Effects of Chemical Regulation on Maize Photosynthesis and Yield under Low Temperature Stress during Grain Filling Stage

Field experiment was conducted to compare the effect of three chemicals on leaves photosynthesis and grain yield of maize growing under low temperature stress during grain filling stage.The main results showed that spraying of abscisic acid(ABA) reduced the net photosynthesis rate,30 μmol/L and 10 μmol/L improved the PS II photochemical efficiency(F v /F m),while 60 μmol/L ABA decreased the PSⅡ photochemical efficiency,and spraying of ABA decreased grain yield by 8.0%-14.6%.The spraying of betaine increased leaves net photosynthesis rate and PSⅡ photochemical efficiency,and spraying of betaine increased yield by 0.9%-6.9%.Salicylic acid enhanced leaves photosynthesis effectively,but decreased yield by 1.2%-3.4% with the exception of 0.5 mmol/L.Generally, grain yield was mainly affected due to the regulation on grain weight by spaying of chemicals.High concentration of betaine(10 mmol/L) was the optimal treatment concerning the improving of the leaves photosynthesis and grain yield.