THE IMPACT OF CHEMICAL AND NON-CHEMICAL WEED CONTROL METHODS ON WEEDS DYNAMICS AND ON THE YIELD OF ONION (Allium cepa L.).

Field trials were conducted at Agriculture Research Farm, Khyber Pakhtunkhwa Agricultural University Peshawar to investigate the effect of different mulches a0nd herbicides on weeds dynamics as well as on yield and yield components of onion crop. The experiment was laid out in a randomized complete block design (RCBD), using various treatments including five herbicides (viz. glyphosate @ 2.28, paraquat @ 0.75, fenoxaprop-p-ethyl @ 0.729, s-metolachlor @ 1.2 and pendimethalin @ 0.853 kg a.i. ha-1), two mulches (i.e. wheat straw mulch @ 6 and saw dust @ 8 t ha-1), a hand weeding (done twice) and a weedy check. Glyphosate and paraquat were applied as post-emergence to weeds, pendimethalin and mulches were applied as pre-emergence to weeds and crop and fenoxaprop-p-ethyl was also applied as post-emergence to weeds and crop. The onion nursery was transplanted during the second week of March, 2008. The data were recorded on fresh and dry weed biomass (g m-2), volumetric size of onion bulbs (ml), onion bulb diameter (cm), onion yield (kg ha-1) and economic evaluation. The maximum bulb yield of onion (15.39 t ha-1) was recorded in treatments of pendimethalin and minimum was recorded in weedy check and saw dust (3.62 and 4.21 t ha-1, respectively). Regarding the economic evaluation, the pendimethalin and fenoxaprop-p-ethyl were the most economical treatments that resulted in yields of 15930 and 14210 kg ha-1, respectively. [ABSTRACT FROM AUTHOR]