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变化到pF6约10 d的条件下，测定了中国油松、西番莲、沙棘、红木、柠条、油蒿和日本密松、黄花蒿幼苗在小盆栽中的光合速率和叶绿素荧光。(2)长期水分胁迫：用水溶液在砾石培养中种植幼苗，经聚乙二醇处理后，4年的时间里，溶液的渗透势分别保持在-0.02MPa、-0.04MPa和-0.30MPa。结果和讨论。(1)急性水分胁迫：在土壤水分条件下，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。干旱区松树的光合活性高于日本松。(2)慢性水分胁迫：长期的水分胁迫严重影响了所有树种的根和顶生长。有的种枝条伸长受到限制，有的种叶片闪数减少。水分胁迫处理间蒸腾速率无显著差异，但水分利用效率有显著差异。

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.