Weed Population Dynamics as Influenced by Tillage, Fertilizer and Weed Management in Wheat (Triticum aestivum L.) Cropping Systems of Central Ethiopia

Abstract

Field experiments were conducted at Holetta, central highlands of Ethiopia during 2002 and 2003 to determine the combined effects of tillage, fertilizer and weed management on weed population dynamics in bread wheat (Triticum aestivum L.) field. The results indicated that tillage, fertilizer and weed management systems had a significant effect on weed population dynamics. The total amount of weed density tended to increase in no tillage than conventional tillage or moldboard plow in both years. The magnitude change ranged from two to four folds when comparing densities in no tillage with the others. Among the dominant weeds, Polygonum nepalense, Galinsoga parviflora, Plantago lanceolata, Ganaplium unions, Spergula arvensis, Setaria pumila, Bromus pectinatus, Echinocloa colona, Snowdenia polystachya and Phalaris paradoxa, were significantly reduced in density (P<0.05) by moldboard plowing relative to other tillage systems. Tillage did not influence yield in both years. Tank mixture of fenoxaprop-P-ethyl and fluroxypyr +MCPA resulted in a significant reduction of total weed number and increased wheat yield by 30% followed by hand weeding twice in both years. Applications of fertilizer increased total broad leaf and grass weed biomasses. Fertilizer is more important than tillage in affecting yields and yield components. It improved grain yield up to 40% over the untreated control plots in both years. Weeding without fertilizer did not affect grain yield. Weeding and fertilizer significantly increased grain yield in both years. The interactions between tillage and fertilizer, between tillage and weed management and between fertilizer and weed management for total weed densiies, weed biomasses, plant heights, straw yields and grain yields were significant.