Paul C. Struik, Centre for Crop Systems Analysis, Wageningen University and Research, Netherlands Potato shows strong genotype × environment interactions. Climate change enhances those interactions. Making potato more robust requires control over tuber formation, which consists of a complex and dynamic sequence of several, partly independently regulated, events: induction, initiation, set, bulking and maturation. Better control and predictability of the status of the seed tuber will facilitate control over tuber formation, but requires insight into processes during all phases of the life cycle of a seed tuber, including the production phase, the phase between haulm killing and harvest, the phase of curing and gradual cooling of the seed lot, the actual storage phase, the pre-treatment phase after storage, and the period after planting. A seed tuber goes through a period of increasing dormancy followed by a gradual release of the dormancy, a phase of apical dominance followed by physiological aging until its growth vigour is maximum. Subsequently, the vigour gradually declines until the seed tuber reaches senility. Physiological aging can be affected by seed tuber size, growth conditions during seed tuber production, treatments of the seed tuber crop, time and method of haulm killing, soil conditions from haulm killing until harvest, conditions and treatments/handling during storage and treatments after storage but before planting. Most effective way of manipulating physiological aging is storage temperature. However, there is a huge genotype × storage duration × storage temperature interaction making it hard to optimize storage conditions for each cultivar, planting time, planting site and purpose. We aim to predict the progress of physiological aging, based on (dis)appearance of specific metabolites over time in different parts of the seed tuber from contrasting cultivars stored at different temperatures. While metabolomics data are still being analyzed, we observe changes in some compounds that mirror the genotype × storage time × storage temperature interactions very well. The spud knows why.