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Climate change scenarios and water restrictions are key challenges for Mediterranean citriculture, requiring sustainable deficit irrigation (DI) strategies to ensure sustainable yields. Further research on the physiological pathways that regulate crop responses to water stress is necessary. This work describes the physiological limitations induced under drought conditions in young Navelina orange trees, including the crop's capability to recuperate its physiological status upon rewatering and after water withholding. A trial was conducted in two-year-old trees subjected to three irrigation treatments: a full irrigation treatment (FI) and two different DI strategies. The results show significant decreases in gas exchange rates for stem water potential (ΨStem) values below −1.5 MPa, evidencing diffusive limitations from drought stress. Additionally, there was evidence of increased osmolyte synthesis, a preventative response to oxidative damage. Significantly increased levels of proline (Pro) and malondialdehyde (MDA) were observed with higher levels of water stress (ΨStem < −1.8 MPa), which leads us to assume that this threshold signals the presence of oxidative damage with no capacity for subsequent recovery, probably affecting the final yield. [ABSTRACT FROM AUTHOR]

Due to congenital features, avocado (Persea americana Mill.) trees are substantial water users relative to other fruit trees. The current growing deficiency of water resources, especially in arid and semi-arid avocado-producing areas, has led to the demand for more sustainable water-saving measures. The objective of this review was to analyze the role of deficit irrigation as a strategy to face climate change and water scarcity through achieving efficiency, saving water, and maximizing the benefits that could be achieved at the level of the irrigated agricultural system. Particular attention is devoted to studies performed in the subtropical Mediterranean climate, in which irrigated avocado orchards are common. These studies analyzed irrigation demand, deficit irrigation, and determination of water status through physiological parameters, leading to possible sustainable irrigation programs for avocado in the context of water shortage scenarios. Through these insights, we conclude that under the current climatic circumstances with respect to available water resources, avocado farming requires sustainable resilience strategies to reduce irrigation water consumption without affecting the yield and quality of the fruits. Water stress inevitably affects the physiological processes that determine yield. Therefore, an admissible yield loss is required with smaller fruits and water savings made through deficit irrigation strategies. In addition, modern consumers tend to prefer foods based on sustainability, i.e., there is a high demand for socially responsible and environmentally friendly products. [ABSTRACT FROM AUTHOR]

Water scarcity is a threat to food production systems, with appropriate water management being a major part of the solution. From the adoption of the European Water Framework Directive to the latest proposals for the Common Agricultural Policy Horizon 2020, the strategic lines for establishing a balance between agriculture and water resources in the European Union have been defined, including an emphasis on water pricing. This paper discusses the situation of irrigated agriculture in semi-arid areas such as southern Spain in terms of water scarcity, highlighting the main advantages and disadvantages of water-pricing policies as a solution to more sustainable irrigation management. [ABSTRACT FROM AUTHOR]

Long-term impact of different sustained-deficit irrigation (SDI) treatments on a 13-year-old orange orchard (Citrus sinensis L. Osbeck, cv. Salustiana) was studied from 2004 to 2008. The experiment consisted of a control irrigation treatment which was applied at 100% of the crop evapotranspiration (ETc) values for the whole season, and three SDIs imposed as a function of different water-stress index (WSI) values, defined as the ratio of the actual volume of water supply to the ETc rate. The values defined by the WSI were 0.75, 0.65, and 0.50. The plant-water status was measured through the midday stem-water potential (ΨStem). Yearly, yield and fruit quality were evaluated at harvest in each treatment, and a global analysis was carried out using the whole dataset. Overall, no significant differences were found in fruit yield between SDIs and control treatments, although significant differences appeared in some of the fruit-quality parameters (total soluble solids and titrable acidity) which also showed significant relationships with integrated stem-water potential (ΨInt) and irrigation water applied. These findings lead us to conclude that SDIs have important and statistically significant effects on fruit quality. Thus, the application of sustained-deficit irrigation (SDI with WSI of 50) provides promising possibilities for optimising citrus irrigation and boosting the water productivity for citrus orchards in a semiarid Mediterranean climate. [ABSTRACT FROM AUTHOR]

Introduction Mango (Mangifera indica L.) is a crop of major economic importance in the provinces of Malaga and Granada (SE Spain). A field experiment on mango trees was designed to determine the optimum irrigation scheduling over three seasons. The aim was to evaluate the impact of sustained-deficit irrigation (SDI) strategies on fruit yield and quality, tree growth, and mineral status under a Mediterranean subtropical climate. Materials and methods. Three sustained-deficit irrigation treatments were applied to mango trees: SDI-1 (33% ETc), SDI-2 (50% ETc) and SDI-3 (75% ETc). The stress treatments were compared with a control (C-100) irrigated at 100% ETC. The response of fruit yield, number of fruits, fruit size and quality, and macro- and micronutrients in leaves was determined. Results. The SDI-2 treatment proved to be the most appropriate SDI treatment, since it allowed the trees to reach the highest yield (18.4 t·ha-1) and the best water-use efficiency (7.14 kg·m-3). However, fruit size was higher for trees of the SDI-3 and C-100 treatments, since they reached significantly higher length and width. The total soluble solids were affected by the SDI treatments only for one year, being highest in fruits from trees of the SDI-1 and SDI-2 treatments. Macro- and micronutrients in the leaves were affected by the SDI treatment only for the P, Mg and Mn contents. Conclusion The SDI treatment providing 50% of ETC is recommended for mango orchards in order to attain the highest yields and the best water-use efficiency under a Mediterranean subtropical climate. [ABSTRACT FROM PUBLISHER]

Almond (Prunus dulcis Mill. (D.A. Webb)) plantations in irrigated semi-arid areas need to successfully face the new scenarios of climate change combining sustainable irrigation strategies and tolerant cultivars to water stress. This work examines the response of young almond (cvs. Guara, Marta, and Lauranne) subjected to different irrigation doses under semi-arid conditions (South-West Spain). The trial was conducted during two seasons (2018–2019) with three irrigation strategies: A full-irrigated treatment (FI), which received 100% of the irrigation requirements (IR), and two sustained-deficit irrigation strategies that received 75% (SDI75) and 65% (SDI65) of IR. Crop water status was assessed by leaf water potential (Ψleaf) and stomatal conductance (gs) measurements, determining the yield response at the end of each season. Different physiological responses for the studied cultivars were observed, especially considering the Ψleaf measurements. In this way, cv. Marta behaved more tolerant, while cvs. Guara and Lauranne maintained higher gs rates in response to water stress. These differences were also observed in terms of yield. The cv. Lauranne did not reflect yield losses, and the opposite trend was observed for cv. Guara, in which reductions on fruit numbers per tree were detected. On overall, effective irrigation water savings (≈2100 m3·ha−1 in SDI65) could be feasible, although these responses are going to be substantially different, depending on the used cultivar. [ABSTRACT FROM AUTHOR]