膜下滴灌条件下不同土壤盐度和施氮量对棉花生长的影响

通过盆栽试验研究了膜下滴灌条件下不同土壤盐度水平和施氮量对棉花生长的影响。研究结果表明低盐度处理,随着施氮量的增加棉花株高显著增加;而在土壤盐度较高的条件下棉花株高则随着施氮量的增加显著降低。棉花籽棉和总干物质重随土壤盐度的增加显著降低,合理的施用氮肥可显著提高籽棉重和总干物质积累量。棉花的氮素吸收量受盐分、施氮量和盐氮交互作用影响显著。随着土壤盐度的增加,棉花氮素吸收量显著降低。在低盐度条件下,增加氮肥施用量可显著提高棉花的氮素吸收量;中量盐度下,适量的氮肥施用可显著提高棉花的氮素吸收量,但施用量过大并不能增加棉花的氮素吸收量;高盐度条件下,盐分是限制棉花生长和氮素吸收的主要因素,施用氮肥对棉花的氮素吸收量无显著影响。

Effect of Different Soil Salinity Levels and Application Rates of Nitrogen on the Growth of Cotton under Drip Irrigation

The influence of different N fertilization rates and soil salinity levels on the growth and nitrogen uptake of cotton was evaluated with a pot experiment under greenhouse conditions.Cotton was grown in plastic containers(height 57cm,diameter 50cm) filled with a loamy soil.The experimental design was a 4×4 factorial with four salinity treatments(0.37,0.99,1.60 and 2.19dS m-1 as the electrical conductivity of 5:1 soil extract(EC)) and four levels of N(0,135,270,and 405kg N hm-2 as urea).Plant height was significantly affected by salinity and N-salinity interaction,but not by N.At low salinities,the plant height increased with increased N fertilization rates.At higher salinities,the plant height decreased with increased N fertilization rates.Seed cotton dry weight was significantly by salinity and N,but not by N-salinity interaction.Increased in salinity from 0.99 to 2.19dS m-1,dry weight of seed cotton was reduced by 52.33%,159.38%,and 864.63% respectively.Seed cotton dry weight increased with increased N from 0 to 270 kg hm-2,while further increase in N to 405kg hm-2 significantly reduced dry weight by 29.15% and 19.70%,respectively.Total dry biomass accumulation was significantly by salinity and N-salinity interaction,but not by N.Total dry biomass accumulation was significantly decreased with increased salinity from 0.37 to 2.19dS m-1 and increased with increased N from 0 to 135kg hm-2,while further increase of N application made no difference for total dry biomass accumulation.N uptake,which was significantly affected by salinity,N and N-salinity interaction,decreased with increase in salinity from 0.37 to 2.19dS m-1.This study indicates that the proper use of nitrogen fertilizer increased seed cotton and total dry matter weight of salt-stressed cotton.At low salinities,nitrogen content increased with increased N fertilization rates.At medium salinities,N uptake was enhanced when nitrogen properly fertilized,but not influenced by over-fertilization.At higher salinities,N uptake was independent of N rates and mainly influenced by soil salinity.