EFFECT OF ROW SPACING AND WEED CONTROL METHODS ON WEED DYNAMICS, YIELD COMPONENTS AND YIELD OF BREAD WHEAT (Triticum aestivum L.) AT BALE HIGHLANDS, SOUTH EASTERN ETHIOPIA

ABSTRACT Weed infestation can cause a substantial yield loss in bread wheat in Ethiopia. Hence, the present study was conducted to: assess the effect of row spacing and weed control practices on weed, yield components and yield of bread wheat . Three row spacing (15, 20, 25 cm) and five weed control practices (Pyroxsulam 0.5, 0.37 and 0.25 lt ha-1, weed free and weedy check) were laid out in randomized complete block design (RCBD) in factorial arrangement with three replications. The two experiment field was infested mostly with broad leaf weeds belonging to seven plant families and two major grass weed species (Avena fatual.L) and (Digitaria abyssinica.) were observed on the experimental area while sedge weed were observed only at SARC. The lowest total weed density (7 m-2) and (11.8 m-2) was obtained from 15 cm row spacing with Pyroxsulam 0.5 lt ha-1 at MWU and SARC, respectively. Total weed density, Total weed dry weight and aboveground biomass were also significantly influenced by weed control methods. The lowest total weed dry matter (5.5 g m-2) and (8.1 g m-2 ) was obtained at 15 cm row spacing with 0.5 lt ha-1 Pyroxsulam treatments at MWU and SARC , respectively. Weed free treatment with 15 cm row spacing produced the highest (12417.4 Kg ha-1) above ground biomass. The interaction effect of row spacing and herbicide rate influenced broad leaf weed density, broad leaf dry matter, total and productive tillers, seed per spike, grain yield and harvest index. The minimum broad leafed density (4, 6.1 m-2) was obtained at 15 and 20 cm row spacing combined with 0.5 lt ha-1 pyroxsulam at MWU and SARC, respectively. The maximum weed control efficiency 74, 68.3% were obtained with 15 and 20 cm row spacing respectively. The maximum productive tiller (7.6 per plant) was obtained at 25 cm weed free treatment at SARC. While maximum (57) seed per spike was recorded at 15 cm with Pyroxsulam 0.5 lt ha-1. The maximum grain yield (4985.7kg ha-1) was obtained from plot treated with 15 cm with weed free plot and the maximum (40 %) harvest index was recorded at 15 cm Pyroxsulam at 0.5lt ha-1. Regarding economic analysis the maximum (49246.5 Birr ha-1) net benefit was obtained at combination of 15 cm row spacing and Pyroxsulam 0.5 ha-1. Thus, using of 15 cm row spacing with Pyroxsulam at 0.5lt ha-1 can tentatively be recommended. However, the experiment has to be repeated with different methods of integrated weed management including herbicide combinations for sustainable weed management in wheat