<正>应用温室盆栽方法。研究了土壤水分胁迫对4个银杏品系1年生实生苗叶片超微结构的影响，结果表明：（1）在正常土壤水分条件下，银杏签品糸叶肉细胞及细胞核正常，核膜清晰，少数叶绿体中含淀粉粒和嗜锇颗粒，细胞质申含较多电子密度强的黑色物质；（2）在土壤含水量为田间持水量60%的水分条件下，银杏各品系叶肉细胞及细胞核基本正常，核膜基本清晰，叶绿体片层较清晰，叶绿体含少量嗜锇颗粒和淀粉粒，叶绿体外膜、细胞核膜和细咆壁卜_附着电子密度强的黑色物质；（3）在土壤含水量为田间持水量40%的条件下，银杏各品糸叶肉细胞核膜大部分消失，多数叶绿体模糊，片层开始紊乱。所含嗜锇颗粒有增大、增多趋势；（4）在土壤含水量为田间持水量20%的条件下，银杏各品系细胞核膜基本消失或消失，多数叶绿体外膜变得模糊，片层基本消失，叶绿体中嗜饿颗粒明显增乡。少教叶绿体中虽舍有片层却出现膨胀现象；（5）从各品系叶肉细胞超微结构的综合情j}乙奇析，44号和1l与品系耐旱能力强于32号和55号品系。

The structure characteristics of biomass and spatial distribution of root system of Pinus massoniana with different dominance were systematically investigated in the acid rain region of Chongqing, China. The results showed that the aboveground biomass accounts for more than 90%of the total biomass and the ratio of roots was less then 10%. The order of biomass ratio of different organs was trunk, branch,root, bark, needle. The depth and width of root distribution varied obviously with the dominance of individual trees. For dominant trees, the vertical root could reach a depth of 130 cm, and the horizontal range of root system with a radius of 3 m. On the other hand, it is less then 80 cm in depth and 1.5 m in radius for the non-dominant trees. The biomass proportion of roots within different diameter range was ordered as stump,large root, middle root, small root, fine root. The biomass sum of stump and large root accounts for more than 90%of the total amount of root system, while the proportion of all other root diameter classes accounts for only less than 10%. The study of fine root distribution of Pinus massoniana using soil coring method showed that the fine root was plentiful in the soil layer of 0--40 cm. It was especially concentrated in the upper soil layer (0--10 cm). Fine root biomass decreased with distance from trunk of sampled trees increased. It reached a minimum at the position of 2.0 m away from the trunk.