WEED COMPETITION AND ITS IMPACT ON GROWTH CHARACTERS OF SOME WHEAT CULTIVARS

Abstract

A field experiment was conducted during 2008-2009 winter season at the Farm of Field Crop Sciences Department, College of Agriculture/ University of Baghdad, to identify the effect of weed competition on growth characters of some wheat cultivars. Randomized Complete Block Design arranged in Split plot was used. The main plots included weed treatments, weedy check treatment, grass weed treatment, broadleaved weed treatment and weed free treatment, while sub plots included wheat cultivars, Tahaddi, Iraq, Fatah, Abu-Graib 3, IPA 95 and IPA 99. The results showed that the percentage of grass weed was 18.75% while the percentage of broadleaf weed was 81.20% , it was also observed that growth characteristics of the different cultivars were affected by weed competition during 92 days after sowing in comparison with other duration, which caused reduction 13.41, 35.37 and 56.8% in leaf area, plant dry weight and crop growth rate respectively at weedy treatments as compared with weed free treatments. Abu-Graib 3 cultivar showed greater tolerance to weed competition as a result of its least affect of growth characteristics of the presence or absence of weeds. Growth characters of IPA 99 cultivar affected by weed competition during the same period with the reduction percentage of weedy treatment were 23.72 and 46.67% in leaf area and plant dry weight respectively. However, Growth characteristics of Fatah cultivar were most affected at 124 days period after sowing with the reduction percentage of 63.3, 94.43, 93.18 and 90.91% in plant dry weight, crop growth rate, net assimilation rate and relative growth rate respectively in comparison with other cultivars. It was concluded from the present study that Abu-Graib 3 cultivar could be the most tolerance one for weed competition, and Fatah and IPA 99 cultivars were the most sensitive to weed competition.