不同水肥运筹对再生季稻根际土壤酶活性及微生物功能多样性的影响

摘要

再生季水、肥管理措施是再生稻尤其是机收中低留桩再生稻获得高产稳产的一项关键措施,明确再生季合理的水肥运筹对提高机收中低留桩再生稻低节位再生芽的萌发成穗具有重要意义.本文以杂交籼稻泸优明占为材料,通过设置再生季分蘖期3个不同水肥处理盆栽试验,即淹水灌溉不施用促苗肥(S处理)、干湿交替灌溉不施用促苗肥(G处理)和干湿交替灌溉施用促苗肥(GN处理),研究不同水肥运筹对再生季稻腋芽、产量、根际土壤酶活性及微生物功能多样性的影响.结果表明,再生季稻不同水肥处理对根际氧化还原电位和根际土壤酶有显著影响,处理后10 d,与S处理相比,G处理可以显著提高根际土壤的氧化还原电位和根际土壤多酚氧化酶、过氧化物酶、磷酸单酯酶、过氧化氢酶活性,与G处理相比,GN处理可显著提高根际土壤多酚氧化酶、过氧化物酶、脲酶、蔗糖酶、磷酸单酯酶、过氧化氢酶活性.不同水肥调控下再生季稻根际土壤微生物对碳源的利用程度和碳源代谢的多样性差异显著,处理后10 d,GN处理和G处理根际微生物对6类碳源的利用程度显著高于S处理,GN处理根际土壤微生物对氨基酸、酚酸、羧酸类碳源的利用程度显著高于G处理.GN处理和G处理的根系伤流量分别比S处理的提高27.27％和14.84％,再生季分蘖数和产量分别比S处理的提高102.50％～111.11％、42.50％～44.44％和91.41％～108.72％、37.93％～40.94％.由此可见,再生季采用干湿交替灌溉或施用促苗肥均可提高根际土壤酶活性,促进再生季稻根际土壤微生物对碳源的利用程度和代谢多样性,从而有利于根际土壤有机质的氧化和腐殖质的形成及增加根际土壤中养分的有效性,促进再生季新根的形成和腋芽的萌发.采用干湿交替灌溉耦合促苗肥对再生季稻的促控效果是最佳的.%Irrigation and fertilizer application regime is one of key measures for high and stable yield of ratooning rice, especially for middle or low stubble ratooning rice by machine-harvest. Ascertaining rational management of water and fertilization is im-portant for improving the axillary bud germination rate of lower nodes in middle or low stubble ratooning rice by machine-harvest. With Luyoumingzhan as a test material, the effects of different irrigation and fertilizer application regimes on ratooning tillers, soil enzyme activity and rhizosphere microbial functional diversity of ratooning rice were studied by setting up three treatments:(1) dry-wet alternate irrigation and nitrogen application for ratooning bud development (GN); (2) dry-wet alternate irrigation and no nitrogen application for ratooning bud development (G); (3) flooding irrigation and no nitrogen application for ratooning bud development (S). The different irrigation and fertilization treatments had a significant impact on the rhizosphere Eh potential and rhizosphere soil enzymes. On the 10th day after treatment, the rhizosphere soil Eh levels and the activities of rhizosphere soil polyphenol oxidase, peroxidase, phosphate monoester enzyme and hydrogen peroxide enzyme were significantly improved in G than in S. The activities of rhizosphere soil polyphenol oxidase, peroxidase, urease, invertase, phosphate monoester enzyme and hydrogen peroxide enzyme were significantly improved in GN than in G. The rhizosphere soil microbe differed significantly in use of single carbon sources and diversity of carbon metabolism under different treatments. On the 10th day after treatment, the uses of single carbon sources and diversity of carbon metabolism in GN and G were significantly greater than those in S. The abilities to utilize amino acids, phenolic acids, carboxylic acid in GN were higher than those in G. Compared with S, bleeding rate of GN and G was increased by 27.27％ and 14.84％, ratooning rice tiller and yield were increased by 102.50％–111.11％, 42.50％–44.44％ and 91.41％–108.72％, 37.93％–40.94％, respectively. All these results indicated that dry-wet alternate irrigation or nitrogen application for ratooning bud development could improve rhizosphere soil enzyme activities and promote the uses of single carbon sources and diversity of carbon metabolism, which is conducive to increasing the effectiveness of nutrient, the for-mation of new roots and the axillary buds germination. The effects of dry-wet alternate irrigation coupling with fertilizer are the best for ratooning rice growth.