Genetics And Correlation Analyses Of Rice Qualities And Physio-biochemical Characteristics In Hybrid Rice

This study was conducted via6indica hybrid rice sterile lines:SHEN95A,389A, ZHONG3A, T98A, WUFENG A and BING1A, and5indica hybrid rice restorer lines: R031, XIANGHUI059, XIANG NONGHUI076, YOUHUI036and R342, which have significant difference in starch RVA profile properties. Thirty different hybrid rice combinations were derived from above hybrid rice lines based on incomplete diallel cross. Two sets of materials were prepared for this study, these hybrid rice combinations and their parents together with Tian You Hua Zhan(Control) were set up as group A; the62indica varieties or hybrid rice combinations with significant difference in amylose contents were set up as group B. The heterosis and combining ability, inheritance traits of starch RVA profile properties, physio-biochemical characteristics and the correlations between RVA profile properties and physio-biochemical characteristics in indica hybrid rice were analyzed for samples of group A, and the correlations between RVA profile properties and the main rice qualities also were analyzed for samples of group B. The main results are listed below:1. There were significant over high-parent heterosis in peak viscosity and over mid-parent heterosis in breakdown, setback, consistency, trough viscosity and final viscosity. Results showed that there were highly significant genetic diversities of the RVA profile properties in hybrid rice combinations, among those RVA profile properties setback had the widest range of variations while the pasting temperature had the narrowest range of variations. The starch viscosity properties in hybrid rice combinations were significantly affected by gene additive effects and non-additive effects, mainly determined by gene additive effects of parents (not covering pasting temperature). Among all the genotype variances, the GCA variance of sterile lines was far higher than that of both GCA variance in restorer lines and SCA variance in hybrid rice combinations, indicating that the starch viscosity properties in hybrid rice combinations were mainly affected by the sterile lines. Results also showed that there were significant positive correlations between the competitive advantages of hybrid rice combinations and the GCA of sterile lines in RVA profile properties with higher determination coefficients, indicating that higher general combining ability of the sterile lines had the higher competitive advantages from those hybrid rice combinations would be obtained.2. The correlations between rice starch viscosity properties and main rice qualities from different combinations were analyzed. There were significant negative correlations between the length, the rate of length and width of polished rice and peak viscosity, breakdown and pasting temperature from different combinations, but significant positive correlations to other RVA profile properties were presented; Transparency was found to have significant positive correlations to peak viscosity and breakdown, but to have significant negative correlations to setback, consistency and peak time. In this case, the rice variety seeds with better transparency should be preferred and the ones with longer length should not be excessively focused on during any selection and breeding activity of high-quality indica hybrid rice varieties (combinations). Results also indicated that cooking/eating and nutritional qualities in different rice varieties (combinations) had close correlations with their RVA profile properties, and the superior or inferior quality of rice could be highly indicated by their RVA profile properties. The rice varieties (combinations) with higher AC content, their breakdown would be smaller while their setback and consistency would be bigger. RVA profile properties would reflect the difference in cooking and eating quality among hybrid rice varieties with similar AC content, from low-mid-level (15%≤AC<17%) to mid-level (17%≤AC≤22%).3. The net photosynthetic rate, stomatal conductance, transpiration rate, Fm、Fv/Fm、 Y(NPQ)、NPQ、qN、qP and qL showed positive effects over mid-parent heterosis. Significant genetic diversities were found in photosynthesis traits and chlorophyll fluorescence parameters of hybrid rice combinations. Photosynthesis traits and chlorophyll fluorescence parameters were mainly affected by non-additive effects. Fm, Y (Ⅱ), Y (NPQ) and stomatal conductance were significantly affected by the sterile lines while chlorophyll a and chlorophyll b were significantly affected by the restorer lines. The net photosynthetic rate, Fv/Fm, Y (Ⅱ) and Y (NPQ) of competitive advantages in hybrid rice combinations were significantly correlated to the GCA of the sterile lines, indicating that the sterile lines with higher GCA would obtain a better competitive advantage of their combinations.4. Heterosis in SOD, MDA and root activity of hybrid rice combinations were not universal. Significant genetic diversities were found in SOD, MDA and root activity among different hybrid rice combinations with below20%heritability from parents and higher broad heritability. SOD, MDA and root activity were mainly affected by non-additive effects. The competitive advantages of SOD and root activity in hybrid rice combinations were significantly correlated to their GCA effects respectively, indicating that the sterile lines with higher GCA effects would obtain a better competitive advantage of their combinations.5. The correlations between RVA profile properties and Physio-biochemical characteristics indicated that there were significant positive correlations between the peak viscosity, breakdown and stomatal conductance. There were positive correlations between pasting temperature and the transpiration rate. The correlations between RVA profile properties and chlorophyll fluorescence parameters showed Y (Ⅱ) had significant positive correlations to peak viscosity, breakdown, pasting temperature but negative correlations to other RVA profile properties; Y (NPQ) and qN had significant negative correlations to peak viscosity and breakdown but significant positive correlations to setback and consistency. The analyses indicated that PS(Ⅱ) antenna pigment of hybrid rice combinations absorbed light energy that the more it transmitted by photochemical electron, the less it dissipated in form of heat, and the actual utilization rate of light energy would be higher, which would result in better grain filling and higher quality in cooking and eating etc. There were significant positive correlations between stomatal conductance, intercellular CO2concentration, chlorophyll and carotenoid content respectively. The results indicated that the hybrid rice combinations would have higher potential photosynthesis efficiency due to bigger stomatal conductance, higher intercellular CO2concentration and chlorophyll content.