Alelopatia de espécies arbóreas da caatinga na germinação e vigor de sementes de feijão macaçar e de milho.

Abstract

The successful implementation of agroforestry systems depends on studies to evaluate the allelopathic effect. The objective of this study was to evaluate the allelopathic effects of Mimosa tenuiflora (Willd) Poir. and Croton sonderianus Mull. Arg in germination and growth of corn and cowpea bean. Aqueous extracts were used at concentrations of 0, 25, 50, 75, and 100% (w / v) from the crude extract, where 250g of thin branches were processed in 1000 ml distilled water. The tests were performed in the laboratory and greenhouse, and in the laboratory were added to 12mL of their dilution by box containing 25 germinated seeds. In the greehouse test, we used the mixture of sand and vermiculite 1:1 (v / v) autoclaved (120 ° C, 1 atm) in polypropylene tubes of 350 cm3 , and humidity of 70% of field capacity. The dilutions of the extract were applied in installments increasing to fourteen after germination. In both experiments, a completely randomized design was used in a factorial scheme (5x3), four dilutions and a control group, three types of extracts, two isolates (M. tenuiflora and C. sonderianus) and one mixed extract (M. tenuiflora plus C. sonderianus) with four replications per treatment. We used two target species (Corn and Cowpea Bean). In laboratory, the germination of corn was more affected by the mixed extract, while the cowpea bean showed greater sensitivity to extracts isolated. The lengths of aerial and root part decreased with increasing concentration. In greenhouse, the initial germination was more affected by higher concentrations, but the extracts didn’t affect the final germination of both species. There wasn’t influence of the concentration of the extract of M. tenuiflora on root length of corn. Only the mixed extract caused a deleterious effect on the roots of cowpea. The results obtained in bioassays showed allelopathic effect of plant extracts on corn and cowpea.