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Study of herbaceous annual and perennial species native to Mediterranean area for landscape purposes
No full text
Physiological parameters and secondary metabolites in dandelion (Taraxacum officinale) grown on contaminated urban solid run off,
No full textThe soil material eroded by urban runoff and collected in the gutters can contain contaminants.
Taraxacum officinale is a very ubiquitous species of degraded soil found in urban environment
and. It can grow in very shallow spaces between the cracks in the pavements. This study
represents a preliminary approach to verify the presence of metals in the soil-like material
collected by urban runoff, the metal uptake by dandelion, and therefore check the possible
alteration of some of its physiological parameters in order to understand the mechanism of its
adaptation. The run off was collected in three sites in the town of Pisa and analyzed for Pb, Cu,
Ni, Zn after nitric-perchloric microwave digestion by Atomic Absorption Spectroscopy. The total
values of Pb and Zn exceeded the limits for residential areas respectively in two and three sites.
Trials were set up growing dandelion seedlings on the soil runoff material in floating cultivation.
Poyphenols, antioxidants, sulphydryl groups and chlorophyll were measured in dandelion leaves
grown on the contaminated material and on the control. The phenolic compound content was
extracted with methanol, and was assayed quantitatively at A765 with Folin-Ciocalteu reagent,
whereas 'antioxidant power' was determined using the FRAP method. Chlorophylls a (Chla) and b
(Chlb) were extracted from young leaf discs (10 mm) with N,Ndimethylformamide (DMF) and
determined spectrophotometrically. The first two parameters (polyphenols and antioxidants) were
higher in the run off samples compared to the control in one case, sulphydryl groups showed no
difference, and chlorophyll was lower in the run off samples. These results indicate thatdandelion
can survive in case of plant stress by simply altering its physiological parameters
Response of sowed, flowering herbaceus communities suitable for anthropic Mediterranea areas under different mowing regimes
No full textGrowing traditional ornamental plants in urban soil often fails, due to the low quality of the soil modified by anthropic activities. The aim of this research was to study the behaviour of herbaceous plants suitable for sowing in mixes in order to revegetate soils in different urban environments.
Three different mixes of herbaceous plants were studied: N (native) was composed of autochthonous species, US (urban short) and UT (urban tall) were composed of both autochthonous and allochthonous species. Plant height was lower than 60 cm in N and US, and above 60 cm in UT. Each mix was sown in three randomized plots and each plot was mown at three different times: 110, 140 and 170 days after sowing (early, mid and late season respectively). The number of plants per square meter, plant height and biomass were recorded at each mowing time. In order to assess how well the plants would establish themselves we calculated the Shannon diversity index, the evenness of species and Simpson’s index of dominance.
The N mix composed of autochthonous species resulted to be well-balanced with an equal number of annual and perennial species grown. The presence of annuals and perennials made the community richer and the individual plants more evenly distributed. The best mowing time to improve diversity in all the mixes was late-season. Our study suggests that native species from southern Europe are suitable for creating diverse herbaceous communities for ornamental purposes, thus enhancing the role of Mediterranean urban areas in the conservation of biodiversity
Substrates to contrast compaction in urban tree plantings
No full textAim of our work was to assess the ability of recycled crushed bricks, employed as a substrate of growth, of contrasting the compaction and improving the development of trees in urban avenues. Soil employed in urban planting is often deep subsoil with a high percentage of fine material (silt and clay) and no organic matter. The soil compaction due to trampling and car parking can seriously affect the survival of trees in these conditions. Coarse recycled materials already used in urban green areas, allow a better air circulation and water drainage in the rizosphere and can be a valid solution to reduce the post transplant crisis. The materials employed as substrate were: compost, soil, crushed bricks 0-30 mm, crushed bricks 6-30 mm The experimental trial was set up planting 36 lindens in 1) soil, 2) soil +15 (v/v) compost; 3) crushed bricks 0-30 mm; 4) crushed bricks 0-30 mm + 15 compost; 5) crushed bricks 6-30 mm; 6) crushed bricks 6-30 mm + 15 compost. The monitoring included: sprouts length, number of sprouts, SPAD chlorophyll, and dynamic plate resistance. In the preliminary results the crushed bricks showed the highest resistance to compaction, and the combination of crushed bricks 0-30 mm + compost produced the average longest sprouts. At this stage of the research the best compromise between resistance to compaction and growth seems to be crushed bricks 6-30 mm + compost
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