ALLELOPATHIC EFFECT OF THREE WEED SPECIES ON THE GERMINATION AND SEEDLING GROWTH OF TOMATO (LYCOPERSICON ESCULENTUM)

Abstract

Laboratory and green house experiments were conducted to ascertain the effect of exudates (from the vegetative parts of the weeds soaked in water) of different ages (36hrs, 72hrs and 120hrs) from three common weed species (namely, Chromolaena odorata, Ageratum conyzoides and Cyperus esculentus) on the seed germination and seedling growth of tomato (Lycopersicum esculentum). Tomato seeds were sown in petri-dishes on filter paper moistened with the treatments, and another set of tomato seeds were sown in soil, and treatments applied. The exudates of C. odorata had the greatest inhibitory effect on seed germination on filter paper, while those of A. conyzoides followed closely. C. esculentus had the least inhibitory effect. The weed exudates however did not have marked inhibition on seed germination and seedling growth in the soil medium; rather, they competed favorably with the Control. It was observed that the longer the soaking duration of the weeds in water, the less inhibitory their exudates were on seed germination, with water dilution. All the three weed species considered showed allelopathic effects, but especially C. odorata and A. conyzoides when in direct contact with tomato seeds