orchards in Xinjiang
WANG Qi, ZHOU Rong-fei, LI Bao-xin, ZHANG Jun-pei, ZHANG Qiang, PEI Dong, BAI Yong-chao
, Available online  , doi: 10.12403/j.1001-1498.20230237
Objective The effects of combined application of organic-inorganic fertilizer on soil and leaf nutrients in walnut orchards were studied, and the main soil chemical factors affecting leaf nutrients were screened, which provides scientific evidence for the efficient management of soil nutrient resources in walnut orchards in Xinjiang. Method Based on the 10-year-old walnut 'Wen 185' (Juglans regia) at walnut main planting areas in Yecheng County, Kashgar, Xinjiang, a single factor completely random plot design was adopted to explore the chemical properties of soil and leaf mineral elements changes of walnut orchard under organic-inorganic compound fertilizer (Mineral source potassium fulvic acid and medium element water-soluble fertilizer, YZ) with the local conventional fertilization (Diammonium hydrogen phosphate and potassium sulfate, YD). Results Compared to YD fertilization measure, YZ treatment significantly reduced soil pH and salt ion content, and increased leaf mineral element content, but there were seasonal differences. In May, the contents of soil NO3-N, AK and leaves N, K and Zn (460.22%, 46.46%, 12.16%, 17.46%, 21.88%, p<0.05) increased significantly under YZ treatment. However, in July, the contents of soil pH, EC, Cl-S, NH4+-N, AP, Na+ and leaf Cl-L (2.21%, 27.25%, 23.37%, 61.09%, 30.03%, 13.24%, 15.94%,p<0.05) significantly reduced. The content of N, P, Ca, Mg, Na, Fe, Mn and B elements in the leaves increased significantly (4.16%, 13.25%, 20.73%, 44.04%, 66.67%, 24.62%, 52.47%, 31.85%, p<0.05). In September, the soil EC, NH4+-N, AP and Na+ (20.45%, 37.31%, 21.74%, 11.36%, p<0.05) reduced significantly under YZ treatment, while the contents of OM, NO3-N and AK were significantly higher than those under YD treatment (22.17%, 59.09%, 56.47%, p<0.05). The results of linear regression analysis showed that soil pH, Na+ and Cl-S were the important soil chemical factors affecting the content of mineral elements in walnut leaves at walnut orchards in Xinjiang. Increasing the application of organic fertilizer and reducing soil pH were beneficial to the accumulation of N, P, K, Na, Fe, Zn elements in walnut leaves. Conclusion The YD treatment increases the salt ion content of soil EC, Na+, Cl-S, NH4+-N, etc., and long-term application may aggravate the level of soil salinization in walnut orchards in Xinjiang. YZ treatment can significantly reduce soil pH, Na+, EC, NH4+-N and other salt ion content, and improve the content of mineral elements such as N, P, K, Fe and other mineral elements. It is recommended that in walnut orchards in the main walnut planting area of Xinjiang, the combined application of organic-inorganic fertilizer can reduce the level of soil salinization to reduce the harm of salinity before July. In addition, balancing the mineral element content of leaves, and avoiding long-term single application of chemical fertilizer as much as possible will be helpful for soil.