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1.
Urban forests (UF) provide a range of important ecosystem services (ES) for human well-being. Relevant ES delivered by UF include urban temperature regulation, runoff mitigation, noise reduction, recreation, and air purification. In this study the potential of air pollution removal by UF in the city of Florence (Italy) was investigated. Two main air pollutants were considered – particulate matter (PM10) and tropospheric ozone (O3) – with the aim of providing a methodological framework for mapping air pollutant removal by UF and assessing the percent removal of air pollutant.The distribution of UF was mapped by high spatial resolution remote sensing data and classified into seven forest categories. The Leaf Area Index (LAI) was estimated spatially using a regression model between in-field LAI survey and Airborne Laser Scanning data and it was found to be in good linear agreement with estimates from ground-based measurements (R2 = 0.88 and RMSE% = 11%). We applied pollution deposition equations by using pollution concentrations measured at urban monitoring stations and then estimated the pollutant removal potential of the UF: annual O3 and PM10 removal accounted for 77.9 t and 171.3 t, respectively. O3 and PM10 removal rates by evergreen broadleaves (16.1 and 27.3 g/m2), conifers (10.9 and 28.5 g/m2), and mixed evergreen species (15.8 and 31.7 g/m2) were higher than by deciduous broadleaf stands (4.1 and 10 g/m2). However, deciduous forests exhibited the largest total removal due to the high percentage of tree cover within the city. The present study confirms that UF play an important role in air purification in Mediterranean cities as they can remove monthly up to 5% of O3 and 13% of PM10. 相似文献
2.
The focus of the work is to define a methodology to evaluate greenhouse gas (GHG) emissions for the nursery industry, comparing two different plant production systems (field- and container-grown plants) and assessing different scenarios for the reduction of the emissions. The Life Cycle Assessment (LCA) methodology, with the “from cradle to gate” approach, was used. The analysis revealed that the total emission of CO2eq is higher in container cultivations than in field cultivations, with emissions ranging between 26.1 and 34.7 Mg ha?1 year?1 for the former, and between 2.3 and 6.6 Mg ha?1 year?1 for the latter; greenhouse horticultural crops emit 2.2–10.3 Mg ha?1 year?1 of CO2eq and arable crop emissions were measured as 6.2 Mg ha?1 year?1 of CO2eq.Different scenarios for the reduction of GHG emission were tested and a 15.5% reduction of GHG emission was achieved. Two of the scenarios applied – 50% recycled water usage (scenario 1) and 10% of green waste recovery for substrates (scenario 3) – are already in use in nursery farms. 相似文献
3.
Atmospheric Particulate Matter (PM) constitutes a considerable fraction of urban air pollution, and urban greening is a potential method of mitigating this pollution. The value of living wall systems has received scant attention in this respect. This study examined the inter-species variation of particulate capture by leaves of seventeen plant species present in a living wall at New Street railway station, Birmingham, UK. The densities of different size fractions of particulate pollutants (PM1, PM2.5 and PM10) on 20 leaves per species were quantified using an Environmental Scanning Electron Microscope (ESEM) and ImageJ image-analysis software. The overall ability of plant leaves to remove PM from air was quantified using PM density and LAI (Leaf Area Index); any inter-species variations were identified using one-way Anova followed by Tukey’s pairwise comparison. This study demonstrates a considerable potential for living wall plants to remove particulate pollutants from the atmosphere. PM capture levels on leaves of different plant species were significantly different for all particle size fractions (P < 0.001). Smaller-leaved Buxus sempervirens L., Hebe albicans Cockayne, Thymus vulgaris L. and Hebe x youngii Metcalf showed significantly higher capture levels for all PM size fractions. PM densities on adaxial surfaces of the leaves were significantly higher compared to abaxial surfaces in the majority of the species studied (t-test, P < 0.05). According to EDX (Energy Dispersive X-ray) analysis, a wide spectrum of elements were captured by the leaves of the living wall plants, which were mainly typical railway exhaust particles and soil dust. Smaller leaves, and hairy and waxy leaf surfaces, appear to be leaf traits facilitating removal of PM from the air, and hence a collection of species which share these characters would probably optimize the benefit of living wall systems as atmospheric PM filters. 相似文献
4.
