关键词: 一年生植物, 生理生态特性, 光合速率, 沙坡头

Abstract: 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.

Key words: annual plant, physio-ecological characteristics, photosynthetic rate, Shapotou region