土壤逐渐干旱下玉米幼苗光合速率与蒸腾速率变化的研究

The changes of photosynthetic rate and transpiration rate of maize seedling under soil progressive drought.

对土壤逐步干旱下玉米幼苗光合速率、蒸腾速率及水分利用效率变化研究表明,土壤逐步干旱初期玉米光合速率、蒸腾速率有所升高,土壤相对含水量为90%时达最大,其后随土壤的继续干旱,玉米光合速率、蒸腾速率开始下降,且降势初期较缓,自70%后几乎呈直线,这是由气孔因子和非气孔因子交替或综合调节所致。叶水势-0.8MPa左右是提高玉米光合速率和水分利用效率的重要阈值之一。

The changes of photosynthetic rate （Pn）, transpiration rate （Tr） and water use efficiency （WUE） of maize seedlings under soil progressive drought were studied. The results show that photosynthetic rate and transpiration rate increase a little with the declining of soil water content during the early drought days. When soil moisture is 90 % of field water capacity （FWC） ,they both reach the maximum. Then they begin to decrease with unceasing drought. The rate of decreasing is slow at first, but when soil moisture is below 70 % of FWC, it decreases linearly with decreasing soil water. The changes are caused synthetically or alternately by stomatal and non-stomatal factors. Leaf water potential - 0.SMPa is an important threshold in enhancing photosynthetic rate and water use efficiency.