宋英 张自常 顾俊荣 董明辉

摘要：为了进一步明确稗草对水稻生长发育的影响，采用大田试验，设置稗草不同出苗时间和不同密度对机直播稻产量的影响。结果表明，随着稗草出苗时间的延迟，稗草对机直播水稻产量的影响逐渐减弱。当稗草密度是1株/m2（B1）时，稗草对机械直播水稻的产量无显著影响，但当稗草密度为3株/m2（B3），出苗时间为水稻播种后0、7、14 d时，水稻产量均显著降低，稗草出苗时间继续延迟对机直播水稻产量无显著影响;当稗草密度为5株/m2（B5）或7株/m2（B7），出苗时间为水稻播种后0、7、14、21 d时，水稻产量均显著降低，其他出苗时间对水稻产量无显著影响。不同稗草密度对机直播水稻产量的影响表现为稗草在水稻播种后0、7、14、21 d出苗时，水稻产量均随着稗草密度的增加而降低，其他出苗时间对稗草密度对机直播产量无明显影响。机直播水稻与稗草共生过程中稗草较高的分蘖数、株高和干物质积累量造成机直播水稻灌浆期的光合速率、根系氧化力和干物质积累量显著降低，这是机直播水稻产量减产的重要原因。

关键词：稗草;机直播水稻;光合速率;根系氧化力;产量

中图分类号：S451  文献标志码：A  文章编号：1003-935X（2021）03-0067-07

Abstract：To better understand the impact of barnyardgrass on rice growth，a field experiment was conducted to evaluate the effect of different emergence times and density of barnyardgrass on the grain yield of mechanically dry-seeded rice. Rice grain yield gradually decreased along with a barnyardgrass delay in emergence. There was no significant difference in grain yield of rice when the barnyardgrass density was 1 plant/m2（B1），but the grain yield significantly decreased when the barnyardgrass emergence time was 0，7，or 14 days after rice sowing under 3 plant/m2（B3） density treatment，and further delay the emergence time of barnyardgrass under this density had no effect on grain yield. Grain yield markedly decreased when barnyardgrass emergence time was 0，7，14，and 21 days after rice sowing under 5 plant/m2（B5） or 7 plant/m2（B7） density treatment，and the other emergence time of barnyardgrass had no difference on grain yield. Furthermore，rice yield decreased with increased barnyardgrass density when it emergenced at 0，7，14 and 21 days after mechanical sowing，but when the weed emergence later it did not affect grain yield. Above all，the higher tiller number，plant height and dry matter accumulation of barnyardgrass that caused reduction in rice photosynthetic rate，root oxidation and dry matter accumulation at grain filling stage are important reasons for grain yield reduction.

Key words：barnyardgrass;mechanical dry-seeded rice;photosynthetic rate;root oxidation activity;yield

水稻是我国主要的粮食作物之一，其种植面积约占粮食作物的27%，产量约占粮食作物产量的40%以上，全国约有2/3的人口以稻米为主食[1]。傳统的水稻种植以手工插秧为主，但是随着社会经济的发展和农村劳动力的转移，直接务农的青壮年劳动力越来越少，亟须用轻简的栽培技术替代传统种植方式。……