Irrigation Regime Effects on Some Physiological Responses of Potato1

Abstract

AbstractPotato is relatively sensitive to water stress, and therefore indices for characterizing the degree of water stress and its relation to tuber yield are sought. During a series of field irrigation experiments on potatoes (Solanum tuberosum L.) conducted on a calcic haploxeralf in the Negev region of Israel, data were collected on leaf permeability (LP), leaf and tuber water potential (Ψ1 and Ψ1, respectively) and photosynthetic rate, with the aim of relating the variables to a range of water stresses caused by the ratio irrigation/evaporation (Kp). Leaf permeability was linearly related to Ψ1, which ranged from −0.7 kJ kg−1 in well irrigated plants to −1.4 kJ kg−1 in severely water‐stressed plants. Tuber water potential, Ψ1, was higher by 0.4 to 0.7 kJ kg−1 than Ψ1, the difference increasing with water stress. In trickle‐irrigated plants, Ψ1 of tubers growing in dry soil was lower by 0.06 to 0.12 kJ kg−1 than Ψ1 of tubers growing in wet soil, even though the tubers were attached to the same stem. Photosynthesis increased with LP up to 0.8 mg CO2 m−2sec−1 and declined with plant age independently of LP. Marketable yield was well related to both seasonal LP and Ψ1, all three variables decreased when Kp dropped below 1.0. Leaf permeability seems to be a better index than leaf water potential for the characterization of water stress of potato in the field.