scholarly journals Chloroplast Ultrastructure, Chlorophyll Fluorescence, and Pigment Composition in Chilling-Stressed Soybeans

1984 ◽  
Vol 74 (4) ◽  
pp. 749-754 ◽  
Author(s):  
Robert L. Musser ◽  
Shirley A. Thomas ◽  
Robert R. Wise ◽  
Thomas C. Peeler ◽  
Aubrey W. Naylor
Keyword(s):  
Chlorophyll Fluorescence ◽  
Chloroplast Ultrastructure ◽  
Pigment Composition

Carotenoids and Photosystem II Characteristics of Upper and Lower Halves of Leaves Acclimated to High Light

1996 ◽  
Vol 23 (6) ◽  
pp. 669 ◽  
Author(s):  
WW Iii Adams ◽  
B Demmig-Adams ◽  
DH Barker ◽  
S Kiley
Keyword(s):  
Chlorophyll Fluorescence ◽  
Photosystem Ii ◽  
Excitation Energy ◽  
Total Energy ◽  
Xanthophyll Cycle ◽  
Lower Surface ◽  
Thylakoid Membranes ◽  
High Light ◽  
Pigment Composition ◽  
Light Gradient

Acclimation of the leaves or stems of four succulent species to different light environments and to the light gradient across high light-acclimated tissues was examined through measurements of chlorophyll fluorescence and characterisation of the pigment composition of the thylakoid membranes. Whereas the total amounts of light striking the upper (sun-exposed) and lower (self-shaded) surfaces were quite different, resulting in a much smaller pool of the xanthophyll cycle carotenoids in the lower halves of high light-acclimated tissues, the conversion state of the xanthophyll cycle (the degree to which violaxanthin is converted to antheraxanthin and zeaxanthin) was similar throughout the tissues during exposure to natural sunlight. Under full sunlight, less than 25% of the light absorbed by the upper surface was utilised through photosynthesis, with the majority of the remaining excitation energy being dissipated thermally. In contrast, a considerably greater fraction of the light absorbed by the lower surface was utilised in photosynthesis, ranging from one-third to more than two-thirds of the total energy absorbed.

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