中粳水稻品种资源的遗传多样性Ⅰ．主要农艺性状的演变特点

Genetic Diversity of Mid-season Japonica Varieties Ⅰ. Changes of Main Agronomic Traits

依据育成或应用时间,将中国黄淮稻区地方品种和50年来育成的中粳稻品种分成4个时期品种,分析了不同育成时期品种的农艺性状演变趋势。结果表明,随着育成时间的推进,水稻品种产量水平显著提高,株高、单株成穗数和单位面积穗数变化不显著,千粒重稍有增加,每穗粒数、结实率、着粒密度、一次枝梗和二次枝梗数显著增加;植株株型发生改变,直立穗型粳稻品种数量明显增加,弯曲穗型粳稻品种数量减少,穗长变短,上部3张叶片变短、变宽,穗颈节缩短,抗倒性提高。通径分析表明,4个时期品种对产量有显著影响的主要性状是单株穗数、每穗实粒数和千粒重,对这3个性状的改进是产量提高的直接原因。

The Japonica rice landraces and varieties bred in the recent 50 years in Huang-huai region were divided into four groups based on the time period of being bred or applied, and the changes of the agronomic traits of the varieties were analyzed. The number of grains per panicle, seed setting rat, density of grain setting, the number of the firest and second branches and yield increased significantly and no obvious changes were observed for plant height, number of panicle per plant and number of panicle per unit area, and 1 000-grain weight enhanced slightly. The plant shape changed, rice varieties with erect panicles being increased and curved panicles decreased, panicle length being shorter, upper three leaves being shorter and wider, and uppermost internode bing shorter. The lodging resistances of rice varieties became stronger. Path analysis showed that the panicle number, number of filled grains per panicle and 1000-grain weight played important roles in yield formation.