Heterosis of Maize Root Activity and Its Relationship with Photosynthetic Characteristics

The use of heterosis was an important method to increase the yield of maize,but the studies of heterosis was centralized in the shoot of maize,whether the root activity has heterosis and the relationship of root activity and photosynthetic characteristics were not clear.The present field shelter-out rain experiment with hybrid maize and its parents under three soil water conditions was designed to study the heterosis on root activity and its declined properties and its relationship with photosynthetic characteristics.The root activity at the start of Head stage and at one month after Head stage,the photosynthetic characteristic and the root activity declined value were measured.The results indicated that for all the three maize genotypes,root activity decreased under drought stress.The root activity had obvious heterosis regardless drought stress or not at two stages,the heterosis on root activity declined under drought stress at the start of Head stage.The root activity declined rate has negative heterosis,root activity declined rate decreased under drought stress,and irrigation after Head stage distinctly reduced the rate of root activity declined.The photosynthetic rate of hybrid was larger than its parents.Analysis results showed that there were significant positive correlation between root activity and photosynthetic characteristics,which meant photosynthetic parameters increased with the increase of root activity.Therefore,the higher drought resistance of hybrid resulted from the combination of root and shoot,the influence of root activity on the shoot physiologic activity should be adequately considered in the breeding and planting practice of maize.