An evaluation of weed interference in rice grown on hydromorphic soils in West Africa.

摘要

Field, screenhouse, and laboratory experiments were conducted to study weed interference in rice grown on hydromorphic soils at the International Institute of Tropical Agriculture (IITA) at Ibadan, Nigeria.;Rice and weeds emerged at the same time, 1 week after planting. Weed dry weight was significantly reduced when the crop was kept weed-free for at least 4 weeks after emergence. Initial weeding for 2 weeks was not effective, because weeds reappeared and competed actively with rice plants. Season-long weed competition reduced rice grain yield by 73%.;Weed competition reduced the number of tillers and panicles of rice. The detrimental effect of early weed interference was not offset by keeping the crop weed-free later in the growing season. At 6 weeks after emergence, most of the weed species had reached flowering stage when rice was still producing tillers. Handweeding at 2 and 6 weeks was effective enough to reduce weed pressure. Rice seems to be most sensitive to weed interference during this period from the second to the sixth week.