At present, research activities on the role of orchard systems in sequestering atmospheric CO2 remain scarce. This paper aimed to contribute to assessing the carbon balance of a Mediterranean olive (Olea europea) orchard. The net ecosystem exchange, the ecosystem respiration and the gross primary production were computed for two consecutive years through eddy covariance, and the different biomass accumulation terms were also inferred in the same period through an inventorial method. The net carbon exchange ranged from 13.45 t(C) ha-1 year-1 to 11.60 t(C) ha-1 year-1. Very similar values [12.2 and 11.5 t(C) ha-1 year-1] were found with the direct carbon accumulation inventory. The intensive farming management (irrigation included) and the young age of the plants (12-16 years old), still in an active growing phase, led the olive plantation to be a higher carbon sink with respect to other evergreen orchards reported in the literature., M. Nardino ... [et al.]., and Obsahuje bibliografii
Anthocyanins and nonphotochemical quenching (NPQ) are two important tools that provide photoprotection in plant leaves. In order to understand how plants use these tools for acclimation to changing seasonal conditions, we investigated pigments, antioxidative capacity, and photosynthesis in leaves of an evergreen tree (Acmena acuminatissima) in two contrasting seasons. Young leaves of A. acuminatissima appeared in distinct colors, being light green in summer and red in winter due to the presence of anthocyanins. In the winter young leaves, anthocyanins contributed less than 2% to the antioxidant pool. In the summer, young leaves had higher NPQ than that of mature leaves, but in the winter, they did not derive any NPQ-related advantage over mature leaves. These results suggest that the accumulation of anthocyanins in young leaves in the winter may compensate for the insufficient photoprotection afforded by NPQ and that anthocyanins function as a light attenuator to protect the photochemical apparatus against excess light., H. Zhu, T.-J. Zhang, J. Zheng, X.-D. Huang, Z.-C. Yu, C.-L. Peng, W. S. Chow., and Obsahuje bibliografické odkazy
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
Low temperature has a negative impact on plant cells and results in the generation of reactive oxygen species (ROS). In order to study the role of ascorbate under chilling stress, the response of an ascorbate-deficient Arabidopsis thaliana mutant vtc2-1 to low temperature (2°C) was investigated. After chilling stress, vtc2-1 mutants exhibited oxidative damage. An increase in the H2O2 generation and the production of thiobarbituric acid reactive substances (TBARS), and a decrease in chlorophyll content, the maximal photochemical efficiency of PSII (Fv/Fm) and oxidizable P700 were also noted. The ratio of ascorbate/dehydroascorbate and reduced glutathione/oxidzed glutathione in the vtc2-1 mutants were reduced, compared with the wild type (WT) plants. The activities of antioxidant enzymes, such as catalase (CAT) and ascorbate peroxidase (APX), and soluble antioxidants were lower in the vtc2-1 mutants than those in WT plants. These results suggested that the ascorbate-deficient mutant vtc2-1 was more sensitive to chilling treatment than WT plants. The low temperature-induced oxidative stress was the major cause of the decrease of PSII and PSI function in the vtc2-1 mutants. Ascorbate plays a critical role of defense without which the rest of the ROS defense network is unable to react effectively., L. Y. Wang ... [et al.]., and Obsahuje bibliografii
Tento článek přibližuje čtenáři svět prvních portugalských mořeplavců a jejich setkání s exotickou faunou Asie v 16. století. Důraz klade především na nosorožce a slona, ale neopomíjí ani další živočichy a věnuje se i původu některých drahocenných orientálních látek živočišného původu, pro Evropany dlouho neznámému. Text bohatě využívá citací z pramenů., This article presents the world of the first Portuguese navigators and their encounters with exotic Asian fauna in the 16th century. It primarily highlights the rhinoceros and elephants, but does not omit other animals. It also focuses on the sources of some valuable oriental substances of animal origin, which was unknown to Europeans for a long time., and Karel Staněk.