Phytochemical Farming: Mineral Nutrients and Elicitors Application to Enhance Olive Leaf Phenolics
ABOUT THE PROJECT
Olive (Olea europaea L.) is among the most important crops, particularly fruit ones, grown in the Mediterranean area. Olive tree is used for its fruits (oil), leaves, wood, and all parts have important role in the Mediterranean diet and way of life. In addition to its role in diet or history, olive has an important economic role in the area.
Olive leaves have been always linked with folk medicine remedies. Oleuropein and hydroxytyrosol are considered the main active olive compounds and their health benefits thought their anti-carcinogenic, anti-inflammatory, and antimicrobial proprieties has been proven. Nevertheless, oleuropein and hydroxytyrosol as well as total phenols, have specific role plant protection and resistance against fungal pathogens which may be of crucial importance for sustainable olive growing. In general, it has been noticed that phenolic and polyphenolic compounds, as pre-formed antibiotic compounds, are ubiquitous in plants and play an important role in host plant’s pre-existing chemical defences against filamentous fungi. The phenolics in olive leaves, beside upgraded resistance to fungal pathogens, may have potential in the production of functional food and nutraceuticals. They could be easily used as oral remedies in the treatment of stomatognatic pathological conditions, where the need of finding new therapeutic procedures has led to increased interest in the use of natural substrates.
There are evidence that agricultural practices can increase phenolics in olive leaves. Only a few studies have been focused on studying the effects of olive mineral nutrition on the olive leaves phenolic profile. In this project, series of experiments are planned to be conducted in order to determine the effect of selected mineral elements and elicitors on leaf phenolic profile of olive cultivars. The effect of previously selected mineral/elicitor treatment as the best phenolic enhancer, on the development of olive leaf spot (Venturia oleaginea – syn. Spilocaea oleaginea), will be tested under greenhouse and field conditions. The impact of best phenolic enhancer will be tested thought quality of olive oil on Leccino cultivar grown at different terroirs. The preclinical and clinical studies investigating the effect of olive leaf extract on oral cavity candidiasis will be conducted during this project as well.
In this multidisciplinary project, agricultural, chemical and medicinal researches are joined together to explore the role of selected plant nutrients in changes of phenolic profile. Effect of changes in phenolic profile on resistance to fungal diseases and olive leaves application in stomatology will be part of the project as well.
· Project title: Phytochemical Farming: Mineral Nutrients and Elicitors Application to Enhance Olive Leaf Phenolics; UIP-2017-05-8464 PhytoFarmOL
· Project financed by: Croatian Science Foundation
· Partner Institutions:
Teaching Institute of Public Health Primorsko-Goranska County (ZZJZPGŽ)
· Project duration: 01/12/2017 – 30/11/2022
· Project value: 270.000,00 €
Published scientific paper
As part of the project PhytoFarmOL (HRZZ, UIP-05-2017-8464) a scientific paper entitled ‘Determination of the Variability of Biophenols and Mineral Nutrients in Olive Leaves with Respect to Cultivar, Collection Period and Geographical Location for Their Targeted and Well-Timed Exploitation’ was published in the prestigious scientific journal Plants.
Fin the full paper HERE.
Published scientific paper
As part of the project PhytoFarmOL (HRZZ, UIP-05-2017-8464) a scientific paper entitled ‘Temporal Variation of Phenolic and Mineral Composition in Olive Leaves Is Cultivar Dependent’ was published in the prestigious journal Plants.
Find the full text HERE.
Project dissemination activities
The PhytoFarmOL project ” Phytochemical Farming: Mineral Nutrients and Elicitors Application to Enhance Olive Leaf Phenolics” (HRZZ, UIP-05-2017-8464) was presented on the Croatian radio (HRT 1) as part of the program Emisija za selo i poljoprivredu (24/11/2019), which covers the current topics in agriculture and food industry for the area of Croatia and the European Union. The second presentation of the project followed on HRT radio Pula within the program Agraria (27/11/2019), which once a week brings news and advice for farmers, recommendations of experts and reports interesting news from the field throughout Istria.
The program editor and presenter was Džana Banić, and the recordings are available on the links below.
Sample preparation, mineral and phenolic composition analysis
In the period between July and the end of November (2019), a series of activities were carried out as part of the hydroponic experiment established in the greenhouse of the Institute of Agriculture and Tourism in Poreč.
Final sampling of the leaves, stems, and roots of all treatments in the experiment was performed with a goal to identify the influence of different nutrient solutions on the composition and distribution of minerals and phenols throughout the plant. All samples were accordingly prepared, dried to constant mass and ground in order to fulfill the needs of further analysis. Analyzes of the content of total and individual phenols, minerals and sugars were carried out by different methods. Root quantitative analysis (root scan with WinRhizoTM) was performed to determine its morphological (length, area, volume) characteristics, while individual leaf samples were prepared for microscopic analysis to identify possible differences in their morphological characteristics.
Specialization on Jožef Stefan Institute
During two weeks (06 – 19/11/2019) dr. Igor Pasković has participated in a MicroPIXE specialization programme at the Jožef Stefan Institute (Ljubljana, Slovenia). The skills acquired and analyzes performed will significantly contribute to the understanding the translocation of observed plant nutrients, as well as finding new directions in research.
The training was carried out as part of the PhytoFarmOL project “Phytochemical Farming: Mineral Nutrients and Elicitors Application to Enhance Olive Leaf Phenolics” (HRZZ, UIP-05-2017-8464).
Project dissemination activities
Publication in journal Scientia Horticulturae
The scientific publication “Boron foliar application enhances oleuropein level and modulates volatile compound composition in olive leaves”, Pasković et al., was published in the new issue of the journal Scientia Horticulturae (Elsevier, Q1, IF: 1.961).
