Mango (Mangifera indica L.) is broadly grown in tropical regions and can also be cultivated in irrigated subtropical semi-arid areas; however, water shortages are a serious problem in the latter region. Among biotic and abiotic factors, water supply is one of the most crucial elements that determine productivity. The allocation of water will be an ever-increasing source of pressure because of vast agricultural demands under changing climatic conditions. Although the mango is considered to be tolerant to drought, water stress during growing cycle can reduce productivity. Here, we review the recent progress in evaluating and augmenting mango water productivity. Developments in physiological and agronomic understanding that have led to a boost in water productivity are presented. In addition, this review deals with deficit irrigation strategies to elucidate the effects on mango yield, water use efficiency, and the response of physiological indicators to water stress. Our main findings were as follows: (1) Under a changing climate, traditional irrigation based on water balance will not be sustainable in the medium/long term; (2) deficit irrigation strategies applied to mango can save irrigation water by up to 40% and improve water use efficiency by up to 30%; and (3) there is valuable potential for further improvement owing to advanced knowledge in terms of the physiological response of mango to water stress, and there are good prospects within the current approaches if they are associated with specific environmental physiology. We concluded that under current medium-/long-term perspectives regarding available water resources, particularly in arid and semi-arid regions, there is an urgent demand for adaptive and water-saving strategies. Thus, it will be vital to redesign irrigation schemes in areas where water is scarce to adjust deficit irrigation strategies not only to save water, enhance water use efficiency, and maintain yield, but also to produce fruits with improved quality.

Avocado (Persea americana Mill.) is a subtropical tree, particularly sensitive to either an excess or a lack of water. Understanding this balance is crucial to determine the optimum water supply and enhance crop productivity. The rising shortage of water resources in semiarid producing regions and the need for irrigation optimization call for sustainable water savings. A 3-year monitoring study with avocado cv. "Hass" tested sustained-deficit irrigation strategies supplying 33, 50 or 75% of the estimated crop water demand. They were compared with a control strategy supplying 100% of the estimated crop water demand. The leaf water potential, stomatal conductance, tree growth, yield and several fruit quality parameters were evaluated. The yield, tree growth and fruit size were significantly and proportionally lessened by deficit irrigation treatments. Over the study, the average yields amounted to 31.6, 38.3 and 43.8 kg tree −1 in the 33, 50 and 75% treatments respectively, which were significantly less than the yield of 47.5 kg tree −1 measured in the control. The 33% and 75% sustained-deficit irrigation treatments increased the omega 3 and omega 6 fatty acids as well as the unsaturated fatty acids (oleic); however, the 33% deficit irrigation treatment significantly reduced the yield, size and fruit weight. We consider, therefore, that approximately 25% of the irrigation water can be saved without adversely affecting the avocado tree performance in short and medium terms and we recommend implementing the 75% sustained-deficit irrigation strategy. Here we show for the first time the key role of redesigning irrigation strategies in Mediterranean areas, focusing on the benefits of sustained-deficit irrigation, which can save water, encourage water use efficiency and enhance fruit quality. In order to save water, it is critical and necessary to implement such novel water shortage strategies, at the affordable cost of reducing fruit yield while enhancing its quality.

The soil erosion rates are high in the rainfed olive (Olea europaea L.) mountain plantations applying conventional practices in a semi-arid Mediterranean environment, which compromise their long-term sustainability. The implementation of sustainable soil management strategies is vital for hillslopes and low-fertility soils where plantations cover vast tracts of land. In Lanjarón (Granada, Spain), the soil erosion and runoff patterns over a 4-year monitoring period were studied in erosion plots on a mountainside under four types of production systems: (1) organic (spontaneous vegetation and leguminous covers), (2) conservation agriculture (combinations of minimum tillage with spontaneous and leguminous strips), (3) integrated (combinations of no-tillage with spontaneous vegetation and leguminous strips), and (4) conventional tillage. The olive yield responses to each production system were evaluated, and the selected physico-chemical soil properties (pH, bulk density, soil organic carbon, cation exchange capacity, and total N, P, and K), soil enzymes (β-glucosidase, protease, dehydrogenase, and phosphatase activities), and soil-microbial biomass C and N were monitored. Throughout the study period, the erosion rates for organic, conservation, integrated, and conventional systems averaged 0.70, 2.10, 1.52, and 3.25 t ha −1 year −1 with runoff of 5.8, 6.3, 11.9, and 17.6 mm year −1 , respectively. The mean olive yield was not significantly affected by the production system applied, being 2.43, 2.10, 2.04, and 2.11 t ha −1 year −1 for integrated, organic, conservation, and conventional, respectively. Here, we show a substantial improvement in soil health restoration using the organic rather than a conventional system. Our findings suggest that sustainable cropping systems on hillslopes integrating a blend between organic and conventional doctrines better maintain or improve soil ecosystem functioning. This study highlights a balanced design for an integrated production system for rainfed olive orchards that can maintain productivity while suitably encouraging environmental quality and ecosystem services.

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