New Elite Potato Clones with Heat Tolerance, Late Blight and Virus Resistance to Address Climate Change

Potato production in developing countries is expanding to warmer environments as farmers search for income opportunities and food security. Meanwhile, climate change is already affecting weather patterns in traditional potato-growing areas, Where unpredictable rains and pressure from pests and disease are increasing farmers' risk. Since 2004, the International Potato Center (CIP) has sought to develop new, more heat-tolerant generations of its tropical highland-adapted late-blight resistant population. Late-blight resistant parents were crossed with early maturing and virus resistant progenitors, and selection practised under warm temperatures, water deficit and mid-latitude conditions. During the 2005-2006 summer season (January March) 20,000 genotypes were exposed to heat in a screen house at CIP's experimental station in San Ramon, a warm rain forest environment at 800 m above sea level (mast) and latitude 11 degrees 08' S. Selected clones were assessed in the field in the same location, Where average night and day temperatures during tuberization were and,-7 _n, respectively; the resulting heat tolerant clones were exposed to high, endemic late blight pressure in Oxapampa (mid-elevation humid tropics) in replicated trials conducted over 4 years. Selected heat tolerant, late blight resistant clones were evaluated for yield components in the spring summer season in La Molina (12 degrees 05' S) and drought sensitivity in Majes (16 degrees 28' S) along the arid coast of Peru. Sixty-one advanced clones were assessed again for yield in San Ramon, La Molina and Majes and yield stability analysed. All trials were conducted in a simple lattice design, using Desiree as a heat tolerant control. Harvesting was performed at 90 days. The 61 clones were screened for resistance to potato virus X (PVX) and potato virus Y (PVY), by mechanical inoculation and grafting under greenhouse conditions. Analysis of variance for marketable tuber yield showed significant differences among clones. In San Ramon, yields were in the range of 16.01-28.43 (t/ha), significantly exceeding the control. Of the 40 mid-maturing elite clones selected from the new 'LBW' (late blight resistant heat tolerant) population, with resistance to late blight, tolerance to heat, 11 carry extreme resistance to PVY, 25 to PVX and seven show tolerance to drought. Eleven mid-maturing clones with heat tolerance, resistance to late blight and PVY that are suitable for mid-elevation zones mid climate change, and all 40 clones, are available for variety development and further use in breeding.