我国西南区近20年玉米杂交种籽粒产量及相关性状的遗传增益

近20年来，我国西南区的玉米育种者们在提高玉米籽粒产量方面已取得了较大进展，从70年代中期到90年代中期，每更替一个年代，杂交种籽粒产量均在上一年代基础上提高5％左右。与籽粒产量有关的农艺性状的遗传改良以株高、穗粗和生育期的改良效果最明显，其次为行粒数，而穗长、穗行数和千粒重的变化较小。

Genetic Gain of Grain Yield and Correlated Traits for Maize Hybrids in Southwestward of China in Recent 20 Years

Since 1974,the maize breeders in Southwestward of China have achieved better progress in increasing grain yield of maize hybrids. Grain yield of hybrids had raised about 5% on the basis of former age with years replaced, from mid 1970s to mid later stage of 1990s. In the genetic improvement of agronomy traits influenced the grain yield of maize hybrids, it was the most obvious for the improved effect of plant height(PH),ear width,and period of growth,the next was grain number of a row. But it was very little for the change of ear length, rows per ear and weight of 1000 kernels. These results indicated that the increase with the grain yield of the maize hybrids in Southwestward should mainly be attributed to the genetic improvement of the PH,ear width, grain number of a row and period of growth.