Genotypic and Phenotypic Association of Agronomic Features in Triticale Genotypes under Drought Stress Conditions

Extended Abstract Background: Many efforts have been made to combine the diverse capabilities of different plant species into a unique plant to increase the quantity and quality of the food product. Accordingly, scientists succeeded in producing triticale as a new pathogen by using a cross between wheat (Triticum spp.) and rye (Secale cereale), which aims to increase the ability of wheat, as one of the most important food sources among grains in the world. It was to withstand harsh environmental conditions such as drought stress. Various studies show that this grain has a high potential to be used as a multipurpose product for direct human use or as a fodder product. Therefore, triticale can be considered a potential product with special genetic conditions, whose yield is still far from its potential. According to scientists of breeding science, creating diversity, whether natural or synthetic, in agricultural products and selecting genotypes with the highest yields and stability in different environments are among the main goals of studies in the field of breeding. It is also reported that the stress tolerance of triticale genotypes is usually higher than wheat genotypes, triticale is less affected by stress conditions, and its yield will be higher than wheat. Resistance to drought stress is a complex process that includes a network of plant responses at the physiological and molecular levels that have not yet been properly discovered and understood. However, creating diversity, selecting genotypes, and studying different traits will help scientists in this direction. In the current study, different triticale genotypes produced by domestic scientists were cultivated and tested under different irrigation conditions to consider the possibility of introducing new cultivars resistant to drought stress and changing environmental conditions. In addition, the relationship between morphological and agronomic traits related to seed yield was evaluated in this research using some advanced statistical methods to find possible traits suitable for indirect selection. The amount of different genetic, phenotypic, and environmental indicators was also investigated to examine the effect of the environment and genetics on the traits. Methods: To reflect the effect of water deficit on triticale and the probability of screening some suitable genotypes tolerant to drought stress, a study was carried out on nine triticale genotypes under four irrigation regimes during two years. These genotypes included Senabad, Pag, Juanillo, ET-85-4, ET-92-15, ET-92-18, ET-83-20, ET-85-17, and ET-83-18. In each year, four different irrigation regimes were applied with interruption of irrigation in three stages, including the flowering stage, the seed milky stage, and the seed pulp stage, along with the control condition. In each year, a split-plot design based on a randomized complete block design with three blocks (replication) was used every two years of the experiment (the growing season 2018-2019) in the research station located in the research complex of the Zarghan Agriculture and Natural Resources Research and Training Center, Fars, Iran. Different traits, including plant height, leaf angle, leaf weight, total dry matter, spike length, spike weight, spike number, grain number, straw yield, harvest index, and grain yield, were measured for all applied genotypes in this study. The data obtained from this experiment were first subjected to the composite analysis of variance, and year variance, environmental variance, genotypic variance, phenotypic variance, and test error variance were estimated based on these calculations. The analysis was performed in SAS-9.4-M6 software using a programming code stored on the GitHub website. Results: The results showed that a lower number of irrigation and earlier withholding of water from the triticale plants can lead to a high decrease in the productivity of triticale genotypes.  Consequently, irrigation treatments and water availability are significant factors in determining the type of breeding programs. Moreover, some genotypes showed a high potential for being considered for releasing cultivars. ET-83-20 and ET-85-04 showed better performance under normal and severe water deficit, respectively, than the other genotypes. Estimation of genotypic features, such as heritability and coefficient of variation, showed a high possibility and potential of producing cultivars with high productivity under either normal or stressed conditions. Conclusion: Overall results indicated that high heritability and the significant association with grain yield for some traits, such as spike weight, spike number, and grain number, suggest that they are suitable traits for indirect screening and selection criteria. In addition, higher variation for triticale is required to find genotypes with the best quality and quantity traits to be released as a new and proper cultivar to be cultivated in environments with changing conditions.