Calligonum caput-medusae is known to grow well when irrigated with water containing NaCl. The aim of this study was to investigate ecophysiological responses of C. caput-medusae to different NaCl concentrations. In our study, we examined the effect of 0, 50, 100, 200, and 400 mM NaCl. Our results demonstrated that maximum seedling growth occurred at 50 mM NaCl. Photosynthetic parameters, such as the photosynthetic pigment content and gas exchange parameters, correlated with growth response. High salinity (≥ 100 mM NaCl) resulted in a significant reduction of the plant growth. Similarly, marked declines in the pigment content, maximal efficiency of PSII photochemistry, net photosynthetic rate, transpiration rate, and stomatal conductance were also detected. However, intercellular CO2 concentration showed a biphasic response, decreasing with water containing less than 200 mM NaCl and increasing with NaCl concentration up to 400 mM. Water-use efficiency and intrinsic water-use efficiency exhibited the opposite response. The reduction of photosynthesis at the high NaCl concentration could be caused by nonstomatal factors. High salinity led also to a decrease in the relative water content and water potential. Correspondingly, an accumulation of soluble sugars and proline was also observed. Na+ and
Cl- concentrations increased in all tissues and K+ concentrations were maintained high during exposure to NaCl compared with the control. High salinity caused oxidative stress, which was evidenced by high malondialdehyde and hydrogen peroxide contents. In order to cope with oxidative stress, the activity of antioxidative enzymes increased to maximum after 50 mM NaCl treatment. The data reported in this study indicate that C. caput-medusae can be utilized in mild salinity-prone environments., Y. Lu, J.-Q. Lei, F.-J. Zeng, B. Zhang, G.-J. Liu, B. Liu, X.-Y. Li., and Obsahuje bibliografii
In order to understand the physiological traits important in conferring salt tolerance in three barley genotypes, this study was performed under field conditions with three water salinity levels (2, 10, and 18 dS m-1). High salinity decreased net photosynthetic rate, transpiration rate, and stomatal conductance, K+ concentration, K+:Na+ ratio, and grain yield, but increased electrolyte leakage and Na+ content. Under 10 and 18 dS m-1 salinity, Khatam (salt-tolerant) had the maximum stomatal conductance, K+, K+:Na+ ratio, and the grain yield, and a minimum Na+ content and electrolyte leakage, whereas Morocco (salt-sensitive) had the lowest net photosynthetic rate, stomatal conductance, K+ content, K+:Na+ ratio, and grain yield, and the highest Na+ content and electrolyte leakage. This study showed that tolerant genotypes of barley may avoid Na+ accumulation in aboveground parts, facilitating a higher photosynthetic rate and higher grain yield., M. Mahlooji, R. Seyed Sharifi, J. Razmjoo, M. R. Sabzalian, M. Sedghi., and Obsahuje bibliografii
Water availability is an important factor for plant growth in arid environments. In recent decades, vermicompost (VC) fertilizer has been used in agriculture as a safe and effective fertilizer with high water-holding capacity. The aim of the present study was to characterize effects of VC fertilizer on photosynthetic activity of chickpea (Cicer arietinum L. cv. Karaj) under drought conditions at three different growth stages. Tests were carried out with four volumetric ratios of VC to soil, i.e., 0:100, 10:90, 20:80, and 30:70, and three levels of drought stress, i.e., no stress (NS), moderate drought (MS), and severe drought (SS) (100, 75, and 25% of field capacity, respectively). Evaluations were performed at the seedling, flowering, and podding stage. We found that the VC treatment under NS conditions significantly increased total chlorophyll content [Chl (a+b)], intercellular CO2 concentration (C i), net photosynthetic rate (P N), transpiration rate (E), and maximal quantum yield of PSII photochemistry (Fv/Fm) at all three stages. The VC addition of 10 and 20% significantly enhanced the Chl content and Fv/Fm under MS and Fv/Fm, C i, and P N under SS at the flowering stage. In conclusion, our results proved a positive effect of the VC fertilizer on photosynthesis of chickpea under NS conditions, but it was not found under MS and SS., S. R. Hosseinzadeh, H. Amiri, A. Ismaili., and Obsahuje seznam literatury
