Effects of simulated harvest injury and relative humidity during the first week post-harvest on potato (Solanum tuberosum L.) tuber weight loss during subsequent storage

Summary

The effects of relative humidity (RH) immediately after harvest, and simulated harvest injury on the loss of fresh weight (FW) in potato (Solanum tuberosum L.) tubers during storage were studied over two years. Tubers were hand-harvested and, within 4 – 6 h, were placed in sealed, ventilated storage chambers at 13ºC and 75, 85, or 95% RH for up to 1 week, with or without a simulated harvest injury (i.e., by abrasion or by excision of a small portion of the tuber surface). Tubers were weighed individually at the start of the trial and re-weighed 12, 24, 48, 72, or 168 h post-harvest. Tubers from the 168 h (1 week) evaluation were subsequently stored on a bench in a walk-in, refrigerated coldroom (109.7 m³) at ca. 88% RH, and were re-weighed 2 and 5 weeks after harvest. Mean total FW loss values 168 h after harvest were 1.2, 1.6, and 2.1% of the initial FW under 95, 85, or 75% RH, respectively. These differences were still apparent after a further 4 weeks in the coldroom. Thus, 5 weeks after harvest, mean total FW loss values were 3.0, 3.3, and 3.8% of the initial FW among tubers originally stored for 1 week at 95, 85, or 75% RH, respectively. Tubers with simulated harvest injuries lost weight more rapidly than intact tubers under all three RH conditions, and during subsequent cold storage. Mean total FW losses 168 h after harvest at 95% RH were 1.2, 1.7, and 2.1% of the initial FW in intact, abraded, or cut tubers, respectively. These values increased to 2.7, 3.4, and 4.0% of FW, respectively, 5 weeks after harvest. Although the interaction between RH and simulated harvest injury was not statistically significant, there was a trend towards a greater loss of FW in tubers with simulated injuries under low RH (P ≤ 0.09), compared to intact tubers kept at high RH. Since the effect of low RH at the start of the storage period continued to affect the quality and quantity of the crop later during storage, lack of attention to RH at this critical time has the potential to reduce economic returns for producers and/or storage managers.