杂种优势效应对中国玉米育种的贡献评价

试验选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3种密度3次重复的裂区试验设计,研究亲本产量、密度和杂种优势对产量的贡献。结果表明:亲本和品种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;杂种优势指数随年代呈"降—升—降"的变化趋势,当前推广的品种杂种优势较低。杂种优势随年代变化并没有显著提高,亲本产量的提高、种植密度的增加、是当前中国玉米产量提高的主要原因。

Contribution Evaluation of Heterosis Effect to Chinese Maize Breeding

Twenty maize single cross hybrids and thirty-two parents in different period utilized widely on maize production in China were chose as the materials in the study by split plot design over 3 sites.It was made for contribution of inbred lines yield,heterosis and planting density to hybrids yield.The results showed that yield of hybrids and parents increased gradually with the varieties replacement;yield of the earlier varieties showed decreasing in high plant density,while yield and plant density increased accordantly in present varieties;heterosis of maize hybrids presented the trend of ＂down-up-down＂ with the varieties replacement,the heterosis was lower in present hybrids.It found that there was conflicting evidence to support the heterosis was the principal contribution to yield increase,the contribution of maize yield increase owed to the increase of parents yield and plant density.