ECOPHYSIOLOGICAL STUDY ON DROUGHT TOLERANCE OF PLANTS LIVING IN ARID REGION

1.研究了长期和短期水分胁迫对干旱半干旱区植物生理生态特性的影响，通过叶绿素荧光反应的测定，比较了中国和日本两种植物叶绿体光化学系统的耐旱性。方法和材料。(1)短期水分胁迫：在土壤水分条件从pF0到pF6的10天左右的时间里，测定了来自日本的中国油松、樟子松、沙棘、红豆杉、锦鸡儿和油蒿幼苗以及日本赤松、毛白松和青蒿苗的光合作用速率和叶绿素荧光。(2)长期水分胁迫：用水溶液进行砂砾培养，用聚乙二醇处理4年后，水溶液的渗透势分别维持在-0.02、-0.04和-0.30 Mpa。结果和讨论。(1)急性水分胁迫：在土壤水分条件下，不同植物在干燥过程中荧光反应的变化存在显著差异。结果表明，中国干旱区植物的耐旱性高于日本。干旱地区的松树能保持比日本松树更高的光合作用活性。(2)长期水分胁迫：长期水分胁迫严重影响了所有树种的顶端和根部的生长。一些树种的枝条伸长受到限制，另一些树种的叶片闪光数减少。不同水分胁迫处理间蒸腾速率差异不显著，但水分利用效率差异显著。

1.Effects of long-term and short-term water stress on the ecophysiological characteristics of plants living in arid and semi-arid regions were investigated, By the measurement of chlorophyll fluorescent reaction, the drought tolerance of photochemcal system in chloroplast was compared among plants in China and Japan2. Methods and materials. (1)Short term water stress : Rate of photosynthesis and chlorophyll fluorescent of seedlings of Pinus tabulaeformis, P.sylvestris, Hippophae rhamnoides, Hedysarum fruticosum, Caragana korshinskii and Artemisia ordosica from China and Pinus densiflora, P.thumbegii and Artemisia princeps from Japan growing in a small jiffy pot were measured under the changes in soil water condition from pF0 to pF6 in about 10 days. (2)Long term water stress : Seedlings were planted in gravel culture using water solution The osmotic potential of the water solution were maintained at -0.02MPa, -0.04MPa and -0.30MPa for four years by polyethylene glycol treatments.3. Results and discussion. (1)Acute water stress : There was a remarkable difference in the changed of fluorescent reaction among plant species during the desiccation process in soil water condition. It indicated that plant species from arid region in China had a higher drought tolerance than these in Japan. Pine trees from arid region could maintain higher photosynthetic activity than Japanese pine species. (2)Chronic water stress : Both the top and root growth of all species were severely affected by long term water stress. Some species was restricted in branch elongation and other species decreased in the number of leaf flash. Although the rate of transpiration did not differ among water stress treatments, the water used efficiency showed significant difference among treatments.