Genotype- environment interaction analysis and selection of sugar beet stable genotypes in terms of white sugar yield using AMMI model

The methods used to analyze genotype-environment interaction and determine the stability and adaptability of genotypes are continuously evolving to improve the accuracy of evaluating genotypes and studying environmental interaction components. Using a combination of several methods provides a more comprehensive understanding of the genotype-environment interaction from multiple dimensions. In this study, the genotype-environment interaction was investigated using the AMMI method, along with the development of appropriate statistical techniques.

For this purpose, 25 sugar beet genotypes, consisting of 18 new hybrids and seven controls, were cultivated in seven environments: Karaj, Mashhad, Shiraz, Miandoab, Kermanshah, Hamadan, and Khoi. The experiment followed a randomized complete block design with four replications during the year 2020. After checking the uniformity of the variance of the experimental errors using Bartlett's test, the stability of the genotypes was analyzed based on the AMMI model. In this study, 12 statistics obtained from the AMMI model, including ASTAB, ASI, ASV, AVAMGE, DA, DZ, EV, FA, MASI, MASV, SIPCi, and Za, were used to identify stable genotypes. To further investigate the stability of the experimental genotypes, the SIIG index was also estimated, taking into account the criteria provided by each index based on the AMMI model.

The results obtained from Bartlett's test confirmed the homogeneity of the variance of experimental errors in experiments from different regions. Therefore, a combined variance analysis was performed based on the AMMI model. The combined analysis of variance, based on the AMMI model, indicated the significance of the additive effects of the environment and genotype, as well as the multiplicative effect of genotype-environment interaction at the 1% probability level. Analyzing the interaction effects into principal components showed that the first four components were significant at the 1% probability level and explained 93.50% of the variations related to genotype-environment interaction. According to the AMMI1 biplot, hybrids 3 and 9 were recognized as the most stable genotypes due to having a sugar yield higher than the overall average and a low value of the first interaction component. According to the AMMI2 biplot, hybrid 3 and BTS 335 with the Miandoab environment, Lexia and 4 with the Mashhad environment, Lexia with the Hamedan environment, 14 and 15 with the Kermanshah environment, 13 and 17 with the Shiraz environment, 11 with the Karaj environment, and Baloo with the Khoi environment have considerable specific adaptability. Hybrid 9, followed by 6, 2, and 8, had general adaptability. The SIIG index, calculated based on AMMI model statistics, identified 2, 9, 10, and 8 as the most stable genotypes with optimal yield.

Based on the obtained results, the environment and its interaction with the genetic structure of different genotypes have played a significant role in the phenotypic expression of white sugar yield and have caused the genotypes to provide different responses in terms of white sugar yield according to the conditions of different environments. In general, based on the results of the present study, hybrid 9 and then hybrids 6, 2, 8, 7, and 10 had high white sugar yield and yield stability. Generally, real progress in sugar beet breeding will be obtained if the genetic factors controlling the sensitivity of sugar beet genotypes to a variable environment are identified.