油-棉连作棉田油菜秸秆覆盖对棉田杂草发生及土壤杂草种子库的动态影响

Dynamic Influence of Rapeseed Straw Mulching on Weed Occurrence and Weed Seed Bank in Cotton Field Under Rape-cotton Continuous Cropping System

在安徽省沿江棉区开展了油菜秸秆覆盖对棉田杂草发生、棉花生长及土壤杂草种子库影响的研究。结果表明:随着油菜秸秆覆盖量的增加,对棉田杂草的抑制效果增强。与未覆盖秸秆且不除草处理相比较,7000 kg/hm^2秸秆覆盖量处理棉花单株铃数和子棉产量显著提高。7000 kg/hm^2秸秆覆盖量处理在覆盖后30、60、120天逐步减少0~20 cm土层杂草种子库密度,与全程除草剂处理较一致;随着覆盖量减少,对0~20 cm土层杂草种子库密度的降低幅度减小。全程除草剂处理降低0~5 cm土层杂草种子库多样性,而油菜秸秆覆盖则可能增加0~5 cm土层的杂草种子库多样性。3500 kg/hm^2覆盖量+秸秆覆盖30天后喷施除草剂处理的抑草效果和增产效果与全程除草剂处理较一致。因此,在安徽省沿江棉区油-棉连作棉田推荐使用3500 kg/hm^2油菜秸秆覆盖量+秸秆覆盖30天后喷施除草剂。

Field studies were conducted in cotton fields under rapeseed-cotton continuous cropping system to determine rapeseed straw mulching effect on weed control,the dynamic pattern of soil weed seed bank,the growth and yield of cotton along the Yangtze River in Anhui Province.The results showed that with the increase of straw mulching,the weed control effect in cotton field was enhanced.The boll number per plant and seed cotton yield in7000 kg/hm^2 straw mulching treatment were significantly higher than those of no-weeding treatment without straw mulching.The weed seed bank density in 0-20 cm soil layer gradually decreased under 7000 kg/hm^2 straw mulching treatment after 30,60 and 120 d,which was in consistent with the whole-course herbicide treatment.The decline degree of the weed seed bank density in 0-20 cm soil layer was decreased by the decline of rapeseed straw mulching amount.The weed seed bank diversity in 0-5 cm soil layer was decreased by whole-course herbicide treatment,while that might be increased by rapeseed straw mulching.In the treatment of 3500 kg/hm^2 mulching+spraying herbicide 30 d later after straw mulching,the effect on weed control and cotton yield was more identical with that of the whole-course herbicide treatment.As a result,it is recommended that 3500 kg/hm^2 mulching+spraying herbicide 30 d later after straw mulching should be put in practice in the rapeseed-cotton continuous cropping system along the Yangtze River in Anhui Province.