Introspection of discriminate function analysis and MGIDI selection index for selection to improve yield in rice (Oryza sativa L.)

In order to improve the grain yield the different selection indices were constructed based on a discriminate function using 36 rice genotypes. Two types of Smith and Hazel selection methods namely equal (Selection Index I) and differential weightage (Selection Index II) were used to construct the selection index using 17 quantitative traits, resulting in 94.34 and 95.88% genetic advance, respectively. The genotypes M7-1, M7-4, M7-6, M7-8, and M7-11 proved their top rankings based on index scores in both cases. To know better understand the selection and identification of superior genotypes the MGIDI were engaged. Based on 15% selection pressure the genotypes F₅-5, M₄-2, Anna (R) 4, M₄-8 and M₄-9 were identified as superior performing genotypes for all the studied variables. However, the ranking of genotypes by MGIDI was not similar to the ranking of Smith Hazel method because this method does not include the variables’ correlation structure. Comparing the classical method of selection index the MGIDI were more advantageous to identify the best performing genotypes based on the factorial analysis of BLUP values and more helpful to identify the traits responsible for selection of superior genotypes.