Jo-Anne E. Cavanagh Peyman Zawar-Reza J. Gaines Wilson 《Urban Forestry & Urban Greening》2009,8(1):21-30
Of interest to researchers and urban planners is the effect of urban forests on concentrations of ambient air pollution. Although estimates of the attenuation effect of urban vegetation on levels of air pollution have been put forward, there have been few monitored data on small-scale changes within forests, especially in urban forest patches. This study explores the spatial attenuation of particulate matter air pollution less than 10 μ in diameter (PM10) within the confines of an evergreen broadleaved urban forest patch in Christchurch, New Zealand, a city with high levels of PM10 winter air pollution. The monitoring network consisted of eight monitoring sites at various distances from the edge of the canopy and was operated on 13 winter nights when conditions were conducive for high pollution events. A negative gradient of particulate concentration was found, moving from higher mean PM10 concentrations outside the forest (mean=31.5 μg m?3) to lower concentrations deep within the forest (mean=22.4 μg m?3). A mixed-effects model applied to monitor meteorological, spatial and pollution data indicated temperature and an interaction between wind speed and temperature were also significant (P?0.05) predictors of particulate concentration. These results provide evidence of the potential role that urban forest patches may play in mitigating particulate matter air pollution and should be considered in plans for improving urban air quality. 相似文献
5.
《Scientia Horticulturae》2005,104(1):25-36
We studied the effects of Fe deficiency on physiological parameters of citrus rootstocks grown in nutrient solution. Three 4-week old rootstocks (‘Troyer’ citrange – Citrus sinensis (L.) Osb. × Poncirus trifoliata (L.) Raf., Citrus taiwanica Tan. and Shim., and ‘Swingle’ citrumelo – Poncirus trifoliata (L.) Raf. × Citrus paradisi Macf.) were grown in nutrient solutions with 0, 5, 10, 15 and 20 μmol Fe dm−3. Calcium carbonate (1 g dm−3) was added to all solutions to mimic the natural conditions in calcareous soils. For each rootstock, shoot length, number of leaves, and root and shoot dry weights were measured at the end of experiment. Chlorophyll concentration was estimated using a portable SPAD-502 meter calibrated for each rootstock. The amount of nutrients (P, K, Mg, Ca, Fe, Zn, Mn, and Cu) was determined in shoots. Chlorophyll fluorescence parameters (F0: basal fluorescence; Fm: maximum fluorescence; Fv = Fm − F0: variable fluorescence) were measured with a portable fluorimeter. ‘Troyer’ citrange rootstock was the most tolerant to Fe deficiency. These plants grew more and accumulated more chlorophyll and nutrients than the others in the presence of low levels of Fe (10 μmol Fe dm−3). ‘Swingle’ citrumelo plants needed 20 μmol Fe dm−3 in the nutrient solution to secure adequate growth. ‘Taiwanica’ orange rootstock had an intermediate behaviour, but could be distinguished from ‘Troyer’ citrange based on fluorescence parameters, since there was a variation in the basal fluorescence in the former, whereas in ‘Troyer’ citrange the basal fluorescence was not affected by the supply of Fe. 相似文献
6.
Volatile organic compounds (VOC) are emitted by many plants. In this study, sixty common plant species of the Vidarbha region of Maharashtra, India were examined for VOC (isoprene and monoterpene) emissions. Plant species VOC emission rates ranged from undetectable to 75.2 μg g?1 h?1. Dalbergia sissoo exhibited a maximum VOC emission rate of 75.2 μg g?1 h?1. Ozone forming potentials (OFP) of the sixty plant species were also estimated using the method of Benjamin and Winer (1998). Maximum ozone forming potential of 77 g O3 (tree)?1 d?1 was observed in the case of Mangifera indica. Out of 60 species, 26 species (43.3%) had low OFP (less than 1 g O3 (tree)?1 d?1), 18 species (30%) had medium OFP (less than 1–10 g O3 (tree)?1 d?1) and 16 species (26.7%) had high OFP (more than 10 g O3 (tree)?1 d?1). 相似文献
7.
