Effects of drought acclimation on drought stress resistance in potato (Solanum tuberosum L.) genotypes

The effects of drought acclimation in three contrasting potato genotypes [‘Fv12246-6’ (Fv) drought stress sensitive, ‘Vigor’ (V) moderately drought resistant and ‘Russet Burbank’ (RB) drought resistant] in a low relative humidity greenhouse were examined. Non-Acclimated and Non-Stressed (NA), Non-Acclimated and Drought Stressed (NAS), Drought Acclimated and Drought Stressed (DAS) treatments were applied. Short term acclimation had no significant long term effect on tuber weight and number under drought stress. However, water conservation mechanisms based on leaf and stem characteristics were both genotype and treatment-dependent. The importance of the stem in water conservation was revealed when leaves were drought stressed while either attached or excised from the stem. When leaves were drought stressed while attached to the stem, both the moderately and drought stress resistant genotype V and RB, respectively, maintained a higher percentage of leaf water content than the drought sensitive Fv. By contrast, when leaves were detached from the stem and moisture loss was monitored, the moderately drought resistant V genotype lost water at the fastest rate. The significantly greater stem water content of V and RB genotypes compared to Fv may have been a source of water to intact leaves during drought stress. Drought resistant RB underwent the fastest recovery from drought stress and had the highest number of drought resistance tools. Finally, compared to an application of drought stress directly (NAS), a pre-treatment of drought acclimation cycles followed by drought stress (DAS) reduced leaf wilting, induced thicker cuticular layer and more open stomata under stress. Without a DAS approach, potentially key drought stress resistance mechanisms will be missed. The role of the stem as a potential water reservoir to adapt against drought stress should be further examined to identify key elements for drought stress survival and recovery at the level of the potato whole plant.