Allelopathic effects of leaf extracts of three agroforestry trees on germination and early seedling growth of wheat (Triticum aestivum L.)
Abdul Majeed1*, Zahir Muhammad2, Habib Ahmad3
Understanding of the growth promotory or inhibitory allelopathic effects of agroforestry trees on other plants is necessary for selection of suitable crops to be cultivated in their vicinity. In this experiment, aqueous leaf extracts of three agroforestry trees (Populus deltoides, Melia azedarach and Morus alba) were evaluated on germination and seedling growth of wheat applied at concentration 1, 1.5, 2.0 and 2.5 g L-1 while distilled water was used as control treatment. Lower concentration of extracts (1 and 1.5 g L-1) of P. deltoides stimulated percent germination, root and stem height and dry biomass while higher concentration (2 and 2.5 g L-1) had no effect on these parameters. Mean germination time (MGT) was not affected by the extract and its concentration. Aqueous extracts of M. azedarach and M. alba at concentration > 1 g L-1 significantly lowered the studied parameters except MGT which was significantly prolonged. Negative allelopathy was more evident at the highest aqueous extract concentration (2.5 g L-1) of the two trees. Extracts of M. alba were found more growth inhibitory than those of M. azedarach. The study suggests that lower concentration of leaf extracts of P. deltoides imparts stimulatory while M. azedarch and M. alba have negative allelopathic effects on wheat germination.
Keywords: Allelopathy, allelochemicals, competitions, intercropping, rhizosphere