The objective of this study was to investigate the relative salt tolerance of four eggplant cultivars (Solanum melongena L.) by studying chlorophyll (Chl) fluorescence parameters during the vegetative growth stage under increasing salinity levels. The plants were grown in pots filled with peat under controlled conditions and were subjected to the salt stress ranging from 0 (control), 20, 40, 80, and 160 mM NaCl for 25 days. The results showed that the increasing NaCl concentration affected hardly the maximum quantum yield of photosystem (PS) II. The quantum yield of PSII (ΦPSII) decreased significantly in ‘Adriatica’ and ‘Black Beauty’ under the salt stress. The photochemical quenching decreased in ‘Black Beauty’ and nonphotochemical quenching increased in ‘Adriatica’ under the salt stress. The Chl fluorescence parameters did not change significantly under the salt stress in ‘Bonica’ and ‘Galine’, revealing their tolerance to salinity. After 25 days of the salt stress, the plant growth was reduced in all cultivars, however, this decline was more pronounced in ‘Adriatica’ and ‘Black Beauty’. Additionally, a significant correlation between the biomass and ΦPSII was observed in ‘Adriatica’ and ‘Black Beauty’. Our results suggest that ΦPSII can be used as a diagnostic tool to identify salt-tolerant egg-plant cultivars., S. Hanachi, M. C. Van Labeke, T. Mehouachi., and Obsahuje bibliografii
The light-induced nonphotochemical quenching (NPQ) can safely dissipate excess of absorbed light to heat. Here we describe an application of spectrally resolved fluorescence induction (SRFI) method for studying spectral variability of NPQ. The approach allows detection of spectrally-resolved nonphotochemical quenching (NPQλ) representing NPQ dependency on fluorescence emission wavelength in the whole spectral range of fluorescence emission. The experimental approach is briefly described and NPQλ is studied for the cryptophyte alga Rhodomonas salina and for green alga Chlorella sp. We confirm presence of NPQλ only in membrane-bound antennae (chlorophyll a/c antennae) and not in phycobiliproteins in lumen in cryptophyte and show that NPQλ is inhibited in the whole spectral range by NPQ inhibitors in Chlorella sp. We discuss variability in the quenching in the particular spectral ranges and applicability of the NPQλ parameter to study quenching locus in vivo., R. Kaňa., and Obsahuje bibliografické odkazy
Saline soils spread wildly in the world, therefore it is important to develop salt-tolerant crops. We carried out a pot study in order to determine effects of arbuscular mycorrhizal fungi (AMF) (Rhizophagus irregularis and Glomus versiforme) in black locust seedlings under salt (NaCl) stress. The results showed that AMF enhanced in seedlings their growth, photosynthetic ability, carbon content, and calorific value. Under salt stress, the biomass of the seedlings with R. irregularis or G. versiforme were greater by 151 and 100%, respectively, while a leaf area increased by 197 and 151%, respectively. The seedlings colonized by R. irregularis exhibited a higher chlorophyll content, net photosynthetic rate, intercellular CO₂ concentration, stomatal conductance, and transpiration rate than that of the nonmycorrhizal seedlings or those colonized by G. versiforme. Both R. irregularis and G. versiforme significantly enhanced a carbon content, calorific value, carbon, and energy accumulations of black locust under conditions of 0 or 1.5 g(NaCl) kg-1(growth substrate). Our results suggested that AMF alleviated salt stress and improved the growth of black locust., X. Q. Zhu, M. Tang, H. Q. Zhang., and Obsahuje bibliografii
