Effect of wider spacing, nutrient levels and bio stimulant on growth and yield of rice (Oryza sativa L.) under transplanted field conditions

A field experiment was conducted during kharif 2024 at the Agronomy Farm, Regional Agricultural Research Station, Karjat, Raigad (M.S.) to assess the effects of spacing, nutrient levels, and bio-stimulant application on growth, yield, and quality of transplanted rice (Oryza sativa L.). The study was arranged in a split-plot design with 18 treatment combinations replicated thrice, comprising three spacings (20 cm × 15 cm, 25 cm × 15 cm, and 30 cm × 15 cm), two nutrient levels (100% and 75% RDF), and three bio-stimulant treatments (control, irradiated chitosan @ 50 ppm, and @ 100 ppm). Results indicated that wider spacing (30 cm × 15 cm) significantly enhanced growth parameters, yield attributes, grain yield, and nutrient uptake. Application of 100% RDF improved growth and yield over 75% RDF, while foliar application of irradiated chitosan @ 50 ppm proved superior to control and 100 ppm for growth, yield, and physiological traits. Economic analysis revealed that 30 cm × 15 cm spacing with 75% RDF and irradiated chitosan @ 50 ppm yielded the highest net returns and benefit-cost ratio. The study suggests that applying 75% RDF with four foliar sprays of irradiated chitosan @ 50 ppm is a cost-effective strategy for maximizing yield and profitability in kharif rice under Konkan conditions.