14 páginas.-- 4 figuras.-- 3 tablas.-- 147 referencias.-- : Galindo,A., et al...Water scarcity in Mediterranean climate areas will be progressively aggravated by climate change, population increase and urban, tourism and industrial activities. To protect water resources and their integrity for future use and to improve biodiversity, besides following advanced deficit irrigation strategies in fruit cultivation, attention could well be directed towards what are at present underused plant materials able to withstand deficit irrigation with minimum impact on yield and fruit quality. To this end, the state of the art as regards deficit irrigation strategies and the response of some very interesting emerging fruit crops [jujube (Zizyphus jujuba Mill.), loquat (Eriobotrya japonica Lindl.), pistachio (Pistacia vera L.) and pomegranate (Punica granatum L.)] are reviewed. The strengths and weaknesses of deficit irrigation strategies and the mechanisms developed by these emerging fruit crops in the face of water stress are discussed. The response of these crops to deficit irrigation, with special attention paid to the effect on yield but also on fruit quality and health-related chemical compounds, was analysed in order to assess their suitability for saving water in Mediterranean semiarid agrosystems and to analyze their potential role as alternatives to currently cultivated fruit crops with higher water requirements. Finally, the factors involved in establishing an identity brand (hydroSOS) to protect fruits obtained under specific DI conditions are discussed.We are also grateful to the Ministerio de Economía y Competitividad de España (MINECO) (CICYT/FEDER AGL2013-45922-C2-1-R, AGL2013-45922-C2-2-R, AGL2016-75794-C4-1-R and AGL2016-75794-C4-4-R) for grants to the authors. AG and JC-G acknowledge the postdoctoral financial support received from the Ramón Areces Fondation and the Juan de la Cierva program, respectively. Also, this work is a result of the PR internship (19925/IV/15) funded by the Fundación Séneca – Agencia de Ciencia y Tecnología de la Región de Murcia (Seneca Foundation – Agency for Science and Technology in the Region of Murcia) under the Jiménez de la Espada Program for Mobility, Cooperation and Internationalization.Peer reviewe

Growing trees are quite vulnerable to cold temperatures. To minimise the effect of these cold temperatures, they stop their growth over the coldest months of the year, a state called dormancy. In particular, endodormancy requires accumulating chilling temperatures to finish this sort of dormancy. The accumulation of cool temperatures according to specific rules is called chilling accumulation, and each tree species and variety has specific chilling requirements for correct plant development. Under global warming, it is expected that the fulfilment of the chilling requirements to break dormancy in fruit trees could be compromised. In this study, the impact of climate change on the chilling accumulation over peninsular Spain and the Balearic Islands was assessed. For this purpose, bias-adjusted results of 10 regional climate models (RCMs) under Representative Concentration Pathways (RCPs) 4.5 and 8.5 were used as inputs of four different models for calculating chilling accumulation, and the results for each model were individually compared for the 2021–2050 and 2071–2100 future periods under both RCPs. These results project a generalised reduction in chilling accumulation regardless of the RCP, future period or chilling calculation model used, with higher reductions for the 2071–2100 period and the RCP8.5 scenario. The projected winter chill decrease may threaten the viability of some tree crops and varieties in some areas where the crop is currently grown, but also shows scope for varieties with lower chilling requirements. The results are relevant for planning future tree plantations under climate change, supporting adaptation of spatial distribution of tree crops and varieties in Spain.

