Description Usage Arguments Details Value References See Also Examples

`SSI`

computes the Simultaneous Selection Index for Yield and Stability
(SSI) according to the methods specified in the argument `method`

.

1 |

`y` |
A numeric vector of the mean yield/performance of genotypes. |

`sp` |
A numeric vector of the stability parameter/index of the genotypes. |

`gen` |
A character vector of the names of the genotypes. |

`method` |
The method for the computation of simultaneous selection index.
Either |

`a` |
The ratio of the weights given to the stability components for
computation of SSI when |

The SSI according to Rao and Prabhakaran (2005)
(*I _{i}*) is computed as
follows:

*I _{i} =
[^{Yi
}⁄^{ }_{Y}_{..}] +
α [^{(1/SPi)} ⁄
_{((1/T) ∑Ti=1
(1/SPi))}]*

Where *SP _{i}* is the
stability measure of the

α | w_{1} |
w_{2} |

1.00 | 0.5 | 0.5 |

0.67 | 0.6 | 0.4 |

0.43 | 0.7 | 0.3 |

0.25 | 0.8 | 0.2 |

The SSI proposed by Farshadfar (2008) is called the Genotype stability index (GSI) or Yield stability index (YSI) (Farshadfar et al., 2011) and is computed by summation of the ranks of the stability index/parameter and the ranks of the mean yields.

*GSI = YSI =
R _{SP} + R_{Y}*

Where, *R _{SP}* is the
stability parameter/index rank of the genotype and

A data frame with the following columns:

`SP` |
The stability parameter values. |

`SSI` |
The computed values of simultaneous selection index for yield and stability. |

`rSP` |
The ranks of the stability parameter. |

`rY` |
The ranks of the mean yield of genotypes. |

`means` |
The mean yield of the genotypes. |

The names of the genotypes are indicated as the row names of the data frame.

rao_use_2005ammistability

\insertReffarshadfar_incorporation_2008ammistability

\insertReffarshadfar_ammi_2011ammistability

`AMGE.AMMI`

,
`ASI.AMMI`

,
`ASTAB.AMMI`

,
`AVAMGE.AMMI`

,
`DA.AMMI`

, `DZ.AMMI`

,
`EV.AMMI`

, `FA.AMMI`

,
`MASV.AMMI`

,
`SIPC.AMMI`

,
`ZA.AMMI`

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 | ```
library(agricolae)
data(plrv)
model <- with(plrv, AMMI(Locality, Genotype, Rep, Yield, console=FALSE))
yield <- aggregate(model$means$Yield, by= list(model$means$GEN),
FUN=mean, na.rm=TRUE)[,2]
stab <- DZ.AMMI(model)$DZ
genotypes <- rownames(DZ.AMMI(model))
# With default ssi.method (farshadfar)
SSI(y = yield, sp = stab, gen = genotypes)
# With ssi.method = "rao"
SSI(y = yield, sp = stab, gen = genotypes, method = "rao")
# Changing the ratio of weights for Rao's SSI
SSI(y = yield, sp = stab, gen = genotypes, method = "rao", a = 0.43)
``` |

Embedding an R snippet on your website

Add the following code to your website.

For more information on customizing the embed code, read Embedding Snippets.