Drought tolerance screening for potato improvement

Six potato genotypes including ‘Desiree’ and five breeding clones (2/14, 95C, 125B, 3589, 4056) were grown in the field under well-watered and stress conditions. The stress response of leaf tissue was assessed 8 and 12 weeks after plant emergence (WAE) by measuring canopy temperature and chlorophyll α fluorescence induction kinetics in detached leaves. Under drought-stress conditions, chlorophyll α fluorescence dropped in clones 2/14 and 4056, remained constant in 95C and 125B and increased in clone 3589. The canopy temperature exhibited little difference between drought and irrigated treatments in clones 95C and 125B, and significant effects in the other genotypes. This performance was interpreted in terms of tolerance to drought stress, and the potential use of canopy temperature and chlorophyll fluorescence as tools for drought screening of potato germplasm and segregant generations is discussed. The physiological properties of 95C and 125B highlighted by this study need further investigation and, if confirmed, they could be recombined with other useful agronomic characters by crossing in a breeding programme.