大田条件下，依据水稻收获时间设置3个晚播播期(10月30日、11月10日和11月20日)。对不同播期处理下紫云英生长状况、鲜草产量、养分积累量以及根际微生物等影响进行研究。结果表明，播期显著影响紫云英的生长及物质养分积累。随着播期的推迟，紫云英的株高、密度、单株复叶数、单株鲜重、单株干重均呈下降趋势。鲜草产量随播期推迟显著降低，10月30日播种的鲜草产量最高，达19 006.35 kg/hm²。不同播期植株地上部C、N、P、K含量差异不显著，积累量则随播期的推迟而显著降低。播期显著影响紫云英根际土壤微生物量，根际土壤中的细菌、真菌、放线菌数量均随播期的推迟而显著减少。本试验条件下，11月10日以后播种的紫云英鲜草产量、养分积累量等指标均显著低于10月30日播种的处理。晚播紫云英播期控制在11月之前可获得较高的产草量和养分积累，取得较好的还田效果。

A field experiment was carried out to study the influence of different late sowing dates on growth, fresh yield, nutrient accumulation and rhizosphere microorganism of Astragalus sinicus L. Three sowing dates (Oct. 30th, Nov. 10th, and Nov. 20th) were designed according to the harvest time of rice. The results showed that late sowing date significantly influenced the growth and nutrition accumulation of astragalus, as the sowing date postponed, plant height and density, number of compound leaves per plant, fresh or dry weight per plant all decreased, fresh yield decreased significantly, highest (19 006.35 kg/hm²) on the late sowing date of Oct. 30th. No difference was found among C, N, P and K contents in the above-ground parts of astragalus on different late sowing dates, but the nutrient accumulation decreased significantly as the sowing date postponed. Late sowing date also had significant effects on population of soil rhizosphere microbes, the numbers of bacteria, fugus and actinomycetes decreased as the sowing date postponed. Fresh yield and nutrient accumulation of astragalus were lower on sowing date of Nov. 11th than that of Oct. 30th. Under the conditions of this experiment, the sowing date of astragalus should be controlled before November for higher biomass and nutrient accumulation and better effect of returning to field.

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江苏省农业三新工程项目(SXGC〔2017〕228)资助。