Evaluating Tuber Maturity of Colorado State University Potato Germplasm (P-05)

Potato maturity has historically been based on vine maturity by research and breeding programs. Vine maturity data is taken on a 1 to 5 scale and indicates at which point in the season the vine dies, no longer contributing to the growth of the tuber, and the tubers are assumed to be mature. Therefore, when a potato variety is described as “early”, that indicates that the vine dies earlier in the season. However, the physiological point of tuber maturity is not necessarily represented by the death of the vine. Defining tuber maturation and assessing the CSU potato breeding germplasm is necessary to facilitate breeding for potato varieties with early maturity. Previous studies have shown that skin set indicates physical maturity, and specific gravity indicates physiological maturity (Heltoft et al. 2017). Potato “skin” or the periderm, is comprised of three layers of tissue that change throughout tuber growth (Reeve et al. 1969). During maturation of the tuber, two of the layers adhere to one another, and this is what is informally known as skin set. We designed a Tuber Maturity trial to evaluate our early generation selections for physiological maturity. We measured traits that include skin set, percent skinning, wound healing, and specific gravity. Using these parameters, we formulated a definition of maturity to guide the breeding program’s objectives and evaluate advanced CSU selections for their maturity and skin set. The methodology defined and data collected will also be used for the eventual development of molecular tools to facilitate selection of early tuber-bulking varieties and skinning resistance or tolerance.