Tools

The fixed capacity of Drying Beads to absorb water across a wide range of relative humidities (RH) enables the calculation of specific bead:seed ratios to attain desired final seed moisture contents (MC). This calculation depends in part on the relationship between seed MC and RH for the species of interest. This relationship at a given temperature is known as a seed moisture isotherm, and is affected primarily by the seed oil content. The higher the oil content of a seed, the less water it contains at a given RH (Figure below).

These relationships have been developed into an equation that allows an estimation of the seed MC at any RH and temperature (T) based upon the seed oil content (Cromarty et al., 1982). This equation has been incorporated into an Excel file, enabling the user to simple enters the ambient RH and estimate the equilibrium seed MC. This information enables the calculation of the bead:seed ratios needed to reduce the seed MC to a desired level (see protocol below). We recommend first drying seeds using traditional sun or air drying to reduce seed MC to equilibrium with ambient conditions to reduce the amount of Drying Beads required. However, Drying Beads can be used to dry seeds from any MC so long as they are surface dry (to avoid heating when beads come into contact with liquid water).