Effects Of Physiological Characteristics And Grain Yield Of Rice To Water Stress At Booting And Grain Filling Stage

To explore responses of eco-physiology under water stress and re-watering, and to provide theory and technology guidance on reasonable irrigation of rice.Taking Guiliangyou2as test material, stimulated water stress by PEG-6000in July2012to November by solution culture experiment, five treatments CK, W1(2.5%PEG, m/v)、 W2(5%PEG, m/v)、W3(7.5%PEG, m/v)and W4(10%PEG, m/v)were set up respectively. Physiological and biochemical indexes such as root activity, MDA, antioxidant enzyme (SOD, POD, CAT) activity and osmotic regulation substances (proline, soluble sugar, soluble protein) in leaves were determined2days,7days,14days and re-watering5days by PEG treatment, grain yield and its components were estimated at mature stage. Water control by soil culture experiment was conducted in March2012to July. Five treatments, CK and Tl(soil moisture was between90%～100%of saturated soil water content), T2(80%～90%)、T3(70%～80%)、T4(60%～70%) were set up. Physiological and biochemical indexes such as root morphological indes, MDA, antioxidant enzyme (SOD, POD, CAT) activity and osmotic regulation substances (proline, soluble sugar, soluble protein) in leaves were determined after15days water deficient and10days re-watering. Grain yield and its components were estimated at mature stage. The main test results are as bellows:(1)The solution culture experiment indicates that, after PEG stress and re-watering, dry matter accumulation and yield was reduced at mature stage of Guiliangyou2. The maximum PEG concentration Guiliangyou2can bear was5%at booting stage, while7.5%at grain filling stage.(2) The solution culture experiment also indicate that, root activity increased under PEG stress, and had not recovered to CK level after re-watering. Antioxidant enzymes activities such as SOD、POD、CAT increased, MDA content and osmotic regulation substances such as proline, soluble sugar, soluble protein in leaves were increased. There were differences among all the indexes of recovery condition after re-watering, explain that the sensitivity degree and recovery capability of each physiological indexes were different.(3)Soil culture experiment indicated that, under water deficient, dry matter accumulation of Guiliangyou2decreased. Soil moisture between90%and100%at booting and grain filling stage, grain yield and yield components were the best at mature stage. The maximum water deficient Guiliangyou2can bear was80%of saturated soil water content at booting stage, and80%of saturated soil water content at grain filling stage.(4)Soil culture experiment also indicated that, under water deficient, chlorophyll content were increased, Net photosynthetic rate decreased, while Net photosynthetic rate were significantly higher than CK when soil moisture was between90%and100%at booting stage. At the same time, it was beneficial to root growth of Guiliangyou2when soil moisture was between90%and100%.(5)Under water deficient, MDA content increased, POD and CAT activities up-regulated while SOD activities down-regulated. After re-watering, content of MDA、SOD、POD and CAT activities up-regulated. Explain that the responses of sensitivity degree and recovery capability among MDA、SOD、POD、CAT were different.(6)Under water deficient, osmotic regulation substances such as soluble sugar, soluble protein and free proline in leaves were increased, after re-watering content of soluble protein and soluble sugar were still higher than CK, free proline content was still increased at booting stage while below to CK at grain filling stage. Explain that the recovery capability (compensation effects) of osmotic regulation substances was related to the treating stage.