| This study used indica-japonica recombinant inbred lines (RILs) constructed in three different ecological regions of China as test materials. The RILs derived from Akihikari (Japonica, Cheng’s Index 22) and Qishanzhan(Indica, Cheng’s Index 7) crosses were respectively constructed in Liaoning(a japonica growing region located in northeast China, 41°48’N,123°25’E,41.6 m asl), Shanghai (middle and lower Yangtze region, an area both growing indica and japonica,31°14’N,121°29’E,4.5 m asl), Sichuan(an indica growing region in southwest China,31°07’N,104°22’E,500.0 m asl) and Guangdong(an indica growing region in south China,23°08’N,113°14’E,6.6 m asl). The objectives of this study were to determine the law of morphological differentiation and genetic differentiation, to analyse the relationship of subspecies characteristics, grain yield, and rice quality of recombinant inbred lines under different environments, to address the effect of environment on rice yield and quality. The main results are as follow:1. Use the method of Cheng’s Index and molecular markers to indicate subspecies characteristics of RILs. It showed continuous variation in different ecological regions. Most lines were intermediate types(indica-like and japonica-like), a few of them were typical indica and japonica. Morphological differentiation and genetic differentiation were all determined that the number of indica was greater than that of japonica. The difference of latitude and altitude had a great effect on subspecies differentiation. As latitude reduced, the number of indica lines was increasing. The percentage of indica lines in Guangdong and Sichuan were greater than that in Shanghai and Liaoning. Only half of the two classification methods were consistent when judging indica-japonica recombinant inbred lines that contained a large number of intermediate type materials. The consistency of two classification methods in determining recombinant inbred lines was far less than that determining indica and japonica rice varieties. Also the result of classification was not consistent with different primers. The materials that contain a large number of intermediate should not be simply divided into indica, indica-like, japonica, or japonica-like. It was helpful to have a quantitative analysis of subspecies differentiation degree with Cheng’s index score or Fj value.2. Yield of indica-japonica recombinant inbred lines in Liaoning and Sichuan were significant greater than that in Shanghai and Guangdong. Growth period of plants in Liaoning and Sichuan was longer influenced by climate, the accumulation of photosynthetic product was greater, so RIL in Liaoning and Sichuan had greater spike grain number and 1000-grains weight. The Pearson correlation coefficient showed that grain yield had a significant positive correlation with primary branch number (except for Liaoning), secondary branch number, spikelet density, spike number, and ear kernel number. The yield was large influenced by seed setting rate,1000-grains weight, and spike number using partial correlation analysis. Yield had no significant correlation with other panicle traits. Spike number had significant negative correlation with seed setting rate and 1000-grains weight. It was useful for increasing yield with an appropriate rise of spike number, especially in Guangdong. Chosing varieties which had big ear and great spike number can increase yield in Guangdong. Seed setting rate, spike number and yield of indica were greater than that of japonica, but the difference was not significant. Yield had a positive correlation with most of the milling quality, chalky rice rate, chalkiness degree, and amylose content. It had a negative correction with protein content. An increase in yield was conducive to improving milling quality, but reduced appearance and nutrition quality.3. The objectives were to determine influencing factors of milling and appearance quality in Liaoning, Shanghai and Sichuan. The results revealed that:milling and appearance quality were most affected by environmental factors. There was difference in milling and appearance quality between subspecies. Milling quality of japonica was better than that of indica, but the difference was far less than that between typical indica and japonica varieties. Grain shape had an effect on milling and appearance quality, within a certain increase of length/width ratio was conducive to improving appearance quality, but reduced milling quality. Overall, the difference of quality in filial generation of indica’xjaponica crosses between ecological regions was greater than that between subspecies. The influence of environmental condition was greater than that of genetic factors. The study indicated that ecological environments not only affected temperature and light but also on the selection of average frequency of japonica alleles and grain shape which indirectly affect milling and appearance quality.4. Using rapid viscosity analyser to determine RVA profiles of filial generation of indica×japonica crosses in three ecological regions, the results revealed that:RVA profiles were most affected by amylase content. Compared with high amylase content materials, low amylase content materials had greater protein content, peak viscosity, and breakdown viscosity, less hot paste viscosity, cool paste viscosity, peak time, consistence viscosity and setback viscosity. The difference of most traits reached significant level. Secondly, environment affected RVA profiles of filial generation of indica×japonica crosses. Peak viscosity and hot paste viscosity in Sichuan was greater than that in Liaoning and Shanghai. Amylase content of RIL in Sichuan was lowest. Overall, RVA profiles of RIL in Sichuan were best. Indica japonica properties had the least impact on amylose content and RVA profiles. The peak viscosity, peak time and breakdown viscosity of japonica were greater than that of indica in Liaoning and Shanghai. The protein content, amylose content, cool paste viscosity, pasting temperature, consistence viscosity, and setback viscosity of indica were greater than that of japonica, the difference were only significant in a few regions. In addition, chalky rice rate and chalkiness degree had a positive correlation with hot paste viscosity and peak time, and which had a negative correlation with breakdown viscosity. Protein content had a significantly positive correlation with pasting temperature, and it had a significantly negative correlation with peak viscosity in Liaoning and Shanghai. But the influence on RVA profiles was lower than the effects of amylose content. |
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