Inhibition Of Combined Plant Extracts On Rot-causing Fungi In Postharvest Nectarine Fruits

On the base of inhibition on Moniliniafructicola, Rhizopus stolonifer, Penicillium expansum rots of postharvest nectarine fruits, four kinds of plant extracts were combined to screen preservatives with synergistic action. In vitro inhibition of preservative candidates on mycelial growth and spore germination of three kinds of pathogens and morphological changes were analyzed in order to evaluate then-application probability in postharvest nectarine fruits and explore the anti-fungal mechnisms. Their control effects in vivo was measured as well.Firstly, according to the results of inhibition experiment by a cross-paper disc method , combinations of Chemical No.3/No.5 showed synergistic action against Monilinia fructicola, and so did No.2/No.5,No.2/No.12 against Rhizopus stolonifer, No.3/No.5 against Penicillium expansum, respectively. Thus, the co-toxicity factor could be used to optimize their combinations .Secondly, in another experiment, these preservative candidates showed significant inhibition on mycelial growth and spore germination in vitro of all the three pathogens. Combinations of No.3/No.5 at a concentration more than 1.56mg/ml completely inhibited mycelial growth and spore germination of Monilinia fructicola, its MIC and MFC were 0.78mg/ml,1.56mg/ml, respectively. Combinations of No.2/No.5 and No.2/No.12 at a concentration more than 1.56mg/ml completely inhibited that of Rhizopus stolonifer, its MIC and MFC were 3.13mg/ml,6.25mg/ml,respectivery. Combinations of No.3/No.5 at a concentration more than 12.5mg/ml completely inhibited that of Penicillium expansum, its MIC and MFC were 12.5mg/ml, 25.0mg/ml, respectively. Furthermore, tested preservatives could cause morphological changes of target pathogen, such as excessive branch , swelling hyphal, shorter and thicker hyphal cell,and more septa.Thirdly, at a concentration of 3.13mg/ml,combinations of No.3/No.5 could absolutely control "Monilinia rot" in vivo,100mg/ml of No.2/No.5 or No.2/No.12 could absolutely control "Rhizopus soft rot",but 100mg/ml of No.3/No.5 could not absolutely control Penicillium mold due to limited inhibition.