PMID- 11275220
OWN - NLM
STAT- PubMed-not-MEDLINE
LR  - 20191120
IS  - 0098-8472 (Print)
IS  - 0098-8472 (Linking)
VI  - 45
IP  - 2
DP  - 2001 Apr
TI  - Morphological and stomatal responses of Norway spruce foliage to irradiance 
      within a canopy depending on shoot age.
PG  - 115-131
AB  - Morphological and stomatal responses of Norway spruce (Picea abies) foliage to 
      light availability were studied in respect to shoot age. Needle minor diameter 
      (D(1), anatomical width), major diameter (D(2), anatomical thickness), dry weight 
      (M), and tissue density index (I(D)) increased, and needle flatness (Fl) and 
      specific leaf area (SLA) decreased with foliage age, while shade foliage 
      demonstrated higher morphological plasticity as compared to sun foliage. Needle 
      minor diameter, dry weight, and the ratio of total to projected leaf area 
      increased, and needle flatness and specific leaf area decreased with daily 
      average photosynthetic photon flux density (Q(D)). The current-year foliage 
      exhibited the highest variation with irradiance, while the morphological 
      plasticity decreased with needle ageing. The morphological characteristics of 
      needles were independent of irradiance if Q(D) was above 300 micromol m(-2) s(-1). 
      D(1) was the only linear needle characteristic which significantly changed with 
      light availability within a canopy, and thus determined needle flatness, SLA, as 
      well as the ratio of total to projected leaf area (TLA/PLA). Needle flatness was 
      a characteristic responding most sensitively to the photosynthetic photon flux 
      density, R(2) was 0.68, 0.44, and 0.49 for the current-year, 1-year-old, and 
      2-year-old foliage, respectively. TLA/PLA ranged from 2.2 to 4.0 depending on 
      D(1). Variation in SLA in response to light availability can be attributed to 
      changes both in needle shape and tissue density. Stomatal responses to 
      photosynthetic photon flux density (Q(P)) depended on foliage type (sun or shade) 
      and age. Sun needles demonstrated higher daily maximum leaf conductances to water 
      vapour compared to shade needles. The shade needles responded more sensitively to 
      changes in Q(P) at dawn and sunset than the sun needles, while older needles of 
      both foliage types exhibited faster stomatal responses. The light-saturation of 
      leaf conductance (g(L)) was achieved by 20 micromol m(-2) s(-1) for shade foliage, 
      and approximately by 50 micromol m(-2) s(-1) for sun foliage. As a rule, g(L) changed 
      in response to irradiance faster in the evening, i.e. at decreasing irradiance. 
      Stomata were not usually completely closed in the dark before sunrise and after 
      sunset, the phenomenon being more pronounced in older shoots and sun needles. 
      Nightly water losses from spruce foliage are attributable primarily to older 
      shoots, and are related to age-dependent changes in stomatal responsiveness.
FAU - Sellin, A
AU  - Sellin A
AD  - Department of Botany and Ecology, University of Tartu, Lai 40, 51005, Tartu, 
      Estonia
LA  - eng
PT  - Journal Article
PL  - England
TA  - Environ Exp Bot
JT  - Environmental and experimental botany
JID - 7610775
EDAT- 2001/03/29 10:00
MHDA- 2001/03/29 10:01
CRDT- 2001/03/29 10:00
PHST- 2001/03/29 10:00 [pubmed]
PHST- 2001/03/29 10:01 [medline]
PHST- 2001/03/29 10:00 [entrez]
AID - S0098847200000861 [pii]
AID - 10.1016/s0098-8472(00)00086-1 [doi]
PST - ppublish
SO  - Environ Exp Bot. 2001 Apr;45(2):115-131. doi: 10.1016/s0098-8472(00)00086-1.