| Analysis on seed, cytoplasmic and maternal genetic effects for soluble sugar content (SSC), total nitrogen content (TNC), ratio of sugar to nitrogen (RSN), brown rice length (BRL), brown rice width (BRW), brown rice thickness (BRT), ratio of length to width of brown rice (RLW), 1000-grain weight (GW) and amylose content (AC) was conducted by using genetic models for quantitative traits of seed in cereal crops. According to complete diallel cross design, parents, F| and Fa genetic generations derived from six different types of rice varieties (parental lines), were used for this experiment. The main results were as follow.Analysis on genetic variance showed that all the traits involved were controlled by genes of seed, cytoplasmic and maternal plant simultaneously. SSC and GW were mainly affected by dominant effects of diploid maternal nuclear genes, while TNC and RSN by dominant effects of seed nuclear genes. BRL, BRW, RLW and AC were mainly controlled by genetic effects of nuclear genes of diploid maternal plant, of which additive effects were considered main genetic factor. BRT was primarily governed by genetic effects of seed nuclear genes, of which additive effects were taken as main genetic factor.The results of heritabilities analysis indicated that heritabilities for SSC, RSN and GW were small or depressive, implying that selection for them might be invalid. Maternal heritability in narrow sense was the main heritability for BRW and RLW, both of them could be improved by single-plant selection, while direct heritability for TNC and BRT appeared to be larger, for which single seed descent method might be better in genetic selection. Both direct heritability and maternal one in narrow sense for BRL and AC tended to be higher, showing both traits could be improved mainly by the method of single-seed descent, complemented with' single-plant selection.Based on heterosis analysis, it was indicated that SSC, RSN, BRL, BRW and GW in hybrid seeds appeared to be increased significantly but TNC, BRT, RLW and AC in hybrid seeds tendedto be decreased markedly, of which increased range of BRW was the largest and that of RLW was the lowest. It was also found that maternal heterosis for SSC, TNC, RSC, BRT, RLW and GW played main roles, direct heterosis for AC was considered as the main effect, both direct heterosis and maternal one for BRW were main genetic factors.Analysis on genetic covariance proved to be helpful to elucidate indirect relationship between paired traits. It was showed that increasing SSC might contribute to significant increase of TNC and RSN and decrease of BRL, GW and AC simultaneously. Increasing TNC might result in increases of BRW and AC and decreases of RSN, BRL and GW simultaneously. Increase of RSN might significantly lead to decline of BRW, GW and AC. Increase of BRL might increase GW and RLW and reduce BRW and BRT significantly at the same time. Increase of BRW might indirectly enhance BRT, GW and AC and decrease RLW. Increase of BRT would significantly induce increase of GW and decrease of RLW and AC, as well. Decrease of RLW might decline GW and AC while decrease of AC might be attributed to increase of GW indirectly.The prediction of seed, cytoplasm and maternal genetic effects of six parental lines indicated that Lemont, ZaoHui 89 or 02428 could be selected as elite parents to increase or decrease SSC of their progenies, respectively, and ZaoHui 89 or 02428 were considered as better lines to increase or decrease RSN, and Lemont could be used to improve grain shape. Progenies with significantly decreased BRW were predicted in genetic populations derived from. The crosses among the parents including Lemont, ZaoHui 89, Jingxian 89 and Jiahezaozhan.
|
PDF Full Text Request