沙坡头地区一年生植物的生理生态特性研究

对腾格里沙漠沙坡头地区一年生植物沙米(Agriophyllum squarrosum)、刺沙蓬(Salsola ruthenica)和虫实(Corispermum declinatum)光合作用日变化的研究结果表明,沙米的光合速率、蒸腾速率和气孔导度均呈单峰型,其最高峰出现在11:00左右。刺沙蓬的光合速率、蒸腾速率和气孔导度均呈"双峰型",光合速率、蒸腾速率在9:00有一个峰值,而后在11:00有一个谷值,13:00至15:00出现一天中的最高峰值;而其气孔导度在早7:00是一天中的最高峰值,而后在13:00有一个谷值,其次高峰出现在15:00~ 17:00,与蒸腾作用的日变化表现出密切的相关性。虫实的光合速率只是在早7:00有一较小的高峰,其余时间基本维持在较低的水平,其蒸腾速率最高峰出现在11:00,气孔导度最高峰出现在9:00~ 11:00,15:00为一天中的最小值,17:00又有所回升,而后开始下降。就3种一年生植物比较而言,在早7:00时光合速率相差不大,随着气温的升高,虫实的光合速率逐渐下降,而沙米和刺沙蓬的光合速率逐渐增高,比虫实的光合速率提高了4~ 6倍。刺沙蓬出现了明显的蒸腾午休现象,这可能是由于刺沙蓬的叶为肉质叶,它对周围环境变化的反应更灵敏,其调控机制变得活跃了,利用蒸腾午休来降低植物水分散失的效率,保证叶片相对稳定的含水量。沙米和虫实的蒸腾速率变化不如刺沙蓬大, 且蒸腾速率的日变化仍表现为单峰型, 从这一点来说, 沙米和虫实对干旱环境的反应不如刺沙蓬敏感。

Physio-ecological Characteristics of Annual Plants in Shapotou Region

The photosynthesis diurnal variation of annual plants Agriophyllum squarrosum, Salsola ruthenica and Corispermum declinatum grown in Shapotou region, Tengger Desert was studied. The results indicated that the photosynthetic rate, transpiration rate and the stomatal conductance have a single peak-pattern variation in Agriophyllum squarrosum, the higher peak occurred at 11:00 am, while for Salsola ruthenica and Corispermum declinatum, they exhibited two-peak pattern. The first higher value of photosynthetic rate, transpiration rate came at 9:00 am, and the highest value came at 15:00~17:00 pm, showing a close relationship with transpiration. The photosynthetic rate in Corispermum declinatum reached a relative higher value at 7:00 am, while maintained small in the remaining time. The highest transpiration rate came at 11:00 am and the stomatal conductance at 9:00~11:00 am, the least one at 15:00 pm, then rose up at 17:00 pm. Comparing the three plants, there were less difference in photosynthesis at 7:00 am. With the temperature increase the photosynthesis in Corispermum declinatum decreased but increased for 4~6 times in Agriophyllum squarrosum and Salsola ruthenica. The transpiration rate in Salsola ruthenica has a noontime break mainly due to the active adjusted function in fleshy leave which was sensitive to environmental changes. In contrast, Agriophyllum squarrosum and Corispermum declinatum were less sensitive to the environmental changes by showing a single-peak pattern in transpiration rate.