Environment Adjusted Yield Model for Ranking and Stability Assessment of Winter Triticale (X Triticosecale Wittm.) Genotypes

Obtaining high yields from crops such as triticale is directly related to the interaction of the used genotypes with the conditions of the environment. Therefore, the breeding of the crop is targeted toward reducing the effects, which various stress factors have on productivity. One of the shortcomings of the interaction of the genotype with the environment is that under contrasting growing conditions the different cultivars are ranked in a different way according to their yield value. This considerably hinders their evaluation and the possibility to choose the most suitable cultivars for the respective geographic area and micro region. In order to adequately assess the different triticale genotypes under contrasting conditions of the environment, a model for yield ranking was developed. It is based on the ratio between the reaction of the genotype under specific conditions of the environment with the mean productivity of the same genotype under the rest of the conditions of testing. This allowed increasing the contrast between differing genotypes and their more adequate ranking under certain conditions, or as a whole during the tested contrasting periods. On the other hand, the model allowed grouping of the genotypes with identical reaction to the conditions of the environment. The model was applied to eleven Bulgarian winter triticale cultivars (Kolorit, Atila, Akord, Respekt, Bumerang, Irnik, Dobrudzhanets, Lovchanets, Doni 52, Blagovest and Borislav) and to six contrasting periods of growing (2015 ndash%253B 2020). The results from the model values showed that the cultivars were grouped in different ways during the individual periods in comparison to their grouping according to yield values. Cultivars with similar productivity having identical ranks contrasted better with each other when applying the model. The genotypes, which possessed high stability, were characterized with lower ranks according to the results from the used model, especially in periods with clearly expressed drought. The ranks of the model values remained significantly high regardless of the conditions of the environments in cultivars Bumerang and Doni 52. The developed model demonstrated considerable similarities to the HARV and Hi models and can be reliably used in practical breeding work under contrasting environments