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
Botanická a mykologická nomenklatura je plná názvů převzatých z antické mytologie. Krása rostlin a hub přinesla do názvosloví mladé bohy a bohyně, motivem pro využití jmen byly také léčivé účinky nebo jedovatost, vzezření či místo výskytu rostlin a hub., Botanical and mycological nomenclature is full of names borrowed from ancient mythology. The beauty of plants and fungi brought young gods and goddesses into nomenclature. Another motive for using the names were the healing properties or toxicity, the appearance and the habitat of plants and fungi., and Tomáš Pavlík.
We studied how the reductions of trienoic fatty acids (TAs) and increases of dienoic fatty acids (DAs) enhanced high-temperature tolerance in antisense expression of tomato chloroplast omega-3 fatty acid desaturase gene (LeFAD7) transgenic tomato (Lycopersicon esculentum Mill.) plants. In transgenic plants, the content of linolenic acid (18:3) was markedly decreased, while linoleic acid (18:2) was increased correspondingly and the similar changes were observed under high-temperature stress as well. Under high-temperature stress, transgenic plants can maintain a relatively higher level of net photosynthetic rate (P N) and chlorophyll (Chl) content than that of wild type (WT) plants. A decreased Chl/Carotenoids (xanthophylls and carotenes, Car) ratio and Chl a/b ratio were observed in transgenic plants. Transgenic plants exhibited visible decrease in the relative electrolyte conductivity, higher activities of antioxidative enzymes and lower reactive oxygen species correspondingly than WT. In addition, high-temperature stress for 24 h caused more extensive changes of chloroplast ultrastructure in WT than in transgenic plants. We therefore suggested that the enhancement of high-temperature tolerance in antisense expression of LeFAD7 transgenic plants might be raised from the reduction of TAs and increase of DAs subsequently leading to series of physiological alterations. and X. Liu ... [et al.].
A tomato (Lycopersicon esculentum Mill.) zeaxanthin epoxidase gene (LeZE) was isolated and antisense transgenic tomato plants were produced. Northern, southern, and western blot analyses demonstrated that antisense LeZE was transferred into the tomato genome and the expression of LeZE was inhibited. The ratio of (A+Z)/(V+A+Z) in antisense transgenic plants was maintained at a higher level than in the wild type (WT) plants under high light and chilling stress with low irradiance. The value of non-photochemical quenching (NPQ) in WT and transgenic plants was not affected during the stresses. The oxidizable P700 and the maximal photochemical efficiency of PSII (Fv/Fm) in transgenic plants decreased more slowly at chilling temperature under low irradiance. These results suggested that suppression of LeZE caused zeaxanthin accumulation, which was helpful in alleviating photoinhibition of PSI and PSII in tomato plants under chilling stress. and N. Wang ... [et al.].
Apostasioideae jsou nejmenší, vývojově nejpůvodnější a současně nejméně prozkoumanou podčeledí vstavačovitých (Orchidaceae). Vyskytují se ve dvou rodech a 17 druzích v podrostu tropických lesů v jihovýchodní Asii. Od ostatních orchidejí se liší mj. specifickou květní morfologii a pylovými zrny nespojenými v brylky. Studium jaderného genomu ukázalo, že Apostasioideae mají jedny z nejmenších genomů mezi orchidejemi a jejich DNA je velice bohatá na adenin a thymin. Skupina je mimo svoji domovinu prakticky nepěstovatelná a chybí proto i ve velkých specializovaných sbírkách., Apostasioideae is the smallest, least specialized orchid subfamily, which is still largely unexplored. It encompasses 17 terrestrial species in two genera native to tropical rain forests of SE Asia. They differ from other orchids in their unique floral morphology and pollen shed in monads. Our flow cytometric analyses showed that apostasioids possess very small genomes with a considerable proportion of adenine and thymine. The lack of information stems at least partly from their extremely difficult cultivation outside native areas., and Jana Jersáková, Jan Ponert, Pavel Trávníček, Jan Suda.
Leaf area estimation is an important measurement for comparing plant growth in field and pot experiments. In this study, determination of the leaf area (LA, cm2) in soybean [Glycine max (L.) Merr] involves measurements of leaf parameters such as maximum terminal leaflet length (L, cm), width (W, cm), product of length and width (LW), green leaf dry matter (GLDM) and the total number of green leaflets per plant (TNLP) as independent variables. A two-year study was carried out during 2009 (three cultivars) and 2010 (four cultivars) under field conditions to build a model for estimation of LA across soybean cultivars. Regression analysis of LA vs. L and W revealed several functions that could be used to estimate the area of individual leaflet (LE), trifoliate (T) and total leaf area (TLA). Results showed that the LW-based models were better (highest R 2 and smallest RMSE) than models based on L or W and models that used GLDM and TNLP as independent variables. The proposed linear models are: LE = 0.754 + 0.655 LW, (R2 = 0.98), T = -4.869 + 1.923 LW, (R2 = 0.97), and TLA = 6.876 + 1.813 ΣLW (summed product of L and W terminal leaflets per plant), (R2 = 0.99). The validation of the models based on LW and developed on cv. DPX showed that the correlation between calculated and measured LA was strong. Therefore, the proposed models can estimate accurately and massively the LA in soybeans without the use of expensive instrumentation. and E. Bakhshandeh, B. Kamkar. J. T. Tsialtas
7-day soil drought followed by 7-day rehydration was applied to potted German chamomile (Chamomilla recutita) plants at the beginning of their generative stage. Plants of a wild type (WT), plus two diploid (2n) and two tetraploid (4n) genotypes were studied, in order to examine the alterations in chlorophyll (Chl) and carotenoids (Car) contents, and chlorophyll fluorescence (CF) parameters during water shortage and rehydration. The fresh mass of the anthodia after the recovery was also studied.
