中国不同时期玉米单交种的产量变化

Study on the Trends in Yield Change of Maize Single Cross Hybrids in Different Periods in China

【目的】分析中国不同时期玉米品种产量、杂种优势及主要农艺性状发展变化规律,为今后玉米育种的发展提供理论依据和参考意见。【方法】利用中国不同时期具有代表性的20个玉米单交种及其32份亲本自交系为材料,采用3点裂区试验设计,分析产量、杂种优势及主要农艺性状的变化规律,产量与各性状间的相关性。【结果】品种产量和中亲产量随年代推进逐渐提高;早期品种高密条件下产量下降,当前品种随密度增加产量逐渐提高;不同时期品种随年代变化杂种优势在低密条件下逐渐增加,而高密条件下逐渐下降,中密和平均杂种优势没有变化;随年代变化,雄穗分枝和穗上叶与主茎夹角逐渐减少,行数、籽粒长和百粒重逐渐增加,行粒数、出籽率和容重没有变化;随年代变化品种产量增加与杂种优势效应相关性不显著,与穗行数、穗粗、籽粒长、百粒重和中亲产量呈极显著正相关,与雄穗分枝数和穗上叶与主茎夹角呈极显著负相关。【结论】杂种优势并没有显著提高,亲本产量的提高、种植密度的增加、株型的改善、雄穗分枝的减少及果穗性状的优化是当前中国玉米产量提高的主要原因。

[Objective] The experiment was conducted to provide a theoretical basis and reference opinions for maize （Zea mays L.） breeding by researching yield, heterosis and main agronomic characters of maize hybrids in different periods in China. [Method] Twenty maize single cross hybrids and thirty-two parents in different periods utilized widely in China were chosen as materials in the study. The changing trend in yield, heterosis and agronomic characters, correlation analysis between yield and agronomic characters were made by split plot design in three regions. [ Result] The results showed that the yield of hybrids and mid-parents increased gradually with the varieties replacement. The yield of the earlier varieties showed a decreasing trend in high plant density, while the yield and plant density increased accordantly in present varieties. The heterosis of hybrids presented a trend of up and down in low and high plant density, respectively, and no change was found in middle and average density. Investigation on the changes in plant traits showed that the tassel branch number and the angle between leaf and the uppermost ear reduced gradually, and rows per ear, ear diameter, kernel length, and 100-kernel weight increased gradually, but the kernels per row, shelling percentage and bulk density not changed. The relationship between yield and heterosis was not significant. Rows per ear, ear diameter, kernel length, 100-kernel weight and yield of mid-parents had a significant positive relationship with yield at 0.01 level. The tassel branch number and the angle between leaf and the uppermost ear had a significant negative relationship with yield at 0.01 level. [ Conclusion ] It was found that there was a conflicting evidence to support the heterosis that is the principal contribution to yield increase, the contribution of maize yield increase should owe to the increase of mid-parents yield and plant density, optimization of plant type and ear traits, decrease of tassel branch number.