Physiological mechanisms involved in potato (Solanum tuberosum) tuber dormancy and the control of sprouting by chemical suppressants

Investigations on potato tuber dormancy are of basic importance for both food products and seed tubers. The physiology of dormancy is not clear, although significant progress has been made in recent years. Plant hormones are involved in dormancy control, but experimental evidence is often contradictory. The auxin indoleacetic acid (IAA) appears to induce sprouting, as its concentration increases in tuber buds during dormancy release. Contrasting results were obtained for abscisic acid. Generally, this hormone is thought to be responsible for both inducing and maintaining bud dormancy, but it was demonstrated that its concentration in bud tissues rises in dormant tubers until they reach sprouting time. Based on recent evidence, a decisive role in tuber dormancy control could be ascribed to sprout-inducing hormones, such as IAA, despite classical hypotheses attributing greater importance to the equilibrium between sprout-promoting and sprout-inhibiting regulators. Potato tuber storage is a crucial phase of the whole production cycle. Storage techniques include physical (low temperature, controlled atmosphere) and chemical (sprout suppressants) treatments, often applied simultaneously, and may change depending on crop product (food or seed). Chemical sprout suppressants may cause food tuber contamination with potentially toxic residues, while their residual phytotoxic activity may negatively affect bud outgrowth of seed tubers. Research has recently highlighted the interesting features of the monoterpene carvone, whose low mammalian toxicity makes its use advisable. The sprout inhibiting activity of this chemical rapidly weakens when treatments are discontinued, thus making it suitable for seed tuber preservation.