Frost damage to the foliage is a common problem where potatoes are grown, and results in significant reductions in tuber yield. Frost injury also limits the cultivation of high-yielding S. tuberosum cultivars in the mountain regions of Central and South America, where potato is a staple crop. Recent studies have shown that some wild potato species possess a high degree of non-acclimated frost tolerance (growing in normal conditions) as well as high cold acclimation capacity (able to increase frost tolerance upon exposure to cold). Natural frosts affecting potatoes are of two types: a) late spring or early fall frost, where the minimum temperature during the frost episode can be very low; b) frost during the growing season, where the minimum temperature during the frost episode is not as low. It is expected that potato species able to acclimate rapidly would survive better from the latter type of frosts, whereas species having higher acclimation capacity might have a great chance to survive better from the former type of frosts. The objective of this study was to find out if there is genetic variability for the speed of acclimation among different tuber-bearing wild potato species. The species used were: S. acaule, S. commersonii, S. megistacrolobum, S. multidissectum, S. polytrichon, S. sanctae-rosae, and S. toralapanum. Relative freezing tolerance of these species was measured during cold acclimation. Preliminary results suggest that there are differences in the speed of acclimation among these species. We found that these species can be divided into four groups: i) non-acclimators; ii) rapid acclimators, with low to medium acclimation capacity; iii) slow acclimators, with low to medium acclimation capacity; iv) slow acclimators, with high acclimation capacity. We plan to use this information in our breeding program aimed at improving the freezing tolerance of potatoes.
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