The influence of various concentrations of imazapic residues (0-800 μg kg-1) on the growth, chlorophyll content, and photosynthetic characteristics of maize seedlings was studied in a greenhouse pot experiment. Plant height, root length, shoot dry mass, root dry mass, and total dry mass of maize declined with the increase of imazapic residue concentrations. The root/shoot ratio initially decreased and then increased in presence of imazapic, which indicated that the effects of imazapic residues on plant height and root length might differ in maize seedlings. Lowered chlorophyll content and net photosynthetic rate were observed in leaves of maize seedlings in all treatments and indicated a dose-response relationship to imazapic concentrations. Intercellular carbon dioxide concentration, transpiration rate, and stomatal conductance also declined to varying extents, but the chlorophyll a/b ratio increased gradually together with the increase of imazapic residue concentrations. Generally, the maize seedlings were negatively affected by the imazapic residues in soil. Response of root length and biomass to imazapic residues could be the important index for maize variety selection., W. C. Su, L. L. Sun, R. H. Wu, Y. H. Ma, H. L. Wang, H. L. Xu, Z. L. Yan, C. T. Lu., and Obsahuje bibliografii
Effects of root treatment with 5-aminolevulinic acid (ALA) on leaf photosynthesis in strawberry (Fragaria ananassa Duch.) plants were investigated by rapid chlorophyll fluorescence and modulated 820 nm reflection using 3-(3,4-dichlorophenyl)-1,1-dimethyl urea (DCMU) and methyl viologen (MV). Our results showed that ALA treatments increased the net photosynthetic rate and decreased the intercelluar CO2 concentration in strawberry leaves. Under DCMU treatment, trapping energy for QA reduction per PSII reaction center increased greatly, indicating DCMU inhibited electron transfer from QA−. The maximum photochemical efficiency of PSII (Fv/Fm) decreased under the DCMU treatment, while a higher Fv/Fm remained in the ALA-pretreated plants. Not only the parameters related to a photochemical phase, but also that one related to a heat phase remained lower after the ALA pretreatment, compared to the sole DCMU treatment. The MV treatment decreased PSI photochemical capacity. The results of modulated 820 nm reflection analysis showed that DCMU and MV treatments had low
re-reduction of P700 and plastocyanin (PSI). However, the strawberry leaf discs pretreated with ALA exhibited high re-reduction of PSI under DCMU and MV treatments. The results of this study suggest that the improvement of photosynthesis by ALA in strawberry was not only related to PSII, but also to PSI and electron transfer chain., Y. P. Sun, J. Liu, R. X. Cao, Y. J. Huang, A. M. Hall, C. B. Guo, L. J. Wang., and Obsahuje bibliografii
Excessive cadmium (Cd) content in soil leads to a number of phytotoxic effects and challenges agricultural production. Aim of this study was to investigate different responses of two maize inbreds and their hybrid to an elevated Cd content in soil by measuring photosynthetic and biochemical activity and to identify a Cd tolerance mechanism. Antioxidant statusrelated parameters varied significantly between inbreds and treatments. Dry mass increased in both inbreds, but remained unchanged in hybrid. After the Cd treatment, parameters of chlorophyll a fluorescence varied between inbreds and hybrid performance was similar to inbred B84. We concluded that inbred B84 is Cd-sensitive compared to Os6-2, which did not appear to be negatively affected by Cd treatment at this growth stage studied. We suspect that due to a dilution effect in the hybrid, there was no or very weak Cd stress detected by biochemical parameters, although stress was detected by chlorophyll a fluorescence., M. Franić, V. Galić, M. Mazur, D. Šimić., and Obsahuje bibliografii
This study focused on the deleterious effect of anthracene (ANT) and role of a surfactant, Triton (TX-100), in recovery from inhibitory effect of ANT. Fast chlorophyll (Chl) fluorescence measurements were performed in wheat plants. Results revealed that maximum quantum yield of PSII, area over the fluorescence curve, performance index (PI), and reaction centre density was negatively affected by ANT treatment. The effects on PSII quantum efficiency, reaction centre density, absorption, and trapping were partially recovered by TX-100. PSII heterogeneity in terms of PSII antenna heterogeneity, corresponding to PSII α, β, and γ centres, and reducing side, corresponding to QB-reducing and QB-nonreducing centres, were also investigated. The damage caused by ANT to PSII antenna heterogeneity was recovered almost by 100% owing to TX-100., C. Sharma, S. Mathur, R. S. Tomar, A. Jajoo., and Obsahuje bibliografii