Dry heat exposure increases hydrogen peroxide levels and breaks physiological seed coat-imposed dormancy in Mesembryanthemum crystallinum (Aizoaceae) seeds

Here we describe for the first time in a species of the Aizoaceae family that exposure of seeds to dry heat can break physiological seed coat-imposed dormancy completely. Although M. crystallinum seeds became more permeable to water following dry heat treatment, this was not the case for methylene blue dye, suggesting that dry heat does not remove a potential barrier to diffusion of high-molecular-weight compounds. However, the observed elevation in H2O2 levels following dry heat treatment, possibly enabled by enhanced oxygen uptake through increased seed permeability, indicates a potential mechanism by which physiological dormancy is released in M. crystallinum seeds.