施肥与秸秆还田对太湖稻-油复种系统春季杂草群落特征的影响

LONG-TERM EFFECTS OF STRAW RETURNING & FERTILIZATION ON COMMUNITY CHARACTERISTICS OF SPRING WEED IN RICE-RAPE SEED CROPPING SYSTEM

掌握不同管理模式下稻田杂草群落特征,可以为杂草综合防治及农田生物多样性的保持提供理论依据和技术途径。借助稻—油复种系统长期定位施肥试验(江苏吴江,始于1987年),于2007年春季监测长期不同施肥和秸秆还田对农田杂草群落的影响。施肥与秸秆还田对春季稻田杂草群落结构特征存在显著作用。长期有机无机肥配合施用下(化肥+猪粪+秸秆)杂草生物多样性和生物量均下降;长期不施氮肥下杂草总密度显著增高,达1 810 ind./m2;长期不施肥时,田间野老鹳草成为优势种群,其相对密度达87.9%;全年秸秆还田(化肥+油菜秸秆+水稻秸秆)下,田间优势杂草种群为禾本科的看麦娘,其相对密度达69.7%;秋熟水稻秸秆还田下杂草生物量下降,而生物多样性显著提高。上述结果表明,通过合理施肥和秸秆还田措施,可以对稻油复种模式中春季杂草群落进行有效调控。

Crop management practices, such as fertilization and straw returning, have great impact on weed community. However, little is known about the effects of long-term fertilization and straw returning on weed community. In this study, we investigated the characteristics of spring weed community in rice-rape seed cropping system with different long-term crop management regimes in 2007 （the site located in Wujiang County,Jiangsu Province,and the experiments started in 1987）. There were significant differences in spring weed community composition among different management patterns. Low biodiversity and total biomass of spring weed existed in the plots with long-term chemical-organic fertilizer （chemical fertilizer plus pig manure and straw returning）. Long-term non-nitrogen fertilization significantly increased the total density of spring weed which was up to 1 810 ind./m^2. In addition,carolina cranesbill gradually became the dominant weed in the non-fertilization plots,its relative density reached at 87. 9 % ;Alopecurus aequalis S. gradually became the dominant weed in crop-straw-returning-in autumn-and-summer （chemical fertilizer plus rice and rape straw returning） plots,the relative density reached at 69.7%. Straw returning in autumn decreased the total biomass of spring weed,but increased weed biodiversity. Spring weed community could be controlled through adjusting the regimes of fertilization and straw returning in rice-rape seed cropping systems.