水直播稻田杂草竞争临界期及苗后一次化除研究

Critical Period of Weeds-Rice Competition and One-Time Herbicide Treatment after Emergence in Direct-Seeding Rice Fields

对冬小麦-水稻连作制度下的水直播稻田杂草发生动态进行监测,建立水稻播后有草/无草天数与水稻产量损失率之间的函数关系,推导出杂草与水稻的竞争临界期,并探讨水直播稻田杂草苗后一次化除技术方案。结果表明,水稻产量损失率随水稻播后有草天数的增加而增大,随无草天数的增加而降低;以3%作为水稻产量损失的最大忍受限度,则四川省水直播稻田杂草与水稻的竞争临界期为播后16~55 d。水稻播后15 d喷施3%氯氟吡啶酯乳油22.5 g a.i./hm^2+300 g/L丙草胺乳油450 g a.i./hm^2,播后20 d喷施20%二氯喹啉草酮可分散油悬浮剂600 g a.i./hm^2+75%氯吡嘧磺隆水分散粒剂33.75 g a.i./hm^2+100 g/L氰氟草酯乳油150 g a.i./hm^2,或11%[口恶]唑酰草胺·五氟磺草胺可分散油悬浮剂123.75 g a.i./hm^2对水直播稻田总杂草的鲜重防效均在98%以上,且对水稻安全。

The occurrence dynamics of weeds in direct-seeding paddy fields under a continuous cropping system of winter wheat and rice was monitored,to establish the functional relationship between days from sowing in presence and absence of weeds and the rice crop yield.The threshold period of weeds-rice competition was determined and the efficacy of a one-time postemergence herbicide treatment was assessed.Crop yield loss rate raised with the number of days weeds interfered with the crop.Conversely,yield losses declined with the period the crop remained weed-free.The critical period of competition between weeds and rice was about 16 to 55 days after sowing in Sichuan province.Florpyrauxifen-benzyl(3%EC)appliedat22.5ga.i./hm^ 2in mixture with pretilachlor(300g/LEC)at 450 g a.i./hm^ 2 at 15 days after sowing provided above 98%weed control and selectivity to rice.Al alternative treatment is the mixture of quintrione(20%OD)at 600 g a.i./hm^ 2 plus halosulfuron-methyl(75%WG)at 33.75 g a.i./hm^ 2 plus either 150 g a.i./hm^ 2 cyhalofop-butyl(100 g/L EC)or 123.75 g a.i./hm^ 2 metamifop·penoxsulam(11%OD)20 days after sowing.