EFFICIENCY OF BREAD YEAST AND SA AGAINST PENICILLIUM DIGITATUM THE CAUSAL AGENT OF GREEN MOLD ON ORANGE

Abstract

The study was conducted to evaluate the efficiency of Saccharomyces cerevisiae and salicylic acid to induce systemic resistance in fruit against Penicillium digitatum which caused green mold on orange fruit Citrus sinensis L. Results showed that the highest inhibitory effect of Saccharomyces cerevisiae.against Penicillium digitatum on PDA was obtained at 1 × 10 8 cell/ml after a week of incubation at 25±2 C. Salicylic acid at 1000 ppm have completely inhibited P. digitatum growth on PDA after a week of incubation at 25±2 C. S. cerevesiae filtrate induced high reduction in spore germination 38% and germ tube length 15 micrometers compared with 98 % and 65.1 µm in control respectively . the liquid culture of S. cerevesiae containing living cells showed higher reduction in spore germination percentage 11 % and germ tube length ‎2 µm. Salicylic acid at 1000 ppm completely inhibited spore germination.and germ tube elongation on PDB after 19 hours of incubation at 25±2 C. All the concentrations of salicylic acid (SA) used have positively influenced the growth of S. cerevesiae. The addition of SA to in cell suspension of S. cerevesiae at 500 ppm significant induced increase (p=0.05) in the yeast population 25-28 % compared with 0.0 % in control after 19 hour of incubation at 28±2 C on NYDB. Results showed that all the inducing factors were able.to induce resistance in orange fruit and the best treatment was the combination of SA and S. cerevesiae compared with SA acid and as proved by the activity of peroxidase 600 and 450 units/ml after 6 days of treatment. Results of cold storage experiment showed the efficiency of the combination SA+S. cerevesiae with wax vapor gard has completely prevented the incidence of green mold on orange fruits. inoculated with P. digitatum during 60 d of storage at 4 C.