agricolae (version 1.3-7)

index.AMMI: AMMI index and yield stability

Description

calculate AMMI stability value (ASV) and Yield stability index (YSI).

Usage

index.AMMI(model)

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

Arguments

model

object AMMI

Author

F. de Mendiburu

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)

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

AMMI,plot.AMMI

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]),])