Apart from influencing the amount of leaf-deposited particles, tree crown morphology will influence the local distribution of atmospheric particles. Nevertheless, tree crowns are often represented very rudimentary in three-dimensional air quality models. Therefore, the influence of tree crown representation on the local ambient PM10 concentration and resulting leaf-deposited PM10 mass was evaluated, using the three-dimensional computational fluid dynamics (CFD) model ENVI-met® and ground-based LiDAR imaging. The modelled leaf-deposited PM10 mass was compared to gravimetric results within three different particle size fractions (0.2–3, 3–10 and >10 μm), obtained at 20 locations within the tree crown. Modelling of the LiDAR-derived tree crown resulted in altered atmospheric PM10 concentrations in the vicinity of the tree crown. Although this model study was limited to a single tree and model configuration, our results demonstrate that improving tree crown characteristics (shape, dimensions and LAD) affects the resulting local PM10 distribution in ENVI-met. An accurate tree crown representation seems, therefore, of great importance when aiming at modelling the local PM distribution. 相似文献
8.
《Scientia Horticulturae》2001,89(2):115-128
The possible application of some less commonly used in vitro growth regulating compounds is outlined. A number of treatments were applied to determine the best way of inducing in vitro shoot proliferation and rooting on a modified Driver–Kuniyuki [HortScience 19 (1984) 507] basal medium of lemon (Citrus limon (L.) Burm, f. cv. Interdonato) seedlings. 6-Benzyladenine (BA) alone (1, 2 and 4 mg l−1) and in combination with either orange juice (10%, v/v), silver nitrate (3 mg l−1), gibberellic acid (GA3) (0.1 mg l−1 at the establishment stage and 0.5 mg l−1 at all combinations during the proliferation stage) or abscisic acid (ABA) (0.2 mg l−1 only at the establishment stage) were used to stimulate shoot formation during the establishment and the proliferation stage. The combination of BA with ABA gave a high rate of shoot formation, while GA3 and silver nitrate enhanced shoot elongation. When these shoots were transferred to the rooting stage, the effect of application of two different auxins (indole-3-butyric acid (IBA) and α-napthaleneacetic acid) was examined, as well as different methods of application (auxin added to the basal medium and auxin application by dipping the base of the explant in auxin solution). Dipping the base of the explants in a 50% ethanol solution of IBA at 1000 mg l−1 for 5 s resulted in 80% rooting with subsequent 90% survival of these explants, during acclimatization under mist. 相似文献
9.
Urban parks form the largest proportion of public green spaces contributing to both physical and mental well-being of people living in urban areas. CO2 sequestration capability of the vegetation developing in parks of four historical residences (Villa Pamphjli, Villa Ada Savoia, Villa Borghese and Villa Torlonia) in Rome and its economic value were analyzed. Villa Pamphjli and Villa Ada Savoia having a larger vegetation extension (165.04 ha and 134.33 ha, respectively), also had a larger total yearly CO2 sequestration per hectare (CS) (780 MgCO2 ha−1 year−1 and 998 MgCO2 ha−1 year−1, respectively) than Villa Borghese (664 MgCO2 ha−1 year−1) and Villa Torlonia (755 MgCO2 ha−1 year−1), which had a lower vegetation extension (56.72 ha and 9.70 ha, respectively). CS was significantly correlated with leaf area index (LAI). The calculated CS for the four parks (3197 MgCO2 ha−1 year−1), corresponding to 3.6% of the total greenhouse gas emissions of Rome for 2010, resulted in an annual economic value of $ 23537 /ha. 相似文献
10.
