Zommick Daniel H, Knowles Lisa O, Pavek Mark J, Knowles N Richard
Postharvest Physiology and Biochemistry Laboratory, Department of Horticulture, Washington State University, P.O. Box 646414, Pullman, WA, 99164-6414, USA.
Planta. 2014 Jun;239(6):1243-63. doi: 10.1007/s00425-014-2048-8. Epub 2014 Mar 11.
The effects of soil temperature during tuber development on physiological processes affecting retention of postharvest quality in low-temperature sweetening (LTS) resistant and susceptible potato cultivars were investigated. 'Premier Russet' (LTS resistant), AO02183-2 (LTS resistant) and 'Ranger Russet' (LTS susceptible) tubers were grown at 16 (ambient), 23 and 29 °C during bulking (111-164 DAP) and maturation (151-180 DAP). Bulking at 29 °C virtually eliminated yield despite vigorous vine growth. Tuber specific gravity decreased as soil temperature increased during bulking, but was not affected by temperature during maturation. Bulking at 23 °C and maturation at 29 °C induced higher reducing sugar levels in the proximal (basal) ends of tubers, resulting in non-uniform fry color at harvest, and abolished the LTS-resistant phenotype of 'Premier Russet' tubers. AO02183-2 tubers were more tolerant of heat for retention of LTS resistance. Higher bulking and maturation temperatures also accelerated LTS and loss of process quality of 'Ranger Russet' tubers, consistent with increased invertase and lower invertase inhibitor activities. During LTS, tuber respiration fell rapidly to a minimum as temperature decreased from 9 to 4 °C, followed by an increase to a maximum as tubers acclimated to 4 °C; respiration then declined over the remaining storage period. The magnitude of this cold-induced acclimation response correlated directly with the extent of buildup in sugars over the 24-day LTS period and thus reflected the effects of in-season heat stress on propensity of tubers to sweeten and lose process quality at 4 °C. While morphologically indistinguishable from control tubers, tubers grown at elevated temperature had different basal metabolic (respiration) rates at harvest and during cold acclimation, reduced dormancy during storage, greater increases in sucrose and reducing sugars and associated loss of process quality during LTS, and reduced ability to improve process quality through reconditioning. Breeding for retention of postharvest quality and LTS resistance should consider strategies for incorporating more robust tolerance to in-season heat stress.
研究了块茎发育期间土壤温度对影响抗低温糖化（LTS）和易感低温糖化马铃薯品种采后品质保持的生理过程的影响。“总理褐皮”（抗LTS）、AO02183 - 2（抗LTS）和“游侠褐皮”（易感LTS）块茎在块茎膨大期（111 - 164天生育期）和成熟期（151 - 180天生育期）分别在16℃（环境温度）、23℃和29℃下种植。尽管藤蔓生长旺盛，但在29℃下块茎膨大实际上消除了产量。块茎比重在块茎膨大期间随着土壤温度升高而降低，但在成熟期不受温度影响。在23℃下块茎膨大以及在29℃下成熟会导致块茎近端（基部）还原糖水平升高，从而在收获时产生不均匀的薯条颜色，并消除了“总理褐皮”块茎的抗LTS表型。AO02183 - 2块茎对高温更耐受，从而保持LTS抗性。更高的块茎膨大温度和成熟温度也加速了“游侠褐皮”块茎的LTS和加工品质损失，这与转化酶活性增加和转化酶抑制剂活性降低一致。在LTS期间，随着温度从9℃降至4℃，块茎呼吸迅速降至最低，随后随着块茎适应4℃而升至最高；然后呼吸在剩余的储存期内下降。这种冷诱导适应反应的幅度与24天LTS期间糖分积累的程度直接相关，因此反映了季内热应激对块茎在4℃下变甜和加工品质损失倾向的影响。虽然在形态上与对照块茎无法区分，但在高温下生长的块茎在收获时和冷适应期间具有不同的基础代谢（呼吸）速率，储存期间休眠减少，蔗糖和还原糖增加幅度更大，以及在LTS期间加工品质相关损失，并且通过调理改善加工品质的能力降低。培育具有采后品质和LTS抗性的品种应考虑纳入对季内热应激更强耐受性的策略。
