| The process of genetic improvement of rice varieties in different historical stages due to the different of breeding objectives, the yield of rice varieties released and plant type, agronomic traits and characteristics such as significantly different. Genetic improvement of fice varieties have been researched, little is known about physiological and agronomical of rice varieties released in the different historical stages. In this study,53typical japonica rice cultivars applied in the production in Jilin province during the last78years were used, and classified intothree historical periods (1931-1969,1970-1999, since2000). All the tested cultivars were grown in the same field and the evolution characteristics of grain yield and its components, agronomic traits,morphology,organ characteristics and physiology were investigated and its relationship with yield. In order to clarify the formation mechanism of yield of varieties released in three historical periods, to provide the plant type mode reference for rice variety improvement, and at the same time provide a quantitative reference for the super rice cultivation practice in Jilin province.The results show that:(1) The evolution characteristics of the yield and its composition, grain yield were progressively increased with the evolution of the cultivars from1931to2009, the entire historical period of "low-high-low-high-bottleneck" characteristics, before1960s is low,1960s is high,1970s and1980s is low,1990is high and into the bottleneck since2000. Grain yield were progressively increased from1931to1969, the increase in yield was mainly due to the increase in the panicles and grains per panicle improved; Increasing the yield of rice varieties bred between1970-1999, because of the panicles, grains per panicle, grain weight and seed setting rate increase improved the results of comprehensive; A downward trend in the yield of varieties released since2000, decrease in grain yield was attributed mainly to in the number of panicle gradually reduced.(2) The evolution characteristics of agronomic traits, with the improvement of rice cultivars from1931to1969, plant height was significantly degraded, a significant increase in harvest index, biomass, panicle weight was not significantly increased. Harvest index increased from an average of0.49of the1940s to the1960s an average of0.55. There were extremely significant increases in biomass, single panicle weight and grass weight per hole of rice varieties released between the years1970to1999with year of release increased and the correlation coefficients were0.49*,0.5*and0.48*, and harvest index has not been improved in this period, the correlation with the index was not significant, but to maintain a high level. Breeding strategy of rice is to maintain a high harvest index. increased biomass yield in this period. Since2000, Single panicle weight were increased significantly, biomass increase was not significant, while harvest index was reduced with year of release increased.(3) The evolution characteristics of the various organs of the plants before heading. Rice tillering ability is gradually increased, top3rd leaf area and fresh weight of rice varieties released was significantly reduced from1931to1969. Leaf dry weight of varieties released before heading and yield was significant positive correlation in this period, and correlation coefficient is0.54*. Top3rd leaf area of rice varieties released were th increased from1970to1999. the correlation coefficient was0.52*for years of released. Heading tiller and population structure of rice varieties were relativey reasonable in the1090s. the number of tillers before heading varieties bred was28.3per hole, top3rd leaf area was28.5cm2. top3rd leaf fresh weight was0.5lg. top3rd leaf dry weight was0.16g. similar to the average of several varieties of the output of800kg/mn. Since2000, tiller number and leaf dry weight were negative decreased. Yield and leaf dry weight was negatively correlated, and a correlation coefficient of-0.39. This experiment integrated top3rd leaf traits and the relationship of the maximum number of tillers, and proposed one can determine whether a reasonable population structure before heading groups as " top3rd leaf area per hole", the30cmxl3cm planting conditions before heading groups the " top3rd leaf area per hole " should be greater than850cm" is a reasonable population structure of super-high-yield.(4) The characteristics of plant organ evolution after heading, from1931to1969, value of plant traits index of rice varieties released were decreased at the grain filling stage, but there is an increasing stem and sheath dry weight. The flag leaf area and top3rd leaf area were negatively correlated with the stem and sheath, with other plant traits were significantly positively correlated, increase in grain yield was attributed mainly to the increase in flag leaf and top3rd leaf area, leaf dry weight. From1970to1999, values of traits were increased with years of release beside panicle and top3rd leaf fresh weight; various organ traits in plants and the yield were not significantly positively correlated. Top3rd leaf are and fresh weight, flag leaf area and fresh weight of rice varieties released were decreased with years of release from2000to2009, and top3rd leaf fresh weight and leaf dry weight was significant positive relation with yield, the correlation coefficient of0.61*and0.56*, which shows the decline in yield and improvement of the top3rd leaf and leaf unsuccessful, maybe the plant type is not clear.(5) The fundamental strategy of super high-yield breeding wound been breeding in the late-maturing of varieties in Jilin province, and the ideal plant type of super high-yield rice varieties were proposed from this study also concluded with the results of previous studies put forward in Jilin province. Plant height is110-115cm, leaves numbers is14-15piece, upright leaves, compact and semi-erect panicle type, the flag leaf area is greater than35cm2, well-developed root system, and live mature stalk. Effective panicles are30×l04-33×l04/mu. grains per panicle in the140-160grain.1000-grain weight for23-25g, setting rate above90%,85.5-90.0kg/hm2per day production of the reproductive period, harvest index is greater than0.55, yield is more than800kg/mu.In summary, yield integrative traits of rice varieties released in the1960s and1990s, which were better than other historical periods in Jilin province from evolution of varieties bred. The yield of varieties released were declined since2000, the breeding objectives unclear cause. Jilin Province super high-yield breeding objectives detailed research should be carried out explicitly, this study proposes a detailed plant type and yield traits and physiological traits data for breeder’s reference. |
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