Profiles of fruit density, fruit size, and oil content were measured on 12 occasions in 7 olive orchards in Spain and 2 in Australia. Orchard structure varied widely. Height ranged from 2.0 to 5.5 m, row spacing from 3 to 6 m, and canopy width from 0.7 to 3 m. Most orchards were oriented north–south (N–S) but one in Spain was oriented close to east–west (E–W) (20° NE–SW). All orchards in Spain were cv. Arbequina, and in Australia they were cvv. Barnea and Picual. Analyses with a model of interception and transmission that estimated interception by individual sides of hedgerows revealed that fruit size and oil content were strongly related to intercepted radiation during the month before harvest across all orchards. Relationships were also evident between fruit density and interception but varied among orchards and years, indicating the importance of other environmental and probably physiological effects. In N–S orchards of cv. Arbequina, average fruit size and oil content increased linearly from 0.40 g (dry weight) to 0.72 g, and from 36 to 49% (of dry weight), as daily intercepted PAR increased from 6 to 25 mol/m2 (15–60% of horizontally incident radiation). The general principles of response extended to E–W orchards. There, it was shown that generally large fruit with high oil content on S sides was consistent with the plateau responses to radiation evident in the more extensive N–S data. On the N side, however, and accounting for transmission through the hedgerow, both fruit size and oil content were greater than in positions intercepting equivalent radiation in N–S orchards. Examples are provided of the utility of responses of fruit density, size, and oil content in establishing combinations of row height, row width, and row distance to improve or maintain productivity in some of the orchards included in the study.

Limited water supply in arid and semiarid Mediterranean environments demands improving irrigation efficiency. The purpose of this study was to determine a functional relationship between soil water availability and wine grape ( Vitis vinifera ) water status to determine a threshold value of soil matric potential to trigger irrigation. Seasonal trends of soil water potential, leaf water potential, and stomatal conductance ( g _S ) of ‘Tempranillo’ wine grape were determined in two deficit irrigation treatments replenishing 45% and 30% of the reference evapotranspiration, and in a third non-irrigated treatment during 2001 and 2002. Soil water potential was measured with granular matrix soil moisture sensors placed at 0.3 m (Ψ _0.3 ), 0.6 m (Ψ _0.6 ), and 1.2 m (Ψ _1.2 ) depths. The sensors at 0.3 m depth quickly responded to irrigation by increasing Ψ _0.3 levels. At the 0.6 m depth, Ψ _0.6 progressively decreased, showing significant differences between T1 and the rest of the treatments, while no significant differences in Ψ _1.2 were found. All relationships between profile soil matric potential and leaf water potential and g _S were highly correlated. After integrating our data with previous studies, we suggest a whole profile soil water potential value of –0.12 MPa as threshold to trigger irrigation and avoid severe water stress during berry growth.

9 páginas.-- 5 figuras.-- 8 tablas.-- 31 referencias.-- Corell, M. et al. (2016) Comparison of the water potential baseline in different locations. Usefulness for irrigation scheduling of olive orchards. Agricultural Water Management (177) 308-316Deficit irrigation scheduling needs accurate indicators and in recent decades, continuous plant indicators have been developed. However, threshold values that could be useful in commercial orchards are not commonly reported. The water potential is a discontinuous measurement commonly used as a reference in the description of water stress level. In some fruit trees, such as olive trees, there are several works suggesting threshold values in fully irrigated conditions, but the influence of the evaporative demand is not taken into account. The aim of this work is to compare the values of the fully irrigated water potential in different locations in order to study the estimation of a common baseline. Three mature olive orchards were selected, two in Seville (South Spain) and one in Ciudad Real (Central Spain). There were clear differences between the three orchards during the 2015 season. Orchards in Seville (S-1 and S-2) were close (10 km apart) and had the same cultivar (table olive, cv Manzanilla) but they were different in terms of the fruit load (almost no fruit in S-1, medium fruit load in S-2) and distribution of water (single drip line in S-1, double drip line in S-2). The orchard in Ciudad Real (CR) was very different with regards to the olive cultivar (cv Cornicabra) and the location, as it was in a borderline zone for olives growing with very low temperatures that delay the phenological development. In all the orchards, the best baseline was obtained with different climatic measurements, even in S-1 and S-2. When all the data were considered, the best fit was obtained with the average vapour pressure deficit (VPDav). Influence of the location was significant in the interception term of the equations when Temperature was used but not with VPD. This source of variation was reltade with the level of fruit load. Slope of the equations was not affected for the location. The equation obtained was validated with water potential data from previous seasons of S-1 and CR orchards. Maximum temperature presented the best validation results. The usefulness of this baseline is discussedThis research was supported by the Spanish Ministerio de Ciencia e Innovación (MICINN), (AGL2013-45922-C2-1-R).Peer reviewe