Melia dubia Cav. leaf litter allelochemicals have ephemeral allelopathic proclivity

Abstract

A study was undertaken to analyse the allelochemicals in Melia dubia Cav. leaf litter and to test the allelopathic proclivity of aqueous leaf extracts and leaf litter on germination and early growth, and biomass of chilli (Capsicum frutescens L.) and eggplant (Solanum melongena L.) in laboratory and pot culture bioassay. A separate pot experiment was conducted to examine the allelopathic effect of leaf litter on growth, biomass and fruit yield of test crops. Gas chromatography–mass spectrometry (GC–MS) analysis of M. dubia leaf litter revealed many compounds, which were phenolic acids and their derivatives, alkaloids, methyl ketones (volatile allelochemical), unsaturated fatty acids, omega-3 fatty acid, aromatic ketone, chromene and others. The leaf aqueous extract and leaf litter inhibited the germination traits (germination per cent, mean daily germination, peak value, germination value and germination rate index) as well as early growth and biomass of both the test crops in laboratory bioassay and pot culture. The inhibitory effect was higher in laboratory bioassay as compared to pot culture. However, in pot experiments, none of the leaf litter treatments significantly affected the later growth, biomass and fruit yield. The allelochemicals detected in leaf litter of M. dubia, thus, have ephemeral allelopathic proclivity. Allelochemicals might have diluted through cultural practices or due to their ephemeral nature and, hence, allelopathic effect was only seen in germination and early stage of growth and it disappeared in later stage of growth and fruit yield of test crops. Hence, M. dubia is suggested for growing in different agroforestry systems.