How timing of stem girdling affects needle xylem structure in Scots pine

Gebauer, Roman; Plichta, Roman; Bednářová, Emilie; Foit, Jiří; Čermák, Václav; Urban, Josef

doi:10.1007/s10342-017-1090-z

Cited by 7 publications

(9 citation statements)

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“…While the morphological and anatomical structures of needles 227 DAG were very similar to those of the control trees (the only marked difference was an increase of 9% in LMA, that is, the first hypothesis was not confirmed), seven of the eleven studied needle parameters were significantly different 411 DAG (in part, supporting our second hypothesis). The increase in LMA 227 DAG could be partly explained by a 5% increase in NSC in needles 227 DAG (Gebauer et al 2017). LMA has previously been proposed as a useful indirect proxy for studying changes in carbohydrate concentrations (Day & DeJong 1990, Domec & Pruyn 2008, Lopéz et al 2015.…”

Section: Discussionmentioning

confidence: 96%

“…Current year needles from sun-exposed branches were also used to analyze levels of non-structural carbohydrates (NSC). A detailed description of girdling treatment, sap flow, and NSC analysis is given in Gebauer et al (2017).…”

Section: Study Site and Description Of The Experimentsmentioning

confidence: 99%

“…Although the structural adaptation of stems to disruption in phloem long-distance transport has been studied in detail, to the best of our knowledge no research exists on the structural adaptation of leaves or needles in response to stem girdling. Only a handful of studies have focused on the development of leaf area and leaf mass per unit area (LMA) after girdling (Day & DeJong 1990, Domec & Pruyn 2008 and only one study focused on needle xylem structure development after stem girdling (Gebauer et al 2017). It was observed that long-term stem girdling led to a reduction in the theoretical hydraulic conductivity of Scots pine needles, and in their xylem area and number of tracheids (Gebauer et al 2017).…”

Section: Introductionmentioning

confidence: 99%

“…Only a handful of studies have focused on the development of leaf area and leaf mass per unit area (LMA) after girdling (Day & DeJong 1990, Domec & Pruyn 2008 and only one study focused on needle xylem structure development after stem girdling (Gebauer et al 2017). It was observed that long-term stem girdling led to a reduction in the theoretical hydraulic conductivity of Scots pine needles, and in their xylem area and number of tracheids (Gebauer et al 2017). The physiological adaptation of leaves after girdling, on the other hand, has been studied more thoroughly.…”

Section: Introductionmentioning

confidence: 99%

“…We focused on needle structural development 8 and 14 months after girdling (hereafter referred to as 227 and 411 DAG, days after girdling, respectively). This study follows up on our previous work (Gebauer et al 2017), in which needle xylem structure, sap flow, and non-structural carbohydrate (NSC) changes after stem girdling were analyzed. We hypothesize that (i) needle growth will increase in response to carbohydrate accumulation 227 DAG, (ii) needle growth will be reduced 411 DAG, as root starvation will lead to decreased sap flow and to a subsequent water shortage in the needles, and (iii) correlations among the studied needle morphological parameters will be different in girdled and control trees.…”

Section: Introductionmentioning

confidence: 99%

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Long-term effects of stem girdling on needle structure in Scots pine

Gebauer¹,

Plichta²,

Foit³

et al. 2018

iForest

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Stem girdling is the process of completely removing a strip of cork and phloem tissue. Phloem is the living tissue which serves as the main long-distance pathway for transporting carbohydrates produced during photosynthesis to all parts of the plant where needed, from source leaves to sinks. Stem girdling has been used to study several functional aspects of phloem and their direct impacts on tree growth. Although both photosynthesis and transpiration processes take place in needles, no studies exist which investigate the effect of source-sink disturbance on needle structure. In this study, we evaluated changes in needle morphology and anatomy in current-year Scots pine needles 227 and 411 days after girdling (DAG). Although the studied needle parameters recorded 227 DAG were from 2 to 20% higher than the same parameters in control needles, the differences were not significant. On the other hand, needles 411 DAG were thinner, with decreased cross-sectional areas, phloem areas, vascular cylinder areas, needle dry mass, needle density, and needle flatness when compared to control needles. Marked variations in needle growth were observed 411 DAG, with a smaller number of correlations among almost all studied needle parameters in needles 411 DAG when compared to control needles or needles 227 DAG. Structural development determining needle flatness, needle density, and leaf mass per area (LMA) appeared to have driving factors that were independent of the other studied needle parameters, as correlations with other parameters were not significant in any treatment. The changes in overall needle structure observed after long-term stem girdling provide new insights into the processes that occur as a result of source-sink disturbances. This type of data could be helpful, for example, in studies specifically focused on phloem transport, tree carbon relationships, or investigations modeling gas exchange. Our study might also support gene expression studies, which could provide further knowledge about the regulatory mechanisms that determine needle size and structural form.

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Section: Discussionmentioning

confidence: 96%

Section: Study Site and Description Of The Experimentsmentioning

confidence: 99%