Bio-efficacy of sequentially applied herbicides on weed competition and crop performance in dry direct-seeded rice (Oryza sativa)

A field experiment was planned and executed in a randomized block design at New Delhi, during the rainy season of 2016, to evaluate the bio-efficacy of different pre-and post-emergence herbicides applied sequentially on weed dynamics and crop performance in direct-seeded rice (Oryza sativa L.). The soil of the experimental plot was sandy loam in texture with pH 7.9, low in organic C (0.49%) and available N (220 kg/ha), and medium in available P (16 kg/ha) and K (255 kg/ha). All the treatments involving pre-and post-emergence herbicides reduced the total weed density and weed biomass significantly. Season-long weedy condition reduced the grain yield to the extent of 81% as compared with weed-free check. Sequential application of pendimethalin (1 kg a.i./ha) as preemergence followed by a mixture of penoxsulam + cyhalofop butyl (130 g a.i./ha) as post-emergence exhibited significant reduction in weed density and dry-biomass accumulation, resulting in a considerable increase in weedcontrol efficiency (84.49%) and productivity (3.92 t/ha).