dc.description.abstract |
Durum wheat (Triticum turgidum ssp. durum) is the only tetraploid species of wheat
grown in the world. Productivity of this crop is very low in Ethiopia due to lack of
improved varieties. Estimation of genotype by environment interaction (GEI) can facilitate
variety development. Therefore, this study was carried out with the objectives of
understanding the relative contribution of GEI, assessing the stability of varieties in grain
yield, characterizing the environments, and understanding the associations of traits. The
experiment was conducted at Takusa, Dembia, Dabat, Debark, Debre Tabor and Moretina
Jiru during 2018 main cropping season. Twelve durum wheat varieties were used using
randomized complete block design with three replications. The experimental unit had a
plot size of 3 m2. Spacing between plots and rows were 0.5 m and 0.2 m, respectively. A
seed rate of 150 kg ha-1 with the recommended fertilizer rate for the respective areas was
used. Yield, yield related and quality data were collected and subjected to analysis of
variance for individual and combined locations. Stability analysis of grain yield was
executed using Ebrehart and Russel’s, Wricks’ ecovalence (Wi), cultivar superiority
measure (Pi), Nassar and Huehn’s mean absolute rank difference (Si1) and variance of
ranks (Si2), Kang’s yield stability index (YSI), AMMI stability value (ASV), AMMI and
GGE biplot models. Analysis of variance for individual locations showed significant
difference among the genotypes in most of the traits, indicating the presence of variability
among the genotypes. Combined analysis of variance revealed highly significant
difference among genotypes, environments and GEI for grain yield and yield-related
traits, indicating the presence of adequate variability among the genotypes, environments
and the differential response of the genotypes across environments. Cultivar superiority
measure and YSI were positively and significantly correlated with grain yield indicating
these models were best in identifying stable durum wheat varieties. Based on ‘which won
where’ of GGE biplot model, the locations were classified in to two mega-environments.
The first mega-environment consists of Moretina Jiru, Debre Tabor, Takusa and Dembia
with the best performing variety Fetan, while the second mega-environment consists of
Debark and Dabat with the best performing variety Hitossa. Takusa, Dembia and Debark
should be included for future testing locations for durum wheat breeding program because
of their good discriminative abilities. Grain yield had negative and significant association
with days to heading, days to maturity, and grain protein content, providing these traits
could be used as the main selection criteria for the breeders with the index selection
method to improve several traits at a time. Since, this study was limited to a small number
of locations with one year data, it is better to undertake further study including more
number of locations across years.
Keywords: AMMI, Correlation, Durum Wheat, GEI, GGE, Stability parameter
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