Root Characteristics Of Vigorous Wheat And The Effects On Nitrogen And Water Uptake

Improving early vigour is very important for the crops grown in the Mediterranean-type climate of Western Australia. Field and glasshouse experiments were conducted using wheat cv. Janz, a current wheat commercial cultivar widely adapted in Western Australia, along with 4 vigorous wheat lines, including Vigor18,37-6,38-19 and 92-11. The aim of the experiment was to examine the root characteristics of vigorous wheat, and determine the effects of nutrition and water uptake. In addition, the nitrogen accumulation and transference, yield and quality of seeds affected by drought after anthesis were also conducted.The most important results are as follow:1. The advance of vigorous wheat lines appeared from 2-leaves stage at 17 DAS (day after sowing). Shoot biomass, leaf area and N (nitrogen) uptake improved mostly at 17-21 DAS. Root growth faster from 21 DAS. Shoot biomass, leaf area and N uptake in vigorous lines were significantly higher than that in Janz. The relative growth rates of shoot biomass, leaf area and N uptake were also higher in vigorous lines. The seedling characteristics from 2-leaves stage to tillering (17-24 DAS) indicated the difference in vigour of wheat lines.2. Vigorous lines had higher root growth rate than Janz from 1-leaf stage to stem elongation. Root length in vigorous lines was similar but 32.86%,38.57%,44.29% and 64.29% higher than that in Janz separately. N uptake in vigorous lines was also higher than that in Janz. N uptake in vigorous lines was similar but 39.27%,34.07%,29.06% and 36.27% higher than that in Janz separately. This indicates that the early and more extensive horizontal growth of the roots was responsible for the superior uptake of N by the vigorous lines.3. The N uptake rate in the middle layer (20-70cm) of Janz, Vigor18 and 38-19 was higher than that in upper (0-20cm) and bottom layer (70-100cm). Vigorous wheat lines Vigor18 and 38-19 had more branches in the middle layer so that had bigger root length density and root number density than Janz, which resulted in higher N uptake by the vigorous lines.4. Root length density in vigorous lines 38-19 and 92-11 was higher than that in Janz, especially in 0-20cm layer. Root deeps of vigorous lines 38-19 and 92-11 were as much as 60-80cm, up to 20cm deeper than that in Janz under the drought stress after anthesis. Vigorous lines also had higher water use in both water conditions than Janz. The deeper roots under the drought stress after anthesis and bigger root length density of vigorous lines were responsible for the higher water use by vigorous lines.5. The nitrogen uptake ability after anthesis in vigorous lines was significantly higher than that in Janz, while the nitrogen translation ability was much lower. It resulted in similar grain N yield in vigorous lines and Janz. The grain N yield mostly depended on the translation from nitrogen accumuled before anthesis under drought stress. The influence of drought after anthesis was much lower in vigorous lines than that in Janz, so that vigorous lines could uptake nitrogen from soil under the drought condition. Drought after anthesis improved grain protein in Janz while had no significantly effect on that in vigorous lines. Drought after anthesis decreased yield in Janz by 38.01%, while did not have significantly effect to vigorous lines. The influence of drough after anthesis was lower in vigorous lines than that in Janz. It indicated that vigorous lines have higer potential for improving wheat yield and quality in the Mediterranean-type climate region.