Analysis Of Correlation, Path, Combining Ability And Heritability For Major Economical Traits In Hybrid Rice

In order to find out the genetic laws of the major traits in hybrid rice, and better understand the performance of the current-used parents, and provide reference for hybrid rice breeding, hybrids made from five different male sterile lines and four different restorers in the incomplete diallel pattern of 5 X4 were planted in 1999 late season and 2001 early season respectively, to evaluate their growth duration (GD),plant height (PH), panicles per plant (PP) , spikelets per panicle (SP), filled grains per panicle (FGP) , seed setting rate (SSR), 1000 梘rain weight (GW) and grains weight per plant (GWP). Not only the analysis of simple correlation, partial correlation, path coefficiency, combining ability and heritability on these traits was calculated, a comparison between the results from different seasons was made also. The conclusions are as follows:1. The twoine hybrids were inferior to the threeine ones with respect to most of the traits. This implies that it is very difficult to bring out two條ine hybrids with yield potential superior to threeine ones with the TGMS lines studied.2. The results from analysis of simple correlation for each season were not completely the same. But significant negative correlations between PP and SP, SP and GW, and significant positive correlations between GWP and SSR, SP and FGP, PH and GW were obtained for both of the season.3. Partial analysis had the same result from each season: All the partial coefficients between GWP and PP, FGP, GW were positively significant at 1% level, while partial coefficients among the later three ones were negatively significant at 1% level. Relations among the yield ?related characters in hybrid rice indicate that hybrids with high yield potential must have optimal paniclpikelrain weight structure.4. Result from analysis of path coefficiency for each season was not the same, either. In 1999's trial, economical characters affecting yield were FGP>PP>GW, but in 2001's trial, they were GW>FGP>PP. These showed that the main yield-affected traits were different from one hybrid to another, when their parents are quite different. There are combinations with many panicles, or many spikelets or great grain, each has its unique characteristic and great heterosis.5. The three CMS lines, Zhenshan 97A, Longtepu A, and K18A, and the three restorers, Minghui 63, Zhilong, and 1025 show good general combining ability (GCA). Hybrids from them show generally high heterosis. But the three TGMS lines, K1405S, Anxiang S, Pei'ai 64S, the three CMS lines, Liu A, Qi A, Zhenong 8010A, and the four restorers, Gui 99, Gui 33, 128, 938 have poor gereral combining ability. However, when 128 and 938 are crossed with male sterile lines with good GCA, the chance to breed hybrids with high specific combining ability (SCA) and high yield potential will be high.6. The five traits, GD, PH, SP,PP and GW are mainly controlled by GCA, which expresses the additive effect of genes, while the other traits, FGP, SSR and GWP are affected by both of the GCA and SCA, That is they are controlled by both of additive and non梐dditive effect of genes.7. The maternal influence on the traits of GD GW and GWP is much higher than on the other traits. This indicates that it will be more effective! to improve these traits through female than through male parent. So in hybrid rice breeding, more attention would be paid to male sterile lines improvement in uhe near future.8. GCA and SCA are independent to each other. All the traits in! hybrid rice are affected by both of GCA and SCA. Only those hybrids from both or either of the parents with high GCA, and show high SCA itself will show real high yield potential. While those from the parents with poor GCA and show high SCA itself will only perform heter-obeltiosis but no standard heterosis. Therefore, in hybrid rice breeding, it is the foundation to have parents with good GCA, and-the key to develop combinations with high SCA.9^GD and GW show highly heritability, while PH and SP are intermediate, and P...