Assessment of Seaweed Extract (Sagarika) as a Bio-stimulant for Enhancing Rice Productivity in an Inceptisol

Abstract

Seaweed-derived biostimulants may complement conventional nutrient management in rice, but their performance requires evaluation under specific soil and agroclimatic conditions. A field experiment was conducted during the kharif season of 2022–2023 at the Agricultural Research Farm, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, to assess Sagarika seaweed extract in an Inceptisol. The experiment followed a randomised block design with 11 treatments and three replications. Treatments included an absolute control, the recommended dose of fertilisers (RDF), reduced soil-applied urea, an NPK biofertiliser consortium, Sagarika granules, Sagarika liquid sprays, nano urea, and selected combinations of these inputs. Plant growth was recorded at 30, 60, and 90 days after transplanting, and yield attributes, grain yield, straw yield, biological yield, and harvest index were measured. Treatment T7, comprising 100% RDF, Sagarika granules at 10 kg acre⁻¹, and two Sagarika liquid sprays at 5 mL L⁻¹, recorded the highest numerical grain yield (61.63 q ha⁻¹), straw yield (77.02 q ha⁻¹), and biological yield (138.66 q ha⁻¹). Several fertilised treatments were statistically comparable with T7 based on the reported critical difference. The highest harvest index was recorded under T10 (44.95%). The findings indicate that integrated Sagarika treatments were associated with favourable rice growth and yield under the conditions evaluated. Multi-season and multi-location studies incorporating economic, soil-health, nutrient-use-efficiency, and environmental measurements are required before wider recommendations are made.