[Show abstract][Hide abstract] ABSTRACT: The aim of this study is to determine the drought stress index through photochemical analysis in red pepper (Capsiumannuum L.). The photochemical interpretation was performed in the basis of the relation between Kautsky effect and Photosystem II (PSII) following the measurement of chlorophyll, pheophytin contents, and assimilation in drought stressed 5-week-old red pepper plants. The assimilation rate was severely lowered with almost 77% reduction of chlorophyll and pheophytin contents at four days after non-irrigation. It was clearly observed that the chlorophyll fluorescence intensity rose from a minimum level (the O level), in less than one second, to a maximum level (the P-level) via two intermediate steps labeled J and I (OJIP process). Drought factor index (DFI) was also calculated using measured OJIP parameters. The DFI was -0.22, meaning not only the initial inhibition of PSII but also sequential inhibition of PSI. In real, most of all photochemical parameters such as quantum yield of the electron transport flux from Quinone A () to Quinone B (), quantum yield of the electron transport flux until the PSI electron acceptors, quantum yield of the electron transport flux until the PSI electron acceptors, average absorbed photon flux per PSII reaction center, and electron transport flux until PSI acceptors per cross section were profoundly reduced except number of QA reducing reaction centers (RCs) per PSII antenna chlorophyll (RC/ABS). It was illuminated that at least 6 parameters related with quantum yield/efficiency and specific energy fluxes (per active PSII RC) could be applied to be used as the drought stress index. Furthermore, in the combination of parameters, driving forces (DF) for photochemical activity could be deduced from the performance index (PI) for energy conservation from photons absorbed by PSII antenna until the reduction of PSI acceptors. In conclusion, photochemical responses and their related parameters can be used as physiological DFI.
Korean Journal of Soil Science and Fertilizer. 01/2013; 46(6).
[Show abstract][Hide abstract] ABSTRACT: Scytonema javanicum (Kutz.) Born et Flah (cyanobacterium) is one of the species distributed widely in the crust of desert
soils regularly subjected to severe water stress. To investigate the response of the species to salt stress, many physiological
and biochemical parameters, including growth rate, ratio of variable fluorescence to maximum fluorescence (Fv/Fm),
reactive oxidative species (ROS), malondialdehyde (MDA), catalase (CAT), and superoxide dismutase (SOD), were
determined in culture. The results showed that 50mM NaCl inhibited growth and Fv/Fm in the medium BG-110, and that
the inhibition was maximum after 1–2 days’ exposure to salt stress; 50mM NaCl also increased the contents of ROS and
MDA in treated cells, which suggests that salt stress may lead to oxidative damage and lipid peroxidation in the alga.
Further, changes in the antioxidative enzymes SOD and CAT in the treated alga were consistent with changes in ROS and
MDA at certain extent. These observations suggest that oxidative stress resulting from salt stress in S. javanicum could
result in the production of antioxidative enzymes to counteract the oxidative damage, and the enzymes may contribute to
the ability of S. javanicum to survive the adverse desert environment.
r 2007 Elsevier Ltd. All rights reserved.
Journal of Arid Environments 02/2007; 71(2):312–320. · 1.82 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Leaf chlorophyll (Chl) concentration can be an indicator of plant health, including photosynthetic potential and nutrient status. In some cases, this measure can indicate the degree to which plants are water-stressed. Traditional methods of measuring Chl concentration have involved a destructive sampling technique: extraction and spectrophotometric analysis. A compatible nondestructive method to measure leaf Chl concentration exists and applies transmittance spectroscopy to plants with a Minolta SPAD-502 meter. These techniques were evaluated by comparing leaf Chl concentration in big bluestem (Andropogon gerardii). Leaves were sampled from plants representing three ecotypes (originating from Central Kansas, Eastern Kansas, and Illinois, USA) and two cultivars of A. gerardii growing in Hays, Kansas, USA. Leaf Chl concentration was measured using nondestructive and destructive techniques. We documented a saturating relationship between destructively measured leaf Chl concentration and SPAD index resulting from a decelerating change in SPAD index as Chl concentration increased. The comparison of A. gerardii ecotypes and cultivars demonstrated highest Chl concentration in the ecotype and cultivar from areas with historically low precipitation, Central Kansas and A. gerardii var. hallii, respectively. A high ratio of Chl a to Chl b is an index of drought adaptation and was also manifested in A. gerardii from drier regions. Thus, drought-adapted ecotypes and cultivars might be able to maintain high photosynthetic productivity and protect photosystem II during dry periods. Conversely, the ecotypes and cultivar originating from areas with higher precipitation had lower leaf Chl and a lower Chl a/b ratio.
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.