Response of Clementine Mandarin to Water-Saving Strategies under Water Scarcity Conditions

Abstract

Water scarcity is the most constraining factor for crop production, especially in arid and semi-arid areas of Mediterranean countries such as Morocco. Within these conditions, different water-saving strategies using deficit irrigation (DI) were tested on two six-years old clementine varieties (‘Sidi Aissa’ and ‘Orogrande’). These DI strategies were applied during the second part of fruit growth and during fruit maturation and included: the control treatment (Cntl), in which the trees received 100% of crop evapotranspiration (ETc) for the entire irrigation season; regulated deficit irrigation (RDI), with an application of 75% of ETc (RDI-1); partial rootzone drying (PRD), with an alternating irrigation between the two root system halves for 3–4 (PRD-3/4) and 7 (PRD-7) days, with an application of 50% crop water requirements; and RDI-2, with an application of 50% of crop water needs during fruit maturation. The results indicate that the trees preferably absorb the water from the upper 0–30 cm-depth soil profile and that fruit drop was increased by PRD for ‘Sidi Aissa’, whereas RDI-1 had no effect on this parameter. The DI strategies had no effect on fruit drop for ‘Orogrande’. The PRD reduced fruit size, yield and fruit juice content, with the effect being more pronounced on ‘Sidi Aissa’. The RDI-1 had no effect on fruit yield for ‘Orogrande’ but reduced it for ‘Sidi Aissa’. RDI-2 had no effect on yield, fruit size or fruit juice content. The DIs tested increased water use efficiency and enhanced fruit maturation as a result of increased juice sugar content and reduced acidity. The PRD tends to increase salt accumulation in the rootzone. Overall, ‘Orogrande’ was less sensitive to water stress and was more water-use efficient, and, under the semi-arid conditions of the experimental zone, PRD should not be used on clementine.

Assessment of Crop Evapotranspiration and Deep Percolation in a Commercial Irrigated Citrus Orchard Under Semi-Arid Climate: Combined Eddy-Covariance Measurement and Soil Water Balance-Based Approach

“…The different patterns of ET o under semi-arid climates reported in the literature (Er-Raki et al, 2009Jafari et al, 2021;Tabari et al, 2012) do not differ from the pattern of the experiment. However, ET a values fall in the conventional range of 700-1300 (mm/year), with an average of 1000 (mm/year) (El-Otmani et al, 2020). The same range of values (765, 820, and 786 mm/year) was reported for citrus orchards in the Haouz region (Er-Raki et al, 2009, 2012El Hari et al, 2010;Nassah et al, 2018).…”

“…The assessment of crop evapotranspiration was done following the FAO-56 approach. Overall, the meteorological conditions are not strange in a region characterized by a semi-arid climate, which is dry and hot in summer and relatively cold in winter (El-Otmani et al, 2020). The issue of water scarcity in the area has been made worse by climate change and agricultural development (Marieme et al, 2017), which is confirmed by the low values of the aridity index.…”

Climate change impacts on temperate fruit and nut production: a systematic review

“…Water scarcity, aggravated by the effects of climate change, is predicted to worsen due to more severe and frequent drought events in warm temperate climate regions ( Ronco et al., 2017 ; Galindo et al., 2018 ; Pedrero et al., 2020 ). This will decrease land suitability for fruit crops in many regions, especially in arid and semi-arid areas where rainfall is becoming less intense and frequent ( Ronchail et al., 2014 ; Galindo et al., 2018 ; Araya-Osses et al., 2020 ; El-Otmani et al., 2020 ; Meza et al., 2023 ). Increasing annual mean temperature due to climate change also threatens the availability of freshwater.…”

“…Along with reductions in water availability, higher temperatures increase evapotranspiration and crop water demand(Rai et al, 2015;del Pozo et al, 2019;Arenas-Castro et al, 2020;Fraga et al, 2020). The aforementioned conditions may explain the strong focus on water-saving strategies, such as water deficit irrigation management, that we observed in our analysis.Deficit irrigation has historically been the main strategy used in olive trees and grapevine to manage fruit quality(Fernandes de Oliveira et al, 2013;Galindo et al, 2018;Araujo et al, 2019;Buesa et al, 2019;Kokkotos et al, 2020;Siakou et al, 2021;Ibba et al, 2023; Ferrara et al, 2024), and it is becoming a popular strategy in other crops, including mandarins(El-Otmani et al, 2020), pomegranates(Galindo et al, 2018;Adiba et al, 2022), apples(Panzacchi et al, 2012;Kendall et al, 2022), almonds(Gutierrez- Gordillo et al, 2020;Barreales et al, 2023), peaches(Ruiz-Sańchez et al, 2018), apricots (Ezzat et al, 2021, and pistachios(Marino et al, 2018). In brief, the idea is to reduce the amount of water provided to the crop during the growing season, improving marketable yield per unit of water and end-product quality, rather than achieving maximum yields(Ronco et al, 2017;Galindo et al, 2018;El-Otmani et al, 2020).…”