Abstract:

Rice plants may suffer serious water stress during its growth period, so that change their morphological characteristics and the process of physiological metabolic activity. Screening indexes of drought resistance has been focused in the concerned researched. To explore the morphological and physiological mechanisms and screen indexes of drought resistance during seedling stage in rice, in this paper, morphological and physiological characteristics correlating with drought resistance were monitored under both normal and drought conditions during seedling stage using 15 paddy rice cultivars. The results showed that relative leaf age, relative area of first leaf under the central leaf, relative leaf fresh weight, relative root length were significantly and very significantly correlated with survival percentage under repeated drought condition and could be used as the morphological indexes to identify the drought resistance. Relative activities of superoxide dismutase(SOD), catalase(CAT), peroxidase(POD) and relative contents of amino acid(AA), ascorbic acid(AsA), reduced glutathione (GSH), soluble protein and malondialdehyde(MDA) were significantly and very significantly correlated with the survival percentage under repeated drought condition and could be used as the physiological indexes to identify the drought resistance. The integrated drought resistance indexes including the relative activity of SOD, relative GSH content, leaf fresh weight, and leaf age were established by principal components analysis. The drought resistance of 15 rice cultivars was evaluated by stepwise regression equation and was basically consistent with the results from paddy field, proving it is effective to predict the drought resistance during seedling stage in rice using the integrated identification index screened out in this study.

Key words: Rice, Seedling stage, Drought resistance index