Effects of Different Soil Salinity Stress on Nitrogen Use Efficiency and Cotton Growth
In order to clarify the effects of soil salinity stress on the efficient utilization of nitrogen and growth and development of cotton,a field plot experiment was carried out by using 15N isotope technology.Four soil salinization levels of weak(2.0 g/kg),mild(6.5 g/kg),moderate(13.0 g/kg)and severe(17.9 g/kg)were designed to analyze the effects of soil salinity stress on cotton dry matter quality,total nitrogen content,15N utilization efficiency,growth index and yield.The results showed that the dry matter weight,total nitrogen content and 15N utilization efficiency of cotton were significantly increased when the soil salinity increased from weak salinization to mild salinization,and the ability of cotton stem and fruit to absorb nitrogen was generally enhanced.However,when the soil salinity further increased to moderate salinization level,the day matter quality,total nitrogen content and 15N utilization efficiency of cotton sig-nificantly reduced.Pearson correlation analysis showed that the 15N utilization efficiency of cotton was sig-nificantly positively correlated with the emergence rate(P＜0.01),and the seed cotton yield was the high-est under mild soil salt stress,which was 6456.9 kg/hm2.Moderate and severe soil salt stress caused the growth of cotton roots and seedlings in the 40-60 cm soil layer to be hindered.Compared with mild salt stress,the emergence rate of cotton decreased by 33.1%,and the seed cotton yield decreased by 37.7%.Based on the above determination indexes and yield,it is suggested that the reasonable soil salt and nitro-gen control measures in northern Xinjiang should include strict control of field groundwater level,scientific mechanical soil preparation and continuous fertilization of soil.
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