1,721,015 research outputs found
Red-leafed species for urban “greening” in the age of global climate change
Full text linkUrban trees provide vital ecosystem services such as mitigating heat island, improving air quality by removing various air pollutants, capturing rainwater, and acting as topsoil carbon storage. The aesthetic value of urban trees is also another feature that has to be considered in the context of urban greening. Classical criteria for the selection of urban trees have to respond to new challenges imposed to the cities in a near future. Global climate change factors increase the harshness of our cities, and thereby the plant resilience to abiotic stresses has also to be seriously considered for planning the urban greening. Red-leafed species, characterized by the permanent presence of foliar anthocyanins, show a greater tolerance to different environmental cues than green-leafed species commonly used in our cities. In addition, red tree species own a great aesthetic value which has been underestimated in the context of urban areas, especially in the harsh Mediterranean cities. In this study, we emphasize the “privilege of being red” from different point of view, in order to drive the attention to the possibility to increase the use of red-leafed species for urban “greening”. Some possible negative aspects related to their use are rebutted and the direction of future researches are proposed
Chlorophyll fluorescence, photoinhibition and abiotic stress: does it make any difference the fact to be a C3 or C4 species?
Full text linkChlorophyll fluorescence analysis is one of the most powerful and widely used techniques to study the effect of stresses on the photosynthetic process. From the first utilization, the Fv/Fm ratio has been largely used as a sensitive indicator of plant photosynthetic performance. Decreases of this index are indicative of the reduction of photosystem II (PSII) efficiency, namely photoinhibition. In the last 20 years, application of chlorophyll fluorescence has been largely improved, and many other informative parameters have been established to detect PSII photochemical efficiency and the partitioning of light energy to alternative dissipative mechanisms (qE, energy-dependent quenching; qZ, zeaxanthin-dependent quenching and qI, photoinhibitory quenching; qH, sustained photoprotective antenna quenching; qM, quenching dependent to chloroplast movement; qT, light harvesting complexes II–I state-transition) such as the recently developed “photoprotective power” of non-photochemical quenching (pNPQ). This review reports a brief description of the main chlorophyll fluorescence parameters and a wide analysis of the current bibliography on the use of different parameters which are useful to detect events of PSII photoinhibition. In addition, in view of the inherent differences in morpho-anatomical, physiological and biochemical features between C3 and C4 metabolism, possible differences in terms of photoinhibition between C3 and C4 plant species under stress conditions are proposed. The attempt is to highlight the limits of their comparison in terms of susceptibility to photoinhibition and to propose direction of future research which, assisted by chlorophyll fluorescence, should improve the knowledge of the different sensitivity of C3 and C4 to abiotic stressors
The influence of water deficit and re-watering on flower bud morphogenesis in young apricot trees (Prunus armeniaca L.)
No full textIn deciduous fruit species, as well as in apricot, floral bud initiation, differentiation and organogenesis take place during the summer season that precedes anthesis. A number of factors (environmental conditions, cultural practices, abiotic stresses) have been identified as important triggers able to modify the regularity of floral differentiation. The water availability represents a crucial key factor, particularly under Mediterranean climates characterized by long drought periods. This investigation aimed to assess the influence of summer water deficit and re-watering treatments on floral morphogenesis, growth and quality of flower buds in apricot. Trials were carried out on two-year-old potted trees ('Portici') grown at the research station of University of Pisa. Plants were divided into three uniform groups: the first one was watered daily maintaining soil water content around 90% of field capacity, whereas second and third ones were subjected, in June or July, to 30 days of imposed water deficit followed to re-watering. In order to determine the evolution of floral bud differentiation, prior, during and after the imposed water stress, histological analyses were carried out. From autumn to spring, qualitative traits of flower buds (growth, anomalies) were also analyzed. Midday stem water potential was used to determining water status, and leaf gas exchanges were measured during trials. Both water stress periods affected the floral differentiation leading to a temporary shutdown. The plants stressed in June were able to recover the development of meristematic apices already after two weeks from the regular re-watering, while those stressed in July showed a strong delay up to the end of summer. As a consequence, variations in bud size and flower anomalies were observed. Results confirm that water stress may play an important role in flower bud differentiation and development influencing the quality of flower buds
Role of beneficial elements in plants: Implications for the photosynthetic process
No full textEssential macro-and microelements availability strictly influences photosynthetic process as well as the overall plant status. Besides essential macro-and micronutrients, a group of other elements described as ‘beneficial’ has been proposed to ameliorate plant performances under optimal and/or stressful conditions. The first explanation of the term ‘essential’, as suggested by Arnon and Stout in 1939, defined beneficial elements as not essential since they are not necessary for plants to complete their life cycle. However, at low amounts, they can exert promoting effects on plant performances, including photosynthesis. In this review, we summarize the positive effect of seven beneficial elements (Se, Si, Na, I, Ti, Ce, and La) on plant photosynthetic processes to depict a clear picture of the influences of these beneficial elements on photosynthesis
