Potential effects of plant growth promoting rhizobacteria (Pseudomonas fluorescens) on cowpea seedling health and damping off disease control

Abstract

Damping off caused by Sclerotium rolfsii on cowpea results in yield losses with serious socioeconomic implication. Induction of defense responses by plant growth promoting rhizobacteria (PGPR) is largely associated with the production of defense enzyme phenyl ammonia lyase (PAL) and oxidative enzymes like peroxidases (PO) and poly phenol oxidase (PPO). In the present study, the effect of plant growth promoting rhizobacteria (Pseudomonas fluorescence (bv. V)) on both damping off development and growth parameters in cow pea seedlings were investigated. The best reduction in pre and post emergence damping off in cowpea seedlings was observed in BCPF 8-treated samples. Seed bacterization with BCPF 8 significantly increased peroxidase (PO), polyphenol oxidase (PPO), and phenylalanine ammonia-lyase (PAL) activities. The activation of these defense reactions by BCPF 8 was correlated with an enhanced resistance to damping-off caused by S. rolfsii. This study demonstrated the ability of the rhizobacteria BCPF 8 to induce systemic resistance in cowpea, suggesting that this legume is an Induced systemic resistance (ISR)-positive plant.