
%0 Journal Article
%A Pearcy, RW 
%T Photosynthetic Utilisation of Lightflecks by Understory Plants
%J Functional Plant Biology
%D 1988/03/01
%V 15
%N 2
%P 223-238
%K 
%R https://doi.org/10.1071/PP9880223
%U https://www.publish.csiro.au/paper/PP9880223 
%X The light environment in forest understories is highly dynamic because the weak shade light is period- ically punctuated by lightflecks lasting from a second or less to tens of minutes. Although present for only a small fraction of the day, these lightflecks can contribute more than two-thirds of the photosynthetically active radiation. Several factots are of importance in determining the capacity of a leaf to utilise lightflecks. Following long low-light periods the induction state of the photosynthetic apparatus is limiting. During induction, 20-60 min may be required before maximum assimilation rates are reached due first to a light activation requirement. of ribulose-1,5-bisphosphate carboxylasel oxygenase and later to the light-induced stomatal opening. Continuous light is not required and induction occurring during a series of lightflecks results in higher carbon gain for later as compared to earlier lightflecks. Post-illumination CO2 fixation resulting from utilisation of metabolite pools built up during the lightfleck can significantly enhance carbon gain during short (5-20 s) lightflecks. The carbon gain of a leaf in response to a lightfleck is a consequence of the limitations imposed by induction state plus the enhancements due to post-illumination CO2 fixation. In the field, this will depend on the frequency and duration of the lightflecks and the duration of the intervening low-light periods. 
