Agriculture in the Mediterranean region is substantially challenged by climate change, and olive growers in particular are facing difficulties because of its effects. In this regard, the olive sector can adopt deficit irrigation strategies, to achieve sustainable management practices that improve water productivity and save irrigation water. This chapter aims to investigate the potential impacts of deficit irrigation strategies on Menara olive tree. Agronomical parameters were assessed in 2021 and 2022, focusing on trees subjected to regulated (RDI) and sustained (SDI) deficit irrigation. The results showed that the performances of Menara olive trees under controlled water stress are better under RDI strategy compared to SDI one. Moreover, the RDI strategy, particularly under specific treatment, allowed to reduction of supplied water by 20% and 40% during sensitive and normal periods, respectively. These results highlight the importance of water management strategies and the need to consider their implications on flowering traits, crop yield, and fruit quality over consecutive growing seasons.
TopIntroduction
The Olive tree (Olea europaea L.), native to the Mediterranean basin, is an evergreen tree considered highly suitable and well-suited to the Mediterranean environmental conditions (Kassout et al., 2021). Nevertheless, the Mediterranean area is recognized as a climate change trouble spot, experiencing notable trends of warming and drying. Presently, olive groves encounter new challenges and risks, with climate change being one of the most significant (Kassout et al., 2023). In the coming decades, and following recent climate change scenarios, olive growers will confront rising temperatures, drought, and increased occurrences of severe weather incidents, exemplified by extreme heat events, necessitating their attention and adaptation (Fraga et al., 2020a).
Morocco, with its arid and semi-arid climate marked by hot and dry summer conditions, limited and irregular precipitation, is grappling with a considerable water scarcity challenge, reflecting the global issue of declining water resources (Er-Raki et al., 2010). Moreover, crop production in Morocco heavily relies on irrigation due to the limited productivity of rainfed cropping (Taheripour et al., 2020). Precipitation decreases overall, leading to a reduction in soil water availability and resulting water stress can have various adverse effects on olive trees (Arampatzis et al., 2018). Although olive trees are considered resilient to drought conditions, adequate water availability is beneficial for olive cultivation and is considered a vital resource for improving final yields. Considering the pivotal importance of the olive sector within the Mediterranean region, there is an urgent need for sustainable water management practices. This includes adopting efficient irrigation systems and implementing water-saving strategies, such as regulated and sustained deficit irrigation (RDI and SDI), to sustain olive production and enhance the sector's resilience to climate change and water scarcity, particularly in areas facing drastic reductions in available water resources.
Nowadays, many studies have demonstrated that appropriate deficit irrigation strategies can maintain profitable olive productivity (Fernández et al., 2013; Gucci et al., 2019; Ibba et al., 2023). Deficit irrigation is a water management strategy that intentionally applies less water than the crop's full water requirement, aiming to optimize water use efficiency and enhance crop resilience. Deficit irrigation strategies are necessary for optimizing the application of irrigation concerning both oil quality and production (Fernández and Moreno, 1999). These strategies can assist farmers in determining the ideal timing and quantity of required irrigation water. Over recent years, there has been a progressive rise in research related to regulated deficit irrigation, contributing to its enrichment and extensive application across diverse crop species (Guo et al., 2021; Romero‐Trigueros et al., 2020; Wu et al., 2020; Yang et al., 2022). This, innovative irrigation approach, known as RDI, has the capability to substantially enhance the adaptive capacity of olive trees in agriculture when facing drought stress and ultimately fulfill the aim of enhancing economic benefits for orchards (Gucci et al., 2019; Ibba et al., 2023; Lima et al., 2019). In this regard, the optimization of regulated and sustained deficit irrigation strategies involves exploring various treatments aimed at achieving an optimal balance between yield and water productivity. Several studies have reported that the RDI strategy involves inducing stress in the pit hardening and the initial stages of oil synthesis (Fereres et al., 2012; Goldhamer, 1999; Gucci et al., 2019). However, maintaining a full water supply during spring and oil synthesis is recommended (Hueso, Camacho, & Gómez-del-Campo, 2021; Moriana et al., 2003). Meanwhile, the SDI strategy entails supplying water throughout the irrigation season at a level below the crop's evapotranspiration (ETc) demand (Moriana et al., 2003). On the other hand, forthcoming climatic changes will have a significant impact on the entire agricultural sector, encompassing the olive tree industry as well (Fraga et al., 2020b; Ponti et al., 2014). Given the present worldwide changes, understanding how olive cultivars adapt and respond to drought stress is critical, specifically in the context of deficit irrigation strategies. According to Fraga et al. (2020b), irrigation has been identified as a potentially impactful strategy for olive tree cultivators to adapt to the challenges posed by climate change. Furthermore, Mairech et al. (2020) suggest that deficit irrigation is currently regarded as a sustainable management approach.