Effect of sequential application of herbicides on yield and nutrient uptake of greengram (Vigna radiata L. Wilczek), soil microbial parameters and imazethapyr residue status in soil

摘要

The present field experiment was conducted at New Delhi during rainy season (2013) to evaluate the effect of sequential application of herbicides on yield, nutrient uptake of greengram, soil microbial parameter and status of imazethapyr residue in soil after crop harvest. Sequential application of herbicides found to be more efficient in improving yield, nutrient uptake by greengram and soil microbial parameters compared to their one-time application. Pendimethalin @ 1 kg/ha pre-emergence (PE) followed by (fb) 1 hand weeding (HW) at 30 days after sowing (DAS) resulted in highest seed yield (1.1 t/ha), stover yield (1.85 t/ha), protein content (24.12%). The same treatment also recorded maximum nutrient uptake by the crop, lowest nutrient uptake by weeds and maximum value of microbial biomass carbon (MBC) and dehydrogenase activity (DHA). However, this treatment did not differ significantly from pendimethalin @ 0.75 kg/ha PE fb imazethapyr @ 75g/ha POE at 30 DAS indicating that sequential applicationof herbicides could be an efficient alternative to manage weeds in greengram, particularly under labour constrained conditions. Imazethapyr degrades in soil by the time of crop harvest since no residues were found in soil after greengram harvest.