Growth Rate and Nutrient Uptake of Stevia rebaudiana Bertoni as Influenced by Organic Manures in Laterite Soils of Kerala, India

A field experiment was conducted to understand the effect of organic manures on the crop growth rate (CGR), relative growth rate (RGR), and nutrient uptake of stevia (Stevia rebaudiana Bertoni) from April to August of 2022 and 2023 at the Agronomy farm, Department of Agronomy, College of Agriculture, Vellanikkara, Thrissur. The experiment was laid out in randomized block design (RBD) with 7 treatments replicated thrice which consisted of different levels of organic manures viz., three levels of farmyard manure (FYM@ 5, 10, 15 t ha­-1), three levels of vermicompost (VC@ 2.5, 5, 7.5 kg ha-1) and a control. The organic manure treatments significantly affected crop growth rate (CGR) and relative growth rate (RGR) in all the growth periods. The two-year pooled mean of CGR of stevia was significantly superior in FYM@15 t ha-1 over control in all the three growth periods i.e., at 0-30 DAP, 30-45 DAP and 45 DAP to harvest. Whereas, the two-year mean of RGR of stevia was found statistically higher in FYM@15 t ha-1 over control in the first two growth periods only. The organic manure treatments had a significant influence on the plant nutrient (NPK) uptake as well in both the years. The two-year pooled mean data regarding plant uptake of nitrogen and phosphorous was found significantly higher in FYM@15 t ha-1 over control whereas statistically higher pooled mean potassium uptake by stevia was found in VC@7.5 kg ha-1 over control. Overall, the higher levels of organic manure, especially FYM, significantly improve growth and nutrient uptake in stevia.