Weed management in a direct-seeded rice-ratoon rice cropping system

A field study was conducted to evaluate the effect of weed management practices in the main crop on growth, yield and economics of rice- ratoon rice cropping system in two consecutive years i.e., 2014-15 and 2015-16. The result showed that Cyperus difformis was the most dominant weed in the main rice crop, whereas Ludwigia adscendes was the dominant weed in ratoon rice. In weed-free plots, the main crop recorded the highest productivity of 47.52 kg/ha/day, whereas the ratoon crop registered productivity of 37.70 kg/ha/day which was the 79.3% of the main crop productivity. In the weedy plot, crop-weed competition caused 28.8 and 37.5% reduction in energy use efficiency and energy productivity of the rice-ratoon rice cropping system respectively. Yield reduction of 37.3 and 43.6% in the main crop and ratoon crop respectively recorded due to weed infestation in weedy check. All the weed control practices registered an increase in system productivity, nutrient uptake and energy use efficiency. Among the herbicidal treatments, application of bensulfuron-methyl + pretilachlor (60 + 600 g/ha) at 10 DAS to the main crop registered a higher net return of USD$ 639.2 and 260.1 of main crop and ratoon crop, respectively. Hence it can be recommended for weed management in rice-ratoon rice cropping system.