In this study, we hypothesized that colonization of olive trees (Olea europaea L.) with the arbuscular mycorrhizal fungus Rhizophagus irregularis could modify the profiles of rhizosphere microbial communities with subsequent effects on nutrient uptake that directly affects olive tree physiology and performance. In this context, a greenhouse experiment was carried out in order to study the effects of mycorrhizal colonization by R. irregularis on photosynthesis, pigment content, carbohydrate profile, and nutrient uptake in olive tree. After six months of growth, photosynthetic rate in mycorrhizal (M) plants was significantly higher than that of nonmycorrhizal plants. A sugar content analysis showed enhanced concentrations of mannitol, fructose, sucrose, raffinose, and trehalose in M roots. We also observed a significant increase in P, K, Ca, Mg, Zn, Fe, and Mn contents in leaves of the M plants. These results are important, since nutrient deficiency often occurs in Mediterranean semiarid ecosystems, where olive trees occupy a major place., M. Tekaya, B. Mechri, N. Mbarki, H. Cheheb, M. Hammami, F. Attia., and Obsahuje bibliografii
a1_This study evaluated the relationship between photosynthetic carbon accumulation and symbiotic nitrogen nutrition in young fully expanded leaves of 30 nodulated cowpea genotypes grown in the field at Manga, Ghana, in 2005 and 2006. Estimates of fixed-N in photosynthetic leaves revealed greater symbiotic N in genotypes with higher photosynthetic rates and increased leaf transpiration rate/efficiency. There was also greater C accumulation in genotypes with higher symbiotic N and/or total N. Additionally, genotypes with high contents of C per unit of leaf total N exhibited greater C per unit of leaf N-fixed. The C/N and C/Rubisco-N ratios were generally similar in their magnitude when compared to the C/N-fixed ratio due possibly to the fact that Rubisco accounts for a high proportion of photosynthetic leaf N, irrespective of whether the enzyme was formed from soil N or symbiotic N. Cowpea genotypes that relied heavily on soil N for their N nutrition exhibited much higher C/N-fixed ratios, while conversely those that depended more on symbiosis for meeting their N demands showed markedly lower C/N-fixed values. For example, genotypes Omondaw, Bensogla, IT93K-2045-29, and Sanzie, which respectively derived 83.9, 83.1, 82.9, and 76.3% N from fixation, recorded lower C/N-fixed ratios of 10.7, 12.2, 12.1, and 13.0 mg mg-1 in that order in 2005. In contrast, genotypes Botswana White, IT94D-437-1, TVu1509, and Apagbaala, which obtained 14.8, 15.0, 26.4, and 26.0% of their N nutrition from fixation, showed high C/N-fixed values of 84.0, 69.0, 35.2, and 40.6 mg.mg-1, respectively, in 2005., a2_This clearly indicates that genotypes that obtained less N from symbiosis and more N from soil revealed very high C/N-fixed values, an argument that was reinforced by the negative correlations obtained between the three C/N ratios (i.e. C/N, C/Rubisco-N, and C/N-fixed) and leaf N concentration, percentage nitrogen derived from fixation, total N content, amount of N-fixed, and Rubisco N. These data suggest a direct link between photosynthetic C accumulation and symbiotic N assimilation in leaves of nodulated cowpea, and where genotypes derived a large proportion of their N from fixation, photosynthetic C yield substantially increased., A. K. Belane, F. D. Dakora., and Obsahuje seznam literatury
The aim of this study was to investigate the effects of silicon in alleviating cadmium stress in maize plants grown in a nutrient solution and to evaluate the potential of the spectral emission parameters and the ratio of red fluorescence (Fr) to far-red fluorescence (Ffr) in assessing the beneficial effects of Si. An experiment was carried out using a nutrient solution with a toxic dose of Cd and six doses of Si; biomass, Cd, Si, and photosynthetic pigments of the plants were measured. Chlorophyll (Chl) a fluorescence analysis demonstrated that Si alleviated Cd toxicity in plants. Chl fluorescence measurements were sensitive in detecting such effects even when significant changes in biomass production and concentrations of photosynthetic pigments were not observed. The spectral emission and the Fr/Ffr ratio were sensitive to the effects of Si. Silicon caused a reduction in the translocation of Cd to the shoots of maize plants., A. J. Silva, C. W. A. Nascimento, A. S. Gouveia-Neto., and Obsahuje seznam literatury
Based on the examination and quantitative comparison of the approaches used to assess the energy partitioning in photosystem II, the unified method was proposed to calculate the contribution of the components of nonphotochemical quenching. and D. Kornyeyev, C. R. Guadagno, N. D’Ambrosio.
