Comparison Studies On Ratooning Characters Of Different Hybrid Rice Combinations

6 and 8 hybrid rice combinations were used to study their growth and development characters, yield formation, sprouting characters of axillary buds, physiological characters in 2001 and 2002 respectively. The main results were as follows:1. There existed significant difference of the axillary bud sprouting in ratooning rice because of the difference of ratooning ability between different combinations. So there were significant differences of ratooning rice yield. The yields of Peiai64S/E32 Peiliangyou 500 were 26.19% 23.81% higher than that of ShanYou63, and the total yields of main crop and ratooning crop of Peiai64S/E32 Peiliangyou 500 were 13.94% 14.35% higher than that of ShanYou63 respectively in 2001. In 2002, the total yield of main crop and ratooningcrop of Peiai64S/E32 was the highest, and that of Peiai64S/B52 and Lul8S/53159 lined in the second and the third.2. The correlation coefficients between the effective tiller number grains per parrle seed-setting percentage and 1000-grain weight with yield of ratooning crop were significant; The effective tiller number had largest effect on yield, larger than seed-setting grains per panicle and 1000 grains weight. In order to increase the grain yield of ratooning rice, increasing the effective tiller number and seed-setting percentage was of most important.3. Compared with main crop, the leaf number of ratooning rice was less, leaf area of single plant was lower, the ratio of grains to leaf area was higher, which source - sink relation belonged to source restricted type. The upper second and third axillary buds were doeminent buds in ratooning rice of two-line hybrid combinations, which contributed to the yield more than 70%. The contribution of different axillary buds to ratooning yield showed different trends under different stubble heights. Compared with lower nodes', upper nodes' ratooning rice had its distinguishing feature: less leaf number per culm , smaller leaf area per culm , bigger ratio of grain number to leaf area.4. The correlation coefficient between a single stem weight at maturing stage and grain yield of ratooning rice was significant (0.760**); The activity of SOD and Pox was highest during fully heading stage in main crop, decreased gradually after full heading, waslowest at 15 to 20 days after full heading of main crop, and then increased gradually; Nonstructural carbohydrate decreased gradually after heading stage and increased slightly later; The root activity and the area of root absorption decreased gradually after heading stage, lowest in maturing stage and increased gradually after the harvest of main crop. Nutrition condition in early productive phase of main crop had decisive effect on ratooning rate, and N content was the dominant factor. Accumulation of nitrogen and carbohydrates in stem and sheath in late productive phase had no significant correlation to ratooning rate, but had close correlation to growth and development of axillary buds.5. As for the choice of ratooning rice variety, the varieties (combinations) with longer growth duration, more number of leaves, middle grain number per panicle, high 1000-grain weight, higher LAI and moderate ratio of grain number to leaf area were suitable. Higher tiller-bearing percent is advantageous to enhancing the yield of main crop and ratooning rice. In addition, in order to gain high yield of ratooning rice, we should pay attention following points: fertilizing to urge the growth of axillary buds in appropriate stage, shifting reaping stage to an appropriate earlier time, leaving high stubble.