Evaluating the Allelopathic Effect of Jatropha curcas Aqueous Extract on Germination, Radicle and Plumule Length of Crops

Investigations to find out the effect of aqueous extracts of Jatropha curcas on four traditional crops (Phaseolus vulgaris, Zea mays, Lycopersicon lycopersicum & Hibiscus esculentus) was examined. Aqueous extracts from leaves (L) and roots (R) of Jatropha curcas were prepared at different concentrations of 2%, 4%, 6%, 8%, 10% and applied to the test crops. All the crops were affected by the different concentrations of aqueous extracts. The most pronounced effect was on H. esculentus, where germination, radicle and plumule length were reduced by a range of 58.34%-97.92%, 35.84-94.33% and 1.65-87.55%, respectively. Extract at higher concentrations of J. curcas had a strong inhibitory effect on germination, radicle and plumule length of all the test crops. The highest inhibition of seed germination was by 5.26% in R for Z. mays, 24.28% in R10 for L. lycopersicum, 15.41% in R10 for P. vulgaris and 97.92% in Li0 for H. esculentus. The highest reduction in radicle length of 65.34%, 91.03%, 65.95% and 94.33% was recorded at L8, L8, L10, L10 for Z. mays, L. lycopersicum, P. vulgaris and H. esculentus, respectively. The highest inhibitory effect in plumule length was 70.08%, 87.15%, 66.35% and 87.55% at L8, L10, L10 and L10 for Z. mays, L. lycopersicum, P. vulgaris and H. esculentus, respectively. The inhibitory effect suggests the presence of allelochemicals that could inhibit the growth of the crops. © 2010 Friends Science Publishers