Abstract:

The pattern of leaves senescence was studied to provide the reference for the planting technology and breeding to resist premature senescence in rice. Six of hybrid rice combination were used. The limited and conventional irrigation managements were compared after the heading of rice. The root activities, nitrogen content of leaves, and chlorophyll content (SPAD value), net photosynthetic rate and protect enzyme activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) were discussed. The results indicated that xylem sap of roots, nitrogen content of leaves, chlorophyll content (SPAD value), net photosynthetic rate were obvious difference of rhythm, that attenuation starting time, attenuation frequency, and attenuation quantity exhibited difference. Physiology index of different combination responded inconsistently for water shortage. Positive correlation was found between the decline rates of chlorophyll and N content in leaves and xylem sap of roots. Positive correlation was between the photosynthetic rate and chlorophyll. The activities dynamic of SOD, CAT and POD were different, and the response of water shortage of different combination were different. The change dynamic of leaves nitrogen content and chlorophyll content was positively related with the activities dynamic of SOD and CAT. The change dynamic of leaves nitrogen content and chlorophyll content was negatively related with the malondialdehyde (MDA). The difference on the attenuation rhythm of physiology index of leaves and response of water shortage of different hybrid rice were genotype difference. Increase roots activities and protect enzyme activities of leaves benefit to defer attenuation of chlorophyll and nitrogen content of leaves and to keep stronger photosynthetic function.