Effect of the season on the free phytoprostanes content in Cornicabra extra virgin olive oil from deficit irrigated olive trees

BACKGROUND: The effect of regulated deficit irrigation (RDI) on the phytoprostane (PhytoP) content in extra virgin olive (Olea europaea L., cv. Cornicabra) oil (EVOO) was studied. During the 2012 and 2013 seasons, T0 plants were irrigated at 100% ETc, while T1 and T2 plants were irrigated avoiding water deficit during phases I and III of fruit growth and saving water during the non-critical phenological period of pit hardening (phase II), developing amore severewater deficit in T2 plants. In 2013, a fourth treatment (T3) was also performed, which was similar to T2 except that water saving was from the beginning of phase II to 15 days after the end of phase II. RESULTS: 9-F1t-PhytoP, 9-epi-9-F1t-PhytoP, 9-epi-9-D1t-PhytoP, 9-D1t-PhytoP, 16-B1-PhytoP and 9-L1-PhytoP were present in Cornicabra EVOO, and their contents increased in the EVOO fromRDI plants. CONCLUSION: Deficit irrigation during pit hardening or for a further period of 2 weeks thereafter to increase irrigation water saving is clearly critical for EVOO composition because of the enhancement of free PhytoPs, which have potential beneficial effects on human health. The response of individual free PhytoPs to changes in plant water status was not as perceptible as expected, preventing their use as biomarkers of water stress.

Jujube fruit water relations during fruit maturation stage under different water deficit conditions

The fruit maturation stage is considered the optimal phenological stage for implementing water deficitin jujube (Zizyphus jujuba Mill.), since a low, moderate or severe water deficit at this time has no effect onyield, fruit volume or eating quality. However, no information exists at fruit water relations level on themechanisms developed by Z. jujuba to confront drought. The purpose of the present study was to increaseour understanding of the relationship between leaf and fruit water relations of jujube plants under dif-ferent irrigation conditions during fruit maturation, paying special attention to analysing whether fruitsize depends on fruit turgor. For this, adult jujube trees (cv. Grande de Albatera) were subjected to fiveirrigation treatments. Control plants (T0) were irrigated daily above their crop water requirements inorder to attain non-limiting soil water conditions in 2012 and 2013. T1 plants were subjected to deficitirrigation throughout the 2012 season, according to the criteria frequently used by the growers in thearea. T2 (2012), T3 and T4 (2013) were irrigated as T0 except during fruit maturation, in which irrigationwas withheld for 32, 17 and 24 days, respectively. The results indicated that the jujube fruit maturationperiod was clearly sensitive to water deficit. During most of this stage water could enter the fruits viathe phloem rather than via the xylem. From the beginning of water withholding to when maximumwater stress levels were achieved, fruit and leaf turgor were maintained in plants under water deficit.However, a direct relation between turgor and fruit size was not found in jujube fruits, which could bedue to an enhancement of a cell elasticity mechanism (elastic adjustment) which maintains fruit turgorby reducing fruit cells size or to the fact that jujube fruit growth depends on the fruit growth-effectiveturgor rather than just turgor pressure.