seed.extreme {HTSeed}

Title Extreme value distribution of base seed water potential

Description

The distribution of base seed water potential is following the extreme value distribution. Here, the stress tolerance parameter is characterised by 63 percentile in the distribution of base seed water potential.

Usage

seed.extreme(psi, time, c.germinated, N, d=NULL, theta)

Arguments

psi

Soil water potential

time

Time taken to germinate

c.germinated

Cumulative number of seeds germinated

N

Total number of seeds under each soil water potential

d

Proportion of viability

theta

Hydrotime constant

Value

• parameters: mu (stress tolerance parameter)and sigma (uniformity of germination parameter)

• Result_fitting: Actual cumulative seed germination fraction (Actual_CGfraction) and Fitted cumulative seed germination fraction (Fitted_CGfraction)

References

• Bradford, K. J. (2002). Applications of Hydrothermal Time to Quantifying and Modeling Seed Germination and Dormancy. Weed Science, 50(2), 248–260. http://www.jstor.org/stable/4046371.

• Bradford, K. J., & Still, D. W. (2004). Applications of Hydrotime Analysis in Seed Testing. Seed Technology, 26(1), 75–85. http://www.jstor.org/stable/23433495

Examples

psi<-c(rep(0, 19), rep(-0.2, 6), rep(-0.4, 10))
time<- c(1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 6, 7, 9, 10, 12, 16, 18, 20, 23, 26,
30, 4.5, 5, 6, 20, 23, 30, 3, 3.5, 4, 4.5, 5, 6, 7, 9, 12, 16)
c.germinated<- c(1, 2, 6, 11, 20, 24, 30, 34, 39, 41, 43, 47, 56, 58, 59, 63,
67, 72, 73, 29, 31, 35, 63, 64, 65, 11, 13, 18, 21, 22, 25, 26, 28, 29, 30)
d<- c(0.8, 0.8, 0.6)
my.extreme<-seed.extreme(psi= psi, time= time, c.germinated= c.germinated, N=100, d=d, theta= 90)