Weed management approaches in transplanted rice in Mollisols of Uttarakhand

摘要

Rice (Oryza sativa L.) is one of the most important cereal crops in India cultivated in 43.9 Mha area with the total production of 106.5 Mt and a productivity of 2.4 t/ha (Economic Survey, 2014-15). Rice as staple food has tremendous influence on agrarian economy of India since it contributes 45% of the total food grain production. Infestation of weeds is one of the most important causes for low yield of rice (Pandey 2009). Transplanted rice is infested with heterogeneous group of weeds comprising ofgrasses, broad-leaf weeds and sedges causing yield reduction up to 76% (Singh et al. 2004). Among different weed species, grassy weeds pose greater competition as they have an extensive and fibrous root system. Similarly, sedges grow in huge number andcause serious competition for nutrients as they dominate the surface feeding zone and obstruct nutrient flow to crop roots. Broad-leaf weeds being deep rooted explore the sub-surface zone for minerals and exert less competition for nutrients with rice (Puniya et al. 2007). Manual weeding is expensive, time consuming, labour intensive, tedious, back-breaking, difficult and often limited by scarcity of "laborers in time. Herbicidal weed control offers an advantage to save labour and money, as a result, regarded as cost-effective (Ahmed et al. 2000). Application of herbicide mixture or sequential application of pre- and post-emergence herbicides or its integration with other methods of weed control may be effective for broad-spectrum management of weed flora in transplanted rice. Therefore, the present study was undertaken to quantify the effect of different weed control treatments either alone or in combination on weed abundance, growth parameters and yield performance of transplanted rice.