Lyubov V. Panina 《Urban Forestry & Urban Greening》2010,9(3):253-260
There are clear and commonly accepted design criteria for the construction of golf greens. Accordingly, top layers contain at least 90% sand, which often becomes water repellent. Drought is therefore common on golf greens and it may manifest itself as spots of wilted or dead turfgrass, known as localized dry spots (LDSs).The aims of the current paper are to review soil water repellency and localized dry spots on golf greens; and to study the turfgrass appearance regarding dependence of water repellency under the moderately continental climate in the Moscow region. The study was conducted during the growing seasons of 2007 and 2008 by Moscow State Forest University, Russia, in collaboration with Wageningen University, the Netherlands.Green 4 of the Moscow golf course was intensively studied. The texture of the top layer met the USGA, German and British specifications for golf greens. The organic matter content was also as desired. The low soil water content (down to 0.80%) in top 5–10 cm layer, high reference evapotranspiration and low amount of applied water in May and June of 2007 (2.52 against 1.20 mm/day) and of 2008 (2.41 against 1.73 mm/day), resulted in drought and LDS occurrence. Severe water repellency as determined by water drop penetration time (WDPT) test was found in the 5–10 cm depth (up to 1536 s). It decreased with depth (at depth 5–10 cm 33.3% of samples were strongly and 66.7% severely water repellent; at depth 20–25 cm 41.6% of samples were strongly and 41.6% slightly water repellent, and 16.8% were wettable). However, samples from the same depth from good areas (GAs) of the turf were also water repellent – at depth 5–10 cm all samples were slightly or strongly water repellent; at depth 20–25 cm 66.7% were non-repellent.In this study, the poorest turfgrass condition was found in plots with LDSs (the scores of turfgrass quality and living ground cover were lower than 5). A negative correlation was found between WDPT and turfgrass parameters (shoot density, living ground cover and turfgrass quality). A positive correlation between water content and shoot density was found. LDSs exhibited low shoot density (which did not exceed 20 per cm2 whereas in GA it exceeded 32 per cm2) and low water content (in the range 0.8–6.75% whereas in GA it was in the range 7.8–14.47%). This means that the reason of unacceptable turfgrass condition is related to water deficit and severity of water repellency. 相似文献
11.
Leaf area of urban vegetation is an important ecological characteristic, influencing urban climate through shading and transpiration cooling and air quality through air pollutant deposition. Accurate estimates of leaf area over large areas are fundamental to model such processes. The aim of this study was to explore if an aerial LiDAR dataset acquired to create a high resolution digital terrain model could be used to map effective leaf area index (Le) and to assess the Le variation in a high latitude urban area, here represented by the city of Gothenburg, Sweden. Le was estimated from LiDAR data using a Beer-Lambert law based approach and compared to ground-based measurements with hemispherical photography and the Plant Canopy Analyser LAI-2200. Even though the LiDAR dataset was not optimized for Le mapping, the comparison with hemispherical photography showed good agreement (r2 = 0.72, RMSE = 0.97) for urban parks and woodlands. Leaf area density of single trees, estimated from LiDAR and LAI-2200, did not show as good agreement (r2 = 0.53, RMSE = 0.49). Le in 10 m resolution covering most of Gothenburg municipality ranged from 0 to 14 (0.3% of the values >7) with an average Le of 3.5 in deciduous forests and 1.2 in urban built-up areas. When Le was averaged over larger scales there was a high correlation with canopy cover (r2 = 0.97 in 1 × 1 km2 scale) implying that at this scale Le is rather homogenous. However, when Le was averaged only over the vegetated parts, differences in Le became clear. Detailed study of Le in seven urban green areas with different amount and type of greenery showed a large variation in Le, ranging from average Le of 0.9 in a residential area to 4.1 in an urban woodland. The use of LiDAR data has the potential to considerably increase information of forest structure in the urban environment. 相似文献
12.
