Allelopathic effects of aqueous extracts of the legumes crotalaria [Crotalaria juncea (L.) 'Tropic Sun'], jack bean [Canavalia ensiformis (L.)] and pigeon pea [Cajanus cajan (L.) 'Lázaro'] on crop development

Abstract

Allelopathic effects of aqueous extracts 3.3% w/v of crotalaria [Crotalaria juncea (L.)' Tropic Sun'], jack bean [Canavalia ensiformis (L.)] and pigeon pea [Cajanus cajan (L.) 'Lázaro'] were determined on seven agronomic crops: corn (Zea mays 'Mayorbela 2011'), sorghum (Sorghum bicolor), bean (Phaseolus vulgaris 'Verano'), soybean (Glycine max), cowpea [Vigna unguiculata (L.)], lettuce [Lactuca sativa (L.) 'Nevada'] and pigeon pea in the laboratory. There was interaction between aqueous extracts x agronomic crops on the seventh day of germination. Allelopathic effect was determined by contrasting with the control coleoptile and radicle length in corn and sorghum, and the hypocotyl and radicle length in bean, soybean, cowpea, lettuce and pigeon pea. Sorghum and lettuce showed growth inhibition of the coleoptile and hypocotyl (respectively) and radicle when treated with the three aqueous extracts, where jack bean aqueous extracts showed higher inhibitions percentages (66% in lettuce and 49% in sorghum). By contrast, corn, bean and cowpea treated with crotalaria aqueous extracts exhibited growth stimulation. According to these results, field experiments must be conducted using legume associations with agronomic crops to confirm if the interactions stimulate or inhibit crop development because environmental factors are a major determinant of allelopathic effects.