遗传改良对中国华北不同年代玉米单交种产量的贡献

 【目的】为提高中国玉米育种技术水平而探索突破方向和寻找理论依据，对不同年代玉米杂交种的产量与年代的回归进行研究。【方法】试验于2005－2006年在新疆省农业科学院科研基地和北京顺义屯玉公司北京研究院进行。采用裂区试验设计，3个密度为主区，华北地区近40年有代表性的23个单杂交种为副区。【结果】新疆点1980s－2000s中密度下的产量年代响应>高密度，北京点1980s－2000s中密度下的产量年代响应与高密度下的差异不显著，表明1980s年代以后中国华北地区玉米杂交种在每公顷60 000株的密度水平上没有实现更高的产量年代响应;1980s－2000s产量显著提高主要是由于千粒重、穗行数的正向改良，而秃尖度、出籽率的消极改良同时又限制了1980s－2000s年代玉米产量的提高;此外，空秆率、茎倒折率、根倒伏率、秃尖度等性状在1980s－2000s间没有得到显著改良。【结论】1980s－2000s期间中国玉米杂交种在高密度条件下玉米产量的年代响应取得了一定的进展，但与国外还有相当大的差距，今后的玉米育种应强化和完善高密度育种技术路线，使未来中国玉米单交种向依靠群体增产的早熟、耐密、出籽率高、秃顶度小的育种目标方向发展。

Contributions of Genetic Improvement to Yields of Maize Hybrids During Different Eras in North China

【Objective】 To make a survey of the advances of maize breeding efforts in north China and find the strategies to continuously improve the yields of maize hybrids in the future, the regression of maize hybrid agronomic traits on year of introduction was calculated. 【Method】 The regression of agronomic traits in yields of hybrids, which was based on the split-spot experimental design with 25 hybrids released during 1970s-2000s eras in north China as sub-plot and population density as main plot, was carried out in Xinjiang and Beijing in 2005 and 2006, respectively. 【Result】 By means of comprehensive analysis on response between yields and eras from 1980s to 2000s, it showed that the yield response of medium density was higher than that of high density in Xinjiang, and the response of medium density was also not significant compared with that of high density in Beijing. It indicated that higher yield response of high density had not been achieved between 1980s and 2000s. In addition, increasing improvement of 1000-kernel weight and rows per ear was the major positive factor that enhances yield of hybrids between 1980-2000 while improvements for decreasing barren rate and shelling percentage were the important negative factors. Through the pooled ANOVA, it showed that there were no significant improvements for traits such as ears per plant, stock lodging, barren tip rate which were closely associated with adaptability of high density between 1980s and 2000s. 【Conclusion】 Therefore, it could be concluded that higher density strategy and technology routine of maize breeding activity should be strengthened and improved although some yield response of high density has been achieved in the last few decades. As a result, the future hybrids in China can be developed towards the modern breeding goals such as early maturity, tolerance to high density, higher shelling rate, no bare tip.