Estimate current moisture content(MC) of the seed
Put the temperature/relative humidity (T/RH) meter or humidicator strip with seed inside a moisture-proof container for 2 hours. Enter the output of the meter into cells B2 (T) and D3 (RH) to estimate current MC (column D) using the spreadsheets (eqn i). If a T/RH meter is not available, determine or estimate the ambient RH by consulting weather stations, newspapers, internet, etc. If seeds are in porous containers, they will be in near equilibrium with the ambient RH.
Seed equilibrium moisture content (Me)
Seed moisture content (MC) is determined by the storage Relative Humidity (RH) and Temperature (T). Determination of seed MC requires a sensitive balance and oven. Seed consumers, growers, agriculture extension workers and seed dealers generally do not have access to such equipment.
An alternative seed MC determination protocol
uses output from inexpensive T and RH meters placed with seed inside a moisture-proof container. After 2 hour equilibration, the T and RH values can be used with the attached spreadsheet to determine seed MC from this information. Simple humidity strips can also be used to approximate seed equilibrium RH. If a RH meter is not available and the seeds are stored in porous containers, the seed MC can be estimated from the ambient RH from weather service information.
Seed equilibrium moisture content, Me, (% dry weight) was calculated by Cromarty et al. (1982) where R is Relative Humidity/100, Do is seed oil content (proportion of dry weight), T is temperature (°C).
Cromarty et al., 1982
We have used existing Seed Information Database (SID) ( http://data.kew.org/sid/viability/) and other published literature for seed oil content.
Relationship between Fresh and Dry weight calculations
FW% = Dw%/(100+DW%)*100
DW%= Fw%/(100-FW%)*100