地膜残留对连作棉田土壤氮素、根系形态及产量形成的影响

摘要

[目的]为探讨土壤中的残膜含量对棉花根区环境及生长发育的影响.[方法]在大田条件下,以新陆中47号为供试材料,设置了0(CK)、225、450、675和900 kg·hm-2共5个残膜量处理,于2013-2014开展2年小区模拟试验,研究了棉田土壤氮素、根系形态、产量性状随土壤中残膜含量的变化规律.[结果]随着残膜量的增大产量均呈下降趋势,450、675、900 kg·hm-2残膜量处理的产量均显著(P＜0.05)低于0kg·hm-2(CK),其中900 kg·hm-2处理的产量降低了22.2％.残膜阻碍根系生长,根长、根直径、根表面积、根体积、根尖数均随残膜量的增加而下降,其中,900 kg·hm-2处理较0 kg·hm-2 (CK)分别下降了33.7％,24.3％,19.72％,66.4％和35.3％;0 kg·hm-2与225、450、675、900 kg·hm-2残膜量处理在花期和铃期均具有显著性差异(P＜0.05).随着残膜量的增加土壤中的铵态氮和硝态氮呈增加趋势,与0 kg·hm-2(CK)相比,900 kg·hm 2处理在铃期铵态氮增加了36.6％、硝态氮增加了40.1％.[结论]残膜降低氮素利用率,阻碍了根系生长,不利于棉花产量的提高.%[Objective] The objective of this field experiment was to study the effects of plastic film residues on soil nitrogen content,root distribution,and cotton yield in field for long-term continuous cropping of cotton (Gossypium hirsutum L.).[Method] The cotton variety'Xinluzhong 47'was used in a field experiment conducted during the cotton-growing season in 2013-2014.The experiment involved the following five plastic film residue treatments:0 (control),225,450,675,and 900 kg·hm2.We analyzed changes in soil nitrogen content,root morphology,and cotton yields.[Result] Seed cotton yields decreased with increasing amounts of plastic film residue,and significantly affected the number of bolls per plant and boll weight,but not by lint percentage.The treatments with 450,675,and 900 kg·hm-2 plastic film residues had significant effects on seed cotton yields (P＜ 0.05).The seed cotton yield following the 900 kg·hm-2 treatment was 22.2％ lower than the control yield.Additionally,exposure to the plastic film residues decreased root growth,root length,root diameter,root surface area,root volume,and the number of root tips.There were significant differences in these root-growth indices (P ＜ 0.05) between the control and plastic film residue treatments.The 900 kg·hm-2 treatment decreased the root length by 33.7％,root diameter by 24.3％,root surface area by 19.72％,root volume by 66.4％,and the number of root tips by 35.3％.These results confirmed that the ammonium and nitrate levels increased with increasing concentrations of residual film.At the boll stage,the ammonium and nitrate levels following the 900 kg·hm-2 treatment were 36.6％ and 40.1％ higher than the control levels,respectively.[Conclusion] Exposure to plastic film residues inhibits cotton root growth and decreases nitrogen use,leading to decreased cotton yields.