Physiological Age Of Seed Tubers Research Articles

Dormancy and Physiological Age of Seed Tubers from a Diverse Set of Potato Cultivars Grown at Different Altitudes and in Different Seasons in Kenya

The study was conducted to determine the dormancy and physiological age characteristics of diverse potato genotypes as influenced by growing altitudes and seasons for future breeding strategies and optimal patterns of use. Dormancy and sprouting characteristics have an impact on tuber production, storability and seed quality for planting and ware for consumption and the market. This study presents the results of dormancy and physiological age measurements conducted on 47 potato genotypes grown at three altitudes with three replications at each location and in two contrasting growing seasons. The seed tubers were evaluated at low altitude under darkness on moist sand storage conditions to assess their dormancy release, number of sprouts, sprout weight, sprout length and percentage tuber weight loss. Results showed significant (p < 0.001) differences among genotypes, locations and seasons, and significant interactions between these factors for days to dormancy release, number of sprouts per tuber at dormancy release and at 45 days after dormancy release, length of longest sprout, weight loss percentage of unsprouted and sprouted tubers at dormancy release and at 45 days after dormancy release, respectively. There was a wide variation in time to dormancy release (54 to 136 days); most genotypes showed medium to long dormancy. Seed tubers grown at low altitude showed longer dormancy than those grown at higher altitudes, while genotypic differences in dormancy were very consistent across environments. Genotypes strongly differed in sprouting characteristics and weight loss. There were highly significant interactions between altitude and season for all variables assessed, except for the number of sprouts 45 days after dormancy release and the weight loss after sprouting. Generally, the genotypic effects were larger than those of altitude, season and the interaction effects for all variables evaluated. This paper will allow variety selection to optimize seed quality at planting and minimize storage losses while providing new targets for breeders.

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

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