Comparative evaluation of seed coat dormancy breaking treatments in Stylosanthes seabrana

Abstract

AbstractThe efficiency of microwave treatment in breaking the hard seed coat dormancy in Stylosanthes seabrana was compared with three other conventional methods including mechanical scarification, hot water treatment (100°C for 1 min) and acid scarification (5 min). The microwave treatment was as efficient in breaking hard seed coat dormancy as the hot water treatment. The ranking of treatments followed the order microwave ≥ hot water ≥ acid > mechanical scarification > control. The electrical conductivity of microwave‐treated seeds, although less than that of hot water, was greater than untreated control seeds, indicating increased permeability of the seed coat for water uptake. Seedling vigour, based on seedling length, was also similar for these treatments. Respiration was found to be higher in microwave‐treated seeds. Although levels of food reserves were not measured, future studies could hypothesize that increased imbibition of water in microwave‐treated seeds could cause a faster breakdown of food‐reserve material that is supplied to the germinating seed, resulting in increased evolution of CO2 through respiration. Scanning electron micrographs indicated the appearance of cracks and blisters on the seed surface of microwave‐treated seeds. These are most likely the sites of water entry during imbibition.