《Scientia Horticulturae》2001,88(1):11-29
We investigated the hypothesis that manipulating water out-flow of a plant through the shoot environment (potential transpiration, ET0) in a glasshouse could modulate the effect of salinity/osmotic potential in the root environment upon yield of tomatoes. Contrasting root-zone salinity treatments were combined with two climate treatments — a reference (high transpiration, HET0) and a “depressed” transpiration (low transpiration, LET0). The salinity treatments, characterised by their electrical conductivity (EC) were 6.5, 8 and 9.5 dS m−1, were always coupled with a reference treatment of EC=2 dS m−1. In another experiment, concentrated nutrients (Nutrients) and nutrients with sodium chloride (NaCl) at the same EC of 9 dS m−1 were compared.Marketable fresh-yield production efficiency decreased by 5.1% for each dS m−1 in excess of 2 dS m−1. The number of harvested fruits was not affected; yield loss resulted from reduced fruit weight (3.8% per dS m−1) and an increased fraction of unmarketable harvest. At the LET0 treatments, yield loss was only 3.4% per dS m−1 in accordance with the reduction in fruit weight. Low transpiration did increase fruit fresh yield by 8% in both NaCl and Nutrients treatments at an EC=9 dS m−1. Neither EC nor ET0 affected individual fruit dry weight. Accordingly, fruit dry matter content was significantly higher at high EC than in the reference (4% per each EC unit in excess of 2 dS m−1) and responded to ET0 to a minor extent. Control of the shoot environment in a greenhouse to manipulate the fresh weight of the product may mitigate the effects of poor quality irrigation water without affecting product quality. 相似文献
13.
Across cities worldwide, people are recognizing the value of greenspace in ameliorating the health and well-being of those living there, and are investing significant resources to improve their greenspace. Although models have been developed to allow the quantification of ecosystem services provided by urban trees, refinement and calibration of these models with more accurate site- and species-specific data can increase confidence in their outcomes. We used data from two street tree surveys in Cambridge, MA, to estimate annual tree mortality for 592 trees and diameter growth rates for 498 trees. Overall tree turnover between 2012 and 2015 was relatively low (annualized 3.6% y−1), and mortality rate varied by species. Tree growth rates also varied by species and size. We used stem diameter (DBH) and species identity to estimate CO2 sequestration rates for each of 463 trees using three different model variations: (1) i-Tree Streets, (2) Urban Tree Database (UTD) species-specific biomass allometries and growth rates, and (3) empirically measured growth rates combined with UTD biomass allometries (Empirical + UTD). For most species, the rate of CO2 sequestration varied significantly with the model used. CO2 sequestration estimates calculated using i-Tree Streets were often higher than estimates calculated with the UTD equations. CO2 sequestration estimates were often the lowest when calculated using empirical tree growth estimates and the UTD equations (Empirical + UTD). The differences among CO2 sequestration estimates were highest for large trees. When scaled up to the entire city, CO2 sequestration estimates for the Empirical + UTD model were 49.2% and 56.5% of the i-Tree Streets and UTD estimates, respectively. We suggest future derivations of ecosystem service provision models allow localities to input their own species-specific growth values. By adding capacity to easy-to-use tools, such as i-Tree Streets, we can increase confidence in the model output. 相似文献
14.
《Scientia Horticulturae》2005,105(2):197-211
CO2 concentration was monitored during three 15-day subculturing cycles in vessels containing actively proliferating plum cultures of Prunus cerasifera, clone Mr.S. 2/5. The effects of two photosynthetic photon flux density regimes: 50 ± 5 μmol m−2 s−1 and 210 ± 5 μmol m−2 s−1 were compared. Three distinct phases in the CO2 trend were distinguished during each culturing cycle of both light treatments. In the first, occurring at the beginning of the culture cycle, the amount of CO2 emitted by the cultures during dark periods was greater than that assimilated during the light periods. In the second phase, the opposite trend was detected, while in the third, the range of CO2 day–night fluctuations increased or remained stable according to the number of explants per vessel. The treatment with 210 ± 5 μmol m−2 s−1 did not modify the CO2 phase trend but induced more pronounced fluctuations in day–night CO2 concentration. Under this light treatment, cultures reached CO2 compensation point for a period as long as 48% of the total number of light hours, while under 50 ± 5 μmol m−2 s−1, it was only 8%. The different range in CO2 day–night fluctuations monitored throughout a subculturing cycle, appeared to be mainly induced by changes in culture growth dynamics. 相似文献
15.
