江苏省棉区棉田杂草群落发生分布规律的数量分析

Quantitative analysis of weed communities in cotton fields in cotton growing regions of Jiangsu Province

在对江苏省四大主产棉区82个样点727块田地共57.5hm2棉田杂草群落及草害进行7级目测法调查采集数据后,对其进行主成分分析(PCA),并赋以生态学意义的解释。研究表明,江苏省棉田杂草的发生和分布与轮作种植制度和地理区域性密切相关,其中轮作制度导致的田间水分的巨大差异是决定杂草群落结构特征的最深刻的原因,导致全省水旱轮作棉田的杂草群落有趋同性。而地理区域性构成的土壤、气候等生态因子的差异的显著影响表现在对旱地棉田的杂草群落上。数量分析的结果,可将全部样点分成4个组,即1个水旱轮作组和3个旱地组(淮北棉区、沿海棉区和沿江棉区旱地组),每组都对应着相应的优势杂草种。其中稗、马唐、鳢肠和千金子是水旱轮作组的优势杂草;淮北棉区旱地组的优势种为牛筋草,马唐和马齿苋,马唐、铁苋菜和刺儿菜为沿海棉区旱地组的优势杂草,沿江棉区旱地组的是马唐、狗尾草和铁苋菜。根据杂草群落发生的特点,提出了相应的杂草防除策略。

The outputs of a principal component analysis (PCA) were ecologically interpreted, after the overall weed infestation indexes of all weed populations occurred in 82 sampling sites amounted to 57 5hm 2 cotton fields was assessed by visual scoring the level of weed infestation to cotton in seven scales. There was a close correlationship among the structure of weed community, crop rotation system and geographical factors. The marked difference in water content of soil resulted from the different crop rotation system with rice or dry crop significantly diversified weed distribution and occurrence in the cotton fields. The cropping rotation system with cotton rice resulted in identity of weed communities in the cotton fields. While soil and climate factors determined by geographical regions significantly influenced the communities in the cotton fields with succession of dry cropping system. All sampling sites were divided into four groups by PCA. The group of cotton cropping of rotation with rice had such dominants as Echinochloa crusgalli, Digitaria sanguinalis, Eclipta prostrata and Leptochloa chinensis. Three dry cropping succession groups respectively were Huaibei cotton growing region group with dominant weed Eleusine indica, Digitaria sanguinalis and Portulaca oleracea, Yanhai cotton growing group with Digitaria sanguinalis, Acalypha australis and Cephalanoplos segetum, and Yanjiang cotton growing group with Digitaria sanguinalis, Setaria viridis and Acalypha australis from the north to the south. According to the above weed distribution and occurrence pattern, weed control strategy was suggested.