Vapor conductance of wounded potato tuber tissue

Abstract

An understanding of wound healing in potato tubers is important for reducing shipping and storage losses. Because excised tissue cores are often used in studies of the wound responses of tubers, we compared the healing of cores to that of cuts and bruises on whole tubers. To do this, we measured water loss from cores by weighing and the vapor transfer from both cut areas and bruises on tubers using a commercial leaf porometer (stomatal meter). Vapor loss from cut surfaces on whole tubers decreased more rapidly than that from cores of tissue. Variability of conductance measurements among individual tubers with cut surfaces was less than that among cores measured on a given day after excision. The rate at which either cores or the cuts on tubers healed did not change significantly as time in storage varied from 2 to 27 weeks before injury. Bruises made on whole tubers usually healed more slowly than cut surfaces on tubers. Severity of the bruise made by a pendulum striker depended on the turgor pressure of the tuber tissue. Tubers cells had high turgor pressure (nearly 0.4 MPa) early in the storage season and the striker created shatter bruises. With a decline in turgor to < 0.2 MPa with storage time, little or no shatter bruising occurred. Wound healing differed among tissue cores, cut surfaces on whole tubers and bruises on whole tubers, raising concern over the suitability of cores as a model for studying tuber response to injuries. The porometer was a reliable and relatively convenient method of assessing wound healing of both cuts and bruises on whole tubers.