In order to evaluate effect of weedy rice on the photosynthesis and grain filling of cultivated rice, cultivated rice ‘Nanjing 44‘ was planted in the field under different densities of weedy rice ‘JS-Y1‘ for two years. The results showed that net photosynthetic rate (PN), net assimilation rate, grain filling rate, and the grain yield of cultivated rice all decreased with increasing weedy rice density. Furthermore, yield component analysis revealed that increasing weedy rice density had the most significant effect on the percentage of filled grains and the number of rice panicles. The correlation analyses indicated that the yield of cultivated rice was highly correlated with the net photosynthetic rate and the net assimilation rate. Our results illustrated that high density of weedy rice might cause yield losses in cultivated rice by inhibition of photosynthesis and grain filling., X. M. Xu, G. Li, Y. Su, X. L. Wang., and Obsahuje bibliografii
The physiological response of plants to triple foliar biofertilization with cyanobacteria and green algae under the conditions of limited use of chemical fertilizers was investigated. Triple foliar biofertilization with intact cells of Microcystis aeruginosa MKR 0105, Anabaena sp. PCC 7120, and Chlorella sp. significantly enhanced physiological performance and growth of plants fertilized with a synthetic fertilizer YaraMila Complex (1.0, 0.5, and 0.0 g per plant). This biofertilization increased the stability of cytomembranes, chlorophyll content, intensity of net photosynthesis, transpiration, stomatal conductance, and decreased intercellular CO2 concentration. Applied monocultures augmented the quantity of N, P, K in plants, the activity of enzymes, such as dehydrogenases, RNase, acid or alkaline phosphatase and nitrate reductase. They also improved the growth of willow plants. This study revealed that the applied nontoxic cyanobacteria and green algae monocultures have a very useful potential to increase production of willow, and needed doses of chemical fertilizers can be reduced., M. Grzesik, Z. Romanowska-Duda, H. M. Kalaji., 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
Arbuscular mycorrhizal fungi (AMF) form symbioses with many plants. Black locust (Robinia pseudoacacia L.) is an important energy tree species that can associate with AMF. We investigated the effects of AMF (Rhizophagus irregularis and Glomus versiforme) on the growth, gas exchange, chlorophyll (Chl) fluorescence, carbon content, and calorific value of black locust seedlings in the greenhouse. The total biomass of the arbuscular mycorrhizal (AM) seedlings was 4 times greater than that of the nonmycorrhizal (NM) seedlings. AMF greatly promoted the photosynthesis of black locust seedlings. AM seedlings had a significantly greater leaf area, higher carboxylation efficiency, Chl content, and net photosynthetic rate (PN) than NM seedlings. AMF also significantly increased the effective photochemical efficiency of PSII and significantly enhanced the carbon content and calorific value of black locust seedlings. Seedlings inoculated with G. versiforme had the largest leaf area and highest biomass, Chl content, PN, and calorific value., X. Q. Zhu, C. Y. Wang, H. Chen, M. Tang., and Obsahuje bibliografii
Brassinosteroids (BRs) have been reported to counteract various stresses. We investigated effects of exogenously applied brassinosteroid, 24-epibrassinolide (EBR), and brassinosteroid-mimic compound, 7,8-dihydro-8α-20-hydroxyecdysone (DHECD), on the photosynthetic efficiency and yield of rice (Oryza sativa L. cv. Pathum Thani 1) under heat stress. Solutions (1 nM) of EBR and DHECD were separately sprayed onto foliage of individual rice plants during their reproductive stage. Five days after the application, the plants were transferred to the day/night temperature regime of 40/30°C for 7 days and then allowed to recover at normal temperature for 7 days. We demonstrated that both DHECD and EBR helped maintain the net photosynthetic rate. The DHECD and EBR application enhanced stomatal conductance, stomatal limitation, and water-use efficiency under the high-temperature regime. DHECD- and EBR-treated plants showed an increase in the nonphotochemical quenching that was lower than that in the control plants. Moreover, DHECD and EBR treatments maintained the maximal quantum efficiency of PSII photochemistry and the efficiency of excitation capture of the open PSII center. Furthermore, the treatments with DHECD or EBR resulted in higher chlorophyll content during the heat treatment compared with the control plants. The paddy field application of 1 nM EBR and/or 1 nM DHECD at the reproductive stage during the hot season could increase the rice yield, especially, the number of filled seeds. DHECD and EBR enhanced total soluble sugar and reducing sugar in straw and more starch was accumulated in rice seeds. Consequently, our results confirmed that DHECD showed biological activities mimicking EBR in the improvement of photosynthetic efficiency and in rising the rice yield under heat stress., J. Thussagunpanit, K. Jutamanee, W. Sonjaroon, L. Kaveeta,
