Abstract :
A field experiment was conducted at the Research Block of Institute of Agriculture and Animal Science (IAAS), Rampur, Chitwan, Nepal during winter season of 2007/08 to assess the effect of long-term tillage, mulch and time of N application on weeds in wheat. The experiment consisted of two levels of tillage (no tillage and conventional tillage), two levels of mulch (no mulch and mulch with rice straw @ 4 t ha-1) and two timings of nitrogen application (half at sprouting and half at CRI stage and half at CRI stage and half at 40 days after sowing) and was laid out in factorial RCBD with three replications. This experiment was the continuation of ongoing experiment conducted jointly by IAAS and Cornel University from 2002-2007. The data on weed growth were taken in 2007/08 to determine impact of treatments for long term. Result showed that density and dry matter of weeds were higher in surface seeded plot. In contrast, mulch showed suppressive effect and significantly lower density and dry matter of weeds were found in mulched plot. Different weed species were also observed in weed seed bank of different treatments and the higher numbers of weed species were observed in surface seeded plot, no mulch and half N at sprouting and half at CRI stage. Significantly, higher total weed dry matter, total weed N uptake and wheat grain yield was observed in surface seeded plot. V. spp. in surface seeded plot and C. album in conventionally tilled plot had the highest value of all the quantitative characteristics.
