稗草对双季稻生长的影响及其防除经济阈值研究

稗草是中国南方双季稻稻田的恶性杂草,对水稻生产造成严重威胁。为明确稗草对双季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生长与产量性状的变化规律。结果表明,在稗草的竞争干扰下,双季早、晚稻的株高、分蘖数、有效穗数、每穗实粒数、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=be^ax可以较好地拟合稗草对早稻分蘖数、有效穗数和产量的影响,而二次曲线模型y=ax²+bx+c拟合稗草与株高、每穗实粒数、千粒重和产量损失间的关系最佳;二次曲线模型y=ax²+bx+c均可较好地拟合稗草与晚稻株高、分蘖数、有效穗数、每穗实粒数、千粒重、产量和产量损失间的关系。稻田使用化学除草剂(丁草胺、二氯喹啉酸、五氟磺草胺)防除时,双季早、晚稻稻田稗草的经济危害水平分别为1.64%~2.91%和1.28%~2.28%,经济阈值分别为0.63~1.23株/m²和1.30~1.85株/m²。稗草对水稻生长有抑制作用, 并导致水稻产量损失;通过对经济阈值分析,化学除草剂防治稗草具有明显的经济优势。

Influence of barnyardgrass (Echinochloa crusgalli)on the growth of double-cropping paddy rice and its economic threshold

Barnyardgrass (Echinochloa crusgalli )is an important weed in double-cropped paddy fields in south-ern China and a significant threat to rice production.To determine the influence of barnyardgrass on the growth of double-cropped paddy rice and its economic infestation threshold,the growth and yield of paddy rice under different barnyardgrass densities were investigated using field experiments and modelling.Results showed that plant height,tiller numbers,effective spikes,grain numbers/panicle,1000-grain weight and grain yield of double-cropped early and late rice decreased with increasing barnyardgrass density.The exponential regression model “y =beax ”was able to adequately describe the relationship between barnyardgrass density and tillers,ef-fective spikes and yield of double-cropped early rice,while a quadratic regression model “y =ax 2 +bx +c ”was best for plant height,grains/panicle,1000-grain weight and yield loss.A quadratic regression model “y =ax 2+bx +c”was best able to describe the relationship between barnyardgrass density and plant height,tillers,ef-fective spikes,grains/panicle,1000-grain weight,grain yield and yield loss of double-cropping late rice.Herbi-cides (butachlor,quinclorac,or penoxsulam)were applied to control barnyardgrass;the economic infestation
levels for barnyardgrass were 1.64% -2.91% and 1.28% -2.28% in double-cropped early and late paddy fields,respectively,and the economic thresholds were 0.63-1.23 plant/m2 and 1.30-1.85 plant/m2 ,respec-tively.Barnyardgrass severely inhibited rice growth and yield.Herbicide application effectively and economical-ly controlled barnyardgrass.