Mitigation of High-Temperature Damage by Application of Kaolin and Pinolene on Young Olive Trees (Olea europaea L.): A Preliminary Experiment to Assess Biometric, Eco-Physiological and Nutraceutical Parameters

Aurora Cirillo,Stefano Conti,Youssef Rouphael,Alberto Ritieni,Giulia Graziani,Claudio Di Vaio,Christophe El-Nakhel

doi:10.3390/agronomy11091884

Aurora Cirillo, Stefano Conti + Show 5 more

Open Access

https://doi.org/10.3390/agronomy11091884

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Journal: Agronomy (Basel, Switzerland)	Publication Date: Sep 20, 2021
Citations: 10	License type: CC BY 4.0

Affiliation: University of Naples Federico II

Abstract

Various products are used to mitigate the negative effects of abiotic stress in olive trees. The aim of the research was to examine an anti-transpirant product (Vapor Gard®, V) and a kaolin- based product (Manisol, K) effect on the growth of two-year-old olive tree seedlings under high temperature. The study was conducted in a greenhouse on trees of a native cultivar of Campania (cv. Salella) grown in pot during the growing season from May to September 2020. The experimental design included two products: di-1-p-menthene (product V) and kaolin (product K), applied five times at 20 day intervals compared with a control. The following biometric, physiological, and nutraceutical parameters were evaluated: stomatal conductance, chlorophyll a fluorescence, Soil Plant Analysis Development (SPAD) index, relative water content (RWC), shoots growth, total leaf area per plant, trunk cross-sectional area, dry matter partitioning, total polyphenols, and antioxidant activity. The results obtained showed that the application of di-1-p-menthene (V) was able to induce a significant improvement of shoots growth (+37.22%) and trunk cross-sectional area (+46.60%) and a reduction of the stomatal conductance and an increase of leaf RWC values. Application with kaolin had positive effects on the total polyphenol content, with an increase over the control of 240.33% and higher antioxidant activity values. Further studies are necessary to determine the effect of these products on the biometric, physiological and nutraceutical parameters of mature olive trees cultivated in open field conditions.

Highlights

The olive tree (Olea europaea L.) is one of the most important crops in the Mediterranean basin, and its growth and development are mainly controlled by atmospheric conditions [1,2]
The results obtained showed that the application of di-1-p-menthene (V) was able to induce a significant improvement of shoots growth (+37.22%) and trunk cross-sectional area (+46.60%) and a reduction of the stomatal conductance and an increase of leaf relative water content (RWC) values
Further studies are necessary to determine the effect of these products on the biometric, physiological and nutraceutical parameters of mature olive trees cultivated in open field conditions

Summary

Introduction

The olive tree (Olea europaea L.) is one of the most important crops in the Mediterranean basin, and its growth and development are mainly controlled by atmospheric conditions [1,2]. With the scenario of climate change, this cultivar is strongly exposed to thermal and hydric stresses during the growing season, mostly during summer and in the innermost areas of Europe [3]. These changes in temperature and precipitation along with a greater frequency of extreme weather have reduced agricultural yield [4,5]. The recovery after stress is a complex process; the trees restore the water status rapidly along with a slow recovery of stomatal conductance [15]. A conservative bearing after re-watering has been identified, as trees rapidly restore the water status along with a slow recovery of stomatal conductance [16]

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