当前位置： SCI文献检索 > PLANT PHYSIOLOGY期刊下所有文献 > Kok effect and the quantum yield of photosynthesis : light partially inhibits dark respiration.

Kok effect and the quantum yield of photosynthesis : light partially inhibits dark respiration.

Abstract：

:The linear response of photosynthesis to light at low photon flux densities is known to change abruptly in the vicinity of the light compensation point so that the quantum yield seems to decrease as radiation increases. We studied this ;Kok effect' in attached sunflower (Helianthus annuus L. cv IS894) leaves using gas exchange techniques. The effect was present even though respiration was constant in the dark. It was observed at a similar photon flux density (7 to 11 micromole photons per square meter per second absorbed photosynthetically active radiation) despite a wide range of light compensation points as well as rates of photosynthesis. The effect was not apparent when photorespiration was inhibited at low pO(2) (1 kilopascal), but this result was complicated because dark respiration was quite O(2)-sensitive and was partially suppressed under these conditions. The Kok effect was observed at saturating pCO(2) and, therefore, could not be explained by a change in photorespiration. Instead, the magnitude of the effect varied as dark respiration varied in a single leaf, and was minimized when dark respiration was minimized, indicating that a partial suppression of dark respiration by light is responsible. Quantum yields measured at photon flux densities between 0 and 7 to 11 micromole photons per square meter per second, therefore, represent the combined yields of photosynthesis and of the suppression of a component of dark respiration by light. This leads to an overestimate of the quantum yield of photosynthesis. In view of these results, quantum yields of photosynthesis must be measured (a) when respiration is constant in the dark, and (b) when dark respiration has been inhibited either at low pO(2) to eliminate most of the light-induced suppression of dark respiration or at photon flux densities above that required to saturate the light-induced suppression of dark respiration. Significant errors in quantum yields of photosynthesis can result in leaves exhibiting this respiratory behavior if these principles are not followed.

journal_name

Plant Physiol

journal_title

Plant physiology

authors

Sharp RE,Matthews MA,Boyer JS

doi

10.1104/pp.75.1.95

subject

Has Abstract

pub_date

1984-05-01 00:00:00

pages

95-101

issue

eissn

0032-0889

issn

1532-2548

journal_volume

pub_type

杂志文章

在线工具

Kok effect and the quantum yield of photosynthesis : light partially inhibits dark respiration.