Physiological and Biochemical Responses of Orange Trees to Different Deficit Irrigation Regimes.

Puglisi Puglisi,Roccuzzo Roccuzzo,Stagno Stagno,Nicolosi Nicolosi,Vanella Vanella,Baglieri Baglieri,Saitta Saitta,Piero Piero,Consoli Consoli

doi:10.3390/plants8100423

Puglisi Puglisi, Roccuzzo Roccuzzo + Show 7 more

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https://doi.org/10.3390/plants8100423

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Abstract

The article presents the results of research consisting of the application of deficit irrigation (DI) criteria, combined with the adoption of micro-irrigation methods, on orange orchards (Citrus sinensis (L.) Osbeck) in Sicily (Italy) during the irrigation season of 2015. Regulated deficit irrigation (RDI, T3) and partial root-zone drying (PRD, T4) strategies were compared with full irrigation (T1) and sustained deficit irrigation (SDI, T2) treatments in terms of physiological, biochemical, and productive crop response. A geophysical survey (electrical resistivity tomography, ERT) was carried out to identify a link between the percentages of drying soil volume in T4 with leaves abscisic acid (ABA) signal. Results highlight that the orange trees physiological response to water stress conditions did not show particular differences among the different irrigation treatments, not inducing detrimental effects on crop production features. ABA levels in leaves were rather constant in all the treatments, except in T4 during late irrigation season. ERT technique identified that prolonged drying cycles during alternate PRD exposed more roots to severe soil drying, thus increasing leaf ABA accumulation.

Highlights

IntroductionCitrus species are among the most important tree crops for the Mediterranean agricultural sector.Increasing water use efficiency associated with improved irrigation strategies is a priority for these groves to maintain market competitiveness [1]
Citrus species are among the most important tree crops for the Mediterranean agricultural sector.Increasing water use efficiency associated with improved irrigation strategies is a priority for these groves to maintain market competitiveness [1]
This study shows that it is possible to maintain soil fertility even in severe deficit irrigated treatments, as already shown in different works [17]

Summary

Introduction

Citrus species are among the most important tree crops for the Mediterranean agricultural sector.Increasing water use efficiency associated with improved irrigation strategies is a priority for these groves to maintain market competitiveness [1]. Citrus species are among the most important tree crops for the Mediterranean agricultural sector. Applied research has already proved that the application of deficit irrigation (DI) strategies for Citrus cultivation is effective and sustainable by maximizing water saving without affecting crop yield [2] and quality parameters [3,4,5,6,7,8]. It is necessary to quantify the changes in biochemical mechanisms induced by the application of moderate/severe water deficit conditions by analyzing the role of abscisic acid (ABA) [9] and proline accumulations [10,11]. ABA is recognized as an important stress-signaling hormone, acting in the regulation of stomatal closure, synthesis of compatible osmolytes, and in the upregulation of genes leading to adaptive responses [9]. In Citrus trees, proline accumulation is generally associated with water loss induced by soil water depletion, elevated

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