Heterosis of Plant Characters for Elite Maize Hybrids and Their Correlations with Parent Lines

In this study,seven excellent maize hybrids and their 13 parent lines were studied for 13 plant traits,including plant height,ear height,top height,top height/plant height,tassel length,tassel branch number,leaves above ear,leaf angle,leaf orientation value,leaf area,aerial root layers,first layer aerial roots and stem diameter.The mid-parent heterosis(MH),over-high parent heterosis(HH) of all hybrids,and the correlations of hybrid with its two parent lines were analyzed for all traits.The results showed that great differences existed among hybrids and parent lines for all traits.MH and HH were greatly different among different hybrids for the same trait and among different traits for the same hybrid.The heteroses of plant height,ear height,top height,tassel length,tassel branch number,the leaves above ear,leaf angle,leaf area and stem diameter were high,but the heteroses of top height/plant height,leaf orientation value,aerial roots layers,first layer aerial roots were low.Significant positive correlations were found between hybrid and its male parent line for top height,top height/plant height,leaves above ear,between hybrid and its female parent line for tassel length and leaf area,and between hybrid and mid-parent value for top height,tassel branches,leaf angle,and leaf area.This result could provide useful information for cross-making in the improvement of plant traits in maize breeding.