Hybrid Rice Ratooning Property And Its Relationship To Photosynthesis Of Main Crop During Later Growing Period

9 hybrid rice combinations were used as materials in the experiment. Yield and its relationship with yield components were studied; Ratooning ability and its relationship with function of leaf , dry matter weight activities of Superoxide dismutase(SOD) and Peroxidase(POD) during later growing period of main crop were studied as well. Its purpose is to find the simple, easy index for selecting ratooning rice combination. The main results of this study are summarized as follows:1 Among the combinations tested, Zhunliangyou527, Lul8s/159 and 8015s/500 showed superiorities in yield or ratooning ability. For their potentiality of yield and that of ratooning ability weren' t be expressed completely due to objective factors, the 3 combinations are worthy of studing furthermore.2 Main crop' s yield was significantly correlated to seed setting percentage; ratooning crop' s yield was significantly correlated to seed setting percentage and total grains per panicle. Therefore to improve seed setting percentage of each crop and total grains of per panicle of ratooning crop are important ways for insuring high yield.3 1000-grain weight. seed setting percentage and total grains of main crop were correlated to some yield factors of ratooning rice. they could be used as indexs for selecting ratooning rice combination, ie combination with moderate total grains per panicle, high seed setting percentage, high 1000-grain weight could be chosen for ratooning rice.4 The effective panicles of ratooning crop was significantly correlated to ratooning ratio during later growing period of ratooning crop, but no significant correlation to that during early growing period .This showed that it is better to use the ratooning ratio of later growing period to measure ratooning ability5 The leaf area and flag leaf net photosynthetic rate of main crop during later growing period were positively correlated to ratooningability. So combination with large leaf area, high net photosynthetic rate could be chosen for ratooning rice.6 After full heading of main crop , the duration of high net photosynthesisN high Chlorphy II contents and large leaf area were longer, and ratooning ability was higher, which could be indexs for selecting ratooning rice combination.7 The panicle weight during later growing period of main crop was negatively correlated to ratooning ability; the leaf weight during growing period was positively correlated to ratooning ability; and the stem-sheath weight was not correlated to ratooning ability. Therefore selecting ratooning rice combinations should collaborate the ratio of panicle weight leaf weight and stem-sheath weight, and find the most fit balance point among the three factors .8 The activity of SOD in upper-three leaf of main crop during later growing period was positively correlated to ratooning ability. Improving the activity of SOD can postphone aging of leaf and decreasing of photosynthesis, decrease the exportation of carbohydrate of stem-sheath matter, promote transportation of carbohydrate to axillary buds, and increase the ratooning ratio.