WT plants adjust better to water stress than modern breeding genotypes, because drought resulted in the low fall in leaf water content of WT, the lowest decrease in the fresh mass of its anthodia (a 41% decrease from the control), and the most elastic response of the photosynthetic apparatus. 4n C11/2 strain plants suffered from the highest reduction in anthodia yield (87%), and had the lowest constitutive pigment contents. It was also the only genotype which revealed nontypical alterations in various CF parameters obtained on a dark- and light-adapted leaf. During drought, a big increase was noticed in minimal, maximal, and variable fluorescence of PSII reaction centres in the dark- adapted (F0, Fm and Fv, respectively), and in the light-adapted state (F0', Fm' and Fv')., It was accompanied by the biggest decline in linear electron transport rate (ETR), quantum efficiency of PSII electron transport (ΦPSII) and photochemical quenching coefficient (qP). These alterations were prolonged to the stage when the normal leaf water content was retained. On the contrary, C6/2 strain plants had the highest constitutive Chl and Car contents, which additionally increased after rehydration, similarly to the values of F0, Fm and Fv, which reflects the high photosynthetic potential of this genotype. It was accompanied by the relatively high yield of its anthodia after drought. Considering the drop in the yield triggered by drought, it seems to be the only parameter which may be linked with the ploidy level.
Although the yield formation of chamomile strains cannot simply be estimated by CF assay, this technique may serve as an additional tool in the selection of plants to drought. The following circumstances should be submitted; namely: measurement at the proper developmental stage of plants, in different water regimes, and an analysis of various CF parameters. The increase in F0 and F0', and the reduction in ETR, Fv'/Fm', ΦPSII and qP values in response to water deficit should be an indicator of the impairment of the photosynthetic apparatus through drought., and R. Bączek-Kwinta ... [et al.].
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
Previous evidence has demonstrated that vertical leaves of Styrax camporum, a woody shrub from the Brazilian savanna, have a higher net photosynthetic rate (PN) compared with horizontal leaves, and that it is detected only if gas exchange is measured with light interception by both leaf surfaces. In the present study, leaf temperature (T leaf), gas exchange and chlorophyll (Chl) a fluorescence with light interception on adaxial and also on abaxial surfaces of vertical and horizontal mature fully-expanded leaves subjected to water deficit (WD) were measured. Similar
gas-exchange and fluorescence values were found when the leaves were measured with light interception on the respective surfaces of horizontal and vertical leaves. WD reduced N values measured with light interception on leaf surfaces of both leaf types, but the effective quantum yield of PSII (ΦPSII) and the apparent electron transport rate (ETR) were reduced only when the leaves were measured with light interception on the adaxial surface. WD did not decrease the maximum quantum yield of PSII (Fv/Fm) or increase T leaf, even at the peak of WD stress. Vertical leaf orientation in S. camporum is not related to leaf heat avoidance. In addition, the similar P N values and the lack of higher values of ΦPSII and ETR in vertical compared with horizontal leaves measured with light interception by each of the leaf surfaces suggests that the vertical leaf position is not related to photoprotection in this species, even when subjected to drought conditions. The exclusion of this photoprotective role could raise the alternative hypothesis that diverse leaf angles sustain whole plant light interception efficiency increased in this species., A. M. Feistler, G. Habermann., and Obsahuje bibliografii
Mezinárodní vědecký časopis rostlinných biologů, který vydává Ústav experimentální botaniky AV ČR, představoval v době svého založení, v roce 1959, jedno z mála dostupných spojení s mezinárodní vědeckou komunitou a zároveň nabízel i nastupující generaci prostor pro uplatnění prvních výsledků. Spojil iniciativu a entuziasmus Bohdana Slavíka s věhlasem nestora botaniků Bohumila Němce a v průběhu šedesátých let minulého století byl většinovým publikačním médiem nastupující vědecké generace zabývající se rostlinnou fyziologií, anatomií, cytologií, fyziologickou ekologií a fytopatologií. and Jan Krekule, Jana Pospíšilová.