Yield response, accumulation of bioactive ingredient and ion uptake of Stevia rebaudiana to different soil-moisture and nitrogen levels

The importance of stevia (Stevia rebaudiana) is increasing rapidly as a potential industrial crop throughout the world. Soil-moisture and nitrogen (N) are the key components for agricultural productivity. However, the information on the effects of availability of soil moisture and N dose on the growth of stevia, N dynamics in the plant and soil, and NUE is limited. Thus, a field study involving three soil-water regimes (irrigation schedule at 20–75 kPa) and five different levels of N (0–140 kg ha−1) was conducted. Results showed that the dry leaf and total steviol glycosides (SGs) yield of stevia was found maximum with the irrigation at 50 kPa. At harvest, the plants irrigated at 50 kPa produced 26.9–32.5% higher dry matter over limited application of water (75 kPa). The N at 105 kg ha−1 registered maximum leaf yield (2.59 and 2.37 t ha−1) and N uptake (83.23 and 74.73 kg ha−1). The higher dose of N (140 kg ha−1) did not enhance dry leaf and total SGs yield compared with N at 105 kg ha−1. The low apparent N-recovery and agronomic N-efficiency at higher doses of N indicate higher accumulations of N into the environment. The soil N-balance sheet indicates that the maximum N has been harvested with the higher N under water limiting conditions. Thus, it can be concluded that the irrigation at 50 kPa in combination with N at 105 kg ha−1 could improve leaf and total SGs yield, N uptake, and NUE of stevia without deteriorating soil health.