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Iskalni niz: "ključne besede" (phloem) .

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Odziv kambija navadne smreke (Picea abies) na ogrevanje in hlajenje debla
Jožica Gričar, Martin Zupančič, Katarina Čufar, Primož Oven, 2004

Povzetek: Proučili smo vpliv eksperimentalnega ogrevanja in hlajenja dela debla navadne smreke (Picea abies) na kambijevo aktivnost in celično diferenciacijo. Poskusasta potekala 30 dni; ogrevanje od 29.3.2004 do 3.5.2004, hlajenje pa od14.6.2004 do 20.7.2004. Vzorce floema, kambija in ksilema smo iz dreves odvzeli vsakih 10 dni, pripravili prečne prereze tkiv in preparate opazovali ssvetlobnim mikroskopom. Lokalno ogrevanje je po 10 dneh induciralo delitveno aktivnost kambija na floemsko stran, po 20 dneh pa tudi na ksilemsko. Po 30 dneh je pri ogrevanem vzorcu nastalo do 15 celic ranega lesa. V tem času se jeredna delitvena aktivnost kambija pri kontrolnem drevesu šele začela. Odziv kambija na hlajenje debla je bil manj izrazit. Anatomskih razlik med kontrolnim in hlajenim vzorcem po 10 in 20 dneh ni bilo. Po 30 dneh je pri hlajenem vzorcu začel nastajati kasni les, pri kontrolnem drevesu pa šele prehodni rani-kasni les. S poskusom smo demonstrirali, da je mogoče pri smrekiz umetnim ogrevanjem in hlajenjem debla vplivati na ksilo- in floemogenezo.
Ključne besede: navadna smreka, Picea abies, kambij, celična diferenciacija, ksilem, floem, ogrevanje, hlajenje, svetlobna mikroskopija, Norway spruce, cambium, cell differentiation, xylem, phloem, heating, cooling, light microscopy
DiRROS - Objavljeno: 12.07.2017; Ogledov: 1374; Prenosov: 343
URL Celotno besedilo (0,00 KB)
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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: 261; Prenosov: 129
URL Celotno besedilo (0,00 KB)

Post-fire effects on development of leaves and secondary vascular tissues in Quercus pubescens
Jožica Gričar, Polona Hafner, Martina Lavrič, Mitja Ferlan, Nives Ogrinc, Bor Krajnc, Klemen Eler, Dominik Vodnik, 2020

Povzetek: An increased frequency of fire events on the Slovenian Karst is in line with future climate-change scenarios for drought-prone environments worldwide. It is therefore of the utmost importance to better understand tree-fire-climate interactions for predicting the impact of changing environment on tree functioning. To this purpose, we studied the post-fire effects on leaf development, leaf carbon isotope composition (%13C), radial growth patterns and the xylem and phloem anatomy in undamaged (H-trees) and fire-damaged trees (F-trees) of Q. pubescens with good re-sprouting ability in spring 2017, the growing season after a rangeland fire in August 2016. We found that the fully developed canopy of F-trees reached only half of the LAI values measured in H-trees. Throughout the season, F-trees were characterised by higher water potential and stomatal conductivity and achieved higher photosynthetic rates compared to unburnt H-trees. The foliage of F-trees had more negative %13C values than those of H-trees. This reflects that F-trees less frequently meet stomatal limitations due to reduced transpirational area and more favourable leaf-to-root ratio. In addition, the growth of leaves in F-trees relied more on the recent photosynthates than on reserves due to the fire disturbed starch accumulation in the previous season. Cambial production stopped 3 weeks later in F-trees, resulting in 60% and 22% wider xylem and phloem increments, respectively. A novel approach by including phloem anatomy in the analyses revealed that fire caused changes in conduit dimensions in the early phloem but not in the earlywood. However, premature formation of the tyloses in the earlywood vessels of the youngest two xylem increments in F-trees implies that xylem hydraulic integrity was also affected by heat. Analyses of secondary tissues showed that although xylem and phloem tissues are interlinked changes in their transport systems due to heat damage are not necessarily coordinated.
Ključne besede: pubescent oak, cambium, radial growth, xylem, phloem, anatomy, sub-Mediterranean
DiRROS - Objavljeno: 19.03.2020; Ogledov: 269; Prenosov: 132
URL Celotno besedilo (0,00 KB)
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