Attaining higher biomass and steviol glycosides yields of Stevia rebaudiana through adjustment of plant population and nitrogen rate

Abstract

Stevia rebaudiana is being cultivated in many parts of the world for its industrial uses as a low-caloric natural sweetener. However, the effects of plant population and nitrogen (N) levels and their interactions on biomass yield and steviol glycosides accumulation are not properly known in the mild-temperate conditions. Therefore, an experiment was laid out with ten treatment combinations having two plant densities (50,000 and 100,000 plants ha−1) and five N levels (0 to 160 kg ha−1). The overall dry leaf yield of stevia ranged from 1.74 to 3.35 Mg ha−1, while total steviol glycosides (SGs) concentration of the stevia leaf varied from 7.6 to 9.3%. The dense population (100,000 plants ha−1) registered about 64.9 and 71.8% higher dry leaf yields compared with thin population (50,000 plants ha−1) during 2014 and 2015, respectively. Irrespective of plant density, N at 120 kg ha-1 recorded significantly (P ≤ 0.05) higher dry leaf yields (3.35 and 2.83 Mg ha−1) compared with control during both the experimental years. However, substantially higher apparent N-recovery and agronomic N-efficiency were registered with lower doses (40−80 kg ha−1) of N. The total SGs yield (g plant−1) was not reduced with dense plantation. Similarly, the significantly higher total SGs yield was recorded with the application of N at 120 kg ha−1. The response curve suggests that the dense plantation and N up to 143 kg ha−1 can be practiced to increase dry leaf yield of stevia without sacrificing the production of total SGs under mild temperate conditions.