Light absorption by isolated chloroplasts and leaves: effects of scattering and 'packing'.
Light absorption was quantified in the following systems: isolated chloroplasts and leaves of spinach (Spinacea oleracea L.), a mutant of geranium (Pelargonium zonale L.) widely differing in pigment content, and coleus (Coleus blumei Benth.) at different stages of leaf ontogenesis. For these species and pea (Pisum sativum L.), scattering-compensated absorption spectra of chloroplast suspensions are presented. Comparison of leaf and chloroplast spectra showed considerable changes in the extent of the 'package' effect and the lengthening of the effective optical path in a leaf. The difference between leaf and isolated chloroplast absorption could be quantitatively described by adapting Duysens's treatment of flattening. It was found that the accumulation of chlorophyll in leaves is accompanied by a monotonous enhancement of the package effect. The results are discussed with special reference to the role of light scattering in leaf optics, light utilization in photosynthesis and wavelength-dependent light gradients in a leaf.
Merzlyak
Mark N
MN
Department of Physiology of Microorganisms, Faculty of Biology, Moscow State University, Moscow, Russia. m_merzlyak@mail.ru
Chivkunova
Olga B
OB
Zhigalova
Tatiana V
TV
Naqvi
K Razi
KR
D000042:Absorption / Q000528:radiation effects; D002736:Chloroplasts / Q000378:metabolism* / Q000528:radiation effects*; D008027:Light; D018532:Pisum sativum / Q000378:metabolism / Q000528:radiation effects; D031316:Pelargonium / Q000378:metabolism / Q000528:radiation effects; D018515:Plant Leaves / Q000378:metabolism* / Q000528:radiation effects*; D013057:Spectrum Analysis; D018724:Spinacia oleracea / Q000378:metabolism / Q000528:radiation effects