Combining abilities and inbreeding depression in commercial maize hybrids

Abstract

The objective of this study was to evaluate the combining ability and inbreeding depression of commercial maize hybrids for agricultural traits. Twenty-two commercial maize hybrids, 96 F 1 crosses from a partial diallel scheme, 22 S 1 populations and 4 controls were evaluated in a 12x12 simples square lattice experimental setup, totaling 144 treatments, in the municipality of Sabáudia (PR), Brazil, for harvests from 2011/2012 and 2012/2013. Three traits were evaluated: grain yield, plant height and ear height. The Griffing method (1956) was applied for the evaluation of the general combining ability (GCA) and specific combining ability (SCA). The 30B39, 30K64 and 30B30 hybrids showed increased yield, 30F53 and P1630 showed reduced plant height and AG9040 and AG7010 showed reduced ear height. These hybrids can be recommended for the extraction of inbred lines and formation of composites followed by intrapopulation selection. The combinations 30B39 x AG8088, 30B39 x AG9045 and P1630 x AG8021 showed desirable SCA effects for grain yield, plant height and ear height and are recommended for use in reciprocal recurrent selection programs. High magnitudes of inbreeding depression were verified for yield and lower values for inbreeding depression for plant and ear heights. Thus, strategies are recommended for interpopulation breeding accompanied by inbred lines extraction.

Inbreeding depression and average genetic components in green corn genotypes

“…This result was predictable given the importance of the non-additive genetic effects that control the inheritance of polygenic traits as well as the role of genic complementation in the heterotic expression observed in simple hybrids. The ID results obtained in the present study are consistent with the variation in ID in other studies of grain yield (BERNINI et al, 2013;SENHORINHO et al, 2015) and silage (SOUZA NETO et al, 2015).…”

“…Based on the estimates of µ + α and the contribution of heterozygous loci, the simple and triple hybrids showed superior green corn productivity traits, and this can be attributed to the high frequency of favorable alleles in the commercial genotypes that accumulated over several breeding cycles as well as the different cultivation conditions. Simple and triple hybrids represent an excellent alternative for the generation of base populations in breeding programs (SENHORINHO et al, 2015).…”

Inbreeding depression and performance of partially self-fertilized maize progenies in a top cross

“…Genotype 1 showed the greatest reduction (ĝi = -1.165 t ha -1 ). According to Senhorinho et al (2015), positive values of ĝi indicate that genotypes used as parents contributed with favorable alleles with additive effects to their progenies.…”

Genetic divergence among corn hybrids and combining ability for agronomic and bromatological traits of silage

“…It is recommended that new base populations are not formed based only on their phenotype, adaptation, and the resistance of their genitors, but on other genetic parameters such as reduced inbreeding, combining ability, and genetic distance (Oliboni et al, 2013;de Souza Neto et al, 2015;Senhorinho et al, 2015).…”

“…The first and one of the most important stages of a corn breeding program is the formation of a base population, because the sources of extraction of elite inbred lines originate new hybrids (Hallauer et al, 2010). Corn breeders routinely use germplasm with a narrow genetic base to form the base population because such an approach has several advantages: a high frequency of favorable alleles; pest and disease resistance; and, most importantly, high adaptability to different soil and climate conditions (Oliboni et al, 2013;Senhorinho et al, 2015).…”