Irrigation strategies affect quality, mineral composition and internal rind browning of ‘Mollar de Elche’ pomegranate fruits

Water availability for irrigation is a scarce and limiting factor in the southeast of Spain, the main pomegranate-producing area in the country. Therefore, it is necessary to optimize the use of this resource by studying different irrigation strategies to reduce water inputs with the least possible impact on fruit production and quality. On the other hand, a physiological disorder has been recently observed in ‘Mollar de Elche’ pomegranates that causes browning of the inner side of the rind, especially in fruits subjected to long-term cold storage. The purpose of the present study was to determine the effect of irrigation management (different irrigation doses and drip flow rates) on fruit quality, plant nutrition and postharvest internal rind browning. Localized irrigation treatments were 100% ETc and sustained deficit irrigation (SDI) that established a restriction of 50% of the control regime. In addition, for each treatment, drip emitters with different flow rates of 8, 4 and 2 L h^‑1 were used. The experimental design in the orchard was random blocks of 8 trees and 4 repetitions per treatment (T1 to T6). Capacitive sensors (FDR) were installed, and midday stem water potential (Ψstem) measurements were carried out. The parameters measured in fruits were morphological, peel and juice color (CIELab*), juice quality (soluble solids content, pH, titratable acidity, maturity index), mineral nutrient composition (N, P, K, Ca, Mg, S, Na, Fe, Zn, Mn, B, Cu), and the internal rind browning index. The results showed that SDI increased the external coloration of the fruit and the maturity index but reduced the thickness of the rind and did not affect the color of the juice. No significant differences among types of drippers were found. Potassium and boron concentration in the albedo was affected by the irrigation regime. SDI reduced the incidence of internal rind browning, suggesting that this irrigation strategy can reduce this physiological disorder.