Abstract
Differences in respiration rate, C2H4 production, and rate of callus formation in the carrot (Daucus carota L. var. saliva DC) disks of different tissues and cutting modes were measured to determine the effect of cutting direction on the storability of partially processed carrot. The disks (diameter : 7mm, thickness: 1.5mm) were prepared as crosswise cut sections (CCS) or lengthwise cut sections (LCS) from phloem, cambium, or xylem, respectively. Both CCS and LCS of phloem and cambium showed significant increases of CO2 production for the first 18 hr and slight decreases up to the end of storage. The CO2 production of xylem increased through storage and the rate of increase in LCS was faster than that of CCS. Both CCS and LCS of phloem and cambium showed significant rises in C2H4 production and the peak was reached at 9 hr after cutting. The C2H4 production of xylem increased through storage and the rate of increase in LCS was faster than that of CCS. Total microbial count levels increased during storage for all tissue types. The total microbial counts of CCS in all tissues were lower than LCS and xylem tissue had the highest counts at 48 hr storage. The sections were cultured on MS solid media at 25°C. The rate of callus formation in the sections was cambium> phloem>xylem. The rate in CCS was greater than LCS in all tissues. The formation of callus may be associated with the production of wound healing polymers. These data support the facts that the lengthwise cut sections of carrot decayed more rapidly than the crosswise cut one, and that the deterioration in lengthwise cut one occurred first at the xylem part and subsequently at the phloem in our previous reports.
