Effects of temperature and light induction of CHL a fluorescence in situ: An ecophysiological view

Abstract

The effects of PAR and temperature on induction of Chl a fluorescence were observed on leaves of 20 plant species in their natural environments. Light affects the acceptor side of PS2. Temperature regulation of PS2 activity proceeds by affecting the RC and acceptor side of PS2. The impact of higher temperature can be attributed to greater fluidity of the thylakoid membranes. Photosynthetically active radiation and temperature under the given conditions are in highly significant positive correlation, so it is not clear whether this impact is due to individual or complementary mechanisms of PAR and/or temperature affecting photosynthetic processes in the thylakoid membranes. Also, it is not clear whether species specificity has any significance in the plant photosynthetic response to changes of PAR and temperature. Changes of PAR and temperature during induction of Chl a fluorescence do not affect Pindex, as a parameter of total photosynthesis.

Praćen je uticaj PAR i temperature na indukciju fluorescencije Chl a na listovima 20 biljnih vrsta u njihovom prirodnom okruženju. Svetlost deluje na akceptorsku stranu PS2. Regulacija aktivnosti PS2 temperaturom odvija se uticajem na RC i akceptorsku stranu PS2. Uticaj povišene temperature moguće je objasniti i povećanom fluidnošću tilakoidnih membrana. PAR i temperatura u datim uslovima nalaze se u visokoznačajnoj pozitivnoj korelaciji, tako da nije jasno da li se radi o posebnim ili komplementarnim mehanizmima dejstva PAR i/ili temperature na fotosintetske procese u tilakoidnim membranama. Takođe nije jasno da li specijska specifičnost ima neki značaj u fotosintetskoj reakciji biljaka na promene PAR i temperature. U ovim procesima promene PAR i temperature ne utiču na Pindex, kao pokazatelj ukupne fotosinteze.