Abstract:

Along with the increasing scarcity of global water resource, water shortage is crucial for restricting agricultural development in china. Rice is one of the main staple food crops in the world, and may suffer serious water stress during its growth period. Water stress during grain filling results in decreasing grain yield, and its physiological mechanism is unclear under continuance of the water stress. So study on the relationship between water stress and drought resistance in rice have become increasingly important proposals of rice scientific researches. The experiments were carried out in growth chamber to investigate the effects of water stress on MDA，photosynthetic rate, stomatal conductance, osmotic regulators and antioxidative enzyme activities in three hybrid rice cultivars (combinations) with different drought resistant abilities under both normal and drought conditions during grain filling stage. The results indicated that water stress aggravated the membrane lipid peroxidation in rice leaves, and it was more severe in weaker drought resistant cultivars than in better drought resistant cultivars. During the period of water stress, decreases of photosynthetic rate, stomatal conductance and chlorophyll content in better drought resistant cultivars were obvious less than those in weaker drought resistant ones. Contents of soluble sugar and amino acid and activities of superoxide dismutase(SOD), catalase(CAT) and peroxidase(POD) in leaves increased obviously in 0–14 d after anthesis and subsequently decreased rapidly, and the increases were more in better drought resistant cultivars than in weaker drought resistant ones in 0–14 d after anthesis. These results suggest that water stress can induce physiological and biochemical changes in rice, and the changes indicate drought resistance of rice during grain filling stage. Changes of MDA content, photosynthesis, osmotic regulators and antioxidative enzyme activities are correlated significantly to drought resistance of rice varieties.

Key words: Rice, Water stress, Grain filling stage, Physiological characteristic