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1.
Sezonska dinamika ksilogeneze in floemogeneze pri navadni jelki (Abies alba Mill.)
Jožica Gričar, Primož Oven, Katarina Čufar, 2005

Povzetek: Preučili smo dinamiko nastajanja ksilemskega in floemskega letnega prirastnegaplašča oz. branike pri navadni jelki (Abies alba) v rastni sezoni 2003. Vzorce floema, kambija in ksilema smo vsak teden vzeli iz dveh navideznozdravih odraslih jelk. Raziskave s svetlobnim mikroskopom so pokazale, da se je na floemski strani začela diferenciacija enega do dveh slojev floemskih derivatov še pred začetkom kambijeve aktivnosti. Kambijeva delitvena aktivnost se je začela hkrati na ksilemski in floemski strani v začetku maja. Kambijeva aktivnost se je zaključila konec avgusta. Diferenciacija terminalnih traheid kasnega lesa je potekala do konca oktobra, floemskih celic pa do konca septembra. Število celic, nastalih na ksilemski strani, je bilo večje kot na floemski. Zdi se, da je bila po obodu drevesa širina ksilemske branike bolj variabilna od floemske.
Ključne besede: navadna jelka, Abies alba Mill., kambij, ksilem, floem, traheide, sitaste celice, diferenciacija
DiRROS - Objavljeno: 12.07.2017; Ogledov: 1297; Prenosov: 345
URL Celotno besedilo (0,00 KB)
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2.
Intra-seasonal trends in phloem traits in Pinus spp. from drought-prone environments
Angela Balzano, Veronica De Micco, Katarina Čufar, Martin De Luis, Jožica Gričar, 2020

Povzetek: Recent studies on the seasonal dynamics of secondary tissue formation in Mediterranean trees have shown that xylogenesis depends on species and site conditions, but many questions still remain open. On the other side of the cambium, even less information is available about phloem structure and timing of its formation. We analysed intra-annual phloem variation in width and cell traits in the conducting, non-collapsed phloem (CPH) of Pinus pinea and Pinus halepensis at Mediterranean sites in southern Italy and Spain. In all investigated trees, it was possible to differentiate among the non-conducting, collapsed phloem (NCPH), and the CPH. CPH showed no evident annual growth layers; no differences in radial dimensions of early- and late phloem sieve cells, and no cyclic patterns of axial parenchyma distribution. Since it was not possible to study the seasonality of the phloem growth, we analysed the entire CPH. CPH width showed seasonal fluctuations and was generally the widest during the maximum cambial activity and narrowest during summer and winter. The radial size of newly formed sieve cells varied in relation to seasonal dynamics of cambial activity and fluctuations in local weather conditions. The number of axial parenchyma cells in CPH increased during the summer. The observed intra-annual variations in CPH width and structure seemed to be correlated with seasonal weather conditions in order to ensure a sufficient amount of conducting phloem tissue for translocation of photosynthates and signalling molecules to the actively growing tissues along the stem of a tree growing in the harsh Mediterranean conditions.
Ključne besede: anatomija floema, nekolabrani floem, prevodni floem, sitaste celice, aksialni parenhim, Pinus halepensis, Pinus pinea, sredozemski bori, phloem anatomy, non-collapsed phloem, conducting phloem, sieve cell, axial parenchyma, Mediterranean pines
DiRROS - Objavljeno: 20.02.2020; Ogledov: 350; Prenosov: 152
URL Celotno besedilo (0,00 KB)

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