| Northeast China is an important commodity grain production base, especially in recent years, whether rice planting area or production Northeast China played an important role in the Northern Japonica rice area, moreover, which obtained the national people’s favorite. In order to explore the profound reasons of contribution of the indica -japonica crossing for rice breeding, some cultivars with different periods in northeast China had been used as materials to analyze indica genotype frequency of popular rice with different periods at phenotype and genome level, changes and relationships in yield and quality traits of rice among different provinces and different released years, by using typical rice varieties in Liaoning, Jilin and Heilongjiang provinces from 1970 to 2000 as trial materials. The main results were showed as follows:1. The yield of rice in Northeast China increased 9.66% from 1970 to 1990, despite a slight decrease in the beginning of 21st century.In recent years, Northeast China of increased production is mainly attributed to the increase of grains per panicle and the raise of biomass, In recent years, the seed setting rate also improved significantly in Liaoning province. With the development of times, the milling quality traits, appearance quality and eating value had been significantly enhanced in three provinces.The grain yield in Liaoning province was significantly higher than Jilin and Heilongjiang, grain yield of Jilin was significantly higher than Heilongjiang. The grain number per panicle and biomass in Liaoning were significantly higher than Jilin and Heilongjiang; In Jilin province, the number of panicle per unit area and harvest index was higher than the other two provinces. The seed setting rate and the 1000-grain weight of Heilongjiang was significantly higher than Jilin and Liaoning. 2. With the development of times, the milling quality traits, appearance quality and eating value had been significantly enhanced in three provinces, meanwhile the cooking quality was decreased from 1990s to the beginning of 21st century. The brown rice percentage, milled rice percentage, chalky grain rate, chalkiness, amylose content and score were significantly negative correlated with the grain length and aspect ratio, the chalky grain rate and chalkiness were significantly negative correlated with the head rice percentage, amylose content and score, the score was significantly positive correlated with the amylose content, aroma, burnish, flavour and taste. In the comparison of the quality and the milling quality traits, Liaoning showed advantage in milled rice percentage and head rice percentage; Jilin had the better score, burnish, flavour, taste and integra also better than the other two provinces. Heilongjiang showed advantage in appearance quality, the grain length and the aspect ratio, the chalky grain rate, aroma and chalkiness were remarked significantly better than Liaoning and Jilin.3. Genetic diversity of japonica cultivars from large to small sequenced for Liaoning, Heilongjiang, Jilin at phenotype level and DNA level; 2001-2008,1981-1990,1991-2000, 1963-1980 at DNA level but 1980-1990,2001-2008,1991-2000,1963-1980 at phenotype level, among different periods. Liaoning group kept maximum Nei’s genetic identity with Jilin group, 2001-2008 group kept maximum Nei’s genetic identity with 1991-2000 group. The trend of gene flow and Nei’s genetic identity was the similar. We used subspecies differentiating InDel markers and ILP markers to calculated indica(japonica) genotype frequency of different periods northeast China rice cultivars, it had high significant negative (positive) correlation with six subspecies characteristics and comprehensive discriminant value, the results explained molecular marker method and Cheng’s index method had high consistency. InDel markers and ILP markers had high significant positive correlation, and not overlaped on the same chromosome position, which illustrated this two markers were consistency and complementary to each other in detecting indica and japonica differentiation.4. Most of the rice cultivars contained a certain content of the indica genotype frequency in different periods and regions of northeast China. Indica genotype frequency in japonica cultivars from large to small sequenced for Liaoning, Jilin, Heilongjiang; 1980-1990, 2001-2008,1991-2000,1963-1980, among periods, and its tendency was entirely consistent with phenotype genetic diversity among periods. From 1980s on, hybrid breeding between indica and japonica rices affected genetic diversity variation in Liaoning, subspecies differentiating locus maybe link to phenotype level functional genes segment of DNA. Indica genotype frequencies of Northeast Japonica rice varieties has negatively correlated with panicle number and positively correlated with grain number per panicle at 00.1 level5. There were moderate relationships between comparison of yield and quality traits. The milling quality traits was significantly positive correlated with yield, grain number per panicle, panicle length, panicle weight, grains density, primary branches and secondary branches, primary branch grains, secondary branch grains and secondary branch grains rate; The chalky grain rate and chalkiness were significantly positive correlated with yield, panicle length,1000-graint weigh of primary branch and secondary branch grains rate, whereas these character were significantly negative correlated with seed setting rate, the seed setting rate of primary branches and secondary branches and the primary branch grains. Consequently, improving seed setting rate was conducive to the improvement of traits chalkiness; The score was significantly positive correlated with seed setting rate, the seed setting rate of primary branches, secondary branches and the primary branch grains, at the same time the score was significantly negative correlated with 1000-grain weight,1000-grain weight of secondary branch and secondary branch grains rate, appropriately reducing secondary branch grains rate may contribute the improvement of score. |
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