T.K. Behera S.S. Dey A.D. Munshi Ambika B. Gaikwad Anand Pal Iqbal Singh 《Scientia Horticulturae》2009,120(1):130-133
Gynoecism has been used on a large scale in heterosis breeding of cucumber. Production of hybrid seeds in bitter gourd is highly expensive because it is done mainly through hand pollination. But utilization of a gynoecious line would be more economical and easier method. Since gynoecious parent has only female flowers, the open pollinated seeds it produces will be F1 hybrid. It will reduce the cost of male flower pinching and hand pollination. Two gynoecious lines, DBGY-201 and DBGY-202 were crossed with two monoecious cultivars, “Pusa Do Mausami” and “Pusa Vishesh” and their F2 populations were observed to determine the inheritance pattern of gynoecious sex form. Another experiment was conducted to determine magnitude of heterosis by utilizing nine inbred lines including one gynoecious line, DBGY-201 in diallel (without reciprocal) mating system. All the gynoecious hybrids showed significant heterosis in a desirable direction for traits like sex ratio (male:female), days to first picking, number of fruits per plant, yield per plant, and vine length. The segregation pattern in F2 suggested that gynoecious sex form in bitter gourd was governed by single recessive gene. The gynoecious hybrids DBGY-201 × “Pusa Vishesh” and DBGY-201 × “Pusa Do Mausami” were important for early harvest (～50 days after sowing) whereas DBGY-201 × “Priya” and DBGY-201 × “Arka Harit” were promising for higher yield. 相似文献
16.
Increasing use of recycled water that is often high in salinity warrants further examination of irrigation practices for turfgrass health and salinity management. A study was conducted during 2011–2012 in Riverside, CA to evaluate the response of perennial ryegrass (Lolium perenne L.) ‘SR 4550’ turf to varying quality and quantity of irrigation water. A modified line-source sprinkler irrigation system provided a salinity gradient (ECw ∼0.6–4.2 dS m−1) in between lines. Irrigation was scheduled in four separate irrigation zones perpendicular to the irrigation lines according to 80, 100, 120, and 140% ETo. Changes in turf quality (R2 = 0.30***), were primarily driven by the number of days that the area had been irrigated with saline water. When data were separated by irrigation amount, both time and water quality accounted for 54% and 46% of the variability (P < 0.001) in quality and cover, respectively at 80% ETo. A model was created to quantify decline in turf quality in relationship to %ETo replacement and salinity accumulation in the rootzone (R2 = 0.57). Our results suggest that perennial ryegrass requires irrigation scheduling at 140% ETo, irrigation water quality below ECw ∼1.7 dS m−1, and ECe below 3.8 dS m−1 to maintain acceptable quality for 442 d in Riverside, CA. 相似文献
17.
《Scientia Horticulturae》2005,106(2):190-202
The response of petunia (Petunia x hybrida Vilm.-Andr. ‘Countdown Burgundy’) and impatiens (Impatiens wallerana Hook ‘Accent Orange Tempo’) to Prohexadione-calcium was evaluated under a clear and a far-red light absorbing greenhouse (AFR) film to investigate the dosage effect of Prohexadione-Ca and to determine if it can overcome the flowering delay under FR deficient greenhouse environments. Prohexadione-Ca reduced stem elongation of petunia and impatiens under AFR and clear films when applied 3 weeks after germination. Late applications were less effective. In both crops, main stem length decreased in a quadratic pattern as the concentration of Prohexadione-Ca increased. Under both films, 50–100 mg l−1 Prohexadione-Ca resulted in ≈30% shorter petunia plants. Greater concentrations (500 and 1000 mg l−1) resulted in excessively short plants (over 70%). Prohexadione-Ca at 100 mg l−1 delayed anthesis of petunia by 8 and 3 days under the clear film and the AFR film, respectively during less inductive photoperiods but had no effect during inductive photoperiods. In impatiens, Prohexadione-Ca at 100 mg l−1 delayed anthesis over 10 days under clear or AFR film. Greater concentrations (200 and 300 mg l−1) inhibited flowering of impatiens. Prohexadione-Ca treatments significantly affected flower color development. Untreated petunia plants had dark burgundy flowers. Prohexadione-Ca treatment increased L*, a*, and C* values and decreased hue angle indicating that the flowers were faded. Flowers of untreated impatiens plants were bright orange color. Prohexadione-Ca at 100 mg l−1 increased L* value and decreased a*, b*, and C* values indicating that significant petal fading had occurred. Flowers of treated plants were nearly white under both films. Although effective in height control, loss of color would be a major limitation to the use of Prohexadione-Ca on flowering crops. 相似文献
18.
