Contents of chlorophyll and selected mineral components and the yield of common thyme (Thymus vulgaris L.) at differentiated nitrogen fertilization
The vegetation experiment was carried out in pots, in an unheated greenhouse of Experimental Station ‘Marcelin’, Poznań University of Life Sciences. The studies were carried out on the effect of nitrogen nutrition on the herb fresh matter and on its dry crumbled matter as well as on the contents of chlorophyll a and b, nitrogen, magnesium and iron in leaves of common thyme of ‘Słoneczko’ cultivar. Nitrogen was applied in the form of NH4NO3 before vegetation (control – without nitrogen addition, 60, 120, 180 and 240 mg N dm-3 substrate) and as a top dressing with an addition of 60 mg N dm-3 in all variants with nitrogen fertilization. Herb harvest was carried out twice. It was found that nitrogen, irrespective of its dose, significantly decreased the level of chlorophyll a and b (on the average by 60%) and the iron content (on the average by 40%). The decreased chlorophyll level in thyme leaves with nitrogen application was positively correlated with iron content. No dependence was found between the level of chlorophyll and the nitrogen content in the herb. Nitrogen fertilization significantly increased both the yield of herb fresh matter and of the dry raw material. In case of dry raw material, no differences were found in the yield depending on the differentiated nitrogen nutrition.