Genetic improvement of yield and plant-type traits of inbred indica rice cultivars in south China | 华南地区常规籼稻品种产量和株型性状的遗传改良

Chinese. 【目的】研究矮化育种以来华南地区常规籼稻品种产量与株型性状的改良及其关系,为进一步提高品种产量潜力探索新的突破方向。【方法】以华南地区自矮化育种以来育成推广的65个主要栽培品种为试验材料,通过在相同生态和栽培条件下的栽培试验,研究不同年份育成品种产量和株型性状的演变,将植株形态性状与产量性状进行相关分析,并将几个主要产量性状与产量进行通径分析。【结果】从矮化育种开始,华南地区常规籼稻品种产量水平不断提高,至20世纪80年代中期达到最高水平,随后产量水平处于停滞状态,直到2000年又开始形成上升趋势。品种株高随育成年份缓慢上升,但上升幅度不大;在叶形性状中,上三叶长和上三叶宽未有明显变化,但上三叶基角和上三叶曲率则有较显著的改良;穗粒性状中单株穗数和结实率逐渐降低,一次枝梗数、二次枝梗数和每穗粒数则呈线性增加,千粒重呈阶梯式下降;单株库容量、单株生物产量和单株产量表现为20世纪50年代至80年代中后期显著上升,随后上升趋势停滞。【结论】自矮化育种以来,华南地区常规籼稻品种产量水平显著提高,但自20世纪80年代中后期开始未能取得进一步突破。在株型性状的遗传改良方面,叶片形态性状改良显著,品种由大粒穗数型向小粒大穗型演进。今后品种改良的重点是通过株型改良提高库容量。

English. 【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.