Root Growth And Function Of Different Genotype Maize And Its Effection On Water Use Efficiency

Heterosis was one important way to improve yield of maize, but whether the root distribution and its water use efficiency have heterosis hasn't been knew well. The present potted condition and field experiment with three maize (Zea Mays L. ) varieties, HD4 (F1) , 478 (♂) and TS (♀) was conducted in a rainout shelter to study the root distribution and water use efficiency characteristic, the effect of soil water condition on root distribution and water use efficiency were studied either. The main result were as follows:1. There were significant difference between root growth and distribution characteristic of hybrid maize and its parents. Under sufficient water supply and drought stress, the total root weight, total root system surface areas, total root length of hybrid maize were higher than its parents. The percent of depth root to total root of hybrid were higher than parents under drought. Under field experiment condition, the root activity, the proportion of root in deeper soil of hybrid under water deficit at jointing stage were larger than its of parents, and after re-irrigation at later stage, the root length density of hybrid in up-layer soil was larger than parents, the root activity declined rate of hybrid was less than parents, all of those were benefit to the water uptake at later stage.2. The result of field experiment indicated that yield and yield water use efficiency of hybrid was larger than parents. The water use efficiency of hybrid larger than parents was resulted in many factors. Present experiment result indicated that the root growth and distribution characteristic of hybrid were reasons of its larger water use efficiency, the higher proportion of deeper root was benefit to water uptake from deeper soil layer, and improved water use efficiency. On the other hand, the ear proportion to total up-ground dry weight of hybrid was greater significantly than parents, it was one of the reasons of the greater water use efficiency of hybrid.3. Water deficit decreased the total root weight, total root system surface area and total root length, the percent of root in deep soil to total root under drought stress higher than sufficient water supply. The biomasses of maize and water use efficiency were cut down greatly by drought stress. Under field experiment, water deficit decreased root activity of maize, the water deficit at jointing stage increased the root growing in deep layer soil, and the re-irrigation at tasselling stage and filling stage increased root growing in up layer soil at later stage, increased root activity and decreased root activity declined rate. The water deficit at later stage enhanced the decline of root activity at procreate growing stage, and induced the decrease of yield.4 The yield of maize of different irrigation styles was different significantly, water deficit decreased the maize yield , but the decrease extent was different. The decrease that was resulted in water deficit at tasselling stage was larger than that resulted in jointing stage. The water use efficiency in the irrigation style that water deficit at jointing stage and irrigated in other stage was larger than that in sufficient irrigation, but the water use efficiency in the irrigation style that water deficited at tasselling stage and irrigated in other stage was lower than that in sufficient irrigation.