Optimum Fertilization Technology to Improve Crop Productivity of Stevia (Stevia rebaudiana Bertoni)

Stevia leaves have the potential to be developed as a natural sweetener, a companion to cane sugar, especially for those who need low-calorie intake. Increasing the productivity of stevia plants is approached by increasing plant biomass accumulation through balanced nitrogen fertilization. This research aims to obtain optimal nitrogen fertilization in the cultivation of stevia plants in which the nitrogen derived from various sources. The experiment was arranged in a factorial Randomized Block Design (RBD) with two factors and three replications. The first factor was organic fertilizer consisting of 4 treatments (C₁: Without Crotalaria juncea; C₂: Crotalaria juncea 6 ton/ha; C₃: Cow-dung manure 6 tons/ha; C₄: Crotalaria juncea L. 3 ton/ha + cow-dung manure 3 tons/ha). The second factor was the dose of N fertilizer which consisted of 4 treatments (D0: 0 kg N ha^-1 fertilizer; D1: 50 kg N ha^-1; D2: 100 kg N ha^-1; D3: 200 kg N ha^-1). The study result showed that the optimum dose of N fertilization was at a level of N 50 kg ha^-1. The leaf weight ratio was higher than the stem weight in all N fertilization treatments. Application of organic material derived from Crotalaria Juncea 6 tons’ ha^-1 gave the highest yield of stevia biomass, followed by the application of organic matter with a combination of crotalaria 3 tons’ ha^-1 + manure 3 tons’ ha^-1. The highest leaf ratio was achieved in the treatment of organic matter derived from Crotalaria juncea, namely 61% of the total weight of the biomass. The application of organic fertilizer derived from Crotalaria juncea would reduce the use of inorganic N fertilizers which leads to reduced stevia farming costs. Moreover, applying a combination of organic and inorganic fertilizers will provide benefits not only for plant growth and yields but for soil health as well.