ALLELOPATHIC ACTIVITY OF SUNFLOWER RESIDUES IN BREAD WHEAT GROWTH

Abstract

Two factorial experiments in RCBD with four replicates were conducted separately during winter season 2001-2002 to evaluate the allelopathic potential effects of sunflower residues cv. Euroflor and Alamo on wheat growth cvs. Abu- ghraib 3 and IPA 99. The results obtained showed that residues in soil of both sunflower cultivars caused significant reduction in plant height and dry weight of both wheat cultivars. Euroflor residues at rate of 6 g/kg soil found to be the most allelopathic which caused 9.98 and 9.34% reduction in height of wheat cv. Abughraib 3 and IPA 99 respectively. Similarly residues of Euroflor significantly reduced dry weight of wheat cv. Abu-ghraib 3 and IPA 99 by 38.8 and 47.4% respectively Euroflor residues at rate of 3 g/kg soil caused 4.40 and 5.45 reduction in plant height, while 18.9 and 31.2% reduction in dry weight of wheat cv. Abu- ghraib and IPA 99 respectively. Alamo residues at rate of 6 g/kg soil, however, appeared to be the least one which caused reduction of 7.24 and 6.65% in height, while 29.7 and 11.5% reduction in dry weight of Abu-ghraib 3 and IPA 99 respectively Alamo residues at rate of 3 g/ kg soil caused 2.50 and 3.60% reduction in plant height while 8.8 and 7.2% reduction in dry weight of wheat cv. Abu-ghraib and IPA 99 respectively. The results indicated that Alamo residues has less allelppathic potential effects then Euroflor residues and differences in allelopathic activity of both sunflower cultivars varies according to the rate of residues presented in soil. Wheat cultivar IPPA 99 appeared to be more sensitive then Abu-ghraib 3 to Euroflor residues presented in soil even at lower rate. The present study suggests that cultivation wheat next to sunflower probably the causative factor responsible for the growth reduction of wheat, although this reduction depends upon cultivars grown. It was concluded that the toxicity of sunflower residues could be minimized by cultivating wheat cultivars which can resist the phytotoxic effect.