Allelopathy of the Melia azedarach L. Leaf Extract on the Germination of Three Selected Atlantic Forest Species

Allelopathy is a naturally occurring phenomenon that results in the release of chemicals capable of stimulating or inhibiting the development of other nearby plants. The objective of this work was to evaluate the allelopathic potential of Melia azedarach on the germination, seed index, length and dry mass of seedlings of three Atlantic Forest species. The treatments were distributed in a bi-factorial scheme consisting of 5 concentrations (0, 2.5, 5.0, 7.5 and 10%) and 3 species (Ceiba speciosa, Leucaena leucocephala and Samanea tubulosa), in four replicates of 25 seeds totaling 100 seeds for each treatment. The Tukey test at 1% was used to compare the means. For quantitative effects, a SISVAR polynomial regression analysis for Windows software version 4.6. The extracts were obtained from 100 mg of dehydrated and crushed leaves of M. azedarach in 1000 ml of distilled water. The sowing was carried out on germitest paper and the seeds kept germinating in germinators of the type Biochemical Oxigen Demand (BOD) at 25°C with photoperiod of 12 h. The germination, germination velocity index (GVI), length and dry mass of shoot and root were evaluated. The results obtained in the laboratory showed that the aqueous extract of leaves M. azedarach has an allelopathic effect on all studied species, reducing the percentage of germination, speed index, length and dry mass of seedlings.