Natural Distribution,Drought-resistant Nature and Moisture Physiology of Fine Host Trees for Lac Insects

Study on natural distribution and biological characters of fine host trees of lac insects have shown that six species of trees, Albizzia kalkora,Dalbergia obtusifolia,D.szemaoensis,Pueraria wallichii,Moghania macrophylla,Ficus racemosa,are fine drought-resistant species of trees. Their moisture physiology indexes such as strength of transpiration,water potential,and water saturation deficit etc. relate to comprehensive climate factors,for example,atmospheric temperature,intensity of illumination,relative humidity of atmosphere,wind velocity etc. The strength of transpiration increased with the rise of temperature,intensity of illumination and wind speed,or decreased with the rise of relative humidity of atmosphere. Variations of water potential are just contrary to the change of strength of transpiration. The water potentials dropped when the strength of transpiration raised,and the capability to absorb water passively increased,and the ability of drought resistance is raised too.The bigger the critical saturation deficits in plant frame,the smaller the water requirement and the stronger the drought hardiness. The results have shown that the drought resistance of the 6 spacies of trees is arranged in order from stronger to weaker as follows: A. kalkora,D.obtusifolia,P.wallichii,D.szemaoensis,M. macrophylla,F.racemosa.