Inbreeding depression in single, three way and double-cross hybrids of maize

et al. 2022

Rev. Ceres

The production of green maize is considerable important for various regions of Brazil. It is vital that breeding programs of public institutions seek to meet the needs of this market sector, which has a relevant social role, mainly on small properties. The aim of this study was to estimate the inbreeding depression and the genetic components (m + a and d) of characters associated with green maize production and quality in three populations of different genetic basis: the variety UFG-Samambaia (P1), and two populations formed by crossing the commercial hybrids (P2 e P3). The S 1 progenies of each population, the three S 0 populations, and two checks were evaluated in a 14 × 14 triple lattice design. Agronomic and ear quality traits were evaluated. Genetic variability and greater inbreeding depression were observed for most of the traits among the P1 progenies. In P2 and P3, greater inbreeding depression was observed for male flowering, ear weight without straw, ear diameter, ear weight, female flowering, breakage and lodging, and grain color. The traits of ear quality, important for green maize production, had greater inbreeding depression than the agronomic traits, indicating that inbreeding depression and exploitation of heterosis should be considered in the selection process for these traits.

Section: Rodrigues Et Al (2011) Evaluated Lines and Hybridsmentioning

confidence: 99%

Inbreeding depression and genetic variability of populations for green maize production

Cascão¹,

Santana

et al. 2022

Rev. Ceres

“…The higher the frequency of heterozygous loci in the genetic material, the greater the possibility of obtaining different gene combinations when total homozygosity is achieved. Inbreeding depression can be predicted if heterozygosity exists (Botelho et al, 2016). However, in the evaluation of genetic material, it is important to consider both the additive effect, which is estimated when all loci are homozygous, and the dominance effect, which is related to the level of inbreeding depression.…”

Section: Introductionmentioning

confidence: 99%

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

Somera

Ragagnin

et al. 2018

Chil. j. agric. res.

Information on the effect of endogamy and combining ability of inbred families is essential in hybrid maize (Zea mays L.) breeding programs. The objective of this study was to evaluate the effect of inbreeding in a maize population and the performance of top-cross hybrids from this population, with a broad genetic base tester. First, 110 S1 families were generated and established in the field along with families from the original population. The experiment was arranged in a randomized block design with three replicates, in 3.0 m plots with 15 plants. Traits of agronomic importance, inbreeding depression, and the general effect of dominance deviations were estimated the first stage. In the second stage, 69 inbred families (S2) with low inbreeding depression were evaluated by top-cross tests using the F2 generation of the commercial hybrid AG 6040 as tester. The same traits from the first stage were evaluated. Inbreeding depression in the first stage was higher for traits related to production, which indicates that the heterozygous loci contribute more to these traits, with the additive effects being less important. In the second stage, the best estimates of the general combining ability (GCA) for grain weight were found in progenies 51, 33, 17, 9, 3, and 67, showing good performance and good potential for use in breeding programs.

“…The estimates of dominance effects that were significant (p ≤ 0.05) were higher than the estimates of additive effects for ear and grain yield (Table 2). These results indicate that the contribution of heterozygous loci is greater for these traits, which present greater genetic complexity in relation to other traits (Botelho et al 2016).…”

Section: Estimates Of Parametersmentioning

confidence: 75%

Selection of maize lines and prediction of hybrid and synthetic means using intergroup topcrosses

Crop Breed. Appl. Biotechnol.

Cascão

Santana

et al. 2022

Topcrosses are routinely used in maize-hybrid programs. This study aimed to evaluate heterosis components and combining ability to predict hybrid means between synthetics from two groups of S 1 maize lines using the intergroup topcrosses model that includes S 2 lines. Two groups, each with 30 S 1 maize lines, were crossed using an intergroup topcross system, with a mixture of lines from one group as a tester for the contrasting group. Simultaneously, 30 S 2 lines from each group were generated via self-pollination. Lines and topcrosses were experimentally evaluated and the data were analyzed using a model adapted to the study design. The results showed the suitability of the proposed model for studying heterosis components and general combining ability, detailing additive and dominance effects. Prediction of hybrid means between synthetics showed the potential of the lines to generate base populations for an interpopulation breeding program.