Morpho-Physiological Responses of Three Italian Olive Tree (Olea europaea L.) Cultivars to Drought Stress

Abstract

Water scarcity in agriculture can limit crop production and trigger the need for more effective water resource management. As a result, it is critical to identify new crop genotypes that are more drought tolerant and perform better under low irrigation or even rain-fed conditions. The olive tree is a high-value crop that is well adapted to dry Mediterranean conditions. However, different genotypes may have developed different mechanisms of tolerance to water stress. To investigate such mechanisms, we examined three Italian olive cultivars (‘Giarraffa’, ‘Leccino’, and ‘Maurino’) grown in a greenhouse under drought stress. We found that single genotypes responded differently to the drought, though not all parameters revealed significant differences. The first major difference among the cultivars was in transpiration: the lower stomatal density and stomatal conductance of ‘Giarraffa’ allow this cultivar to use water more conservatively. In parallel with the reduction in stomatal and mesophyll conductance, the drought-stressed group of ‘Giarraffa’ maintained the electron transport rate and effective efficiency levels of photosystem II similar to those of the control until the fourth week of stress. The fluorescence parameters revealed the earlier closure of reaction photosynthetic centres in ‘Leccino’. Finally, the higher rate of electrolyte leakage in ‘Maurino’ indicated a significant ions loss in this cultivar when it was subjected to the drought. Both water management under stress conditions and the effect of drought on photosynthesis make ‘Giarraffa’ interesting to researchers studying its use in breeding or water-saving programmes.

Comparative metabolomics of leaves and stems of three Italian olive cultivars under drought stress

“…Olive plants were grown and drought-stressed as previously described ( Parri et al., 2023 ). Briefly, 18-month-old olive trees ( Olea europaea L., cultivars Leccino, Maurino, and Giarraffa) were grown in 4-L pots (15x15x20 cm) with a substrate of 50% peat and 50% pumice ( Tosca et al., 2019 ).…”

“…In a previous work ( Parri et al., 2023 ), the drought response of three Italian olive cultivars (‘Giarraffa’, ‘Leccino’ and ‘Maurino’) was studied and it was found that ‘Giarraffa’ decreased its stomatal conductance ( g s ) very early after the onset of stress, while ‘Maurino’ did so later; ‘Leccino’ showed an intermediate response. Interestingly, these g s differences did not significantly affect leaf water content but resulted in higher stem water content in ‘Giarraffa’.…”

Adaptation Mechanisms of Olive Tree under Drought Stress: The Potential of Modern Omics Approaches

“…Olive varieties that perform better under drought conditions usually exhibit reduced leaf area and leaf water potential as well as lower stem growth, in comparison with well-irrigated conditions [47]. Characteristics such as the waxy leaf surface, the trichome's density/diameter and the petial elasticity have also been identified as characteristics that enhance drought tolerance in the olive tree, through reduced transpiration [45,48]. Undoubtedly, olive varieties that develop a longer and deeper root system have the capacity to penetrate deeper into the soil layers, where water is accessible.…”

Olive Leaf Extracts from Three Italian Olive Cultivars Exposed to Drought Stress Differentially Protect Cells against Oxidative Stress

“…Leaves were collected from certified 18-month-old olive trees (Olea europaea L., cultivars Leccino, Maurino and Giarraffa) provided by Spoolivi (Società Pesciatina di Orticoltura, Pescia, PT, Italy). Growing conditions, drought treatments, and the plants' water status have been described in detail by Parri et al (2023) [19]. Briefly, for each cultivar, 10 plants were completely water deprived for 4 weeks (OLE-GS, OLE-LS, and OLE-MS for the Giarraffa, Leccino, and Maurino water deficit stress groups, respectively) and 10 plants were fully watered (OLE-G, OLE-L, and OLE-M for the Giarraffa, Leccino, and Maurino control groups, respectively).…”

“…We previously analyzed three Italian olive cultivars under drought stress conditions, selected on the basis of their geographical origin [19]. The cultivars Leccino' and 'Maurino' are thought to be derived from a local oleaster of central Italy [20].…”