The accessions in this subset combine virus resistant potato accessions with adaptation to mid-elevation subtropical conditions and constitute a valuable resource for further crop improvement.

Breeding efforts of CIP’s potato breeding program using germplasm of wild species, landraces and improved material have resulted in the development of two advanced populations with specific adaptation to the most important agro-ecologies of the tropics and subtropics: the Highland-Tropics Adapted Late Blight Resistant Population and the Lowland Sub-Tropics Virus Resistant Population. The Highland-Tropics Adapted Late Blight Resistant Population combines high levels of resistance to late blight with economically important traits such as tuber yield, tuber quality, processing and improved adaptation to warm environments and mid-season maturity (90 day growing period under short day length conditions). The Lowland Sub-Tropics Virus Resistant Population contains clones with resistance to the most important virus diseases (PVY, PVX and PLRV) of potato and adaptation to warm, arid environments with early maturity under short days and mid-maturity under long days. To promote the exchange and evaluation of CIP’s advanced breeding material, 12 subsets of clones were created (Gastelo et el. 2014). These subsets or “nurseries” offer trait combinations such as adaptation to tropical, subtropical and temperate regions of different altitudes, tolerance and/or resistance to biotic and abiotic constraints as well as agronomic or tuber quality traits: clones for mid-elevation areas in subtropical and temperate regions show high resistance to PVY and PVX and clones for subtropical lowlands have virus tolerance combined with heat and drought tolerance. Generally, the nurseries contain clones that have the potential to counterbalance the effects of increasing temperatures in both traditional and new areas of potato cultivation, e.g. clones with resistance to late blight, PVY, heat tolerance and relative earliness are potentially adapt well to Sub-Saharan Africa and Asia (Gastelo et al. 2013).

The Potato Mid-elevation Subtropics Virus Resistant Nursery is part of the Lowland Sub-Tropics Virus Resistant Population.