index.AMMI {agricolae} | R Documentation |
AMMI index and yield stability
Description
calculate AMMI stability value (ASV) and Yield stability index (YSI).
Usage
index.AMMI(model)
Arguments
model |
object AMMI |
Details
AMMI stability value (ASV) was calculated using the following formula, as suggested by Purchase (1997)
ASV = sqrt((SSpc1/SSpc2 * PC1i)^2+(PC2i)^2)
YSI = RASV + RY
RASV = rank(ASV) and RY = rank(Y across by environment)
Value
ASV |
AMMI stability value |
YSI |
Yield stability index |
rASV |
Rank of AMMI stability value |
rYSI |
Rank of yield stability index |
means |
average genotype by environment |
Author(s)
F. de Mendiburu
References
The use of an AMMI model and its parameters to analyse yield stability in multienvironment trials. N. SABAGHNIA, S.H. SABAGHPOUR AND H. DEHGHANI. Journal of Agricultural Science (2008), 146, 571-581. f 2008 Cambridge University Press 571 doi:10.1017/S0021859608007831 Printed in the United Kingdom
Parametric analysis to describe genotype x environment interaction and yield stability in winter wheat. PURCHASE, J. L. (1997). Ph.D. Thesis, Department of Agronomy, Faculty of Agriculture of the University of the Free State, Bloemfontein, South Africa.
See Also
Examples
library(agricolae)
# Index AMMI
data(plrv)
model<- with(plrv,AMMI(Locality, Genotype, Rep, Yield, console=FALSE))
Idx<-index.AMMI(model)
names(Idx)
# Crops with improved stability according AMMI.
print(Idx[order(Idx[,3]),])
# Crops with better response and improved stability according AMMI.
print(Idx[order(Idx[,4]),])