Both priming (mixing seeds with moist vermiculite for 36 h at 20 °C) and hot water soaking (soaking seeds for 4 h in water at 40 °C) improved the percentage and mean emergence time (MET) of bitter gourd seeds at sub-optimal temperature of 20 °C. The amounts of MDA and total peroxide in imbibing primed and hot water-soaked seeds were reduced and the activities of several free radical and peroxide scavenging enzymes were increased in comparison with imbibing untreated seeds. Thus, the improved emergence performance might be partly contributable to decreased lipid peroxidation during imbibition and peroxide scavenging activities. The percentage of emergence was decreased and MET was increased by accelerated aging. Accelerated aging not only resulted in increased lipid peroxidation, but also in decreased activities of several free radical and peroxide scavenging enzymes. Both percentage and speed of emergence after accelerated aging were decreased to a greater extent in primed and particularly in hot water-soaked seeds than in control seeds. Moreover, lipid peroxidation was increased to a larger extent in pretreated than in untreated seeds after accelerated aging. Therefore, as in the case of pretreated seeds, the increased peroxide accumulation and the reduced enzyme activities appeared to be linked to the reduced emergence performance of aged seeds.
