Large-Scale Evaluation of Potato Improved Varieties, Genetic Stocks and Landraces for Drought Tolerance

Potato production worldwide is strongly affected by water stress, either because of insufficient rainfall or due to inadequate irrigation. Improving drought tolerance is consequently becoming a priority for potato breeders, particularly in the perspective of climate change. In the present study, a set of 918 accessions from CIP world potato collection was evaluated under field conditions with full irrigation and deficit irrigation, on the desertic coast of Peru. The set included improved varieties, genetic stocks and landraces. The subset of landraces comprised accessions from the species Solanum ajanhuiri Juz. & Bukasov, Solanum curtilobum Juz. & Bukasov, Solanum juzepczukii Bukasov and Solanum tuberosum L. S . tuberosum L. included non Andean accessions of the ssp. Chilotanum as well as accessions belonging to the Andean cultivar groups Andigenum, Chaucha, Goniocalyx, Phureja and Stenotomum. Under both drought and irrigated treatments, significant differences were found for tuber yield, tuber number and tuber weight among subsets, cultivar groups and accessions. On average, improved varieties and advanced bred lines yielded more under both deficit and well-irrigated conditions than did landraces, while variation for drought susceptibility was greater in landraces and genetic stocks than in improved varieties. Within the subset of landraces, the species Solanum juzepczukii Bukasov exhibited the lowest average values and highest variation for drought susceptibility. A high proportion of accessions combining low drought susceptibility and high irrigated yield were found in Andean landraces, and particularly in the species Solanum curtilobum Juz. & Bukasov in the S . tuberosum L. cultivar groups Stenotomum, Andigenum and Chaucha. The differences observed among species and cultivar groups were not directly related to their eco-geographic distribution. The polyploid species and cultivars groups appeared more drought tolerant than the diploid ones. The study evidenced the interest of Andean landraces as potential sources of drought tolerance in potato breeding programs.