Response of Stored Potato Seed Tubers from Contrasting Cultivars to Accumulated Day‐Degrees

Abstract

In potato (Solanum tuberosum L.), the accumulated day-degrees (temperature sum, calculated by accumulating the daily temperatures) from dormancy break until seed tuber use has been suggested as an indicator of the physiological status of the seed. We tested whether similar temperature sums differing in timing of a short period of high temperatures gave similar seed performance. Four field experiments were performed in which seed was used that had been exposed to different storage temperature regimes, differing in total temperature sum or in timing or duration of a warm period. Emergence, number of stems, number of tubers, and early and mature tuber yield were assessed. During the storage period, the onset of sprouting was recorded. Cultivars with a high rate of physiological degeneration (''ageing'') were usually sensitive to warm storage during the second part of the storage period, especially if the first 12 to 18 wk of storage had also been warm. This was reflected in reduced emergence (#10%), low densities of stems (#0.5 stems m 22 ) and tubers (#5 tubers m 22 ), and low yields, especially with early harvesting (#20 g m 22 ). Specific phasing of the warm period could reduce yields to levels even below the yield of the seed tubers exposed to the highest accumulated temperature sum. A higher temperature sum after the end of dormancy advanced and accelerated the process of ageing of seed tubers. Cultivars with a high rate of ageing showed much greater difference between the same temperature sums built up over time in different ways than cultivars with a low rate of ageing. The resulting maximum differences in final fresh tuber yield between seed lots exposed to the same temperature sum could be 65 Mg ha 21 for Astarte (a cultivar with a high rate of ageing) compared with nil for Dé siré e (a cultivar with a low rate of ageing).

Assessment of Potato Mother Tuber Vigour Using the Method of Accelerated Ageing

“…In many cases, this indicator is very useful; however, as shown previously (Rykaczewska, 1987a, it is not a universal measure, because the same sum of temperatures accumulated in autumn and in spring have different effects on plant growth and yield of potato. Struik et al (2006) also found that the effect of temperature sum during storage had a different impact on seed age depending on whether warm temperatures occurred at the beginning or at the end of the storage period. Another measure under consideration in research work is the length of the incubation period (time elapsed from sprouting until new tuber formation on the sprouts) (Reust, 1986).…”

“…Therefore, measures and indicators of the physiological age of tubers have been explored. One of these measures is the accumulated degree-days (O'Brien et al, 1983; Struik et al, 2006;Struik, 2007). In many cases, this indicator is very useful; however, as shown previously (Rykaczewska, 1987a, it is not a universal measure, because the same sum of temperatures accumulated in autumn and in spring have different effects on plant growth and yield of potato.…”

Thermal sum of potato plants and tuber sprouting

“…This advancement includes the stages of dormancy (absence of sprouts or dormant buds), apical dominance (just one sprout), full sprouting (several side sprouts) and senescence (intense branching of the sprouts) (WIERSEMA, 1985;STRUIK, 2007;BISOGNIN et al, 2008a). However, the rate of advancement through the different stages is highly dependent on the cultivar (STRUIK, 2007) and the environmental conditions during growth and storage (WIERSEMA, 1985;STRUIK et al, 2006;BISOGNIN et al, 2008a;HELDWEIN et al, 2009). For both scientific and practical purposes, a good indicator of physiological age would be very useful (STRUIK et al, 2006), since it directly influences the yield potential of the tuber seed (STRUIK, 2007).…”

“…However, the rate of advancement through the different stages is highly dependent on the cultivar (STRUIK, 2007) and the environmental conditions during growth and storage (WIERSEMA, 1985;STRUIK et al, 2006;BISOGNIN et al, 2008a;HELDWEIN et al, 2009). For both scientific and practical purposes, a good indicator of physiological age would be very useful (STRUIK et al, 2006), since it directly influences the yield potential of the tuber seed (STRUIK, 2007).…”

“…dominance in tubers, while high temperatures (>25ºC) accelerate sprouting but do not favor breaking of apical dominance (BISOGNIN et al, 2008a;MULLER et al, 2010). Moreover, the advancement of tuber physiological age varies depending on whether storage temperatures are constant or fluctuating (combinations of high and low temperatures) and high temperatures at the end of the storage period are detrimental to cultivars with a high rate of physiological aging (STRUIK et al, 2006). Therefore, temperature is the environmental factor that most affects the period of dormancy and cold storage is the most widely used technology in the world to retard sprouting of potato tubers (ESHEL & TEPER-BAMNOLKER, 2012).…”