双季稻秸秆还田与减施氮肥对水稻产量和品质的影响

Effects of Returning Double-Season Rice Straw to the Field and Reducing N-fertilizer on Yield and Quality of Rice

【目的】研究双季稻稻作区秸秆还田与减施氮肥对水稻产量和品质的影响,为水稻高产、高效施肥与秸秆资源综合利用提供一定的理论依据和技术支撑,指导当地农户在生产实践中运用该成果。【方法】2018—2019年在江西进行了2年试验,均设置6个处理,分别为JN100、JN50、JN30、JN10、JN0和CK。供试早稻品种为潭两优39,每667 m^(2)氮肥施用量(纯N)分别为0,6,8.4,10.8,12 kg,以秸秆不还田10.8 kg施N量作为对照;晚稻品种为甬优538,每667 m^(2)氮肥施用量分别为0,9,14.4,16.2,18 kg,以秸秆不还田16.2 kg施N量作为对照。氮肥施肥比例为m(基肥)∶m(分蘖肥)∶m(穗肥)=5∶2∶3,磷、钾肥每667 m^(2)施用量早稻分别为6 kg(P2O5)和6 kg(K2O),晚稻分别为9 kg(P2O5)和9 kg(K2O),磷肥全部作为基肥施用,钾肥基肥和穗肥比例为6∶4,基肥深施,秸秆还田,耕作方式为耕翻,其他农艺管理措施与当地大田生产一致。【结果】随施氮量的增加,早稻和晚稻的穗数均有所上升,早稻千粒质量略有下降,而晚稻千粒质量的变化不明显,以JN30为最高;与对照CK相比,秸秆还田减氮10%对水稻产量构成无明显影响。秸秆还田条件下,减施10%的氮肥,对早稻产量影响不明显;晚稻对于秸秆还田替代部分氮肥的反应比早稻敏感,秸秆还田减施10%的氮肥比对照增产8%。随着施氮量的增加,早稻的精米率、整精米率呈先上升后下降的趋势,而晚稻则呈上升趋势。早稻和晚稻的垩白粒率、垩白大小、垩白度、直链淀粉含量、胶稠度热浆黏度、崩解值、最终黏度等指标,均随施氮量的增加总体呈下降的趋势。秸秆还田处理下,早稻与晚稻的稻米品质变化趋于一致,均表现为:整精米率、垩白米率和垩白度有所降低,而直链淀粉含量、胶稠度、峰值黏度、热浆黏度、崩解值、最终黏度等指标略有上升。【结论】秸秆还田与减施氮肥,可综合提高水稻的加工品质、外观品质和蒸煮品质,综合考量产量和品质指标,秸秆还田可有效替代10%-30%的纯氮。

[Objective]To study the effects of returning straw to the field and reducing nitrogen fertilizer application on rice yield and quality in double-cropping rice cropping areas,to provide a certain theoretical basis and technical support for high-yield,high-efficiency fertilization and comprehensive utilization of straw resources,and to guide local farmers to use theresults in practical production.[Method]Two years of experiments were conducted in Jiangxi from 2018 to 2019,and 6 treatments were set,namely JN100,JN50,JN30,JN10,JN0 and CK.The tested early rice variety was Tanliangyou 39,and the nitrogen fertilizer application rates per mu(pure N)were 0,6,8.4,10.8,and 12 kg,respectively.The nitrogen application rate of 10.8 kg without straw returning to the field was used as the control;the late rice variety was Yongyou 538.The amounts of nitrogen fertilizer applied per mu were 0,9,14.4,16.2,18 kg,respectively,and 16.2 kg of N fertilizer applied with straws not returned to the field was used as a control.The ratio of nitrogen fertilizer application was basic fertilizer∶tiller fertilizer∶ear fertilizer 5∶2∶3.Phosphorus and potassium fertilizers were 6 kg(P2O5)and 6 kg(K2O)per mu for early rice,and 9 kg(P2O5)and 9 kg(K2O)for late rice.,all phosphate fertilizers were used as basal fertilizer,potash basal fertilizer and panicle fertilizer were respectively applied in the ratio of 6∶4,basal fertilizer was applied deeply,straw was returned to the field,and the preparing method was tillage.Other agronomic management measures were consistent with local field production.[Result]With the increase of nitrogen application rate,the number of ears of the early rice and the late rice increased,the 1000-grain weight of the early rice decreased slightly,but the change in the 1000-grain weight of late rice was not obvious,with JN30 being the highest;compared with the control CK,returning straw to the field and decreasing Nitrogen by 10%had no significant effect on the composition of rice yield.Under the condition of returning straw to the field,reducing the application of nitrogen fertilizer by 10%had little effect on the yield of the early rice;the late rice was more sensitive to the replacement of part of nitrogen fertilizer by returning straw to the field than the early rice.With the increase of nitrogen application rate,the milled rice rate and head rice rate of the early rice increased first and then decreased,while that of the late rice increased.The chalky grain rate,chalky size,chalkiness,amylose content,gel consistency,hot pulp viscosity,disintegration value,final viscosity and other indicators of the early rice and the late rice showed an overall downward trend with the increase of nitrogen application rate.Under the treatment of returning straw to the field,the changes in rice quality of the early rice and the late rice tended to be the same,both showed that the whole rice rate,the chalky rice rate and the chalkiness reduced,while the amylose content,gel consistency,peak viscosity,and hot pulp viscosity,disintegration value,and final viscosity increased slightly.[Conclusion]Returning straw to the field and reducing the application of nitrogen fertilizer can comprehensively improve the processing quality,appearance quality and cooking quality of rice.Considering the yield and quality indicators,returning straw to the field can effectively replace 10%-30%of pure nitrogen.