关键词: 华南地区, 常规籼稻, 产量, 株型性状, 遗传改良

Abstract: 【Objective】 Cultivar yield improvement and plant-type traits development since the beginning of rice dwarfing breeding and their relationship were analyzed in order to search the strategies for continuously improving the yield potential of inbred indica rice in South China. 【Method】 Sixty-five leading cultivars released during 1957 to 2005, which were widely planted in South China, were used as experimental materials. Based on the field experiment under the same ecological and cultivation conditions, the evolution characteristics of yield and plant-type traits were analyzed, and correlation analysis and path analysis were used for detecting the relationship between yield improvement and plant-type traits development. 【Result】 Since the beginning of rice dwarfing breeding, the yield of inbred indica rice cultivars released in South China was improved continually, and it got to a summit in late 1980s, and then showed a downtrend until a new increasing trend began in 2000. Regression analysis result indicated that the plant height slowly increased during the course of cultivar evolution, but the extent was narrow. For leaf-morphologic traits, the length and width of top three leaves nearly had no change, but the angle and curvature of top three leaves decreased and had been improved significantly. Among the panicle-grain traits, the primary branch number, secondary branch number and number of spikelets per panicle increased gradually, but the panicle number per plant and seed setting rate declined and 1000-grain-weight decreased stepwise. The sink size per plant, biomass per plant and grain yield per plant increased significantly until the late 1980s,and then maintained on the plateau in the next tweenty years. 【Conclusion】 Yield level of inbred indica rice in South China has remarkably increased since the beginning of rice dwarfing breeding in 1950s, but stagnated in the past twenty years. The plant-type traits have been improved observably. It had been a main way of cultivar development that bred panicle-weight type cultivars for replacing gradually panicle-number type cultivars. In the next stage, the major approach of rice cultivar development in South China should be the increasing of sink size based on development of plant types.

Key words: South China, inbred indica rice, yield, plant-type traits, genetic improvement