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Physilogical changes in response to light intensity and R:FR ratio in Scots pine (Pinus Sylvestris)
Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
2014 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

Light is crucial to plants and plants are sensitive to different aspects of light such as; light quality, quantity, duration and direction. The light signals are perceived by light receptors or photoreceptors; where phytochrome is one of the most important light receptor that perceives R and FR light and initiates the photomorphogenesis response. We studied the effect of Red (R) and Far-Red (FR) light with a range of intensities (1 µmol m-2s-1, 10 µmol m-2s-1, 25 µmol m-2s-1 and 100 µmol m-2s-1) and two R: FR ratios, 1.2 (SUN) and 0.2 (SHADOW) in Scots pine from two different latitudinal populations in Sweden (56°N and 63°N). We found that continuous R and FR light treatments significantly inhibit hypocotyl elongation and the effect was stronger with increasing light intensity. However, there was no significant effect of R light exposure on root and cotyledon growth whereas exposure to FR showed significant effect on root and cotyledon length. In addition, we observed that accumulation of chlorophyll and anthocyanin increased with increasing light intensity for both R and FR treatments. When seedlings were grown under shadow (R: FR, 0.2) longer hypocotyls were observed compared to the SUN (R: FR, 1.2) condition which is a characteristics of the shade avoidance syndrome (SAS) of the shade intolerant Scots pine. With regard to the light dominant behaviour of northern Scots pine and dark dominant behaviour of southern Scots pine (Clapham et al, 2002), ecotypic variation was observed in the the physiological responses. For instance, the pattern of development of chloroplasts differed between the two different populations from different latitudes, a significant difference of hypocotyl length following D (dark) and R light was observed between the northern and southern ecotypes. Furthermore, the southern seedlings accumulated more chlorophyll compared to the northern seedlings under SUN condition and seedlings of northern population accumulated more anthocyanin compared to seedlings of the southern population grown under both SUN and SHADOW conditions. Thus, the southern and northern populations demonstrated significant differences in many aspects of their light responses.

Place, publisher, year, edition, pages
National Category
Biochemistry and Molecular Biology
URN: urn:nbn:se:umu:diva-88889OAI: diva2:717910
External cooperation
SLU, Inst för skoglig genetik och växtfysiologi
Educational program
Master's Programme in Plant and Forest Biotechnology
Available from: 2014-05-20 Created: 2014-05-19 Last updated: 2014-05-20Bibliographically approved

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Department of Plant PhysiologyUmeå Plant Science Centre (UPSC)
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