Investigating the utility of potato (Solanum tuberosum L.) canopy temperature and leaf greenness responses to water-restriction for the improvement of irrigation management

Traits that rapidly respond to stress in important agricultural crops have the potential to provide growers with actionable feedback. Traits that respond to water-restriction could inform irrigation systems by identifying crop water status and requirements in real-time. This would be particularly useful for potato, which is extremely susceptible to drought. We conducted two pot experiments and one field experiment to evaluate the utility of two traits, canopy temperature and leaf greenness, for informing irrigation management in potatoes. We also evaluated the efficacy of Phenospex PlantEye F500 sensors for the remote sensing of leaf greenness. We found that canopy temperatures of the cvs. Maris Piper (Spring Pot Experiment, + 0.8 °C; Autumn Pot Experiment, + 5.3 °C) and Désirée (Autumn Pot Experiment, + 2.5 °C) increased with water-restriction and that the canopy temperatures of Maris Piper returned to its baseline within three days after the resumption of well-watered conditions. We also found that these responses varied between cultivars, with predictable outcomes based on reported and corroborated drought tolerance ratings. Leaf greenness was not affected by water restriction in the Spring pot experiment but had a significant interaction with sampling date and water restriction in the Autumn pot experiment. However, leaf greenness measurements from the Phenospex PlantEye F500 were significantly correlated with SPAD values, suggesting this tool might be useful in the screening for drought-tolerant cultivars in the future.