Abstract
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.
Highlights
Deficit irrigation (DI) strategies cannot be considered as a novelty, and their effects and consequences have been widely studied in order to improve water resources management under water shortage conditions
On overall as Ψleaf as gs evidenced similar results for the studied treatments; afterwards, the analysis done independently for each monitoring day reflected significant differences between treatments. These differences between treatments were especially noticeable for the case Ψleaf (Figure 2), in comparison to the higher similarities reported by gs measurements (Figure 3)
Combining the type of almond cultivars with water stress through deficit irrigation will be vital to reach an equilibrium between water allocations and sustainable nut yields under climate change scenarios
Summary
Deficit irrigation (DI) strategies cannot be considered as a novelty, and their effects and consequences have been widely studied in order to improve water resources management under water shortage conditions. The RDI is the most-studied strategy for the case of almond and many authors have described its response under different water stress levels [9,14,15,16], but there are few works about the response of almond trees to SDI. Plants’ reactions to water stress are complex, implicating adaptive changes and/or detrimental consequences, and the different responses are regulated by the innate plant features as well as the duration and intensity of the imposed stress In this line, we hypothesize that under water stress almond cultivars are able to exhibit different tolerance levels, and the physiological reactions could be Agronomy 2020, 10, x FOR PEER REVIEW components. Elucidating the tolerant cultivar under these strategies in a semi-arid Mediterranean environment
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