Research Article Indices estimated using REML/BLUP and introduction of a super-trait for the selection of progenies in popcorn.

Abstract

ABSTRACT. Selection indices commonly utilize economic weights, which become arbitrary genetic gains. In popcorn, this is even more evident due to the negative correlation between the main characteristics of economic importance -grain yield and popping expansion. As an option in the use of classical biometrics as a selection index, the optimal procedure restricted maximum likelihood/best linear unbiased predictor (REML/BLUP) allows the simultaneous estimation of genetic parameters and the prediction of genotypic values. Based on the mixed model methodology, the objective of this study was to investigate the comparative efficiency of eight selection indices estimated by REML/ BLUP for the effective selection of superior popcorn families in the eighth intrapopulation recurrent selection cycle. We also investigated the efficiency of the inclusion of the variable "expanded popcorn volume per hectare" in the most advantageous selection of superior progenies. In total, 200 full-sib families were evaluated in two different areas in the North and Northwest regions of the State of Rio de Janeiro, Brazil. The REML/BLUP procedure resulted in higher estimated gains than those obtained with classical biometric selection index methodologies and should be incorporated into the selection of progenies. The following indices resulted in higher gains in the characteristics of greatest economic importance: the classical selection index/values attributed by trial, via REML/BLUP, and the greatest genotypic values/expanded popcorn volume per hectare, via REML. The expanded popcorn volume per hectare characteristic enabled satisfactory gains in grain yield and popping expansion; this characteristic should be considered super-trait in popcorn breeding programs.

Production and Selection of Quality Protein Popcorn Hybrids Using a Novel Ranking System and Combining Ability Estimates

“…Though conflicting results as to the nature and extent of agronomic correlations are not difficult to find in the literature, our study supported the prevailing notion of moderately positive correlations between ear and yield traits. Likewise, correlations found in this study between expansion volume and agronomic traits were negative, as has been observed multiple times (Brunson, 1937;Dofing et al, 1991;Ziegler and Ashman, 1994;Pereira and Amaral Júnior, 2001;Daros et al, 2002;Li et al, 2002Li et al, , 2007Li et al, , 2008Li et al, , 2009Dhliwayo, 2008). The genetic repeatability estimate for 100-grain weight was found at 0.683, a similar estimate to that found previously (Spaner et al, 1992).…”

“…Due to primary selection of popping traits such as expansion volume and popability, popcorn is less optimized than other maize types in multiple agronomic traits such as pest susceptibility, stalk strength, and grain yield, and it has a relatively narrow breeding pool to integrate and improve agronomic traits (Robbins and Ashman, 1984;Sprague and Dudley, 1988;Dofing et al, 1991;Ziegler and Ashman, 1994). Previously, breeders' attempts at introducing dent corn germplasm into popcorn to improve its agronomic fitness have met with little success because of a negative correlation between expansion volume, a key popcorn quality trait, and grain yield (Brunson, 1937;Dofing et al, 1991;Ziegler and Ashman, 1994;Pereira and Amaral Júnior, 2001;Daros et al, 2002;Li et al, 2002Li et al, , 2007Li et al, , 2008Li et al, , 2009Dhliwayo, 2008). However, in 2018, Ren et al (2018) described an interpopulation breeding system between popcorn lines and dent "Quality Protein Maize" (QPM) varieties capable of increasing essential amino acid lysine in the seed proteome to more suitable levels for human dietary needs, and restored popping at early stages in the breeding program.…”

Selection indexes in the simultaneous increment of yield components in topcross hybrids of green maize

“…Despite the positive gains from commercial ear yields, they were low when compared to gains for the same trait obtained by the REML/BLUP methodology (27.32%) ( Table 2). Vittorazzi et al (2017) achieved similar results in genetic gains when applying the REML/BLUP methodology for the analysis of popcorn yield. Furthermore, it can be observed that, for the same index, negative gains resulted for the NER trait when the economic weights used were 1, CV g , CV g /CV e , and h², pointing out to a reduction of the trait, which may be an undesirable factor in advancing the maize breeding program.…”

Selection indexes based on linear‐bilinear models applied to soybean breeding

“…Vittorazzi et al. () compared selection with indices, with and without the use of REML/BLUP, and showed superior results using multivariate statistics for the selection of popcorn lines, both for GY and popping expansion.…”

“…Nunes, Resende, Santos, and Alves (2017) observed high precision conferred by genotypic values predicted using REML/BLUP when the selection index was compared in Eucalyptus breeding. Vittorazzi et al (2017) compared selection with indices, with and without the use of REML/BLUP, and showed superior results using multivariate statistics for the selection of popcorn lines, both for GY and popping expansion.…”