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
Salt stress is one of the most critical factors hindering the growth and development of plants. Paclobutrazol (PBZ) is widely used to minimize this problem in agriculture because it can induce salt stress tolerance in plants. This study investigated the effects of PBZ on salt tolerance of seedlings from two Chinese bayberry cultivars (i.e., Wangdao and Shenhong). Plants were treated with three salt concentrations (0, 0.2, and 0.4 % NaCl) and two PBZ concentrations (0 and 2.0 μmol L-1). Application of PBZ increased a relative water content, proline content, chlorophyll (a+b) content, and antioxidant enzyme activities in both cultivars, resulting in a better acclimation to salt stress and an increase in dry matter production. We concluded that PBZ ameliorated the negative effects of salt stress in Chinese bayberry seedlings., Y. Hu, W. Yu, T. Liu, M. Shafi, L. Song, X. Du, X. Huang, Y. Yue, J. Wu., and Obsahuje bibliografii
The effect of drought stress on energy dissipation and antioxidant enzyme system in two sweet sorghum inbred lines (M-81E and Roma) was investigated. Results showed that the germination indicator increased more in M-81E than that in Roma under rehydration. Under drought stress, both the maximal photochemical efficiency of PSII (Fv/Fm) and oxidoreductive activity (ΔI/I0) of Roma decreased more than those in M-81E. Relative to Fv/Fm, the ΔI/I0 decreased markedly, which indicated that PSI was more sensitive to drought stress than PSII. Increases in the reduction state of QA (1-qp), nonphotochemical quenching (NPQ) and minimal fluorescence yield of the dark-adapted state (F0) were greater in Roma than those in M-81E; meanwhile, the H2O2 content was lower in M-81E than that in Roma. Our results suggested that the photoinhibition might be related to the accumulation of reactive oxygen species (ROS). The antioxidant enzyme system and energy dissipation of M-81E could respectively increase drought tolerance by eliminating ROS and excess energy more efficiently than that of Roma., Y. Y. Guo, S. S. Tian, S. S. Liu, W. Q. Wang, N. Sui., and Obsahuje bibliografii
Low temperature during the vegetative stage affects rice (Oryza sativa L.) seed-setting rate in Heilongjiang province at Northeast China. However, little is known about changes of the photosynthetic rate and physiological response in contrasting rice cultivars during chilling periods. In this study, two rice cultivars with different chilling tolerance were treated with 15°C from June 27 to July 7. The chilling-susceptive cultivar, Longjing11 (LJ11), showed a significant decrease in a ripening rate and seed-setting rate after being treated for four days, whilst chilling-tolerant cultivar, Kongyu131 (KY131), was only slightly affected after 4-d treatment. The photosynthetic activities, chlorophyll contents, and antioxidative enzyme activities in LJ11 decreased significantly along with the chilling treatment. The decrease in ß-carotene contents might play a role as it could cause direct photooxidation of chlorophylls and lead to the inhibition of the photosynthetic apparatus. In the meantime, no significant damage was found in leaves of KY131 from June 27 to July 11. In conclusion, the chilling-tolerance mechanism of rice is tightly related to the photosynthetic rate, metabolism of reactive oxygen species, and scavenging system in the vegetative stage., L.-Z. Wang, L.-M. Wang, H.-T. Xiang, Y. Luo, R. Li, Z.-J. Li, C.-Y. Wang, Y. Meng., and Obsahuje bibliografii
The present study was carried out to assess the role of zinc oxide nanoparticles (ZnO-NPs) in tomato plants on growth, photosynthetic efficiency, and antioxidant system. At 20-d stage of growth, roots of tomato plants were dipped into 0, 2, 4, 8, or 16 mg(ZnO-NPs) L-1 for 15, 30, and 45 min and then seedlings were transplanted in their respective cups and allowed to grow under natural environmental conditions. At 45-d stage of growth, the
ZnO-NPs treatments significantly increased growth, photosynthetic efficiency together with activities of carbonic anhydrase and antioxidant systems in a concentration- and duration-dependent manner. Moreover, the treatment by 8 mg(ZnO-NPs) L-1 for 30 min proved to be the most effective and resulted in maximum activities of antioxidant enzymes, proline accumulation and the photosynthetic rate. We concluded that presence of ZnO-NPs improved the antioxidant systems and speeded up proline accumulation that could provide stability to plants and improved photosynthetic efficiency., M. Faizan, A. Faraz, M. Yusuf, S. T. Khan, S. Hayat., and Obsahuje bibliografii