Effect of sowing time and in-season growth manipulations on phenology of Indian mustard (Brassica juncea)"

Abstract

Field trials were conducted at the research farm of the University, Misar for 2 consecutive crop seasons to study the phenological development and thermal requirement of 'Laxmi' an Indian mustard (Brassicu juncea L. Czem & Coss.) variety grown under different environments. The treatments comprised three dates of sowing, viz 5 October (S,), 20 October (S,) and 5 November (S,) and 7 growth manipulations, viz control or no manipulation (L,), main shoot cut-off at 15 cm on 40 days after sowing (L,), main shoot cut-off at 15 cm on 50 days after sowing (L,), first primary branch cut-off on 55 days after sowing (L,), second primary branch cut-off on 60 days after sowing (L,), plant defoliated to 50 cm above ground on 60 days after sowing (L,) and Plant defoliated to 50 cm above ground on 75 days after sowing (L,). Early sowing resulted in short vegetative phase and (30 days- averaged for two crop seasons) advancement of reproductive phase but extended seed filling (63 days) and physiological maturity (152 days). However reverse trend was observed under delayed sown conditions. Early sown crop availed highest heat units to reach physiological maturity (1757 day "C). Among growth manipulations, main shoot cut-off at 15 cm on 40 or 50 days after sowing also resulted into significantly extended maturity duration (146 and 149 days respectively) as well as accumulated heat units. A positive correlation was obtained between seed yield, yield attributes and various phenophases.