EFFECTS OF DIFFERENT PLANT EXTRACTS ON THE MINERAL CONTENT OF BLACKBERRY LEAF (R. fruticosus) IN ORGANIC PRODUCTION

The aims of this study were to investigate the chemical content of plant extracts of nettle (Urtica dioica), alfalfa (Medicago sativa) and dandelion (Taraxacum officinale) and to determine their effect on the chemical content of blackberry leaves grown in organic production. Field and laboratory analysis were conducted over a two-year period. The plant extracts were fermented for 14 days before analysis. The field trial adopted a randomised block design with four repetitions. Each repetition included five blackberry bushes. The following properties were analysed: the chemical composition of plant extracts, macroelement concentration (%), microelement concentration (mg kg^-1) and the fresh and dry weights of blackberry leaves (g). Analysis of the macronutrient content revealed the highest N content in the alfalfa plant extract, the highest P concentration in nettle plant extract, while the highest concentration of K was found in dandelion plant extract. The N and P concentrations were higher in all treatments than in the controls. The Fe concentration in blackberry leaves ranged from 70.63 mg/kg^-1 (treatment with alfalfa plant extract) to 76.68 mg kg^-1 (treatment with nettle plant extract). The difference in blackberry leaf Mn concentration between the dandelion treatment and the control were highly significant. The nettle and dandelion plant extracts influenced the Cu content of blackberry leaves. The Zn concentration in blackberry leaves treated with plant extracts was significantly higher than that in the controls. The highest dry mass content was found in blackberry leaves treated with nettle plant extract.