Oxalis acetosella L. is a common, edible wild plant native to the northern hemisphere. The contents of selected antioxidants, and the antioxidant capacity of young and old spring leaves of
O. ...acetosella, were evaluated. The present study reports foliar contents of ascorbic acid, tocopherols, carotenoids, chlorophyll, flavonoids, phenolic acids and total phenolics, and compares the nutritional value of
O. acetosella with other cultivated and wild plants. The composition of foliar antioxidants was found to depend on leaf age. On the other hand, the antioxidant capacity of old leaves were in the same range as young leaves. A comparison between
O. acetosela with lettuce analysed in our study, and with numerous cultivated and wild edible plants from other studies, showed that
O. acetosella is very rich in β-carotene, ascorbic acid, tocopherols and xanthophylls, and that it is one of the best sources of flavonoids (flavonol glycosides and flavan-3-ols), especially rutin. Therefore,
O. acetosella is a potentially important dietary source of antioxidants.
•Eddy covariance performed on abandoned karst grassland overgrown partially by trees and shrubs.•Poor rain-use efficiency of the ecosystem due to highly permeable calcareous bedrock.•Large yearly ...variability in carbon uptake, governed mostly by summer drought duration.•Different phenology and drought tolerance of grassy gaps and tree-shrub patches.•Magnifying effects of heat and high VPD during drought on ecosystem carbon uptake capacity.
Successional ecosystems developed spontaneously on agricultural lands cover a substantial area worldwide, particularly in Europe and North America. The functioning of these ecosystems in terms of carbon and water fluxes remains fairly under-investigated. Here, carbon and water exchanges of a spatially heterogeneous tree-shrub-grassland mosaic developed on former semi-dry calcareous grassland in the sub-Mediterranean region of Slovenia were studied. Using eddy covariance, the annual, seasonal and daily dynamics of net ecosystem exchange (NEE) and water vapor exchange were examined, together with their environmental controls during the period August 2008–December 2012. Over this period, the ecosystem appeared to be a carbon sink but the annual carbon fixation had a span of more than four-fold, from 82 to 351gCm−2yr−1. This variability was largely explained by different durations of drought events that occurred during the summer despite the high and relatively evenly distributed rainfall. This is related to the poor ecosystem rain use efficiency, only 0.10–0.35gCm−2yr−1 was taken up per mm of rain and the estimated deep water drainage ranged between 44 and 72% of the incoming rain. Drought periods were identified by deriving the critical soil water content (SWC) (here 0.145m3m−3) at which evapotranspiration and carbon fluxes started to be limited by water availability. The estimated annual gross primary productivity was shown to be linearly dependent on the duration of the longest annual drought period and not on the drought intensity. Despite a severe drought in the summer of 2012, the ecosystem proved quite resilient to drought stress and restored its carbon uptake after several rain events. As shown by the light response curves, the light dependency of carbon exchange was affected by seasonality and environmental factors, particularly SWC, vapor pressure deficit (VPD) and air temperature (Ta). Interaction between the factors was also observed; negative effect of low SWC was significantly enhanced in the conditions of higher Ta or higher VPD.
Within this research paper, the enforcement of agricultural policy measures for farms that have their agricultural lands within the Radensko Polje Landscape Park (RPLP) were studied. The purpose of ...the study was to evaluate the effectiveness of the additional payment for the extensive rearing of female bovine animals (ERB) and agrienvironmental measures (AE measures) in terms of maintaining extensive agricultural systems or transitions from intensive systems to sustainable ones. This is especially desirable in the protected areas that also include landscape parks. The results of the survey of farmers of RPLP showed that both the ERB and AE measures are inefficient and fail to encourage farmers to implement more extensive farming. The main reasons for the poor enforcement of claims for ERB are intensive livestock production (milk production or bovine animals fattening), and the lack of information about the possibility of claim enforcement for ERB. Regarding AE measures, the main reasons for the failure are burdensome conditions and low financial compensation. Inventories of the composition of plant species on sample grasslands showed that the conditions of the habitats are still relatively good, because a relatively large number of species of high conservation value is present.
As common ragweed (Ambrosia artemisiifolia L.) spreads across Europe and other regions, it is becoming both a health and an economic threat. To better understand which environmental conditions ...facilitate the spread of the invasive species, in 2010, a greenhouse experiment was conducted determining the effects of various nitrogen levels (10, 50 and 100 kg N/ha), soil moisture level (low and high) and competition levels (no competition, medium competition and high competition) on the growth parameters of ragweed. Single-grown ragweed responded favourably to the medium nitrogen and water increase, whereas the ragweed growth parameters in competition stands increased only when high levels of nitrogen and water were added. High competition reduced the total dry matter of ragweed by up to 83%, but the ragweed continued to increase its relative growth rate during the full-flowering stage and allocate its dry matter to reproductive parts, producing up to 70 seeds per plant. Ragweed is a poor competitor when there is high resource availability; however, under disturbance and in the shortage of nutrients and water conditions, the intensity of competition decreases and the ragweed performance is minimally affected. The addition of medium levels of nitrogen to promote the growth of competitive species, prevention of disturbance and establishment of plant communities with stress-tolerant species is measures that should help to prevent the further spread of ragweed.
