Efficacy of herbicides and fertilizer management on weed dynamics in wheat (Triticum aestivum)

A field experiment was conducted during winter (rabl) season of 2002-03 and 2003-04 to study the efficacy of herbicides and fertilizer management on weed dynamics of wheat (Tn'ticum aestivum L. emend. Fiori & Paol.). The intensity of weeds as well as total weed count were unaffected by the method and level of fertilizer applica- tion, but side placement of fertilizer significantly reduced the total dry biomass of weeds, NPK depletion by weeds that improved the NPK uptake by the crop and produced 13.5 per cent higher grain yield than broadcast method of fertilizer application. Application of 125 per cent of the recommended dose of fertilizer (RDF) although recorded significantly higher dry biomass of weeds and NPK depletion by weeds than 75 per cent of the RDF, it increased the NPK uptake by crop and grain yield. Weed-control treatments significantly reduced the intensity of broad-leaf weeds, annual and perennial grasses, total weed count, dry biomass of weeds and NPK depletion by weeds, and increased the NPK uptake by the crop. These treatments increased the grain yield by 26.3-35.9 per cent than the weedy check. Among the weed-control treatments, sulfosulfuron proved the most effective herbi- cide against broad-leaf weeds and annual grasses, reducing their intensity as well as that of total weeds than the mixture of 2,4-D + isoproturon and hand-weeding but had no adverse effect on perennial grasses and sedges. However, hand-weeding significantly reduced the intensity of perennial grasses and sedges. Sulfosulfuron also recorded significanty lower total dry biomass of weeds and NPK depletion by weeds than the mixture of 2,4-D + isoproturon and showed the highest weed-control efficiency.