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Oulun yliopiston väitöskirjat

ELONGATION OF SCOTS PINE SEEDLINGS UNDER BLUE LIGHT DEPLETION, ACTA UNIVERSITATIS OULUENSIS A Scientiae Rerum Naturalium 562

ISBN-13:	978-951-42-6280-7
Kieli:	englanti
Kustantaja:	Oulun yliopisto
Oppiaine:	Luonnontieteet
Painosvuosi:	2010
Sidosasu:	pehmeäkantinen
Sijainti:	Print Tietotalo
Sivumäärä:	112
Tekijät:	SARALA MARIAN

20.00 €

The elongation response of Scots pine (Pinus sylvestris L.) seedlings to the removal of blue light(400–500 nm) was studied in field experiments in northern Finland. The seedlings were grown inorange or transparent plexiglass chambers or in ambient control plots. The orange plexiglassremoved the blue wavelengths from sunlight, while the others served as controls. The experimentwas conducted at sub-arctic (69°N) and mid-boreal (64°N) latitudes with three- and two-year-oldseedlings originating from 67°N latitude. The response to blue light depletion was alsoinvestigated at the 69°N latitude in the following plant subjects: one-year-old Scots pine seedlingsof northern (67°N) and southern (62°N) provenances, deciduous Betula pubescens ssp.czerepanovii and Betula pubescens f. rubra seedlings and herbaceous Epilobium angustifoliumand Glechoma hederacea plants. Additionally, diurnal change in light quality at the 69°N latitudeduring the summer was measured. The elongation of Scots pine seedlings was increased by the removal of blue wavelengths. Theincrease was more pronounced at the 69°N latitude, while at the 64°N latitude the response wassmaller or absent. This is due to increased amount of scattered growth-inhibiting blue light duringthe nights at the high latitude. The removal of blue light increased stem elongation in northern origin Scots pine seedlingsmuch more compared to the southern origin seedlings, which suggests that the northernprovenance is more sensitive to blue light. Irrespective of that, southern origins also suffer fromreduced elongation in the north as they migrate according to climatic change scenarios. However,it is obvious that they grow longer than local origins in the north. Morphological variables and photosynthetic pigments confirm that the increased elongation ofScots pine seedlings under blue light depletion is not a result of etiolation or it is only a marginalfactor. Also, it was neither dependent on temperature nor photosynthesis and growth resources.Instead, the increased elongation is probably a photomorphogenic regulation response ofmetabolism. In addition, shade intolerant Scots pine, Betula seedlings and herbaceous Epilobiumangustifolium responded stronger to blue light removal compared to the more shade-tolerantherbaceous Glechoma hederacea.

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