The influence of water deprivation on potted apple trees (
Malus domestica Borkh.) was investigated. Biochemical responses including ascorbic acid, glutathione (GSH), tocopherols, chlorophylls, ...carotenoids, free amino acids, and soluble carbohydrates were measured in leaves of diploid ‘Elstar’ and triploid ‘Jonagold Wilmuta’ subjected to progressive drought. Leaf water potential was chosen to be the primary indicator of water stress in tested plants. Time courses of measured biochemical parameters showed that mild drought did not significantly affect the chosen stress indicators. Moderate drought increased the concentrations of ascorbic acid, total GSH,
β-carotene, zeaxanthin and
α-tocopherol, indicating the adaptation to oxidative stress in apple trees. Moderate drought also increased concentration of soluble carbohydrates, mostly due to increased sorbitol concentration. Severe drought negatively affected vitality of apple trees, and caused a decrease in sorbitol concentration. Severe drought also caused decreases in ascorbic acid, total GSH,
β-carotene,
α-tocopherol and chlorophyll concentrations, which, together with the increase in oxidised GSH concentration, indicated severe damage due to oxidative stress. Severe drought increased free amino acid concentration, which was probably the result of increased proteolysis. Zeaxanthin concentration remained high even in leaves of apple trees subjected to severe drought stress. The results were similar for both tested apple cultivars.
Samples of Hypnum cupressiforme were collected at two types of site in forest areas: within the forest stand and within forest openings, and analyzed for N and S concentrations and δ15N. Mosses ...sampled within forest openings reflect the atmospheric N deposition; however, no influence of throughfall N deposition on the N in the moss that was sampled within the forest stand was found, nor was any influence of S deposition on the S in the moss found. For the N and S concentrations in the mosses sampled within forest openings, the within-site variability was comparable to the between-site variability, and for the δ15N, the within-site variability was lower than the between-site. The results showed that a short distance (<1 m) between the sampling location and the nearest tree canopy increases the N in the moss, and significantly higher values are found in mosses sampled in areas within the forest stand.
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•We collected moss samples within the forest stand and within the forest openings.•We examine dependence of N, S and δ15N content in moss on atmospheric deposition.•Moss sampled within forest openings reflect the atmospheric N but not S deposition.•Higher N and S content was found in mosses sampled in areas within the forest stand.•Metadata describing the boundary condition of moss sampling location is important.
H. cupressiforme reflects the atmospheric deposition of N but not S; a distance less than 1 m between the sampling site and the nearest tree crown increases the N and S concentrations in the moss.
Rational irrigation scheduling based on sensing drought stress directly in plants is becoming more important due to increasing worldwide scarcity of fresh water supplies. In order to evaluate a set ...of potential biochemical and physiological stress indicators and select the best drought stress markers in apple trees, two experiments with potted trees and an experiment with intensive orchard grown apple trees ‘Elstar’ and ‘Jonagold Wilmuta’ were conducted in early summer in tree following years. Biochemical parameters: ascorbic acid, glutathione, tocopherols, chlorophylls, carotenoids, free amino acids, soluble carbohydrates, and physiological parameters already known as stress indicators in apple trees: predawn and midday leaf water potential, net photosynthesis (Pn), stomatal conductance (
g
s), transpiration (Tr) and intercellular CO
2 concentration (Ci) were measured in leaves of apple trees subjected to different intensities of slowly progressing drought or no drought. Our study pointed out zeaxanthin and glutathione as the best drought stress markers in apple trees. Ascorbate and sorbitol appeared to be reliable indicators of moderate drought only. Responses of other tested biochemical parameters were not consistent enough to prove their role as drought stress markers in apple trees. Relative air humidity should be taken in consideration when physiological parameters
g
s, Pn, Tr and Ci are used as drought stress markers in apple trees. Our study revealed that in situations where low relative air humidity affects
g
s and with
g
s connected physiological parameters, biochemical markers may be better tool for determination of drought stress intensities in apple trees.
Samples of Hypnum cupressiforme were collected at two types of site in forest areas: within the forest stand and within forest openings, and analyzed for N and S concentrations and δ(15)N. Mosses ...sampled within forest openings reflect the atmospheric N deposition; however, no influence of throughfall N deposition on the N in the moss that was sampled within the forest stand was found, nor was any influence of S deposition on the S in the moss found. For the N and S concentrations in the mosses sampled within forest openings, the within-site variability was comparable to the between-site variability, and for the δ(15)N, the within-site variability was lower than the between-site. The results showed that a short distance (<1 m) between the sampling location and the nearest tree canopy increases the N in the moss, and significantly higher values are found in mosses sampled in areas within the forest stand.
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