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The Effect of Organic Materials with Different Degrees of Decomposition on the Content of Nickel in the Lettuce Leaves Cultivated in Mineral Soil
Four taxa of Spiraea were selected for this study: S. × cinerea Zabel ‘Grefsheim’, S. nipponica Maxim. ‘Snowmound’, S. splendens É. N. Baumann ex K. Koch and S. × vanhouttei (Briot) Carrière growing for a minimum of 5 years along heavily trafficked traffic routes. This study included the genus Spiraea due to its popularity in horticultural practice (commercial availability, widespread in urban environments). In addition, the use of ornamental shrubs for phytoremediation in urban green spaces effectively combines the aesthetic needs of residents with those of caring for the urban environment. This study was conducted in Poznań (population 550,000, the fifth largest city in Poland). Soils and foliage were examined in spring and autumn. Soil pH and specific electrolytic conductivity (EC) were determined. The content of micronutrients (Cu, Fe, Mn, Ni, Zn) and toxic heavy metals (Cd, Cr, Pb) in soil dry matter and leaves was determined. The uptake capacity of bioavailable forms of heavy metals by Spiraea from the soil was analyzed by determining the bioconcentration factor (BCF). It was found that the studied taxa meet the basic requirements for plants used for soil phytoremediation processes, especially for chromium phytoextraction. The degree of salinity of the tested soils did not pose a threat to the shrubs growing there, and most of the sites, despite the alkaline reaction, are suitable for their cultivation. S. × cinerea and S. × vanhouttei have BCFs for lead <1. The remaining taxa are characterized by strong concentrations of all analyzed elements. A particularly high BCF, above 10, was recorded for chromium and high for manganese and nickel.
The Effect of Foliar Spray Treatments with Various Biostimulants and Fertilisers on the Growth of M.9 Rootstock Stoolings
An experiment was conducted to compare the effect of applying half a dose of a mineral fertiliser combined with a foliar treatment with four biostimulants and two fertilisers in relation to a full dose of a mineral fertiliser. The M.9 rootstock stoolings were sprayed four times during their growth. Each year of the experiment, the height, the diameter, the fresh weight of leaves and the leaf surface area of all stoolings were measured. The efficiency of rootstocks from one mother plant was assessed. Some parameters of physiological processes as well as the content of micro- and macronutrients in the leaves were also assessed. The research results showed that the reduced dose of the mineral fertiliser with foliar treatment did not significantly decrease the growth parameters of the M.9 rootstock stoolings. Some foliar treatments, especially Bioamino Plant and Bispeed, resulted in higher fresh weight and larger leaf area of the stoolings. The treatment with the Bioamino Plant biostimulant and two foliar fertilisers resulted in parameters of the physiological processes of stoolings that were the same as or better than those in the control plants. After the foliar application of two fertilisers, the content of macronutrients in the leaves of the stoolings was usually the same as in the control. The treatment with the biostimulants resulted in a lower content of most macronutrients in the plants (N, K and Ca). The only exception was the higher magnesium content than in the control after the treatment with all biostimulants and the same phosphorus content after the treatment with most of the biostimulants. The Aminoplant and Bispeed biostimulants increased the accumulation of iron in the leaves, whereas the Basfoliar 6-12-6 fertiliser resulted in higher zinc and copper content than in the control plants.
Potential of Selected Species of Spiraea L. for Phytoremediation of Heavy Metals from Soils of Urban Areas
Four taxa of Spiraea were selected for this study: S. × cinerea Zabel ‘Grefsheim’, S. nipponica Maxim. ‘Snowmound’, S. splendens É. N. Baumann ex K. Koch and S. × vanhouttei (Briot) Carrière growing for a minimum of 5 years along heavily trafficked traffic routes. This study included the genus Spiraea due to its popularity in horticultural practice (commercial availability, widespread in urban environments). In addition, the use of ornamental shrubs for phytoremediation in urban green spaces effectively combines the aesthetic needs of residents with those of caring for the urban environment. This study was conducted in Poznań (population 550,000, the fifth largest city in Poland). Soils and foliage were examined in spring and autumn. Soil pH and specific electrolytic conductivity (EC) were determined. The content of micronutrients (Cu, Fe, Mn, Ni, Zn) and toxic heavy metals (Cd, Cr, Pb) in soil dry matter and leaves was determined. The uptake capacity of bioavailable forms of heavy metals by Spiraea from the soil was analyzed by determining the bioconcentration factor (BCF). It was found that the studied taxa meet the basic requirements for plants used for soil phytoremediation processes, especially for chromium phytoextraction. The degree of salinity of the tested soils did not pose a threat to the shrubs growing there, and most of the sites, despite the alkaline reaction, are suitable for their cultivation. S. × cinerea and S. × vanhouttei have BCFs for lead <1. The remaining taxa are characterized by strong concentrations of all analyzed elements. A particularly high BCF, above 10, was recorded for chromium and high for manganese and nickel.