Effect of Some Fructoplane Antagonists and Postharvest Dip Treatments on Litchi Fruit Rots and Shelf Life

Abstract

Litchi (Litchi chinensis) fruits are extremely susceptible to postharvest fungal pathogens. Normally, fungicides are used to gain control over such postharvest pathogens. Carbendazim is popularly used for control of postharvest disease control in litchi. However, use of synthetic chemicals has been curtailed due to safety issues and biological control is increasingly explored as an alternative. Four isolates of Bacillus subtilis and two of antagonistic yeast were isolated from fructoplane of litchi. After preliminary screening, the best isolate was applied individually and in combination with chitosan (1.0%), potassium silicate (0.5%) and carbendazim (0.1%) to test the efficacy against postharvest pathogens of litchi. No incidence of fruit rot (decay) and browning was recorded in fruit treated with B. subtilis NRCL BS-1(1x108 cells/mL) up to 6 days stored at 32-36°C temperature and 65-76% relative humidity. Treatment with antagonists resulted in significantly lower fruit rot (0-10%) as well as lower percent disease index. Disease control obtained through application of B. subtilis, chitosan, and potassium silicate + chitosan were at par with that achieved through application of carbendazim. It is concluded that B. subtilis and chitosan merit as good alternatives to carbendazim to reduce fruit decay and improve shelf life of litchi fruit.