Photosynthetic parameters including net photosynthetic rate (P N), transpiration rate (E), water-use efficiency (WUE), and stomatal conductance (g s) were studied in indoor C3 plants Philodendron domesticum (Pd), Dracaena fragans (Df), Peperomia obtussifolia (Po), Chlorophytum comosum (Cc), and in a CAM plant, Sansevieria trifasciata (St), exposed to various low temperatures (0, 5, 10, 15, 20, and 25°C). All studied plants survived up to 0°C, but only St and Cc endured, while other plants wilted, when the temperature increased back to room temperature (25°C). The P N declined rapidly with the decrease of temperature in all studied plants. St showed the maximum P N of 11.9 μmol m-2 s-1 at 25°C followed by Cc, Po, Pd, and Df. E also followed a trend almost similar to that of P N. St showed minimum E (0.1 mmol m-2 s-1) as compared to other studied C3 plants at 25°C. The E decreased up to ≈4-fold at 5 and 0°C. Furthermore, a considerable decline in WUE was observed under cold stress in all C3 plants, while St showed maximum WUE. Similarly, the g s also declined gradually with the decrease in the temperature in all plants. Among C3 plants, Pd and Po showed the maximum g s of 0.07 mol m-2 s-1 at 25°C followed by Df and Cc. However, St showed the minimum gs that further decreased up to -4-fold at 0°C. In addition, the content of photosynthetic pigments [chlorophyll a, b, (a+b), and carotenoids] was varying in all studied plants at 0°C. Our findings clearly indicated the best photosynthetic potential of St compared to other studied plants. This species might be recommended for improving air quality in high-altitude closed environments., S. M. Gupta, A. Agarwal, B. Dev, K. Kumar, O. Prakash, M. C. Arya, M. Nasim., and Obsahuje seznam literatury
Waterlogging is one of the critical factors controlling the distribution, regeneration, and survival of vegetation in wetlands. Here, we tested the hypothesis that Mitragyna parvifolia (Roxb.) Korth. and Syzygium cumini Keels, inhabiting the Keoladeo National Park, a Ramsar wetland (Bharatpur, India), are tolerant to waterlogging. The morphological and photosynthetic variables of four-month-old seedlings subjected to waterlogging, along with the concentrations of macroand micronutrients, were examined. After 35 days, treatment was halted due to high mortality of S. cumini seedlings in contrast to that of M. parvifolia seedlings. Significant declines in most of the studied variables were observed in both species when compared with their respective controls. In addition, M. parvifolia seedlings developed adventitious roots and lenticels and showed an increased root biomass. Based on the results, we concluded that adaptive traits displayed by M. parvifolia seedlings facilitate its tolerance to waterlogging in contrast to S. cumini seedlings., A. Bidalia, Z. Okram, M. Hanief, K. S. Rao., and Obsahuje bibliografii
The effects of the atomic ratio of N to P (N:P) on the response of Alexandrium tamarense to UV radiation (UVR) were investigated in this study. Artificial sea water of 5 different N:P ratios for indoor culture and with 3 different N:P ratios for outdoor culture were used for a period of 14 and 9 d, respectively. The short-term response of cells to UVR was analyzed using a fluorometer. Cells that acclimated to nutrient conditions at the Redfield value (16:1) showed the fastest growth rate and highest pigment concentrations in both indoor and outdoor conditions, compared to those acclimated to the non-Redfield conditions. Moreover, these physiological parameters were functions of the N:P ratio according to a two-order equation (y = a + bx + cx2, R2>0.95). The fluorescence data of indoor cultures showed that A. tamarense grown at 16:1 (N:P) exhibited the greatest ratio of repair rate/damage rate (r/k) and minimum level of UVR-induced inhibition. among those grown at all of the N:P ratios following UVR exposure. Outdoor cultures had the same patterns of fluorescence as indoor cultures, but the less UVR-induced inhibitions were detected compared the former with the latter. The following three parameters, the r/k, level of inhibition caused by the two radiation treatments following 60 min of exposure (PAR and PAB, respectively), and level of UVR-induced inhibition, were also functions of the N:P ratio according to the two-order equation (R2>0.96). Further, there was a negative correlation between
UVR-induced inhibition and the r/k ratio. In summary, the Redfield value (16:1) was the optimal nutrient stoichiometry for the protection of A. tamarense against the deleterious effects of UVR. Results were not impacted by previous light history experienced by cells., W. C. Guan, L. Li., and Obsahuje bibliografii