Leaves of overwintering evergreen rhododendrons are typically exposed to freezing temperatures and high light during winters which can potentially result in photon flux exceeding that required for photochemistry. This excess energy, if not dissipated as heat or fluorescence, may cause photooxidative damage to PSII. The goal of this study is to compare the photoprotection strategies during seaso...

"NYB" is a chlorophyll-less barley mutant, which grows relatively slow and unhealthily. The effects of water stress on photosystem II (PSII) of NYB and its wild type (WT) were investigated. Unexpected results indicated that the mutant was more resistant to water stress, because: PSII core proteins D1, D2 and LHCII declined more in WT than in NYB under water stress, and the corresponding psbA, p...

The aim of this study is to evaluate the  effects of water deficit stress on chlorophyll fluorescence (CF) characteristics of photosystem II (PSII) and pigment contents in two rootstock seedlings (Pistacia atlantica L. and P. khinjuk L.). Three levels of soil water potential (Ψs) was used, including WWD (-0.05 MPa), MWD (-0.7 MPa) and SWD (-1.5 MPa). It was found that water stress increased the...

A study was conducted over 2 years to determine whether growth under elevated CO(2) (700 μmol mol(-1) ) and temperature (ambient + 4 °C) conditions modifies photochemical efficiency or only the use of electron transport products in spring wheat grown in field chambers. Elevated atmospheric CO(2) concentrations increased crop dry matter at maturity by 12-17%, while above-ambient temperatures d...

Plant photosynthesis and photosystem II (PSII) are susceptible to high temperature. However, photosynthetic electron transport process under heat stress remains unclear. To reveal this issue, chlorophyll a fluorescence and modulated 820 nm reflection were simultaneously detected in sweet sorghum. At 43°C, J step in the chlorophyll a fluorescence transient was significantly elevated, suggesting ...

The efficiency of oxygenic photosynthesis depends on the presence of core antenna chlorophyll closely associated with the photochemical reaction centers of both photosystem II (PSII) and photosystem I (PSI). Although the number and overall arrangement of these chlorophylls in PSII and PSI differ, structural comparison reveals a cluster of 26 conserved chlorophylls in nearly identical positions ...

Rubisco activase plays an important role in the regulation of CO(2) assimilation. However, it is unknown how activase regulates photosystem II (PSII) photochemistry. To investigate the effects of Rubisco activase on PSII photochemistry, we obtained transgenic tobacco (Nicotiana tabacum) plants with 50% (i7), 25% (i28), and 5% (i46) activase levels as compared to wild type plants by using a gene...

Key words: Chlorophyll fluorescence, heat stress, photo-system II photochemistry, water stress, wheat (Tritium Modulated chlorophyll fluorescence, rapid fluores-aestivum L.). cence induction kinetics and the polyphasic fluores-cence transients (OJIP) were used to evaluate PSII photochemistry in wheat plants exposed to water

In this study, the impact of future climate change on photosynthetic efficiency as well as energy partitioning in the Stipa bungeana was investigated by using chlorophyll fluorescence imaging (CFI) technique. Two thermal regimes (room temperature, T0: 23.0/17.0°C; High temperature, T6: 29.0/23.0°C) and three water conditions (Control, W0; Water deficit, W-30; excess precipitation, W+30) were se...