The impact of genotype, environment, and genotype × environment interaction on wheat grain yield and quality
Keywords:
wheat; genotype x environment; grain yield; grain quality; correlationsAbstract
Objects and purpose: In a multifactor field experiment, common winter wheat cultivars developed in Bulgaria were studied. The main factors site (location), season (year) and variety (genotype), the combination of which determines the magnitude and change of the studied characters, have been studied in detail. The aim is to establish and analyze all aspects of the impact of these factors separately, as well as their interaction on yield and several parameters of grain quality. The working hypothesis of the purpose is related to establishing whether there is a sufficiently different magnitude and direction of "genotype x environment" interaction (GE), which can become a prerequisite for a correct assessment of the performance and stability of each variety of the group.
Methods and approaches: Wheat varieties were studied during the period (2017-2019) in four locations of the country: Dobrich, Plovdiv, Trastenik, (Russe) and V. Tarnovo. Five grain characteristics were analyzed - Grain Yield (GY), Test Weight of grain (TW), Wet Gluten content of grain (WGC), Grain Protein Content (PC), and Grain Gluten Index (GI). In the statistical analyses, the parameters indicating the quality were taken as quantitative traits. All possible aspects of the „genotype x environment” interaction were investigated using several specialized statistical programs. The changes in the interrelationships between the traits in dynamically changing environmental conditions (location and year) were determined.
Key results: Genotype-environment (GE) interactions were found for all traits studied. Traits are differentially influenced by these factors, with GI being the most genetically dependent and GY the least. The full GGE interaction accounts for complex directional and magnitude variation of traits by location and variety. The interactions between the factors show a linear (PC1) and non-linear nature (PC2 - PC4), which is the reason for the observed changes in the mean values of each characteristic being statistically reliable in some of the tested varieties. The conditions in the locations differ significantly, which creates prerequisites for the maximum possible expression of GGE in each of the trait, without exception. They cause the established changes in the correlations between the yield and the examined parameters of grain quality, according to the test location.
Conclusions: The influence of the "environment" and "genotype" factors for each trait is different as a share of their total variation. The "genotype x environment" interaction is an essential factor that affects all the traits studied. Its full expression designated as GGE is different depending on the genetics of the trait (G) and its tendency to substantial change (GE) in the specific conditions of the locations. Fluctuations in the mean values of the studied varieties, relative to the environmental conditions, allow their correct comparison according to each of the traits.
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