POMEGRANATE PHYSIOLOGICAL RESPONSES TO PARTIAL ROOT DRYING UNDER FIELD CONDITIONS

Abstract

The effects of different levels of Partial Root Drying (PRD) on pomegranate (Punica granatum L. cv. Wonderful) physiological and fruit quality parameters were studied under field conditions. Three irrigation treatments were applied: control (C) in which plants were irrigated at both parts of the rootzone to fully compensate evapotranspirational water losses; and partial root drying (PRD1 and PRD2) receiving 100% and 50% irrigation water of control plants, respectively. PRD plants exhibited lower stomatal conductance (Gs) and transpiration rate compared to the control plants. PRD1 maintained more favorable plant water status throughout the experimental period. On the contrary, no significant differences in photosynthetic rate (Pn) between PRD1 and control plants were observed. PRD2 plants exhibited significant lower values of all physiological parameters suggesting that the irrigation amount applied could not compensate water losses. Furthermore, higher level of water stress in PRD2 treatment resulted in a significant decrease in mean fruit weight and diameter. No significant effects of different irrigation methodologies on total titratable acidity and juice percentage were evident. Among all treatments, fruit cracking was significantly lower in PRD1 treatment, a fact that was associated with the maintenance of plant water status in this treatment throughout the experimental period.