关键词: LM-BP神经网络, LM-BP神经网络, 灰色关联模型, 主成分分析, 土壤养分等级

Abstract: To clarify the weed community succession and its impact factors, mitigate malignance succession of weed community in paddy field and provide a basis for standard weed control system, by fixed-point notation and random visual inspection, fixed-point system observation and field investigation were conducted, weed species, community composition and damage status were studied, and the survey results were compared with that of 1993. The results showed that the occurrence frequency of cyperus difformis, reed, rice millet, eleocharis congesta decreased, while that of wild arrowhead, Monochoria, monochoria vaginalis, Alisma, leerisia orygoides L, Grape stem Agrostis increased, weed community in paddy field changed from the pattern of“gramineous weeds + sedge weeds + broad leaved weeds”to the pattern of“broad leaved weeds + gramineous weeds + sedge weeds”. The succession of weed communities in paddy field was influenced by the longtime and large amount application of herbicide, the change of irrigation and cultivation methods and climatic conditions.