This study evaluated four potato clones that differ in tuber dormancy and adaptation to crop conditions of southern Brazil, since the advancement of physiological age of tubers is highly dependent on the cultivar (STRUIK, 2007).
TI is considered the most scientifically accepted inference for measuring the physiological age of tubers (WIERSEMA, 1985), but in practice it is much more difficult to determine TI than EM in plants.
Knowing the physiological age is important for post-harvest tuber management, especially when they are used as seed.
Different characteristics have been proposed as indicators of dormancy and/or physiological age of the tubers, including morphological, physiological, (bio) chemical, biophysical and molecular traits (CALDIZ et al.
It has been stressed by many authors that both for scientific and practical purpose a good indicator of dormancy and/or physiological age would be useful.
The most direct and simple way to indicate physiological age is on the basis of the accumulated day-degrees from dormancy break (O'Brien and Allen, 1981; O'Brien et al.
This study shows that the concept of accumulated day-degrees from dormancy break is not a good estimator for physiological age across temperature conditions during storage and across cultivars and, therefore, needs to be refined.
We worked out all of the necessary analytical procedures and mathematics, published 20 research papers, and demonstrated that we could see many useful patterns and could measure physiological age quantitatively.
For example, about 30 percent of the substances in urine are correlated with physiological age.
Differences in the physiological age of tubers may be responsible for the so-called "Northern Vigor" phenomenon (Anon.
Then if we can do this, how do we manipulate either physiological age (before planting) or agronomic management (after planting) so that tuber set and size development can be controlled within an optimum range for a particular market?
The temperature at which heat units are accumulated by seed greatly affects its physiological age, as indicated by differences in plant establishment, stem numbers, tuber set, and yield responses for seed that had accumulated a particular number of degree-days at the different temperatures.