Screening of barley elite genotypes using different selection indices based on multi-traits

Identifying genotypes that combine high performance across many traits has been a challenger task. Classical linear multi-trait selection indexes are available, but the presence of multicollinearity and the arbitrary choosing of weighting coefficients may erode the genetic gains. Therefore it is necessary use novel approach for elite genotype selection based on multiple traits that overcome the fragility of classical linear indexes. The aim of this study was initially to select superior genotypes based on grain yield and a number of morpho-phenological traits and finally to compare different indicators for selecting ideal genotypes.

In order to evaluate a number of pure barley lines using multi-trait selection indicators in the Darab Agricultural Research Station, two one-year experiments in the crop years (2017-19) and one two-year experiment (2019-2021) were done. The first year experiment consisted of 108 pure barley lines which were executed as an Augment design and in the second year 34 lines were selected for Darab region. The selected lines were performed using two separate 1 and 2 experiments in a randomized complete block design with three replications. Then, 11 promising lines were selected and along with 6 other lines that were top in Zabul and Moghan regions, were examined in a two-year experiment. The two-year experiment was performed using a randomized complete block design with three replications.

The results of variance analysis of two-year experiments showed that the effect of year was significant for all traits except plant height. The effect of genotype was significant for all traits except grain yield and on the other hand, the genotype × year interaction was significant only for grain yield at 5% probability level. The Smith-Hazel index selected three genotypes, G7, G2 and G15, as the superior genotypes. In the multi-trait genotype-ideotype distance index (MGIDI), genotypes G15, G2, G16 and G20 were selected as the best genotypes. G14, G8 and G18 genotypes were among the top genotypes using factor analysis and ideotype design via best linear unbiased prediction index (FAI-BLUP). According to the results of selection index of ideal genotype (SIIG), G20, G17, G19 and G15 genotypes were the top genotypes with the highest SIIG values, respectively. The results of correlation between the studied traits and MGIDI, FAI-BLUP and SIIG indices showed that all indices except FAI-BLUP had a significant correlation with grain yield. Among the indicators, FAI-BLUP did not show a significant correlation with any of the indicators.

In general, the results of different indices showed that in the conditions of this study, none of the indices showed superiority over each other, and therefore finally the G15 genotype, which was the ideal genotype based on most indices, and the genotype G14 (selected genotype by FAI-BLUP index) due to its earlier maturity and high grain yield as the best genotypes in this study for cultivation and introduction in the southern regions of the country that have a similar climate to Darab, is recommended.