{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,18]],"date-time":"2026-09-18T07:29:04Z","timestamp":1789716544717,"version":"4.0.1"},"reference-count":49,"publisher":"MDPI AG","issue":"15","license":[{"start":{"date-parts":[[2022,8,6]],"date-time":"2022-08-06T00:00:00Z","timestamp":1659744000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Forschungsf\u00f6rderungsmittel der S\u00fcdtiroler Landesregierung","award":["PJ 81817"],"award-info":[{"award-number":["PJ 81817"]}]},{"name":"Verein zur F\u00f6rderung der wissenschaftlichen Ausbildung und T\u00e4tigkeit von S\u00fcdtirolern an der Landesuniversit\u00e4t Innsbruck","award":["PJ 81817"],"award-info":[{"award-number":["PJ 81817"]}]},{"name":"Department of Innovation, Research, University and Museums of the Autonomous Province of Bozen\/Bolzano","award":["PJ 81817"],"award-info":[{"award-number":["PJ 81817"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Plants"],"abstract":"<jats:p>pH of xylem sap (pHx) was determined in three trees (Malus domestica (apple tree),\u00a0Picea abies and Pinus cembra) in response to seasonal changes. Conifer trees from lowland (600 m) were compared to trees growing at the alpine timberline (1950 m a.s.l.). Xylem sap was extracted with a Scholander pressure bomb and pHx was measured with a pH microsensor. In all species, pHx changed markedly with season. In spring, pHx was acidic; during winter, the pHx was more alkaline. In apple trees, the pHx did not show a significant correlation with temperature but was rather affected by developmental stage. During flushing in spring, xylem sap acidification took place concomitant to the developmental stage \u201ctight cluster\u201d, when foliar development enables a significant transpiration and a consequent movement of water in the xylem. The xylem sap of the two studied conifers showed a significantly larger seasonal alkalinisation (+2.1) than found in apple trees (+1.2) and was significantly more pronounced at the timberline. Xylem sap acidification took place before bud break. pHx had a significant negative correlation with soil temperatures and corresponded to already reported pHx of angiosperms. Overall, pHx appears to be a sensitive stress marker and indicator of activity status in tree xylem.<\/jats:p>","DOI":"10.3390\/plants11152058","type":"journal-article","created":{"date-parts":[[2022,8,9]],"date-time":"2022-08-09T04:16:55Z","timestamp":1660018615000},"page":"2058","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":7,"title":["Seasonal Xylem Sap Acidification Is Governed by Tree Phenology, Temperature and Elevation of Growing Site"],"prefix":"10.3390","volume":"11","author":[{"given":"Manuel","family":"Pramsohler","sequence":"first","affiliation":[{"name":"Laimburg Research Centre, Laimburg 6, Pfatten\/Vadena, 39040 Auer\/Ora, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Edith","family":"Lichtenberger","sequence":"additional","affiliation":[{"name":"Unit of Functional Plant Biology, Department of Botany, University of Innsbruck, Sternwartestra\u00dfe 15, 6020 Innsbruck, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2415-6125","authenticated-orcid":false,"given":"Gilbert","family":"Neuner","sequence":"additional","affiliation":[{"name":"Unit of Functional Plant Biology, Department of Botany, University of Innsbruck, Sternwartestra\u00dfe 15, 6020 Innsbruck, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2022,8,6]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"17","DOI":"10.1111\/j.1469-8137.2007.02286.x","article-title":"Origin, fate and significance of CO\u00b2 in tree stems","volume":"177","author":"Teskey","year":"2008","journal-title":"New Phytol."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"577","DOI":"10.1055\/s-2001-19372","article-title":"pH: Signal and messenger in plant cells","volume":"3","author":"Felle","year":"2001","journal-title":"Plant Biol."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"257","DOI":"10.1111\/j.1438-8677.1980.tb03337.x","article-title":"Spring sap of trees","volume":"93","author":"Essiamah","year":"1980","journal-title":"Ber. 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