Evaluation of growth, yield and economics of Stevia rebaudiana Bertoni under partial shade in a teak-based agroforestry system in the sub-tropical region of Madhya Pradesh

Stevia rebaudiana, a perennial herb prized for its steviol glycosides, is increasingly being cultivated as a natural sweetener. In India, the annual demand for this herb is estimated at approximately 10 metric tons. However, the relationship between agronomic practices and agroforestry systems on leaf yield and economic viability in tropical climates remains underexplored. This study evaluated the effects of spacing and organic amendments on growth, productivity in a teak-based agroforestry system in Central India. A field experiment was conducted in a randomized block design with a factorial concept under a teak-based agroforestry model at the Non Wood Forest Produce (NWFP) nursery, Indian Council of Forestry Research and Education - Tropical Forest Research Institute (ICFRE-TFRI), Jabalpur, Madhya Pradesh. The treatments included plant spacing (S1: 45 × 45 cm, S2: 30 × 30 cm, S3: 20 × 20 cm) and organic nutrient regimes (M7: farmyard manure (FYM) + vermicompost (VC) + poultry manure (PM); M6; VC + PM; M5: FYM + PM; M4: FYM + VC; M3: PM; M2: FYM; M1: VC; M0: control). Growth parameters such as plant height, branch number and leaf count were recorded, along with biomass yield (fresh and dry weight). Economic viability was assessed through input-output ratios. The results indicated enhanced plant height, branching and leaf count perplant under M7. Spacing S3 yielded the maximum fresh and dry biomass. Economic analysis revealed that S3 and M7 are cost-effective with higher net returns. These findings underscore that integrating teak agroforestry and organic amendments enhances both yields, offering a sustainable model for tropical stevia cultivation. This study provides actionable insights into agronomic practices to balance productivity, metabolite quality and profitability in resource-constrained systems.