Responses of photosynthesis and biomass allocation of an understorey herb,Pteridophyllum racemosum, to gradual increases in irradiance

Citation
T. Tani et al., Responses of photosynthesis and biomass allocation of an understorey herb,Pteridophyllum racemosum, to gradual increases in irradiance, ANN BOTANY, 88(3), 2001, pp. 393-402
Citations number
62
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Plant Sciences
Journal title
ANNALS OF BOTANY
ISSN journal
0305-7364 → ACNP
Volume
88
Issue
3
Year of publication
2001
Pages
393 - 402
Database
ISI
SICI code
0305-7364(200109)88:3<393:ROPABA>2.0.ZU;2-X
Abstract
In wave-regenerating Abies forests in central Japan, light availability on the forest floor of a mature-tree stand increases gradually over 4 to 5 yea rs during the senescence of trees. The understorey evergreen perennial Pter idophyllum racemosum Sieb. et Zucc. (Papaveraceae) is commonly found in suc h forests. To determine the acclimation characteristics of this species to gradual changes in light availability, leaf photosynthetic traits and bioma ss allocation patterns were determined along a transect running from fully shaded understorey to a canopy gap. Along the transect, the photon flux den sity on the forest floor relative to full sun (RPFD) varied from 2.3-36.7 % . The light-saturated net photosynthetic rate of field-grown plants increas ed as the light environment increased from 2.3-14.1 % RPFD. However, as lig ht conditions increased from moderate (14.1 %) to high (36.7 %), the light- saturated net photosynthetic rate decreased to a level comparable to that e xhibited by low-light grown plants. On the other hand, root mass per unit l eaf area (RMA) increased with increasing light conditions. A higher RMA con tributes to a higher water uptake capacity per unit leaf area which in turn supports higher rates of photosynthesis and transpiration in high light. W e conclude that in wave-regenerating forests P. racemosum can survive in hi gh-light environments by avoiding a severe water deficit and heat load by i ncreasing RMA. (C) 2001 Annals of Botany Company.