A field study was conducted at RARS, Shillongani during the rabi 2008-09 to 2011, to identify the yield potentials of rajmah varieties at different sowing dates and spacing in CBVZ, Assam. Rajmah varieties ‘HUR 301’and ‘HUR 203’ were evaluated for yields under different weather conditions by adopting sowing dates viz, 13th , 23th November and 3rd December. Among sowing dates, the highest grain yield (1231.94 kg ha-1) was recorded for 23 November for all varieties. On 23 November, ‘HUR-301’ had recorded the highest yield (1275 kg ha-1) followed by ‘HUR-203’. Similar results were also observed under sowing on 13th November and 3rd December sowing. Among varieties, ‘HUR 301’ recorded higher yield in comparison to ‘HUR 203’. The

benefit-cost ratio was found considerably high (1.97) in 23rd November sowing. November 23rd sown crop from sowing to physiological maturity had highest accumulated GDD of 13250C-days which indicated longer crop duration. This resulted in maximum dry matter accumulation during both vegetative and reproductive phases. The temperature, bright sunshine hours (BSSH), GDD and accumulated HTU were positively correlated with grain yield from sowing to branching, branching to flowering and flowering to pod initiation but negatively correlated with yield from pod development to maturity stages. Both the varieties performed well when sown maintaining 30 ×10 cm spacing. Higher temperature during the initial stage of growth invited higher incidence of leaf crinkle virus disease (18.83 per cent) in 13th November sown crop.