Allelopathic effect of aqueous extract of fresh leaf castor beans (Ricinus communis L.) applied to the beginning stage of soy (Glycine max L.) and safflower (Carthamus tinctorius L.)

Allelopathy defines the production of specific biomolecules (allelochemical) by a plant that can induce positive or negative impacts on another culture. The crop of castor beans ( Ricinus communis L.) is being economically valued and receiving attention, mainly by the biodiesel production, castor oil and animal feeding. In this study, the allelopathic effect of aqueous extract from fresh leaves of castor beans ( Ricinus communis L.) applied to the beginning stage of soy ( Glycine max L.) and of safflower ( Carthamus tinctorius L.) was investigated. An experimental was setup with five blocks and four replications, considering that each block refers to a concentration of extract of castor beans fresh leaf (0, 25, 50, 75 and 100%); the one without castor beans leaves was taken as ‘witness’. The statistic treatment was done using analysis of variance (ANOVA) and Tukey test with an error rate of 5%. The result showed evidences that there are allelopathic effects among the extract of castor beans fresh leaf and the beginning stage of soy and safflower only in the root part of the seedling. Key words: Ricinus communis L., Glycine max L., allelopaty.