Phytochemical Constituents and Allelopathy Activities of Azadirachta indica on Germination of Maize Seed.

Abstract

Introduction: Azadirachta indica leaf (AIL) is natural pesticides that has been used on several pests affecting many crops. Nevertheless, most of these pesticidal plants affect the growth of plant negatively. Aim: This study aims at determine the phytoconstituents and the allelopathic effects of Azadirachta indica leaf extracts (AILE) on germination and growth of maize seed and seedling. Methods: The allelopathic activities of n-hexane, ethylacetate and methanol extract of AIL were determined on germination and growth of maize seed and seedling using concentration of 2.5%, 5.0% and 10% for 12 days. On days 3, 6, 9 and 12, the root and shoot development, germination percentage, and seedling vigour of maize seeds were determined. Results: The AILE revealed the presence of B-Caryophyllene, Trans-B-Farnes, Alpha lonone, Phytol, Myricetin, Quercetin, Azadirachtol, Azadirachnol, Azadirachta A, Phyllene while Ascaridol was not revealed in methanol extract of Azadirachta indica leaf. The inhibition of plumule and radicle growth were observed to be concentration-dependent with the highest percentage of inhibition in 10% of n-hexane extract of Azadirachta indica. Germination percentage also decreased with higher concentration, with a maximum of 100% germination in the control group when compared with 50, 60, and 60% of n-hexane, ethylacetate and methanol extract of AIL at 2.5% concentrations respectively. Similarly, Seedling vigour index was drastically reduced at higher concentration of n-hexane, ethylacetate and methanol extract of AIL when compared with 423 in the control group. Conclusion: This finding suggests that high concentrations (5 and 10%) of AILE should be avoided when using as insecticide during germination stage of maize to prevent growth inhibition.