A field investigation was carried put during rabi season of the year 2014 and 2015 at Norman E. Borlaug Crop Research Centre (CRC) of the Govind Ballabh Pant University of Agriculture and Technology, Pantnagar, (Uttarakhand) in split plot design (SPD) taking three dates of sowing i.e. Oct 22, Nov 01and Nov 11 in main plots and five planting geometries viz., 30 × 10 cm, 30 × 20 cm, 30 × 30 cm, 45 × 15 cm and 45 × 30 cm in sub- plots with three replications on the thermal requirement of Indian mustard var. RGN- 73 thermal indices; GDD, PTU, HTU and PTI were calculated at different phenological stages of the Indian mustard The crop sown on 22nd October was found to accumulate more thermal units; and among the planting geometries, the wider geometries (30 × 30 cm, 45 × 15 cm and 45 × 30 cm) accumulated more thermal units.

Keywords: Brassica Juncea; Sowing Dates; Planting Geometries; Thermal Indices; Yield Predictive Models.