Potato tubers age—but how? Linking physiology, metabolite profiles, and field performance of ageing seed tubers

In agricultural production, the quality of planting material is a key determinant of growth vigour and crop yield. Potato is commonly propagated vegetatively using tubers, referred to as ‘seed tubers’. These tubers are active and undergo continuous physiological and biochemical changes as they progress from dormancy to senescence. This process, termed ‘physiological ageing’, is influenced by environmental conditions during growth, handling, and storage and has major implications for subsequent crop performance. Despite its importance, the mechanisms underlying physiological ageing remain poorly understood, and no universal quantification tool or reliable biochemical indicators are known.

This thesis investigated the physiological, metabolic, and agronomic dimensions of seed tuber ageing, aiming to establish reliable indicators and to assess their effects on field performance across cultivar–environment combinations. Four cultivars—Agria, Festien, Innovator, and Lady Claire—were selected for their contrasting maturity types and ageing rates. Seed tubers were stored under controlled temperatures (4, 7, 10, and/or 17 ˚C) to generate distinct physiological ages, and subsequently planted at three field sites in the Netherlands over multiple years.

Physiological progression during storage was quantified through ‘sprouting capacity’, defined as sprout dry weight per tuber following standardised incubation. This parameter proved a robust indicator of physiological age, revealing cultivar-specific and temperature-dependent patterns. A novel piecewise sprouting behaviour function was developed to describe these trajectories, yielding biologically meaningful parameters marking four key phases: dormancy, apical dominance, multiple sprouting, and senescence.

Untargeted metabolomic profiling using GC–MS and LC–MS was applied to characterise biochemical changes accompanying physiological ageing. GC–MS detected relatively stable sets of primary metabolites, whereas LC–MS revealed progressive increases in secondary metabolites over time. Multivariate analyses revealed distinct cultivar-specific metabolic trajectories reflecting both storage temperature and physiological progression. While no universal metabolite marker of physiological ageing was identified, analyses across two storage seasons identified 22 consistent metabolites associated with the transition from dormancy to apical dominance. These compounds were mapped to four key pathways—primary metabolism, phenylpropanoid, oxylipin, and carotenoid metabolism—suggesting two complementary mechanisms underlying dormancy release: mobilisation of storage reserves for sprout growth and enzymatic modification of inhibitory compounds to less active forms.

Field trials using tubers of defined physiological age demonstrated that ageing effects on emergence and early canopy development were cultivar- and environment-dependent. Very high storage temperatures (17 ˚C) accelerated ageing and reduced vigour, while moderate storage (4–10 ˚C) produced seed tubers of optimal physiological age and field performance.

Integrating physiological, metabolic, and agronomic data highlighted both the complexity and practical relevance of physiological ageing. Sprouting capacity emerged as a promising indicator for developing cultivar-specific ageing profiles to guide storage and planting decisions. Linking metabolomics to well-defined physiological phase transitions proved valuable in uncovering novel regulatory mechanisms. While yield effects were inconsistent, incorporating physiological age into existing crop models may improve predictions of growth vigour. Collectively, this work advances understanding of potato seed tuber physiology and provides a framework for monitoring and managing physiological age to enhance sustainability in potato production systems.