Physiological Age Research during the Second Half of the Twentieth Century

As in other crops, yield and quality in the potato is determined by the genotype x environment interaction; limited by seed, crop, and storage management; and reduced by weeds, pests, and diseases. Within the limiting factors, seed tuber quality is crucial, both in low- and high-input crops. If poor seed tubers are used in low- input crops, only low yields can be expected. If poor seed tubers are used in high-input crops, the crops will not take proper advantage of other inputs, such as water, fertilizers, and pesticides applied. At present, physical aspects, such as shape and presence of wounds, seed tuber size, health, and physiological age, are the main components of seed quality, impacting seed vigour. Physiological age is defined as the physiological status of a seed tuber at any time, determined by genotype, chronological age, and environmental conditions from tuber initiation until new plant emergence. This minireview summarizes the physiological age assessment methods and the effects of crop and storage environment and management on physiological age and future crop performance. Possible tactics to reverse physiological age effects are also discussed. More research is still needed to develop a reliable and predictable indicator or index which can relate physiological age to yielding potential.