W. Chai-Arree, P. Pankean, A. Suksamrarn., and Obsahuje bibliografii
Heavy metals such as cadmium (Cd) may affect different physiological functions in plants. We carried out a hydroponic experiment under greenhouse conditions in order to evaluate the effect of Cd on photosynthetic and physiological parameters of safflower. The responses of six safflower genotypes (Nebraska-10, 2811, Kouseh, S149, C111, and K12) to four concentrations of CdCl2 (0, 1.5, 3, and 4.5 mg L-1) were examined. Mean shoot and root dry masses of safflower plants were reduced by nearly 57% after the treatment by 4.5 mg(CdCl2) L-1. Contrary to the mean proline content, which increased by 121%, the mean total leaf area per plant, net photosynthetic rate, stomatal conductance to the CO2, leaf chlorophyll a, b, and (a+b), carotenoid content, and quantum efficiency of PSII decreased by 84.4, 50.5, 50.0, 31.6, 32.2, 31.8, 32.9, and 11.2%, respectively, at the presence of 4.5 mg(CdCl2) L-1. The mean Cd concentration in shoots and roots of safflower genotypes exhibited 52- and 157-fold increase, respectively, due to the addition of 4.5 mg(CdCl2) L-1 to the growing media. The mean malondialdehyde content was enhanced by 110% with the increasing CdCl2 concentration, indicating the occurrence of a considerable lipid peroxidation in the plant tissues. Even though the membrane stability index was adversely affected by the application of 1.5 mg(CdCl2) L-1, the decrease ranged from 45 to 62% when plants were treated with 4.5 mg(CdCl2) L-1. Genotype Nebraska-10 seemed to be different from the remaining genotypes in response to the 4.5 mg(CdCl2) L-1; its net photosynthetic rate tended to be the greatest and the Cd concentration in shoots and roots was the lowest among genotypes studied. This study proved Cd-induced decline in growth, photosynthesis, and physiological functions of safflower., L. Moradi, P. Ehsanzadeh., and Obsahuje seznam literatury
The effects of 20 and 50 µM concentrations of Cu and Cd on photosynthesis in cucumber (Cucumis sativus L.) cotyledons were studied by the measurements of gas exchange characteristics, chlorophyll (Chl) fluorescence parameters, photosynthetic pigment contents, and two Calvin cycle enzymes activities: glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and 3-phosphoglyceric acid kinase (PGK). To minimize indirect metal action, seedlings were treated with metals in the stage of green, fully developed cotyledons. The metals reached the cotyledon tissue after 48 h of treatments, though symptoms of metal action were not visible at that time. The effect of metals on the light phase of the photosynthesis parameters such as potential efficiency of photosystem 2 (PS2; Fv/Fm), and photochemical and nonphotochemical quenching of Chl fluorescence (qP and qNP) was negligible. In contrast, a decrease of PS2 quantum efficiency (ΦPS2) was much more noticeable. Changes in the pigment contents were slight, as only 50 µM Cd decreased Chl a and b contents in small extent. On the contrary, metals in both concentrations drastically decreased (50 and more % of control) the net photosynthetic rate and the stomatal conductance, but not the internal CO2 concentration. The activities of both GAPDH and PGK were also decreased by metals, although the effect on PGK was more prominent, particularly on its potential activity (dithiothreitol in extraction and incubation media). Hence Cu and Cd affected the synthesis of enzyme proteins rather than they influenced their modifications. The effects of both metals on most of the measured photosynthesis parameters were similar, but the accumulation of Cd in the cotyledons was significantly higher than Cu accumulation. Thus Cu was more toxic for the photosynthesis of cucumber cotyledons than Cd. and M. Burzyński, A. Żurek.