ALLELOPATHIC EFFECT OF COWPEA (Vigna unguiculata) SHOOT AND ROOT AQUEOUS EXTRACTS ON GERMINATION AND GROWTH OF MAIZE IN IBADAN, NIGERIA

Abstract

Plants generate various secondary metabolites referred to as allele-chemicals that can be released into the environment and influence the growth and development of other plants. The germination and growth response of seedlings of Zea mays L. to aqueous shoot and root extracts of Vigna unguiculata was assayed in the laboratory and screen house. Shoot and roots of V. unguiculata Walp were harvested, air–dried and milled into fine powder. Milled samples (144, 72, 36 and 0 g), were dissolved in 1 L distilled water to obtain 100, 50, 25 and 0% concentration of Aqueous Shoot Extracts-ASE and Aqueous Root Extracts-ARE. Ten seeds were germinated in Petri dishes lined with filter paper, then soaked with aqueous extract solutions. The treatments (7) were replicated three times. After seven days, data was collected on percentage germination, radical and plumule length. Twenty-eight (10 kg) polyethylene bags comprise of seven treatments and four replicates was used. Two maize seeds were sown and later thinned to one seedling per bag. Thereafter, 300 mls of each treatment was administered from two to eight weeks after sowing. Growth parameters were obtained and data analyzed following standard procedure. Above 70% germination was recorded for maize in all the ASE concentration and ARE-100 gave least (53.33±1.08%). The ASE-25 had highest Dried Shoot Weight-DSW (31.78±1.19g) and Dried Root Weight-DRW (11.90±0.66g), respectively. The ARE-100 gave least DSW (20.02±0.74g) and DRW (6.52±0.87g) in maize. Vigna unguiculata Walp aqueous shoot extract enhanced germination, while aqueous shoot extract at 25% encouraged dry matter accumulation.