Weed Population Dynamics as Influenced by Seed Rates and Herbicides Application Under Rain fed Wheat (Triticum aestivum L.) Production System

Wheat is one of the most important food security crops which is cultivated from small to large scale farms in Ethiopia. However, its productivity has been limited due to various abiotic and biotic factors including weeds. The aim of the study was to investigate the effects of seed rates and post emergence herbicides application on weed management and productivity of wheat. Factorial combinations of three levels of seed rates (100,150 and 200 kg ha-1)and four types of herbicides (Agro 2,4-D 720 g/L 1lt ha-1,Pallas 45 OD 0.5lt ha-1, Derby 175 SC 100ml ha-1 and Lancolet 450 WG 33 gm ha-1)along with control (a weedy check) were laid out in RCBD with three replications. The field was infested with thee grass weeds and nine broad leaved weed species. Weeds species included Phalais paradoxa L.,Setaria pumila L. and Arthraxon prinodes L. were categorized as grass weed while Polygonum nepalense L., Raphanus raphanistrum L., Plantago lanceoleta L., Corrigiola capensis Wild., Spergula arvensis L., Galinsoga pulviflora Cav., Guizotia scabra (Vis)Chiov, Cyanotis barbata D.Don and Oxalis corniculata HBK. The relative weed density indicated that from the total of identified 12 weed species identified 86 % broad leaf weeds and 14 % grass weeds.Results also revealed that significant effects of seed rate by herbicide interaction for all the traits studied. It was observed that the application of 150 kg ha -1 seed rate with Pallas 45 OD resulted in minimum weed densities of all weed species after application while the maximum weed densities were recorded at weedy checks.The minimum weed densities (4.52 m-2 ) at 25 days after planting (DAP).Longer duration of days to heading was recorded at weedy checks but there is no much significant variation due to other interactions. The maximum plant height was recorded from application of 100 kg ha-1 seed rate at weedy check.The highest number of grain yield (4516.42 kg ha-1) was recorded from the combination of 150 kg ha-1 seed rate with Pallas 45 OD while the lowest values were observed from the weedy check . It was also observed that, the combined use of seed rate 150 kg ha -1 with Pallas 45 OD effectively managed weeds, economical and gave maximum yields, which could be recommended for the test environment. Since the experiment was conducted in one location and for a single season, it should be repeated over seasons or multi locations for best recommendation. Keywords: combination, density, maximum, Pallas 45 OD , significant DOI: 10.7176/JEES/10-3-04 Publication date:March 31st 202