Leucaena (Leucaena leucocephala (Lam.) de Wit) has been observed to control weeds when used as soil mulch. It contains mimosine, which, among other allelochemicals, is responsible for the allelopathic effect. The objective of the present study was to evaluate the effect of aqueous extract of leucaena on the development, root mitotic index, peroxidase activity and isoenzymes in the shoots and roots of maize seedlings. Inhibition of root growth and reduction of the mitotic index were proportional to the aqueous extract concentration. Cell division was not observed in extract concentrations equal or above 1.6%. Increase in extract concentration was followed by high peroxidase activity in roots and shoots, but no changes in peroxidase isoenzyme patterns were observed. The peroxidase activity in roots was positively correlated with the increase in anionic isoenzymes, pI 4.99 and 4.86, suggesting their participation in the thickening of roots and increased dry weight (mg/cm). High concentrations of the allelochemical mimosine were detected in concentrated aqueous extracts, possibly influencing seedling development.
Leucaena; leaf and root development; mitosis; peroxidase; isoenzymes; mimosine
