Genetic Analysis For Soluble Sugar Content, Total Nitrogen Content And Ratio Of Sugar To Nitrogen Of Rice(Oryza Sativa.L.) Across Environments

Analysis on seed, cytoplasm and maternal genetic effects for soluble sugar content (SSC), total nitrogen content (TNC), ratio of sugar to nitrogen (RSN) and the connection between them and other quality traits in grain were mainly measured by using genetic models for quantitative characters of seed in cereal crops. According to partial diallel mating design, parents, F1 and F2 genetic generations derived from nine different types of rice varieties (parental lines) used for this experiment separately in early and later season. The main results were as follows.Analysis on genetic variance showed that SSC , TNC and RSN were all controlled by seed, cytoplasm and maternal genetic effects in different environments, in early season cytoplasmic domino effect was little to SSC and RSN. In two seasons, SSC and RSN were mainly affected by seed nuclear genes and diploid maternal nuclear genes, while TNC was governed by seed, cytoplasm and maternal genetic effects at the same time, of which seed nuclear genes and diploid maternal nuclear genes were considered main genetic factors.The results of heritability and response to selection indicated that heritability in narrow sense for SSC and RSN were zeroth in different environments, implying selection for them might be invalid. In later season, direct heritability of TNC appeared to be larger, for which single seed descent method might be better in genetic selection.Based on heterosis analysis, SSC, TNC and RSN all had remarkable change in early and later season in mean genetic heterosis, it was found in two seasons maternal heterosis for SSC and RSN played main roles, direct heterosis for TNC was considered as the main effect. In heterobeltiosis, SSC, TNC and RSN in hybrid seeds appeared to be increased significantly in two seasons,, and direct heterosis for SSC and TNC were main genetic factors, but to RSN direct heterosis and maternal one played main roles in early and later season separately.Analysis on genetic covariance showed in different environments increasing SSC might contribute to a significant increase of TNC and RSN but decrease of amyiose content (AC) and 1000-grain weight (GW), increasing TNC might increase brown rice thickness (BRT) but decline brown rice width (BRW) and GW. With the improvement of RSN, brown rice length (BRL) will be longer, at the same time, BRT, G W and AC will be reduced.The prediction of seed, cytoplasm and maternal genetic effects of nine parental lines indicated that in the two seasons, 02428 could be selected as elite parent to increased TNC during its offspring's progenies. Jingxian 89 decreased TNC but improved RSN synchronously. While Lemont made RSN less. In early season, Duochandao and R669 were considered as better lines to increase RSN. In later season, Zaohui 89 and Jiahezaozhan could be used to lower SSC, at the same time the cross of Zaohui 89 had a little RSN. Progenies with significantly increased TNC were redicted in genetic population derived from the cross of 1R65600-85.