Pakistan Journal of Biological Sciences1028-88801812-5735Asian Network for Scientific Information10.3923/pjbs.2000.463.465Sorghum bicolor L.) under Rainfed Conditions]]>ShakoorAbdul IslamShamsul NaeemM. 3200033Sorghum variety PARC-SS-2 was subjected to five different herbicides with different levels of active ingredients for control of weeds in comparison with hand-weeded and un-weeded check during summer seasons of 1997 and 1998 at the National Agricultural Research Centre Islamabad. Weed population significantly reduced from 73.79 to 90.04 percent due to the application of various herbicides and by 78.69 percent due to hand weeding over the un-weeded check. Reduction in weed population per unit area was more in the increased levels of herbicides. All treatments gave significantly higher grain yields than the unweeded check in both the years. The grain yield of the plots treated with Metolachlor+Atrazine at 1.00 kg ha1 was significantly more than the plots treated with either dose of other herbicides or hand weeded in both the years. At the two levels of herbicides the increase in yield ranged from 845 to 1144 kg ha1 through Metolachlor+Atrazine at 1.00 kg ha1, 328 to 1144 kg ha1 by hand weeding and 665 to 1750 kg ha1 by Metolachlor+Atrazine at 0.75 kg ha1, as compared to no weeding. As such, increase in the levels of herbicides increased the yield. It was found that the yield from hand-weeded plots was more than all the herbicides at either level. However, Metolachlor+Atrazine at 1.00 kg ha1 (ai), higher level resulted significantly higher yields than the hand weeded ones. The effect of the lower level of Metolachlor+Atrazine at 0.75 kg ha1 (ai), was at par with hand-weeded plots. Though the difference was there, but it was non-significant statistically. The higher doses of these herbicides which have resulted significant grain yield, could be considered for higher return. The economic analysis revealed that there was increased net income from the plots treated with herbicides or hand weeded over the unweeded check. The highest marginal rate of return (MMR) of 404.16 percent was obtained from T3 (the plots treated with Metolachlor+Atrazine at 1.00 kg ha1 (ai) followed by T6 (Metolachlor+Atrazine at 0.75 kg ha1 (ai) with MRR of 297.22 percent while that of hand weeded treatment the MRR was 229.54 percent.]]>Balyan, J.S. and R.R. Singh,198631235239Balyan, J.S. and R.R. Singh,19878243251Bishnoi, U.R., D.A. Mays and M.T. Fabasso,1990129117120Dowler, C.C., R.L. Nichols and C.W. Swann,19831983Fisher, R.A. and F. Yates,19385th Edn.,Greer, H.A.L. and C.E. Denman,19831983Gopal, V.R. and S.M. Kondap,198618111Latehanna, A.,198712393394Lee, S.S. and S.J. Choi,198934113119Da Silva, J.B., T. Passini and A.C. Viana,1986124345Tanchev, D.,1989268791