Influence of calcium propionate on the control of post-harvest rots of jujube and the biocontrol activity of an antagonistic yeast

Abstract

ABSTRACTThe effect of calcium propionate (CaP) on post-harvest pathogens of winter jujube (Zizyphus jujuba Mill.), and on improving the efficacy of the biocontrol yeast, Metschnikowia pulcherrima, were evaluated. In vitro, CaP at ≥2% (w/v) had significant inhibitory effects on spore germination and germ-tube growth in Penicillium citrinum and Alternaria alternata. However, the application of 2% (w/v) CaP did not affect population growth of M. pulcherrima in nutrient yeast dextrose in vivo. With or without CaP, yeast cell numbers increased after 72 h by approx. 11.1-fold and 13.4-fold, respectively. The concentration of the antagonistic yeast suspension influenced the incidence of both pathogens and lesion development on jujube fruit, and the effect increased with an increase in yeast cell concentration. A combination of the antagonistic yeast plus 2% (w/v) CaP resulted in a lower incidence of disease and smaller lesion diameters compared to treatments with the antagonistic yeast alone. In this case, the incidence of disease was reduced by 16.8–27.3% for P. citrinum and by 25.2–31.4% for A. alternata. Lesion diameters on these fruit were 2.7–6.2 cm and 1.8–2.4 cm for P. citrinum and A. alternata, respectively. Calcium propionate had a consistent ability to enhance the biocontrol activity of M. pulcherrima against blue mould (P. citrinum) and Alternaria rot on jujube fruit. Thus, the application of 2% (w/v) CaP could be a useful approach to improve the efficacy of the antagonistic yeasts used for post-harvest disease control in jujube.