Non-parametric selection indices in the selection of ornamental pepper genotypes

Abstract

Ornamental peppers (Capsicum spp.) possess several characteristics of interest used in species breeding programs for selection purposes. Selection indices are useful and essential tools that allow simultaneous selection based on various characteristics. Although there are various available indices, do they differ in indicating the best genotypes? This study aimed to estimate genetic parameters to identify variables with moderate to high heritability and subject them to different selection indices in an F3 population of ornamental pepper, observing the congruences in identifying the genotypes to be selected. 400 genotypes in the segregating F3 generation were considered. The trial was conducted in a greenhouse. The variables used were plant height, time to maturity, fruit quantity per plant, and average fruit mass. Genetic parameter estimates were obtained using the REML method for each variable, and subsequently, variables showing moderate to high heritability (Resende, 2002a) were considered for simultaneous selection. The selection indices Mulamba & Mock (MM) and Multiplicative Index (IM) were employed to predict genetic gains, with a selection pressure of 20%. Both indices showed high estimates of genetic gains. MM presented the highest values (ranging from 57.49% to 309.37%), while the multiplicative index varied from 55.53% to 199.2%. The applied selection indices proved suitable for genotype selection due to the high predicted genetic gains. Among the 80 selected genotypes, only 12.5% were present in both indices but in different positions in the rankings. The results showed inconsistencies between the indices in indicating the best genotypes.