Effect of nitrogen form and water stress on basic photosynthetic characteristics of rice at seedling stage

In order to study the photosynthetic characteristics of rice plants under different nitrogen form nutrition and water stress,a hydroponic experiment with simulated water stress by PEG 6000 was conducted.Parameters related to photosynthesis were studied including biomass,leaf area,chlorophyll,net photosynthetic rate(Pn),stomatal conductance(Gs),intercellular CO2 concentration(Ci),carboxylation efficiency(CE),and apparent quantum yield(AQY).The results showed that under ammonium nutrition there were no significant differences on biomass,leaf area,net photosynthetic rate,carboxylation efficiency of rice plant between water stress and non-water stress.However,under nitrate nutrition,the above mentioned parameters decreased under water stress condition.The contents of chlorophyll a and chlorophyll b were higher in the rice plants supplied by ammonium under water stress than that of non-water stress.There were no significant difference in apparent quantum yield of rice plant supplied with three nitrogen form between water stress and non-water stress.