Biocontrol of major postharvest pathogens on apple using Rhodotorula glutinis and its effects on postharvest quality parameters

Abstract

The biocontrol activity of Rhodotorula glutinis on gray mold decay and blue mold decay of apple caused by Botrytis cinerea and Penicillium expansum, respectively, was investigated, as well as its effects on postharvest quality of apple fruits. The results show there was a significant negative correlation between concentrations of the yeast cells and the disease incidence of the pathogens. The higher concentration of the R. glutinis, the better effect of the biocontrol capacity. At concentrations of R. glutinis 1 × 10 8 CFU ml −1, the amount of gray mold decay was completely inhibited after 5 days incubation at 20 °C, after challenge with B. cinerea spores suspension of 1 × 10 5 spores ml −1; While the blue mold decay was completely inhibited at concentrations of 5 × 10 8 CFU ml −1, at challenged with P. expansum spores suspension of 5 × 10 4 spores ml −1 . These results demonstrated that the efficacy of R. glutinis in controlling of gray mold decay of apples was better than the efficacy of controlling blue mold. R. glutinis within inoculated wounds on apples increased in numbers at 20 °C from an initial level of 9.5 × 10 5 CFU per wound to 2.24 × 10 7 CFU at 20 °C after 1 day. The highest population of the yeast was recovered 4 days after inoculation, the yeast population in wounds increased by 56.9 times. After that, the population of the yeast began to decline very slowly. R. glutinis significantly reduced the incidence of natural infections on intact fruit from 75% in the control fruit to 28.3% after 5 days at 20 °C, and from 58.3 to 6.7% after 30 days at 4 °C followed by 4 days at 20 °C. R. glutinis treatment had no deleterious effect on quality parameters after 5 days at 20 °C or after 30 days at 4 °C followed by 4 days at 20 °C.