稗对水稻生长和产量性状的影响及其经济阈值

稗Echinochloa crusgalli Beauv.在稻田的发生危害对水稻生产造成了严重威胁.为明确稗对水稻生长的影响及其经济危害允许水平,采用添加系列试验和模型拟合的方法研究了不同稗草密度下水稻各产量性状的变化规律.研究结果表明,水稻在稗的竞争干扰下,植株的分蘖数、有效穗数、千粒重及产量均随稗草密度的增加而逐渐降低.指数模型y=beax可以较好地拟合稗对水稻分蘖数(y=493.74e-0.0164x,P＜0.0001)、有效穗数(y=437.2e-0.0165x,P＜0.0001)及千粒重(y=21.876e-0.0006x,P＜0.005)的影响,而对数模型y=aLnx b拟合稗与水稻产量(y=-1250.4Lnx 6375.4,P＜0.0001)及产量损失(y=18.844Lnx 3.9182,P＜0.0001)间的关系最佳.稻田使用乙苄、丁草胺、禾大壮、二氯喹啉酸等药剂进行化学除草时,稗的经济危害允许水平在0.71%～1.10%之间,经济阈值在0.85株/m2左右.

Influence of barnyardgrass, Echinochloa crusgalli, on the growth and yield of paddy rice and its economic threshold

The occurrence and infestation of bamyardgrass,Echinochloa crusgalli Beauv.,in paddy fields constitutes a major threat in rice production.To determine the influence of barnyardgrass on the growth of pad- dy rice and its economic infestation level,additive series experiment and curve fit were adopted to study the change of rice yield characters under different density of barnyardgrass.The results showed that with the inter- ference of barnyardgrass,the tillers,effective spikes,1000-grain weight and yield of paddy rice decreased gradually as the weed density increased.The exponential regression model y=be~(ax) was relatively better for de- scribing the relationship between barnyardgrass density and rice tillers (y =493.74e~(-0.0164x),p<0.0001),ef- fective spikes (y=437.2e~(-0.0165x),P<0.0001)and 1000-grain weight (y=21.876e-(0.0006x),P<0.005), while logarithmic regression model y=aLnx+b was the best for rice yield (y=-1250.4Lnx+6375.4,P< 0.0001)or yield loss (y=18.844Lnx+3.9182,P<0.0001).When herbicide such as acetochlor+bensul- furon-methyl,butachlor,molinate or quinclorac was used to control barnyardgrass in paddy fields,the eco- nomic infestation level for barnyardgrass was 0.71%-1.10% and the economic threshold was about 0.85 plant/m~2.