Determination of optimum conditions for suberization, wound periderm formation, cellular desiccation and pathogen resistance in wounded Solanum tuberosum tubers

Abstract

To determine the optimal environment for wound healing, potatoes ( Solanum tuberosum) were wounded and then cured for 7 days at a range of temperatures (10–30 °C) and relative humidities (50–98% RH). An accurate mixing system was used to provide continuous ventilation with air streams of different temperatures and humidities, instead of the closed system used by most previous workers. Histochemical staining was employed to determine the extent and deposition of lipid and lignin (the major components of suberin) and wound periderm formation. Weight loss and the thickness of the desiccated cell layers were also measured, as was the resistance of the cured surface to infection by pathogens. The optimum conditions for formation of suberin, periderm, minimum water loss and resistance to pathogens were found to be at 25 °C and 98% RH. Temperature was the most important factor affecting deposition of lipid, lignin and periderm formation. Humidity had a relatively larger effect on weight loss, thickness of the desiccated cell layers and resistance to infection by Fusarium oxysporum and Erwinia carotovora pv. carotovora. The thickness of the desiccated cell layers was highly correlated with resistance to pathogens. Least infection was most highly correlated with curing conditions that minimized desiccation. Resistance to infection was also significantly correlated with the thickness of the lipid, lignin and periderm layers.