Physiology of tuber dormancy and its mechanism of release in potato

Abstract

The tuber dormancy is an important aspect of tuber’s physiological age and begins with tuber initiation. It is largely dependent on genotype, environmental conditions, and tuber age. The group Phureja among diploid potatoes, has a very short or no tuber dormancy while the tubers of Solanum jamesii, a wild potato species, may remain dormant for more than eight years and have the tendency to sprout in favourable conditions. The dormancy breakage in potato is accompanied by many physiological changes such as changes in the ratios of abscisic acid (ABA)/ cytokinin and ABA/ gibberellic acid (GA3), catalase inhibition and accumulation of soluble sugars. These all changes are interlinked and occur in the same time frame. The dormant buds have 77% of their nuclei in the growth phase (G1), compared to only 13% in the preparation phase for mitosis (G2), resulting in slower development of active buds. This paper reviews various factors involved in natural and forced dormancy breakage of potato tuber in relation to their use as seed potatoes immediately after harvesting and implementation of different exogenous dormancy breaking methods like cold pre-treatment, growth regulators, electric current and irradiation to induce sprouting in potatoes.

Postharvest starch and sugars adjustment in potato tubers of wide-ranging dormancy genotypes subjected to various sprout forcing techniques

“…Moreover, the use of dormancy breaking techniques provides even more exibility in raising consecutive crops 6 . The use of chemicals to shorten tuber dormancy, such as thiourea, bromoethane, and rindite, has been extensively investigated, but these substances are hazardous to both humans and the environment 22 . It is therefore imperative to characterise the germplasm in order of their dormancy period, which either directly or indirectly controls the maturation time 37 and keeping quality 38 of potato crop; and devise an effective, safe, and environmentally acceptable technique for breaking seed-tuber dormancy to enable single or multiple cropping system 6 .…”

“…According to previous studies, immature tubers contain 0.2 to 1.5% sucrose and 0.01 to 0.7% reducing sugars 19 , while mature tubers contain 0.1 to 0.6% sucrose and 0.04 to 0.4% reducing sugars 18,20 . A rapid accumulation of soluble sugars occurs during instinct dormancy breakage 21,22 . Although their exact levels in genotypes are still unknown.…”

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“…Regardless of the growing region, the accumulation of germination inhibitors in maturing tubers largely depends on varietal characteristics. In accordance with the duration of the tuber formation period of each individual variety, the optimal time for harvesting and planting freshly picked tubers is individual (Haider, 2021). Weather conditions have a substantial impact on the physiological and biochemical state of potato plants.…”

“…According to Gemeda (2017), the use of gibberellic acid to disrupt the dormancy of tubers also contributes to an increase in yield by 23-92% and an improvement in potato quality. Haider (2021) draws attention to the physiological changes in tubers that accompany their dormant state. Of particular importance is the ratio between abscisic acid and cytokinin and between abscisic acid and gibberellic acid.…”

Dormancy and Physiological Age of Seed Tubers from a Diverse Set of Potato Cultivars Grown at Different Altitudes and in Different Seasons in Kenya

“…Following dehaulming or haulm killing, the seed tuber becomes physiologically independent from its mother plant and shows its own physiological development as influenced by the existing environmental conditions (Struik and Wiersema 1999). The earliest observable stage of sprouting is characterized by visible small white buds, often termed "pipping" or "peeping" (Daniels-Lake and Prangel 2007) or mini-chitting (Struik and Wiersema 1999), which is influenced by physiological age (Eshel and Teper-Bamnolker 2012;Haider et al 2021). Tuber sprouting is the major visible milestone in determining physiological age (Mani et al 2014), while at the same time it leads to major quality losses of stored potato tubers (Mani and Hannachi 2015).…”