Studies On Heterosis And Combining Ability Of Quality Traits Of Hybrid Rice

Quality of rice is an important content of rice breeding in the current rice breeding.9indica sterility lines (7CMS lines and2TGMS lines) and10indica restorer lines with significant difference in the rice quality traits were chosed to make62hybrid combinations. All these hybrid combinations, their parents and Tian You Hua Zhan as control check used as Group A to study the heterosis in rice quality traits and RVA profile properties.8indica sterility lines (6CMS lines and2TGMS lines) were crossed with4indica restorer lines by NCII desigh to make32combinations as Group B to study the combining ability and genetic characteristics in rice quality traits and RVA profile properties.The following are the results:1. Following results were derived from the analysis of phenotypic differences and heterosis of rice quality traits and RVA profile properties of these hybrid combinations and their parents from Group A.(1)Variance of rice quality traits in hybrid combinations and their parents were very significant.(2)Except for values of mid-parent heterosis in gel consistency and protein content were negative, values of mid-parent heterosis in other quality traits were positive,of them chalkiness score with the strongest mid-parent heterosis. Except for values of the over high-parent heterosis in brown rice recovery, milled rice recovery, chalky rice percentage and chalkiness score were positive, values of the over high-parent heterosis in other quality traits were negative. All quality traits had a positive value of over low-parent heterosis.Except for milled rice recovery, head rice yield, milled rice width, chalky rice percentage, chalkiness score and protein content, the competitive heterosis values of other quality traits were negative.(3)Variance values of RVA profile properties in their parents and hybrid combination were at high significant level.(4)Except for peak time and pasting temperature, the mid-parent heterosis values of other RVA profile properties were positive. The over high-parent heterosis values of RVA profile properties were negative except for peak viscosity, final viscosity and consistency. The over low-parent heterosis values of setback and pasting temperature were negative, the over low-parent heterosis values of other RVA profile properties were positive. The competitive heterosis values of breakdown, peak time and pasting temperature were positive, and other RVA profile properties had a negative value in competitive heterosis.2. Through the analysing of phenotypic difference, combining ability and genetic characteristics of the hybrid combinations from Group B, the results were as follow:(1) In quality traits of rice, head rice yield, milled rice width and protein content were influenced by GCA of restorer lines, and other rice quality traits were mainly influenced by GCA of sterile lines.(2)Except for Milled rice recovery and chalkiness score, additive effect of genes was the most important factor for other rice quality traits. Brown rice recovery and chalky rice percentage were influenced by both the additive and non-additive. Milled rice recovery and chalkiness score were mainly influenced by non-additive effect of genes. The broad-sense heritability of rice quality traits were generally high, which means that they were mainly determined by genetic inheritance. The order of the narrow-sense heritability value from high to low was as follows:Amylose content> Gel consistency> Milled rice width> Milled rice length/width> Milled rice length> Specific gravity> Protein content> Head rice yield> Chalky rice percentage> Brown rice recovery> Chalkiness score> Milled rice recovery.(3) The GCA and SCA of RVA profile properties were different, which means that diversity of intergenic interaction.(4)Except for the value of consistency was mianly influenced by non-additive effect of genes, other RVA profile properties were effectted by additive effect of genes. The sterile lines had stronger effects on RVA profile properties than that of restorer lines.The broad-sense heritability of RVA profile properties were generally high, which means that they were mainly determined by effect of genetic inheritance. The order of the narrow-sense heritability from high to low was as follows:Setback> Final viscosity> Pasting temperature> Breakdown> Peak viscosity> Trough viscosity> Peak time> Consistency.