Interactive effect of water deficit and high temperature on photosynthesis of sunflower and maize plants: 1. Changes in parameters of chlorophyll fluorescence induction kinetics and fluorescence quenching

Yordanov, I.; Tsonev, T.; Goltsev, V.; Kruleva, L.; Velikova, V.

Photosynthetica 33(3-4): 391-402


ISSN/ISBN: 0300-3604
Accession: 008895128

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Effects of high temperature (HT, 42 degree C) and water stress (WD) applied separately and in combination, on the chlorophyll fluorescence kinetics and photochemical (q-P) and non-photochemical (q-N) quenching in 21-d-old sunflower and maize plants were studied. The WD was created by addition of polyethylene glycol (M-r 6000) to the nutrient solution. When the fluorescence was measured at 47 degree C, the F-v/F-0 ratio in sunflower considerably increased in plants under combined stress, whereas in maize plants it remained practically unchanged. The combined action of HT+WD led also to a noticeable (in sunflower) or a weaker (in maize) increase of F-0(25 degree C)/F-0(47 degree C) ratio (a criterion for stability of the light-harvesting complex LHC2 at HT) and a decrease of the F-v(25 degree C)/F-v(47 degree C) ratio (tolerance of the photochemical activity and O-2-evolving system). The q-P and q-N values measured at 47 degree C in maize were different from those of sunflower. The q-P values were high, but practically not influenced by HT and WD. In both plant species most of the effects induced by stress treatments disappeared after a 72 h recovery.