Drought-Adaptive Mechanisms of Young Sweet Cherry Trees in Response to Withholding and Resuming Irrigation Cycles

Pedro José Blaya-Ros,Víctor Blanco,Roque Torres-Sánchez,Rafael Domingo

doi:10.3390/agronomy11091812

Pedro José Blaya-Ros, Víctor Blanco + Show 2 more

Open Access

https://doi.org/10.3390/agronomy11091812

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Abstract

The present work evaluates the main adaptive mechanisms developed by young sweet cherry trees (Prunus avium L.) to cope with drought. For this purpose, the young trees were subjected to two drought cycles with different water stress intensities followed by a recovery period. Three irrigation treatments were applied: control treatment (CTL) irrigated to ensure non-limiting soil water conditions; moderate water stress (MS) subjected to two drying cycles whose duration was dependent on the time elapsed until the trees reached values of midday stem water potential (Ψstem) of −1.3 and −1.7 MPa for the first and second cycle, respectively; and severe water stress (SS) similar to MS, but with reference values of −1.6 and −2.5 MPa. In-between drought cycles, MS and SS trees were irrigated daily as the CTL trees until reaching Ψstem values similar to those of CTL trees. The MS and SS trees showed an important stomatal regulation and lower vegetative growth. The decreasing leaf turgor potential (Ψturgor) during the drought periods accounted for 40–100% of the reduction in leaf water potential at midday (Ψmd). The minimum osmotic potential for mature leaves was about 0.35 MPa lower than in well-irrigated trees. The occasional osmotic adjustment observed in MS and SS trees was not sufficient to maintain Ψturgor values similar to the CTL trees or to increase the specific leaf weight (SLW). The leaf insertion angle increased as the water stress level increased. Severe water stress (Ψstem < −2.0 MPa) resulted in clear early defoliation as a further step in water conservation.

Highlights

In drylands, where scarce water availability is the main restricting factor for crops, drought periods have increased in terms of the geographic area affected, frequency, and intensity as a consequence of global climate change [1]
Just as ∆trunk cross-sectional area (TCSA), canopy volume (CV) and pruning wood (PW) decreased due to the effect of the drought stress, from 68% (MS) to 82% (SS) and from 38% (MS) to 64% (SS) with respect to the control treatment (CTL) trees in 2019 (Table 2), coinciding with the results reported in ‘Brooks’ sweet cherry trees by Livellara et al [21]
The above-mentioned results can contribute to more complete knowledge of droughtadaptive mechanisms in young sweet cherry trees

Summary

Introduction

In drylands, where scarce water availability is the main restricting factor for crops, drought periods have increased in terms of the geographic area affected, frequency, and intensity as a consequence of global climate change [1]. Generally characterized by a combination of high solar radiation, high temperature, and water scarcity [2], is one of the main abiotic stresses worldwide that negatively affects crops’ metabolism, growth, and yield [3]. In these areas, even under irrigated agricultural conditions, crops may be subjected to many instances of stress and recovery from cycle stress [4]. The adaptive responses of plants to drought can be morphological, physiological, or biochemical and are not easy to understand, as they are dependent on the plant type, phenological stage, stress duration, intensity, and rate of stress imposition and frequency [5]. For this reason, understanding the mechanisms involved in a crop’s responses and adaptations to drought periods is essential for the successful implementation of deficit irrigation strategies to minimize the damages caused to yield and fruit quality [6] and to cope with increasingly frequent drought periods

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