减量施肥对冬小麦休闲期农田杂草物种多样性及生态化学计量特征的影响

Effects of reduced fertilization on weeds species diversity and ecological stoichiometry characteristics during the fallow period of winter wheat

【目的】分析减量施肥对冬小麦休闲期农田杂草物种多样性及生态化学计量特征的影响,旨在为化肥农药“双减”政策产生的生态环境效应科学评价提供参考。【方法】以陕西杨凌曹新庄试验地冬小麦肥料试验为基础,设置不施肥(CK)、减量施肥(氮(N)、磷(P_(2)O_(5))用量分别为165和122 kg/hm^(2))和常规施肥(N、P_(2)O_(5)用量分别为220和160 kg/hm^(2))3个处理,测定不同处理小麦产量及夏季休闲期农田杂草的生物量、株高、盖度、多度、频度、丰富度,以及藜、狗尾草和马唐的有机碳、全氮、全磷含量,计算植物多样性指标及生态化学计量比(C/N、C/P、N/P),研究减量施肥对农田杂草物种多样性及生态化学计量特征的影响。【结果】与对照相比,减量施肥和常规施肥处理均对冬小麦休闲期农田杂草的生物量、株高、盖度、多度、频度有明显影响,冬小麦籽粒产量和杂草生物量增加;施肥处理藜和地锦草的株高和生物量均显著增加,其他农田杂草的株高和生物量总体降低。与对照相比,施肥处理苋的有机碳含量以及藜、狗尾草、马唐和葎草的全氮含量均显著增加,藜、马唐全磷含量显著降低。相较于常规施肥,减量施肥处理狗尾草全磷含量显著降低。与对照相比,减量施肥和常规施肥处理藜、狗尾草和马唐氮磷比和碳磷比总体显著增加,碳氮比显著降低。相对于常规施肥处理,减量施肥处理缓解了藜和马唐氮磷比的增加幅度。与对照相比,施肥处理的Shannon-Wiener多样性指数、Simpson多样性指数和Margalef丰富度指数均显著降低;与减量施肥处理相比,常规施肥处理Pielou均匀度指数与丰富度显著降低。植物β多样性指数表明,常规施肥对小区植物多样性的影响最大。【结论】减量施肥和常规施肥处理冬小麦休闲期农田杂草的物种多样性均明显降低,但减量施肥处理缓解了常规施肥对农田杂草生物多样性和生态化学计量特征的影响。

【Objective】The effects of reduced fertilization on species diversity and ecological stoichiometric characteristics of weeds in winter wheat during fallow period were analyzed to provide reference for scientific evaluation of ecological and environmental effects of the“Double Reduction Policy”of chemical fertilizers and pesticides.【Method】The fertilizer trial was conducted on winter wheat at Caoxin Zhuang experimental site in Yangling,Shaanxi,China with treatments of no fertilizer(CK),reduced fertilizer(165 kg/hm^(2)for N and 122 kg/hm^(2)for P_(2)O_(5))and conventional fertilizer(220 kg/hm^(2)for N and 160 kg/hm^(2)for P_(2)O_(5)).The yield of wheat and the biomass,plant height,coverage,abundance,frequency and richness of farmland weeds in different treatments during the summer fallow period were measured,as well as the con-tents of organic carbon,total nitrogen and total phosphorus for Chenopodium album,Setaria viridis and Digitaria sanguinalis.The plant diversity index and ecological stoichiometric ratio(C/N,C/P,N/P)were calculated to study the effects of reduced fertilization on the species diversity and ecological stoichiometric characteristics of farmland weeds.【Result】Compared with CK,both reduced fertilization and conventional fertilization treatments had significant effects on biomass,plant height,coverage,abundance and frequency of weeds in the fallow period of winter wheat,and both grain yield and weed biomass increased.The plant height and biomass of C.album and Euphorbia humifusa were significantly increased under fertilization treatment,while the plant height and biomass of other farmland weeds were generally decreased.Compared with CK,fertilization treatments significantly increased organic carbon contents of Amaranth ustricolor and total nitrogen contents of C.album,S.viridis,D.sanguinalis and Humulus scandens,and they sig-nificantly reduced total phosphorus contents of C.album and D.sanguinalis.Compared with conventional fertilization,reduced fertilization treatment significantly reduced total phosphorus content of S.viridis.Compared with CK,the nitrogen-phosphorus ratio and carbon-phosphorus ratio of C.album,S.viridis and D.sanguinalis increased significantly,while the carbon-nitrogen ratio decreased significantly under re-duced fertilization and conventional fertilization treatments.Compared with the conventional fertilization treatment,the reduction fertilization treatment alleviated the increases of nitrogen-phosphorus ratios of C.album and D.sanguinalis.Compared with CK,the Shannon-Wiener diversity index,Simpson diversity in-dex and Margalef richness index of fertilization treatment were significantly reduced.Compared with the reduced fertilization treatment,the Pielou evenness index and richness of the conventional fertilization treatment were significantly reduced.Plantβdiversity index showed that conventional fertilization had the greatest impact on plant diversity.【Conclusion】The species diversity of farmland weeds in winter wheat fallow period was significantly reduced under reduced fertilization and conventional fertilization treat-ments,and the reduced fertilization treatment alleviated the effects of conventional fertilization on biodiver-sity and ecological stoichiometric characteristics of farmland weeds.