Evaluation of antifungal plant extracts against cereal and legume seed-borne pathogens for effective management

Abstract

Sri Lanka as an agricultural country needs to manage the seed-borne fungal pathogens that have caused infections and diseases that result in significant crop losses and a decline in yield and productivity. Therefore, it is imperative to apply pathogen management strategies that are environmentally friendly, and economically feasible such as plant extractions, to reduce seed-borne fungi and increase the quality of the seed. This study was aimed at identifying the antifungal efficacy of Allium sativum, Aloe vera, Azadirachta indica, and Zingiber officinale extracts and their effective concentrations to control the seed-borne fungal pathogens; Aspergillus flavus, A. niger, Orbilia foliicola, Rhizopus oryzae, and Talaromyces oumae-annae isolated from Arachis hypogea, Oryza sativa, Vigna radiata, and V. sinensis respectively. Antifungal efficacy was determined by the agar well diffusion method and poisoned food technique. Plant extracts’ effectiveness for seed germination and seed quality was evaluated by pot experiments. Zingiber officinale crude extract exhibited the highest antifungal activity against the tested pathogens which was as effective as Captan 50% (WP), a positive control. Further analysis of the results from the pot experiment revealed that O. sativa, and V. radiata seeds treated with A. indica, and Z. officinale aqueous extracts showed 100% germination percentage. Azadirachta indica, and Z. officinale aqueous extracts are the most effective in promoting seed germination and seedling vigor while A. vera extract is the least effective extract. Comparing the two different extracts, aqueous extracts significantly promote seed germination and increase seedling vigor.