Comparison of Parametric and Nonparametric Methods to Describe Genotype by Environment Interaction and Grain Yield Stability of Bread Wheat
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Date
2013-10
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Addis Abeba university
Abstract
The nature and magnitude of the genotype by environment (G×E) interactions is
important to identify superior and stable genotypes under the target environments. One cultivar
may have the highest yield in some environments while a second cultivar may excel in others.
Hence, it is important to know the magnitude of the interactions in the selection of Genotypes
across several environments. Therefore, the objective of this study was to analyze genotype by
environment interaction and stability of 20 Ethiopian wheat genotypes in 8 environments. The
experiment was conducted during 2007/08 growing seasons in a randomized complete block
design with four replications. Parametric and nonparametric statistical methods were used to test
the significance of genotype by environment (G×E) interaction and to identify stable Genotypes
in 8 environments. Combined A NOVA and non parametric tests Kubinger and Hildebrand) of
genotype × environment interaction indicated the presence of significant interactions, as well as
significant differences between genotypes and environments. However no cross-over and noncrossover
interactions were detected by the de Kroon/van der Laan and Bredenkamp procedure
respectively. According to the parametric methods, genotype G11, G10, G5 and G12 were stable
and genotypes G16, G3, G20 & G1 were unstable. According to the nonparametric methods,
genotype G11, G10, G5, G18 & G12 were stable and genotypes G3, G16, G19, G1 and G20
ii
were unstable. The result shows that both the parametric and nonparametric methods gave a
relatively same result. This implied that the nonparametric stability measurements are useful
alternatives to parametric measurements. According to the biplot, Adet was generally
categorized under high yielding wheat environment as compared to the three relatively
categorized under low yielding environments (Holeta, Kulumsa and Sinana). Mean yield
performance across environments was significantly positively correlated with RS and TOP
measures (P<0.05 and P<0.01 respectively) and there were significant negative correlations
between mean yield and si
(3), si
(6), NPi
2 , NPi
3 . This study recommends genotypes G19, G1
and G15 as superior genotypes in favorable environments
Description
Keywords
Nonparametric Methods to Describe Genotype