VOLATILE ANTIFUNGAL COMPOUNDS PRODUCED BY PLANT GROWTH PROMOTING RHIZOBACTERIA (PGPR) AGAINST Phytophthora palmivora
Authors: Nurfadzilah, M.1*, Suhaida, S.¹, Nawi, N.M.2, Mahirah, J.2, Wong, M.Y.,3 and Ishak, Z.4
Journal Issue: Malaysian Cocoa Journal, Volume 17 2025
Keywords: Volatile Compounds (VOCs), Plant Growth Promoting Rhizobacteria (PGPR), Phytophthora palmivora, dual culture method, black pod disease
Published On: 5/11/2025
Abstract
growth-promoting rhizobacteria (PGPR) are a group of bacteria that colonize plant roots and enhance plant growth by a diverse range of mechanisms and activate plant defense against microbial pathogens. In addition, volatile organic compounds (VOCs) are low-molecular-weight, carbon-containing compounds that evaporate easily at normal temperature and pressure. These compounds are biodegradable and can be as effective in disease control as conventional fungicides. In this study, a total of ten rhizospheric microbes were screened in vitro for their antagonistic effects against Phytophthora palmivora, the causal agent of Black Pod disease in cocoa. The effects of these rhizospheric microbes differed significantly in terms of their ability to inhibit the radial growth of P. palmivora after 168 hours of incubation using the dual culture method. After 168 hours of incubation, bacterial strain B2 were identified as the most promising antagonists against P. palmivora, achieving 58.71% inhibition of radial growth followed by B7 (57.59%) and B10 (56.10%). Further analysis of the volatile compound production potential of these three promising rhizospheric microbes revealed that volatile compound production was inversely proportional to the growth of P. palmivora and directly proportional to the percentage of inhibition.