Verso la territorializzazione delle politiche comunitarie: processi di governance e pratiche di Agenda 21 Locale in Europa
No full textVisioni e scenari nei processi di partecipazione. L'esperienza di Vitoria-Gasteiz in Spagna
No full textFirst Characterization of the Formation of Anthocyanin-Ge and Anthocyanin-B Complexes through UV-Vis Spectroscopy and Density Functional Theory Quantum Chemical Calculations
Full text linkThe occurrence of anthocyanin (ACN) and metal (Me) complexes has been widely supported by many research works while the possibility that ACNs bind to metalloids (Mds) is yet to be proven. Here, metalloids (H3BO3 for B; GeO2 for Ge) were added to cyanidin-based solutions at pH 5, 6, and 7 and ACN-Md stoichiometric ratios of 1:1, 1:10, 1:100, and 1:500, and UV-vis transmittance spectroscopy as well as density functional theory (DFT) calculations were performed to test this hypothesis. Ge and B addition caused bathochromic and hyperchromic shifts on ACN UV-vis spectra, particularly pronounced at pH 5 and a 1:500 (ACN:Md) ratio. ACN-Me complexation reactions have been evaluated where Ge showed a higher capability to bind to ACNs than B. Among the complexes envisioned, those labeled as b1, b2, and b3 feature UV-vis spectra compatible with experiments. The combination of experimental and computational data offers for the first time evidence of the formation of ACN-Md complexes
Experimental insights on iron-based alloys corrosion in water cooled loops
Full text linkThis paper presents experimental findings on the behavior of iron-based alloys in environmental conditions typical of nuclear fusion technology, specifically focusing on material degradation, which is a critical aspect for the water cooling system of EU DEMO breeding blankets. The experimental campaign investigates potassium hydroxide's role as an alkalizing agent, testing various concentrations to assess its impact on corrosion resistance. Additionally, it examines how oxygen levels affect localized corrosion development, which is crucial for mitigating corrosion risks in fusion applications. Seven 1000-hour tests were conducted to determine optimal conditions for corrosion reduction. Findings include identifying an oxygen concentration threshold to prevent piping cracking on EUROFER97 specimens
Influences of postharvest storage and processing techniques on antioxidant and nutraceutical properties of rubus idaeus l.: A mini-review
Full text linkThe growth of agricultural mechanization has promoted an increase in raspberry production, and for this reason, the best postharvest storage and processing techniques capable of maintaining the health beneficial properties of these perishable berry fruits have been widely studied. Indeed, raspberries are a rich source of bioactive chemical compounds (e.g., ellagitannins, anthocyanins, and ascorbic acid), but these can be altered by postharvest storage and processing techniques before consumption. Although there are clear differences in storage times and techniques, the content of bioactive chemical compounds is relatively stable with some minor changes in ascorbic acid or anthocyanin content during cold (5◦C) or frozen storage. In the literature, processing techniques such as juicing or drying have negatively affected the content of bioactive chemical compounds. Among drying techniques, hot air (oven) drying is the process that alters the content of bioactive chemical compounds the most. For this reason, new drying technologies such as microwave and heat pumps have been developed. These novel techniques are more successful in retaining bioactive chemical compounds with respect to conventional hot air drying. This mini-review surveys recent literature concerning the effects of postharvest storage and processing techniques on raspberry bioactive chemical compound content
“Metabolight”: how light spectra shape plant growth, development and metabolism
No full textInnovations in light technologies (i.e. Light Emitting Diodes; LED) and cover films with specific optical features (e.g. photo-selective, light-extracting) have revolutionized crop production in both protected environments and open fields. The possibility to modulate the light spectra, thereby enriching/depleting cultivated plants with targeted wavebands has attracted increasing interest from both basic and applicative research. Indeed, the light environment not only influences plant biomass production but is also a pivotal factor in shaping plant size, development and metabolism. In the last decade, the strict interdependence between specific wavebands and the accumulation of targeted secondary metabolites has been exploited to improve the quality of horticultural products. Innovation in LED lighting has also marked the improvement of streetlamp illumination, thereby posing new questions about the possible influence of light pollution on urban tree metabolism. In this case, it is urgent and challenging to propose new, less-impacting solutions by modulating streetlamp spectra in order to preserve the ecosystem services provided by urban trees. The present review critically summarizes the main recent findings related to the morpho-anatomical, physiological, and biochemical changes induced by light spectra management via different techniques in crops as well as in non-cultivated species. This review explores the following topics: (1) plant growth in monochromatic environments, (2) the use of greenhouse light supplementation, (3) the application of covering films with different properties, and (4) the drawbacks of streetlamp illumination on urban trees. Additionally, it proposes new perspectives offered by in planta photomodulation
- …
