Seasonal Xylem Sap Acidification Is Governed by Tree Phenology, Temperature and Elevation of Growing Site

Abstract

pH of xylem sap (pHx) was determined in three trees (Malus domestica (apple tree), Picea 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 “tight cluster”, 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.

Among‐species variation in sap pH affects the xylem CO2 transport potential in trees

“…Aubrey et al, 2011;Erda et al, 2014;Salomón et al, 2016) and seasonal (e.g. Aubrey et al, 2011;Salomón et al, 2016;Losso et al, 2018;Pramsohler et al, 2022) variation in xylem pH. Such patterns may be linked to several interacting factors known to affect xylem pH including within-tree variation in sap chemistry (Schill et al, 1996), phenological stage (Pramsohler et al, 2022), water and nutrient availabilities (e.g.…”

“…Aubrey et al, 2011;Salomón et al, 2016;Losso et al, 2018;Pramsohler et al, 2022) variation in xylem pH. Such patterns may be linked to several interacting factors known to affect xylem pH including within-tree variation in sap chemistry (Schill et al, 1996), phenological stage (Pramsohler et al, 2022), water and nutrient availabilities (e.g. Gollan et al, 1992;Jackson et al, 2003;Sharp & Davies, 2009;Wang et al, 2012), site elevation (Pramsohler et al, 2022), solar radiation, vapor pressure deficit, and air and soil temperatures (Wilkinson & Davies, 2002Wan et al, 2004;Pramsohler et al, 2022).…”

“…Such patterns may be linked to several interacting factors known to affect xylem pH including within-tree variation in sap chemistry (Schill et al, 1996), phenological stage (Pramsohler et al, 2022), water and nutrient availabilities (e.g. Gollan et al, 1992;Jackson et al, 2003;Sharp & Davies, 2009;Wang et al, 2012), site elevation (Pramsohler et al, 2022), solar radiation, vapor pressure deficit, and air and soil temperatures (Wilkinson & Davies, 2002Wan et al, 2004;Pramsohler et al, 2022). Although the magnitude of, and causes for, within-species variation in xylem pH has received considerable attention, few studies to date have compared xylem pH in tree species from different functional types growing under similar climatic and soil conditions.…”

10th Anniversary of Plants—Recent Advances and Further Perspectives

“…are elucidated. This group includes articles [1,2,7,[12][13][14][15][16][17][18][19][20][21][22][23][24][25][26], communications [27,28], and review papers [5,6,11,[29][30][31][32][33][34] with significant results applicable both in science and practice. The biology and ecology of plant secondary metabolites, their identification, and biological and therapeutic activity from different aspects of the phytochemistry of edible, aromatic, medicinal, or potentially medicinal plants are represented in a significant number of articles [3,8,[35][36][37][38][39][40][41][42][43][44][45][46][47][48][49], as well as review papers [9,50,<...…”