Postharvest physiological responses of potato (Solanum tuberosum L.) to temperature stress during production and storage

Strict processing standards necessitate potatoes which produce light-colored, uniform finished fries with low acrylamide forming potential, all of which are dictated by reducing sugar (RS) content. Cultivar and temperature during crop development and storage are important in determining the propensity for RS buildup and associated physiological disorders.;The newly released, low temperature sweetening (LTS)-resistant cultivar Premier Russet can develop translucent tissue defect (TTD) within 5-6 months of storage (9°C), which manifests as random pockets of translucent tissue that fry dark during processing due to RS buildup. Physiologically, TTD is similar to the irreversible senescent-sweetening that occurs during long-term storage of potatoes. Time-course studies and tissue specific analyses demonstrated that TTD is a consequence of oxidative stress associated with an accelerated aging phenotype.;Carbohydrate metabolism was characterized in relation to temperature-induced changes in tuber respiration rate during LTS and reconditioning for four cultivars with disparate resistances to reversible LTS: Premier Russet (highly resistant), GemStar Russet (moderately resistant), Russet Burbank (susceptible) and Defender (highly susceptible). RS accumulation in these cultivars corresponded to sucrose forming potential in relation to activities of invertase and endogenous invertase inhibitors. Exposure to 4°C induced a predictable respiratory acclimation response that correlated with the extent of sweetening and likely reflected the metabolic energy required to catabolize starch to sucrose and RS.;Soil temperature was increased during the tuber bulking and maturation phases of crop development to evaluate the effects of in-season heat on subsequent retention of postharvest quality in LTS resistant and susceptible cultivars. High heat (+13°C above ambient) during bulking virtually eliminated tuber yield while moderate heat (+7°C above ambient) compromised process quality at harvest. Higher soil temperatures during maturation under dead vines reduced dormancy length and modified the basal respiration rates of tubers consistent with over-maturation and advanced physiological age. Heat stress during bulking, maturation or early storage exacerbated sweetening in 'Ranger Russet' tubers and abolished the LTS-resistant phenotype of 'Premier Russet' tubers. AO02183-2 was more tolerant of heat stress for retention of process quality. Breeding for retention of postharvest quality and LTS resistance should consider strategies for incorporating more robust tolerance to in-season heat stress.