Incidence of yam (Discorea rotundata Poir) rots, inoculation-induced quality changes, and control by chemical fungicides and modified atmospheres
Bernard J. O. Efiuvwevwere and Ejikeme Nwachukwu
Postharvest Biology and Technology. Vol. 14, Issue 2, October 1998 , pp. 235-243.
1998
บทคัดย่อ
Five genera of moulds (Aspergillus, Botryodiplodia, Fusarium, Penicillium
and Rhizopus) were isolated from yam (Discorea rotundata) and
used for inoculation of tuber samples at two wound depths of 10 and 15 mm with
either single or paired cultures. The three prevalent isolates (Aspergillus,
Fusarium and Penicillium) were each used to inoculate other yam
samples before dipping in various fungicides to monitor the magnitude of
lesion/rot development. Storage of samples in modified atmospheres and the
effects of inoculation (using Aspergillus) on physico-chemical changes
were also evaluated. Lesions/rots induced at 10 mm depth were significantly
larger than those induced at 15 mm depth. Pair-inoculation of Aspergillus
and Rhizopus induced the most extensive rots, and minimum rot size
occurred when Fusarium was co-inoculated with either Botryodiplodia
or Penicillium. Dithane M-45 (manganese ethylenebis-dithiocarbamate or
Mancozeb) significantly reduced these rots while sodium benzoate was least
effective. Equilibrium modified atmospheres created by packing the samples
inside a polyethylene bag of 18 
m
thickness significantly maintained the quality of the samples. Inoculation of
samples with Aspergillus sp. resulted in a significant decrease in
carbohydrate and moisture content but enhanced crude protein content.
Application of combined control methods (hurdle technology) is therefore
recommended for control of yam storage lesions/rots and enhancement of storage
life.