Screening For Varieties In High N Efficiency And Research On The Mechanism Of N Efficiency In Cotton

This article was studied on the differences of nitrogen efficiency among 48 cotton varieties in pot experiment. Classification in different cotton varieties and some high and low nitrogen efficiency cotton varieties were selected by screening for cotton varieties at seeding stage. Then phenotypic index, physiological index characteristic of cotton was used to study under normal and none-N conditions, the mechanism of the high nitrogen efficiency were discussced. The results were indicated as follow:1.The relative dry weigh was the primary index for varieties screening, relative N uptake and relative N content were the auxiliary index for varieties screening, Varieties of 602,XLZ12,XH12,XLZ8 had high nitrogen efficiency, while varieties of XH14, XH21, PT1, XLZ20 and 18-3 had low nitrogen efficiency by cluster analysis.2.The nitrogen fertilizer can promote the growth of cotton root, improve the dry weight, increase the root total absorption area and raise the pH of nutritional liquid. The root alter the physiological characteristic as the root/shoot ratio, root length and root density etal, alter the biochemistry characteristic as increase the percent of activity absorption area of root, secrete the organic matter or improve the activity of enzyme to adapt to the low nitrogen contents under none nitrogen conditions, in order to improve nitrogen use efficiency.The activity absorption area of root and emulate area under two N levels were significant, it was the main cause of the difference in different N-efficiency varieties, the uptake efficiency and utilization efficiency were also the main cause of this differences.3.The nitrogen fertilizer can promote the plant ability of N absorption.The dry weight and the N accumulation amount of different cotton varieties were increase with the growth of the cotton plant, the nitrogen content and the nitrogen content in root, stem and leaf were decreased with the increased of growth dates. They all assumes that the condition of the nitrogen application were top then the condition without the nitrogen application.The nitrogen content distribution percentage in various organs is the leaf more than stem more than root under two N levels. The 602 and XH12 have good index,show the better nitrogen-resistant.4.The difference of potassium content distribution percentage was consistent in various organs of cotton plant , the distribution percentage assumes the leaf more than stem more than root. The 602 and XH12 have more K in above-ground plant under the condition of without nitrogen application, have dood ability of K translocation, the effects of none nitrogen fertilizerthe on potassium uptake of high nitrogen efficiency cotton varieties is small.