| The pot experiment was conducted to study the effects of water stress on photosynthetic and physiological characteristics of rice in early jointing-booting stage.It was found that the diurnal variation of net photosynthetic rate showed double-peak curve in the treatment of water stress followed by rewatering,while it was single-peak curve in CK.Under the treatment of 5-days mild stress,net photosynthetic rate (Pn),transpiration rate (Tr) and stomatal conductance (Cs) of the second leaf from the top were higher than those of CK; under the treatment of 10-days mild stress or 5-days severe stress,the values of these parameters were lower before midday depression of photosynthesis(MDP) but higher after MDP than those of CK;but under 10-days severe stress,they were always lower than those of CK.Under the treatment of mild stress,the contents of total chlorophyll(a+b),chlorophyll a,chlorophyll b and carotenoid were all higher than those of CK,indicting that there was an over-compensation effect;but under the treatment of severe stress,they were lower than those of CK.In the early stage of rewatering after stress,the content of malondialdehyde (MDA) was less than that of CK,but in the later stage it was larger than that of CK,suggesting that rewatering accelerated the senescence of rice leaves.The yield and accumulation of dry matter were close to those of CK under 5-days stress,but were lower than those of CK under 10-days stress. |