江苏省粳稻品种近60年演进过程中产量与形态生理特征的变化

以江苏省近60年来各阶段具有代表性的12个粳稻品种(含超级稻)为材料,依据种植推广年代结合株型和基因型将其分为20世纪50年代、60年代、70年代、80年代、90年代和2000年以后6个类型,研究了品种演进过程中产量和形态生理的变化特征。结果表明,随着品种演进产量逐步提高,其原因主要是总颖花量的增加,而这又主要由于每穗粒数的显著增多。自早期的50年代品种,结实率逐步提高,但90年代品种和2000年以后的超级稻品种,结实率有下降的趋势,穗数和千粒重无明显变化。随着品种演进,生物产量和收获指数同步提高,以抽穗后增加的量尤为明显,主要生育期根干重、根冠比、根系氧化力和叶片光合速率显著增加,但现代超级稻品种的根系活力和叶片光合速率在结实期下降较快。品种改良提高了抽穗期总叶面积、有效叶面积、高效叶面积和粒叶比,还增加了穗长、着粒密度、一次和二次枝梗数目。由20世纪50年代到90年代品种,植株高度降低,而2000年以后的超级稻品种显著上升,升至120cm左右。抽穗期顶三叶叶片角度则随品种更替显著降低。上述结果说明随品种演进,粳稻的农艺、生理性状和产量均有明显改良,但超级稻较低的结实率限制了其产量潜力的发挥。

Changes in Grain Yield and Morphological and Physiological Characteristics during 60-year Evolution of Japonica Rice Cultivars in Jiangsu Province,China

Great progress has been made in japonica rice breeding. However, little is known about physiological and agronomical features responsible for the improvement. In this study, 12 typical japonica rice cultivars (including super rice) applied in the production in Jiangsu province during the last 60 years were used, and classified into six types of 1950s, 1960s, 1970s, 1980s, and 1990s in the 20th century and since 2000 according to their application times. All the tested cultivars were grown in the field and the evolution characteristics of grain yield and its components, source-sink relationships, morphology and physiology were investigated. Results showed that the grain yield was progressively increased with the evolution of the cultivars. Increase in grain yield was attributed mainly to the increase in total number of spikelets, which resulted mainly from large panicles. The percentage of filled grains was increased for cultivars from 1950s to 1980s in 20th century, whereas it was decreased for those at 1990s in 20th century and since 2000. There was no significant difference in 1000-grain weight among the six types of cultivars. With the improvement of rice cultivars, biomass, especially after heading, and harvest index were simultaneously increased. At main growth stages, with the improvement of rice cultivars, root dry weight, root-shoot ratio, root oxidation activity and leaf photosynthetic rate were increased significantly, but root oxidation activity and leaf photosynthetic rate during grain filing for super rice were declined rapidly. Improvement of rice cultivars significantly increased total, effective, high-effective leaf areas and grain-leaf ratio (the ratio of total spikelet number to leaf area) at heading, and increased panicle length, number of primary and secondary panicle branches greatly. From 1950s to 1990s in the 20th century, plant height was reduced, while it was increased significantly for super rice since 2000, with a plant height of about 120 cm. The leaf angle of the top three leaves on stems were significantly decreased with the improvement of rice cultivars. The results indicate that agronomical and physiological characteristics of japonica cultivars are improved during the evolution, and low percentage of filled grains limits grain yield potential in super rice cultivars.