荒漠植物叶片或同化枝δ^(13)C值及水分利用效率研究

δ^(13) C Values and Water Use Efficiency of the Leaves and Assimilating Shoots of Desert Plants

温带荒漠植物长期生长在夏季炎热高温、冬季寒冷低温、长年干旱缺水的极端环境中,以其特有的形态学特征和生理功能来减少水分损失.为了探讨荒漠植物水分利用效率WUE,为荒漠生态系统保育和退化植被恢复重建提供理论依据,运用稳定碳同位素技术和光合仪测定对比的方法,对河西走廊中段临泽绿洲北部荒漠中5种植物进行了全年生长期研究.结果表明:荒漠植物月水分利用效率与年生长期平均水分利用效率的相关性在8月份最高,其方程式为:WUEgpa=-1.8+1.98WUEAug P=0.011,r=0.96;月稳定碳同位素比率δ13C或13C/12C‰与生长期平均WUE的相关性在8月和9月最大,可靠性最高,其方程式为:WUEgpa=4.7+0.0813C/12Cmon P=0.057,r=0.87.研究得出:用稳定碳同位素比率指示温带荒漠植物的短期水分利用效率,随着叶片或同化枝成熟,越往生长后期,正相关性越高,直至霜降;用稳定碳同位素比率指示植物的长期水分利用效率,以8月下旬至9月下旬采样最好.梭梭和沙拐枣的水分利用效率显著高于其它荒漠植物,5种荒漠植物长期水分利用效率的排列顺序为:梭梭>沙拐枣>柠条>花棒≈泡泡刺.

Desert plants in temperate zones, which long grow in such extreme environments as hot summer with high temperature, cold winter with low temperature, and environment long dominated by drought and water shortage, resort to their specific morphological features and physiological functions to reduce water loss. The study used stable carbon isotope technique and photosynthetic measurements by a photosynthesis system to long study and compare all the year five plants in the desert area to the north of the Linze oasis standing in the middle part of Gansu corridor so as to explore the water use efficiencies of desert plants and provide the theoretical basis for the conservation of desert ecosystems and the rehabilitation of degenerated desert plants. The results showed that there appeared in August the highest correlativity between the monthly water use efficiency and the average water use efficiency during annual growth period in desert plants and its correlation equation was WUE gpa =-1.8+1.98 WUE aug ( P =0.011, r =0.96); There appeared in August and September the highest and the most reliable correlativity between the monthly stable carbon isotope ratio(δ 13 C or δ 13 C/δ 12 C) and the WUE in annual growth period, and its correlation equation was WUE gpa =-4.7+0.08 WUE mon ( P =0.057, r =0.87). Accordingly, the more mature and the later in the period of growth the leaves or assimilating shoots were, the higher the positive correlativity appeared until the first frost in using stable carbon isotope ratio as an indicator of the short term water use efficiencies of desert plants. When stable carbon isotope ratio was adopted to represent the long term water use efficiencies of desert plants, it was advised that sampling should be conducted from the last ten days of August to the last ten days of September. The water use efficiencies of H. ammodendron and C. mongolicum were significantly higher than those of the other desert plants and the long term water use efficiencies of the five desert plants ranked in the order of H. ammodendron > C. mongolicum>C. korshinskii >H. scoparium ≈N. sphaerocarpa.