Abstract:
Green mould, Penicillium digitatum (Pers.: Fr.) Sacc., causes economically
important postharvest disease in citrus. Materials and methods. Ethiopian plant extracts of Acacia
seyal (Del. Var. Seyal) and Withania somnifera (L.) Dual were used to test the control of green mould
in wound-inoculated fruit, stored for 21 d at 7 °C and at > 85% RH. The chemical compositions of the
two extracts were determined using high-performance chromatography. Thereafter, freshly harvested
(naturally infected) fruit were subjected to different postharvest treatments and stored for 50 d to investigate
the effects of the two plant extracts on fruit quality parameters. Treatments included (pre-wax
+ leaf extracts), (wax + leaf extracts incorporated into wax, Citrosol A®), (leaf extract alone), (fruit
washed in chlorinated water at 5.25%), (untreated fruit) and (commercially treated fruit). Results.
Extracts of A. seyal and W. somnifera reduced the incidence of green mould by 56.1% and 50%, respectively,
in wound-inoculated fruit. A. seyal extract contained a high concentration of gallic acid
(60.3 mg·mL–1) whilst W. somnifera contained low concentrations of caffeic acid (8.7 mg·mL–1), salicylic
acid (6.3 mg·mL–1) and 3,4 dihydroxy benzoic acid (3.8 mg·mL–1). Green mould was absent in
naturally infected fruit subjected to (pre-wax + leaf extracts), (wax mixed with leaf extracts) and (leaf
extracts) treatments. (Pre-wax + leaf extracts) and (wax mixed with leaf extract) treatments significantly
reduced weight loss; retained firmness and colour; and they maintained eating qualities and a maturity
index (SSC/TA) similar to commercial treatment. Conclusion. Both extracts of A. seyal and
W. somnifera showed potential to be used as an alternative in combined applications with wax application
under low temperature storage to replace synthetic fungicides, to ultimately control green mould
and retain overall fruit quality.
