Effect of weed and fertilizer management on weed control and productivity of onion (Allium cepa)

Abstract

An experiment was conducted to examine the effect of weed management and plant nutrition practices on weed biomass, growth parameters and bulb yield of onion ( Allium cepa L.). Weed management practices included alone application of herbicides, viz. pendimethalin, oxyfluorfen and fluazipop-p-butyl, their combination with hand weeding, weed free and weedy check. The crop was fertilized with three levels viz., 75% RDF, RDF (100:50:50 NPK kg/ha) and 125% RDF. The results indicated that weed management and fertilizer levels had a significant ef- fect on weed population dynamics and onion bulb crop. The total weed density decreased significantly with appli- cation of pendimethalin 1 kg/ha or oxyfluorfen 0.24 kg/ha + one hand weeding at 40 days after transplanting (DAT) during both the seasons of investigation. Echinochloa ssp., Trianthema portulacastrum, Digera arvensis Forsk. Physalis minima L. and Cynodon dactylon (L.) Pers. were found as major weeds in the crop. Higher onion bulb yield (38.0 t/ha) was recorded with pendimethalin 1 kg/ha + one hand weeding at 40 DAT. The increase in yield was 83.7% compared to the yield obtain in weedy check. Increasing level of fertilizer applications increased the to- tal biomass of grassy and broad leaves weeds. Application of 125% RDF significantly improved bulb yield and in- crease in yield was 19.4 and 10.5 % over 75% RDF and RDF respectively. On the basis of interaction, combina- tion of pendimethalin 1 kg/ha fb 1 hand weeding at 40 DAT and 100 % RDF was most productive (39.8 t/ha) and profitable (Net return `2,69,422/ha and benefit: cost ratio 7.85).