Effects of Water Stress and Rewatering on Photosynthetic Compensatory Effects and Compensatory Mechanism on Maize

摘要

Simulated water stress experiments in five-leaf stage of maize with different concentration of PEG6000 in nutrient solution were conducted to study the effects of water stress and rewatering on net photosynthetic rate(Pn),transpiration rate(Tr),stomatal conductivity(Cs),internal CO2 concentration(Ci),chlorophyll concentration,chlorophyll fluorescence parameters and soluble sugar concentration in plant.Results indicated that the leaf Pn,Cs,Ci,Tr decreased during stress period and could exceed or approach those of full irrigation treatment(CK).The recovery after rewatering depend on stress severity.Under mild water stress,the leaf photosynthetic system Ⅱ(PS Ⅱ) activity (Fv/Fo) and original light energy transforming rate (Fv/Fm) did not decrease obviously during stress period and could be higher than those of CK after rewatering and stomatal factor was the leading limitation of Pn.While for severe stress,Fv/Fo and Fv/Fm showed no decline during the first 3 days and then increased during stress period compared to CK,indicating that both stomatal limitation and decrease of potential photosynthetic rate caused the decline of Pn.Chlorophyll concentration decreased during stress period but increased after rewatering and could be higher than CK for mild stress treatment.Soluble sugar concentration increased both in shoot and root and exceeded that of CK during stress duration but decreased after rewatering.The possible negative feedback between compensatory growth and compensation of photosynthetic rate after rewatering based on the relations between accumulation of assimilate and Pn was also discussed in the paper.