Augmenting Commercial Yield of Stevia ( Stevia rebaudiana ) through Agronomic Interventions in Indian Sub-Tropics

Field experiments were conducted to ascertain the effect of agronomical interventions on vegetative - yield and quality traits of stevia. The experiments were laid out in randomized block design with seven treatments of inorganic fertilizers (NPK @ 80:50:40 kg/ha) alone and integrated with organic sources (25, 50 and 75% N through FYM and vermi-compost) and relative efficacy of these treatments were evaluated on the yield of stevioside. The pooled data for two year showed that the combined application of 75% NPK through inorganic and 25% N through vermi-compost produced highest plant height (64.26 cm), number of branches/plant (14.12), number of leaves/plant (136.54), leaf area/plant (1698 cm 2 ), fresh leaves weight (34.62 g/plant), dry leaves weight (10.18 g/plant) and dry leaves yield (13.92 q/ha). However, the maximum yield of commercial product, i.e. stevioside content (11.88%) and stevioside yield (1.47 q/ha), was recorded in dry leaves of plant fertilized with 50% NPK through inorganic combined with 50% N through vermi-compost. These studies have conclusively established that supplementing NPK with vermicompost or FYM in the range of 25–50% has significant stimulatory effect on stevioside yield (1.09–1.47 q/ha) compared to recommended application of NPK alone (0.68 q/ha). It is therefore surmised that in order to get higher economic yield of stevia under central plain zone of North India, recommended dosage of NPK application should invariably be supplemented with 50% vermi-compost/FYM.