{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,24]],"date-time":"2026-09-24T20:32:18Z","timestamp":1790281938923,"version":"4.1.0"},"reference-count":64,"publisher":"MDPI AG","issue":"16","license":[{"start":{"date-parts":[[2026,8,19]],"date-time":"2026-08-19T00:00:00Z","timestamp":1787097600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100014141","name":"European Agricultural Fund for Rural Development","doi-asserted-by":"crossref","id":[{"id":"10.13039\/501100014141","id-type":"DOI","asserted-by":"crossref"}]},{"DOI":"10.13039\/501100004488","name":"Croatian Science Foundation (CSF","doi-asserted-by":"publisher","award":["HRZZ-IP-2022-10-8305"],"award-info":[{"award-number":["HRZZ-IP-2022-10-8305"]}],"id":[{"id":"10.13039\/501100004488","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100004488","name":"Croatian Science Foundation (CSF","doi-asserted-by":"publisher","award":["HRZZ-DOK-2025-02-7450"],"award-info":[{"award-number":["HRZZ-DOK-2025-02-7450"]}],"id":[{"id":"10.13039\/501100004488","id-type":"DOI","asserted-by":"publisher"}]},{"award":["HRZZ-IP-2022-10-8305"],"award-info":[{"award-number":["HRZZ-IP-2022-10-8305"]}],"id":[{"id":"https:\/\/ror.org\/03n51vw80","id-type":"ROR","asserted-by":"publisher"}]},{"award":["HRZZ-DOK-2025-02-7450"],"award-info":[{"award-number":["HRZZ-DOK-2025-02-7450"]}],"id":[{"id":"https:\/\/ror.org\/03n51vw80","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Plants"],"abstract":"<jats:p>Olive (Olea europaea L.) leaf phenolics are increasingly valued across various industrial sectors. This study evaluated whether foliar application of copper (Cu), zinc (Zn), and manganese (Mn) can influence phenolic accumulation in olive leaves. One-year-old olive plantlets grown under greenhouse conditions were sprayed with these micronutrients. Samples of treated mature leaves were collected at 30, 60, and 90 days after treatment (DAT), whereas young leaves that developed after application were sampled at 90 DAT. Foliar fertilization significantly influenced the phenolic profile of olive leaves depending on the micronutrient applied, the sampling time, and the age of the leaves. The highest mean oleuropein concentration was recorded at 30 DAT (209.43 mg\/100 g DW), driven mainly by the Cu \u00d7 30 combination (302.36 mg\/100 g DW), whereas 90 DAT showed a significant decrease in most phenolic classes. In young leaves, oleuropein concentrations were an order of magnitude higher (2661\u20135105 mg\/100 g DW) than those measured in mature leaves (14.5\u2013302 mg\/100 g DW). Furthermore, correlation analysis revealed nutrient-specific modulation of phenolic metabolism: Cu was positively associated with secoiridoids in mature leaves, Zn was positively associated with secoiridoids at 90 DAT, and Mn was negatively associated with flavonoids and with Cu and Zn at 90 DAT in young leaves. These findings suggest that foliar fertilization affects phenolic pathways differently depending on the applied micronutrient and the leaf developmental stage, providing new insights into the temporal regulation of olive leaf phenolic metabolism and identifying suitable harvest periods for the targeted phenolic compounds.<\/jats:p>","DOI":"10.3390\/plants15162503","type":"journal-article","created":{"date-parts":[[2026,8,19]],"date-time":"2026-08-19T07:58:23Z","timestamp":1787126303000},"page":"2503","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Targeted Foliar Micronutrient Modulates Phenolic Accumulation in Olive Leaves"],"prefix":"10.3390","volume":"15","author":[{"given":"Mariem","family":"Zakraoui","sequence":"first","affiliation":[{"name":"Laboratory of Biodiversity, Biotechnology and Climate Change (LR11ES09), Department of Biology, Faculty of Sciences of Tunis, University of Tunis El Manar, Tunis 1060, Tunisia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7454-8162","authenticated-orcid":false,"given":"Marija","family":"Poli\u0107 Paskovi\u0107","sequence":"additional","affiliation":[{"name":"Department of Agriculture and Nutrition, Institute of Agriculture and Tourism, Karla Huguesa 8, 52440 Pore\u010d, Croatia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sondes","family":"Stambouli-Essassi","sequence":"additional","affiliation":[{"name":"Laboratory of Biodiversity, Biotechnology and Climate Change (LR11ES09), Department of Biology, Faculty of Sciences of Tunis, University of Tunis El Manar, Tunis 1060, Tunisia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2935-9319","authenticated-orcid":false,"given":"Igor","family":"Pal\u010di\u0107","sequence":"additional","affiliation":[{"name":"Department of Agriculture and Nutrition, Institute of Agriculture and Tourism, Karla Huguesa 8, 52440 Pore\u010d, Croatia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0350-5074","authenticated-orcid":false,"given":"Smiljana","family":"Goreta Ban","sequence":"additional","affiliation":[{"name":"Department of Agriculture and Nutrition, Institute of Agriculture and Tourism, Karla Huguesa 8, 52440 Pore\u010d, Croatia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7360-046X","authenticated-orcid":false,"given":"Barbara","family":"Soldo","sequence":"additional","affiliation":[{"name":"Department of Chemistry, Faculty of Science, University of Split, R. Bo\u0161kovi\u0107a 33, 21000 Split, Croatia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0003-0396-4171","authenticated-orcid":false,"given":"Nataly","family":"Milovan","sequence":"additional","affiliation":[{"name":"Department of Agriculture and Nutrition, Institute of Agriculture and Tourism, Karla Huguesa 8, 52440 Pore\u010d, Croatia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0732-4166","authenticated-orcid":false,"given":"Sun\u010dana","family":"Simoni\u0107-Kocijan","sequence":"additional","affiliation":[{"name":"Department of Prosthodontics, Faculty of Dental Medicine, University of Rijeka, Kre\u0161imirova 40, 51000 Rijeka, Croatia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7489-4073","authenticated-orcid":false,"given":"Paula","family":"\u017durga","sequence":"additional","affiliation":[{"name":"Teaching Institute of Public Health Primorsko-Goranska County, Kre\u0161imirova 52a, 51000 Rijeka, Croatia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6687-8017","authenticated-orcid":false,"given":"Danko","family":"Cvitan","sequence":"additional","affiliation":[{"name":"Department of Agriculture and Nutrition, Institute of Agriculture and Tourism, Karla Huguesa 8, 52440 Pore\u010d, Croatia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3937-3926","authenticated-orcid":false,"given":"Igor","family":"Paskovi\u0107","sequence":"additional","affiliation":[{"name":"Department of Agriculture and Nutrition, Institute of Agriculture and Tourism, Karla Huguesa 8, 52440 Pore\u010d, Croatia"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,8,19]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Espeso, J., Isaza, A., Lee, J.Y., S\u00f6rensen, P.M., Jurado, P., Avena-Bustillos, R.D.J., Olaizola, M., and Arboleya, J.C. 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