Effect of planting density and weed management options on growth and productivity of Indian mustard

Abstract

A field experiment was conducted during the winter (rabi) season of 2018–19 and 2019–20 at Kalyani, West Bengal, to study the effect of various planting density and weed-management options on growth and productivity of Indian mustard [Brassica juncea (L.) Czern & Coss.]. The field experiment was conducted in split-plot design with 3 replications, having 30 treatments combinations including 3 planting densities in main-plot, viz. 30 cm × 15 cm, 30 cm × 20 cm and 30 cm × 25 cm; and 10 weed-management options in sub-plots which include pendimethalin @ 1.0 kg a.i./ha, oxadiargyl @ 0.08 kg a.i./ha, pendimethalin @ 1.2 kg a.i./ha, oxadiargyl @ 0.10 kg a.i./ha, pendimethalin @ 1.0 kg a.i./ha + 1 hoeing at 30 days after sowing (DAS), oxadiargyl @ 0.08 kg a.i./ha + one hoeing at 30 DAS, pendimethalin @ 1.2 kg a.i./ha + 1 hoeing at 30 DAS, oxadiargyl @ 0.10 kg a.i./ha + 1 hoeing at 30 DAS, weed free and control. Significantly lower weed density and dry-weight of weight observed with 30 cm × 20 and 30 cm × 15 cm plant spacing. Application of oxadiargyl @ 0.10 kg a.i./ha + 1 hoeing at 30 DAS and pendimethalin @ 1.20 kg a.i./ha + 1 hoeing at 30 DAS, greatly reduced different species of weeds and their dry weight. With various main-plot treatments, higher seed yield (1,838 kg/ha) of mustard was observed with the 30 cm × 20 cm planting and was statistically better than the other plant spacings. These treatments resulted in higher seed yield to the tune of 8.18 and 12.84% over the 30 cm × 15 cm and 30 cm × 25 cm plant spacings. Weed-free situation, resulted in the highest seed yield (2,230 kg/ha) and showed parity with pendimethalin @ 1.2 kg a.i./ha + 1 hoeing at 30 DAS and oxadiargyl @ 0.08 kg a.i./ha + 1 hoeing at 30 DAS. These treatments registered 93.5, 89.8 and 88.8% more seed yield over the control plots respectively. Economics revealed that, 30 cm × 25 cm plant spacing gave the maximum net returns (`29,280/ha) with benefit: cost ratio of 1.70. The highest net returns (33,850/ha) were observed from the treatment of pendimethalin @ 1.2 kg a.i./ha + 1 hoeing at 30 DAS with a benefit: cost ratio of 1.74. This was closely followed by oxadiargyl @ 0.10 kg a.i./ha + 1 hoeing at 30 DAS.