The Use of Rhizobacteria on White Rot Disease and Growth of Lettuce

Abstract

White rot caused by Sclerotinia sclerotiorum [(Lib.) de Bary] is one of the most important diseases negatively affecting lettuce production. In this study, the effects of rhizobacteria containing different species on S. sclerotiorum were investigated. Also effect of rhizobacteria were determined on the growth of lettuce. Eight rhizobacteria strains (Enterobacter cloacae, E. aerogenes, Bacillus cereus, Microbacterium testaceum, Pseudomonas putida, P. chlororaphis, Acinetobacter calcoaceticus, and Burkholderia cepacia) were used in the study. Firstly, the in vitro effects of rhizobacteria strains were investigated on the mycelial growth and sclerotia viability of S. sclerotiorum. Then, pot experiments were carried out under controlled greenhouse conditions to determine the effect of selected strains on white rot disease and the growth of lettuce. The effect of tested bacteria on the mycelial growth of S. sclerotiorum ranged between 38.09-79.84%, and the P. putida strain had the highest impact. The bacterial strains were also effective on the sclerotia viability of S. sclerotiorum. The efficiency in the pot experiment was between 50-90% on white rot, and the highest effect was recorded in A. calcoaceticus strain. In the pot experiment rhizobacteria also increased plant growth. In particular, E. aerogenes was the most successful strain in plant growth. The results revealed that bacterial strains have different inhibitory effects in in vitro and in vivo experiments, while having the potential in the biological control of white rot disease and positive results on lettuce growth.