Yield Component Analysis of Direct Seeded Rice Under Several Densities of Red Sprangletop [Leptochloa chinensis (L.) Nees] in Peninsular Malaysia

Abstract

Red Sprangletop [Leptochloa chinensis (L.) Nees] is one of the most serious grassy weeds in direct seeded rice in Peninsular Malaysia. This study was conducted to investigate the effect of weed density on grain yield and yield components of direct seeded rice. A field experiment was carried out at Sarang Semut, the Training Farm of Muda Agricultural Development Authority (MADA), Kedah. It was found that there was no effect of red sprangletop competition on the vegetative growth of rice plants, since heavy rainfall occurred at seedling stage and inhibited the growth of red sprangletop seedlings. Height and tiller number of rice at 45 days after seeding were not affected by weed competition (Table 1). Among yield components, however, the weight of 1000 filled grains was affected by the competition (Table 2) and panicle number/m² had a significant correlation with red sprangletop density (Fig. 5). Panicle number and number of grains/m² had a significant correlation with the rice yield (Fig. 3 and 4). The yield declined significantly when the rice plants competed with the red sprangletop at a density of 16 plant/m², and was even greater as the weed population increased. More than thirty five percent of yield loss was recorded from the plot which had 40 red sprangletop plants/m², while the highest yield of 4.44t/ha was harvested from the plot which was weed free, as a control. These results suggested that the competition occurred between red Sprangletop and rice from the middle stage of vegetative growth to the grain filling stage.