Seed equilibrium moisture content and equilibrium relative humidity of the seed storage environment

Compute the following metrics:

EqRH: The equilibrium relative humidity of the seed storage environment from seed equilibrium moisture content, oil content and temperature.

SeedEqMC(oilcontent, rh, temp, basis = c("wet", "dry"))

EqRH(oilcontent, mc, temp, basis = c("wet", "dry"))

Arguments

oilcontent	The percentage oil content of seed (dry basis).
rh	Relative humidity expressed in percentage.
temp	Temperature in °C.
basis	The type of estimation of moisture content specified in the argument `mc`. Either `"wet"` or `"dry"`.
mc	The seed equilibrium moisture content on wet or dry basis (according to argument `basis`).

Value

For SeedEqMC, the seed equilibrium moisture content on wet or dry basis (according to argument basis) expressed in percentage.

For EqRH, the equilibrium relative humidity expressed in percentage.

Details

This relationship between seed equilibrium moisture content, seed oil content, the equilibrium relative humidity and temperature of the storage environment was described by Cromarty et al. (1982) as follows.

(1-R) = e ^{−[ ^{[ ^{(Me × (1.1 + T⁄90))}
⁄ (1 − D_o) ]²} ⁄
₄₄₀ ]}

Where, R is the relative humidity expressed as decimal, M_e is the equilibrium percentage moisture content (dry basis), T is the temperature in °C of air or the seed equilibrium, D_O is the oil content of seed (dry basis) expressed as decimal and e is the mathematical constant 2.718282.

For values of oil content (oilcontent), relative humidity (rh) and seed equilibrium moisture content (mc) beyond the limits of 0-100 %, a warning is issued.

Note

The above expression by Cromarty et al. (1982) is recommended for temperature and humidity ranges of 0-40 °C and 10-70% RH for starchy seeds (eg. cereals); and 15-25 °C and 10-70% RH for oilseeds.

References

Cromarty AS, Ellis RH, Roberts EH (1982). The Design of Seed Storage Facilities for Genetic Conservation, Revised 1985 and 1990 edition. International Board for Plant Genetic Resources, Rome, Italy.

Examples

SeedEqMC(oilcontent = 29, rh = 13, temp = 25, basis = "wet")
#> [1] 3.877459
SeedEqMC(oilcontent = 29, rh = 13, temp = 25, basis = "dry")
#> [1] 4.03387

EqRH(oilcontent = 29, mc = 5, temp = 25, basis = "wet")
#> [1] 21.10662
EqRH(oilcontent = 29, mc = 5, temp = 25, basis = "dry")
#> [1] 19.26179

# Warning if oilcontent is beyond limits (0-100 %)
SeedEqMC(oilcontent = 125, rh = 13, temp = 25, basis = "wet")
#> Warning: "oilcontent" is beyond limits (0 < "oilcontent" < 100).
#> Warning: "mc" is beyond limits (0 < "mc" < 100).
#> [1] -1.440842
EqRH(oilcontent = 125, mc = 5, temp = 25, basis = "wet")
#> Warning: "oilcontent" is beyond limits (0 < "oilcontent" < 100).
#> [1] 85.22354

# Warning if relative humidity is beyond limits (0-100 %)
SeedEqMC(oilcontent = 29, rh = 115, temp = 25, basis = "wet")
#> Warning: "rh" is beyond limits (0 < "rh" < 100).
#> Warning: NaNs produced
#> [1] NaN

# Warning if moisture content is beyond limits (0-100 %)
EqRH(oilcontent = 29, mc = 115, temp = 25, basis = "wet")
#> Warning: "mc" is beyond limits (0 < "mc" < 100).
#> Warning: "mc" is beyond limits (0 < "mc" < 50).
#> [1] 100