The full version of the article is available on the link below:
Pasković, I., Soldo, B., Talhaoui, N., Palčić, I., Brkljača, M., Koprivnjak, O., Majetić Germek, V., Ban, D., Klanjac, J., Franić, M., Žurga, P., Grozić, K., Lukić, I., Goreta Ban, S. (2019). Boron foliar application enhances oleuropein level and modulates volatile compound composition in olive leaves. Scientia Horticulturae, 257, 108688.
PhytoFarmOL project meeting
The meeting of the PhytoFarmOL project (CFU, UIP-05-2017-8464) was held on 29/10/2019 at the Institute of Agriculture and Tourism in Poreč. On the meeting were present dr. Igor Pasković and Kristina Grozić, MEng. and project associates from other institutions: MSc Paula Žurga (Teaching Institute of Public Health Primorsko-Goranska County), Prof. Sunčana Simonić-Kocijan (University of Rijeka, Faculty of Medicine, Department of dental Prosthodontics), Dr. Josko Kaliterna (University of Zagreb, Faculty of Agriculture, Department of Phytopathology), Dr. Valerija Majetić Germek (University of Rijeka, Faculty of Medicine, Department of Food Technology and Control) and Šime Marcelić, MEng. (University of Zadar, Department of Ecology, Agriculture and Aquaculture).
Nondestructive measurements in the hydroponic trial
During the last months, measurements of vegetative growth (total plant length, growth length, number of leaves, number of internodes) were performed in the experiment. Furthermore, nondestructive methods were applied to determine the nitrogen concentration in olive leaf (N-tester), the concentration of certain elements by hyperspectral imaging of the olive leaf surface area, and to analyze the photosynthesis and respiration intensity of the olive plantlets.
Project dissemination activities
On the recently held 54 Croatian & 14 International Symposium on Agriculture a part of the project “Phytochemical Farming: Mineral Nutrients and Elicitors Application to Enhance Olive Leaf Phenolics” (UIP-2017-05-8464, PhytoFarmOL) results were presented. The Jana Klanjac, MEng. had oral presentation of the paper entitled The Impact of Mineral Boron Nutrition on the Phenolic Composition of Olive Leaf whose summary is available at the link below.
Klanjac J., Žurga P., Majetić Germek V., Brkljača M., Urlić B., Goreta Ban S., Ban D., Pasković I. (2019) Boron mineral nutrition and its impact on olive leaf phenolics. http://sa.agr.hr/pdf/2019/sa2019_abstracts.pdf
The main hydroponic trial was set up in a greenhouse
During October and November 2018 a hydroponic trial was set up in the greenhouse of the Institute of Agriculture and Tourism. Istrian Bjelica plantlets were potted in plastic pots into a supstrate made by a mixture of quartz sand and perlite (1:1). After the set up of the trial, nutrient solutions were prepared with the modulation of six different concentrations based on seven nutrients (N, Ca, Mg, Mn, Zn, Cu i B) i compared with a standard Hoagland solution as a control treatment. The aim of the trial iz to establish the effect of different nutrient solutions contentrations of N, Ca, Mg, Mn, Zn, Cu and B on the composition of phenolics in olive leaves.
Statistical analysis of the phenolic and mineral composition of the collected olive leaves was carried out
Set-up of additional preliminary hydroponic trial
In July 2018 a preliminary hydroponic experiment was set up at the Institute of Agriculture and Tourism. The experiment was set up testing three treatments where the influence of the application of different boron (B) concentrations and its influence on olive leaf phenolic and mineral composition was investigated.
The phenolic and mineral composition of the collected samples was determined
In the period from April till June 2018 at the Institute of Agriculture and Tourism and Teaching Institute of Public Health Primorsko-Goranska County olive leaves samples collected across Croatia were prepared and analyzed. The phenolic and mineral composition of the most important native olive cultivars was determined.
Spring sampling of different olive cultivars across Croatia
Chemical analysis of additional preliminary foliar experiment
In the fall of 2017, an additional preliminary study was carried out to determine the influence of foliarly applied microelements on mineral composition and bioactive components in olive leaf. Furthermore, olive leaf infusions were prepared and volatile compounds and aromas were determined.
Winter sampling of different olive cultivars across Croatia
Autumn sampling of different olive cultivars across Croatia
OBJECTIVE 1: Installation of the research group
OBJECTIVE 2: to determine olive leaf phenolic and mineral profile of the most important Croatian olive cultivars and compare it to Leccino cultivar as most widespread allochthonous cultivar in Croatian orchards.
OBJECTIVE 3: to determine impact of different levels elements in nutrient solution on olive plantlets leaf phenolic profile under controlled conditions
OBJECTIVE 4: to determine impact of different plant elicitors and selected plant nutrients applied foliarly on olive plantlets leaf phenolic profile under controlled conditions
OBJECTIVE 5: to define foliar application protocol for enhancing olive leaf phenolics
OBJECTIVE 6: to determine effect of selected plant nutrient or elicitor on olive plantlets resistance to fungal pathogen Venturia oleaginea (syn. Spilocaea oleaginea).
OBJECTIVE 7: to determine the effect of foliar application protocol on leaf and oil phenolic profile under field conditions
OBJECTIVE 8: to conduct series of in vitro and clinical experiments to determine the effects of olive leaf extracts on oral candidiasis
OBJECTIVE 9: to apply project(s) of new research group to competitive research grant(s)
PROJECT PhD CANDIDATE
PROJECT PhD CANDIDATE