Influence of the Nitrogen Fertilization on the Yield, Biometric Characteristics and Chemical Composition of Stevia rebaudiana Bertoni Grown in Poland

Abstract

Stevia rebaudiana Bertoni is a plant native to South America that has gathered much interest in recent decades thanks to diterpene glycosides, called steviosides, which it produces. These compounds are characterised by their sweetness, which is 250–300 times higher than saccharose, and they contain almost no caloric value. Stevia is currently also grown outside the South American continent, in various countries characterised by warm weather. This research aimed to determine whether it is viable to grow Stevia rebaudiana plants in Poland, a country characterised by a cooler climate than the native regions for stevia plants. Additionally, the impact of adding various dosages and forms of nitrogen fertiliser was analysed. It was determined that Stevia rebaudiana grown in Poland is characterised by a rather low concentration of steviosides, although proper nitrogen fertilisation can improve various characteristics of the grown plants. The addition of 100 kg or 150 kg of nitrogen per hectare of the field in the form of urea or ammonium nitrate increased the yield of the stevia plants. The stevioside content can be increased by applying fertilisation using 100 kg or 150 kg of nitrogen per hectare in the form of ammonium sulfate. The total yield of the stevia plants grown in Poland was lower than the yield typically recorded in warmer countries, and the low concentration of steviosides in the plant suggests that more research about growing Stevia rebaudiana in Poland would be needed to develop profitable methods of stevia cultivation.

Effect of Spacing on Growth, Yield and Chemical Composition of Stevia Plants (Stevia rebaudiana Bert.)

“…The lateral width of unfertilized stevia plants grown by Śniegowska et al [38] was 26.61 cm, which was comparable to the lateral width of the stevia grown in spacings of 30 cm × 30 cm and 45 cm × 25 cm. The number of shoots in stevia plants grown in spacings of 50 cm × 30 cm and 45 cm × 25 cm was greater than the average number of shoots (10.97) in the study of Śniegowska et al [38]. However, plants in the nitrogen fertilization study had a greater average number of leaves on the lowest lateral shoot (29.21) than those grown in different spacings.…”

“…However, the total potassium content in plants analysed by Büyük [39] was almost two times lower than the content of potassium in the stevia plants grown in Poland. The stevia plants analysed by Śniegowska et al [38] had similar potassium concentrations. However, the phosphorus content of stevia plants grown by Śniegowska et al [38] was similar to that in plants grown in spacings of 45 cm × 25 cm and 30 cm × 30 cm, but it was lower than in stevia plants grown in the spacing of 50 cm × 30 cm.…”

“…In a subsequent study, Kumar et al [37] found a greater number of shoots in plants grown at 45 cm × 45 cm spacing compared to those grown at 30 cm × 30 cm, 45 cm × 30 cm, and 60 cm × 45 cm spacings. A study on the nitrogen fertilization of stevia plants in Poland by Śniegowska et al [38] showed that stevia plants grown with various nitrogen fertilization rates (50, 100 or 150 kg of N per hectare, in the form of ammonium nitrate, ammonium sulfate or urea) in the spacing of 45 cm × 20 cm had an average height of 57.86 cm, which was similar to the height of plants grown in the spacing of 50 cm × 30 cm of this study. The lateral width of unfertilized stevia plants grown by Śniegowska et al [38] was 26.61 cm, which was comparable to the lateral width of the stevia grown in spacings of 30 cm × 30 cm and 45 cm × 25 cm.…”

“…A study on the nitrogen fertilization of stevia plants in Poland by Śniegowska et al [38] showed that stevia plants grown with various nitrogen fertilization rates (50, 100 or 150 kg of N per hectare, in the form of ammonium nitrate, ammonium sulfate or urea) in the spacing of 45 cm × 20 cm had an average height of 57.86 cm, which was similar to the height of plants grown in the spacing of 50 cm × 30 cm of this study. The lateral width of unfertilized stevia plants grown by Śniegowska et al [38] was 26.61 cm, which was comparable to the lateral width of the stevia grown in spacings of 30 cm × 30 cm and 45 cm × 25 cm. The number of shoots in stevia plants grown in spacings of 50 cm × 30 cm and 45 cm × 25 cm was greater than the average number of shoots (10.97) in the study of Śniegowska et al [38].…”

Irrigation Practice in Cultivation of Stevia rebaudiana Bertoni in Cooler Climates—Case Study in Poland

“…A similar level of nitrates as detected in the samples NR, 1 W and 2 W could be noted in stevia leaves grown using different nitrogen fertilisation treatment, using three different nitrogen fertilisers (urea, ammonium nitrate and ammonium sulphate) and three different doses (50 kg, 100 kg and 150 kg per ha). These results suggest that lack of irrigation can disturb the nitrate utilisation in the stevia plants [43].…”