Katarzyna Dzida
Yield and biological value of thyme (Thymus vulgaris L.) and savory (Satureia hortensis L.) herbage depending on nitrogen and potassium fertilization
zeszyt 379, ss. 108
Thyme and savory belong to herbal plants which yield and raw material quality depend on mineral fertilization, primarily with nitrogen and potassium. The aim of this study was to determine the effect of different nitrogen and potassium fertilization levels on yield, biological value, and chemical composition of thyme and savory. The empiric experiences were made with two factor schema. The sort and the amount of nitrogen [Ca(NO3)2, NH4NO3, CO(NH2)2; 0,2; 0,4; 0,8 g N·dm-3] and potassium fertilizer KCl, K2SO4, KCl + K2SO4; 0,6; 0,9; 1,2 g K·dm-3] were the factors of experience.
Fresh weight yield of thyme and savory plants changed under the influence of nitrogen and potassium fertilizers used as well as under the influence of applied rates of nitrogen and potassium. The highest L-ascorbic acid content was found in thyme and savory after the application of the medium rate of nitrogen and potassium. The lowest amount of nitrates was shown in savory plants fertilized with urea as compared to ammonium nitrate and calcium nitrate. No significant effect of the type of nitrogen fertilizer on nitrate accumulation was found in thyme plants. A substantially higher amount of nitrates was found in thyme and savory after the application of K2SO4 compared to KCl. The present study showed a negative correlation in nitrogen and potassium accumulation in herbage of thyme and savory. The herbage plants contained large amounts of minerals, in particular nitrogen, potassium, and calcium. The contents of these nutrients were significantly differentiated by the rate of nitrogen and potassium, but the total nitrogen content increased with the growing rate of nitrogen, whereas the potassium content decreased. The amount of essential oil in air-dried thyme and savory herbage was dependent on the rate and type of nitrogen fertilizer. The application of a 100% higher rate of nitrogen relative to the initial rate caused (of 0,2 to 0,4 g N·dm-3) an increase in essential oil content in plants of both studied species. The highest average amount of essential oil in herbage was obtained when urea was used to fertilize the plants. Potassium applied at a rate 0,9 g K·dm-3 substrate caused an increase in oil content in the investigated plants; the highest oil accumulation was obtained in the treatments with potassium sulphate. The qualitative and quantitative composition of thyme and savory essential oil changed under the influence of the factors applied. The thymol content in thyme oil was the highest after the application of the medium rate of nitrogen, while a further increase in the amount of nitrogen resulted in a decrease in thymol concentration. The average content of carvacrol in savory oil decreased after the application of the increasing rates of nitrogen. Plants fed with calcium nitrate were characterized by the highest content of thymol (thyme) and carvacrol (savory).
The most efecive size and quality of the yield of thyme and savory was obtained after the application of 0,2 and 0,4 g N · dm-3 and 0,6 and 0,9 g of K · dm-3 substrate. The effect coresponds with the content of digestible ingredients in a peat substrate after cultivation of thyme in the amount of 140–240 mg·dm-3 N-NH4 + N-NO3 and 250–570 mg K · dm-3, while in the case of savory the amounts are 170–220 mg of N-NH4 + N-NO3 · dm-3 and 390–700 mg K · dm-3