LABORATORY STUDIES ON THE ALLELOPATHIC POTENTIAL OF SORGHUM AND SUNFLOWER WATER EXTRACT AND POWDER AGAINST NARROW-LEAF SUMMER WEEDS
Abstract
Allelopathy refers to the direct indirect effect of one plant on nearby growing plants of another species in terms of inhibiting the germination and growth through release of chemical compounds. Weeds are major menace in reducing crop yield and can be managed effectively through phytotoxic properties of plants. The laboratory studies were carried out to evaluate the response of summer weeds to sorghum and sunflower water extract and powder in terms of germination and seedling growth at Seed Testing Laboratory, Department of Agronomy, Sindh Agriculture University, Tandojam, Pakistan during Kharif 2010 and 2011. The experiment was laid out in three replicated completely randomized design (CRD). The respective treatments included check (untreated), sorghum/ sunflower shoot/ root powder (10 g kg-1 soil) and shoot/ root water extract (10 ml kg-1 soil). The analysis of variance of two years pooled data showed that water extracts and powders of allelopathic crops caused substantial reduction in germination and growth of tested summer weeds such as jungle rice (Echinochloa colonum L.), bermuda grass (Cynodon dactylon L.) and purple nutsedge (Cyperus rotundus L.). The results revealed that minimum germination, shoot/ root length and fresh/ dry weight of weeds was noticed under sorghum shoot powder (10 g kg-1 soil), followed by sunflower shoot powder (10 g kg-1 soil). The respective water extracts of sorghum and sunflower shoots also exhibited significant allelopathic efficacy. The powder and water extract of shoot were found more allelopathic as compared to powder and water extract of root of both crops. Hence, it is concluded from the trend of above results under laboratory conditions that allelopathic compounds are present in sorghum and sunflower and the plant material of these crops could be utilized as water extracts, mulching or soil incorporation to control narrow-leaf weeds of summer season field crops effectively and with low-cost as environment friendly strategy.
