Phenology, thermal indices and yield of early rice hybrids in red and laterite zone of West Bengal, India

A field experiment was conducted to evaluate the performance of fifteen early rice hybrids along with checks in a randomized block design with 3 replications during wet (kharif) season. Mean number of days from sowing to emergence, 4^th leaf emergence, flowering and maturity were 3.49, 17.18, 76.69 and 105.49 days, respectively; while mean cultivar growing degree days (GDD) for those stages were 61.42, 329.31, 1400.55 and 1867.03°C. Average values with variations for yield associated characters were noted for panicle length (23.11± 4.75 cm), number of panicles m⁻² (322.87± 33.00), filled grains panicle⁻¹ (54.56± 18.55), grain filling (82.26± 6.35%) and 1,000-grain weight (29.35± 4.55 g). The private-bred short duration hybrid AG 8 yielded highest (5.01 t ha⁻¹) due to significant improvement in number of panicles (341 m⁻²) and 1,000-grain weight (31.3 g). Filled grainspanicle⁻¹ showed positive correlation (r= 0.491**) with panicle length, but negative association (r=-0.426**) with test weight. Based on plant characters and yield of 15 early rice hybrids, AG 8 (duration 103.7 days, plant height 103.5 cm, grain yield 5.01 t ha⁻¹ and nearly no-lodging) appeared promising for cultivation in Red and Laterite Zone of West Bengal.