《Scientia Horticulturae》2005,107(1):90-96
Somatic embryogenic cell suspension cultures of four ginger cultivars were established. Somatic embryogenic calli were induced from ginger shoot tips on MS agar medium supplemented with 1.0 mg l−1 2,4-D and 0.2 mg l−1 Kn, which contained only half concentration of NH4NO3. Rapid-growing and well-dispersed suspension cultures were established by subculturing this kind of callus in the same liquid MSN medium. The suspension cultures (about 1–2 mm in diameter) were placed on the MSN agar medium for callus proliferation. Thereafter embryogenic callus (1.5 cm2) was transferred to solid media (MS + 0.2 mg l−1 2,4-D + 5.0 mg l−1 BA + 3% sucrose + 0.7% agar). Somatic embryos produced shoots and roots, and shoots developed into complete plantlets on solid MS medium supplemented with 3.0 mg l−1 BA and 0.1 mg l−1 NAA. The relationship between the DW of suspension cultures and pH changes in medium is also discussed. The suspension cultures still kept their vitalities after subculture for 8 months. 相似文献
19.
The implementation of trees in urban environments can mitigate outdoor thermal stress. Growing global urban population and the risk of heatwaves, compounded by development driven urban warmth (the urban heat island), means more people are at risk of heat stress in our cities. Effective planning of urban environments must minimise heat-health risks through a variety of active and passive design measures at an affordable cost. Using the Solar and Longwave Environmental Irradiance Geometry (SOLWEIG) model and working within the bounds of current urban design, this study aimed to quantify changes in mean radiant temperature (Tmrt) from increased tree cover at five different 200 × 200 m urban forms (including compact mid-rise development, residential and open grassy areas) within a suburb of Adelaide, Australia during summer. Following a successful validation of SOLWEIG, street trees were strategically distributed throughout each of the five urban forms and the model run over five warm sunny days (13–17 February 2011). Results showed spatially averaged daytime (7:30–20:00) Tmrt reduced by between 1.7 °C and 5.1 °C at each site, while under peak heating conditions (16 February, 14:00) Tmrt reduced by between 2.0 °C and 7.1 °C. The largest reduction in Tmrt under peak warming conditions was at the residential site, despite having the fewest number of trees added. Directly below clusters of trees, Tmrt could be reduced by between 14.1 °C and 18.7 °C. SOLWEIG also highlighted that more built-up sites showed higher Tmrt under peak warming conditions due to increased radiation loading from 3D urban surfaces, but over the course of the day, open sites were exposed to greater and more uniform Tmrt. This study clearly demonstrates the capacity of street trees to mitigate outdoor thermal stress and provides guidance for urban planners on strategic street tree implementation. 相似文献
20.
《Scientia Horticulturae》2005,106(1):70-75
The objective of this study was the comparison of the effect of two Mn sources (MnSO4·H2O, MnEDTA) which were applied at various concentrations (0, 200, 400, 800, and 1200 mg Mn l−1) to the leaves of ‘Washington navel’ orange trees in order to correct Mn deficiency.One hundred and seventy days after the foliar application of Mn solutions, the mean Mn concentrations in the leaves treated with MnSO4·H2O (200, 400, 800 or 1200 mg Mn l−1) or MnEDTA (400, 800 or 1200 mg Mn l−1) were significantly higher than those of the control leaves. Manganese sulfate (MnSO4·H2O) was more effective than MnEDTA regarding the improvement of the leaf Mn concentrations of the trees, when applied at equal Mn concentrations. Finally, the leaf Mn concentrations were in the sufficiency range (>25 mg kg−1 d.w.), only after the application of 800 or 1200 mg Mn l−1 as MnSO4·H2O. 相似文献