The Canon of Potato Science: 40. Physiological Age of Seed Tubers

Abstract

What is it? The physiological quality of seed tubers is determined by dormancy and – after the dormancy has been broken – by physiological age. Physiological age is the developmental stage of a potatoseedtuber but itcan alsobedefined as the physiological state of the seed tuber which influences its production capacity. Physiological age determines the behaviour of each bud of the seed tuber thus affecting the number of sprouts per eye and their vigour. Moreover, it also influences the physiological behaviour of the resulting stem, even well after emergence. Physiological age advances progressively by increasing chronological age, but also depends on: a. the size of the individual tuber; b. the growth history of the seed crop from which the seed tuber has been obtained; c. possible treatments applied to the seed crop (e.g., hormonal sprays on the canopy); d. the timing and method of haulm killing; e. the conditions between haulm killing of the seed crop and the harvesting of the seed tuber; f. the conditions during storage and from storage until planting; g. possible treatments during harvesting or storage; h. possible treatments between storage and planting. The temperature sum after the end of dormancy during storage of is the most dominant factor affecting physiological ageing, although its effect is moderated by light conditions and by genotypic characteristics. While the physiological age progresses, the seed tuber goes through different stages, including dormancy (no sprout), apical dominance (only one sprout), normal