Heterosis expression in crosses between maize populations: ear yield

Abstract

The phenomenon of heterosis has been exploited extensively in maize (Zea mays L.) breeding. The objective of this study was to evaluate the genetic potential of ten maize populations for ear yield following the diallel mating scheme. Six parental populations were obtained through phenotypic selection of open-pollinated ears in Rio Verde, GO, Brazil, (GO populations) and four parental populations were synthesized in Piracicaba, SP, Brazil (GN populations): GO-D (DENTADO), GO- F (FLINT), GO-A (AMARELO), GO-B (BRANCO), GO-L (LONGO), GO-G (GROSSO), GN-01, GN-02, GN-03 and GN-04. Experiments were carried out in three environments: Anhembi (SP) and Rio Verde (GO) in 1998/99 (normal season crop) and Piracicaba (SP) in 1999 (off-season crop). All experiments were in completely randomized blocks with six replications. Analysis of variance grouped over environments showed high significance for heterosis and its components, although mid-parent heterosis and average heterosis were of low expression. The interaction treatments x environments was not significant. Total mid-parent heterosis effects ranged from de -4.3% to 17.3% with an average heterosis of 3.37%. Population with the highest yield (7.4 t ha-1) and with the highest effect of population (v i = 0.746) was GN-03, while the highest yielding cross was GO-B x GN-03 with 7,567 t ha-1. The highest specific heterosis effect (s ii' = 0.547) was observed in the cross GO-B x GN-03.

<b>Genetic parameter estimates and identification of superior white maize populations

“…The GY trait showed significance in the heterosis parental effects (h i ), which reveals the existence of variation in the contribution of each parent to the performance of the hybrid, indicating dispersion of allele frequencies in the population (Oliveira et al, 2004). Similar h i results for GY were found by other authors and enabled the selection of the best parents and their respective hybrids (Tonette & Carena, 2014;Bernini & Paterniani, 2012;Doná et al, 2011;Silva & Miranda Filho, 2003;Scapim et al, 2002).…”

Heterosis and combining ability in crosses between two groups of open-pollinated maize populations

“…High heterosis were also reported by Castro et al (1968), Paterniani (1980), Crossa et al (1990) and Ribeiro (2012), with means of 24.8, 39.0, 18.6 and 102,6% respectively. Lower estimates of heterosis for yield were reported by Miranda Filho and Vencovsky (1984), Gorgulho and Miranda Filho (2001), Morello et al (2001), Silva and Miranda Filho (2003), with averages of 7. 4, 9.2, 3.75 and 23.5, 16.7% (two sets), respectively.…”

How Many Parents Give the Highest Yield in Predicted Synthetic and Composite Populations of Maize?

“…Predictions suggest that its yield would not be increased by composite formation. In another case, Silva and Miranda Filho (2003) evaluated a diallel with four broad-based composites crossed with six diff erent selections from a fi fth broad-based population. One of their elite composites, GN-03, yielded 96.9% of the hybrid check (Novartis Seeds Brand G-85; 7602 kg ha −1 ) and 97.3% of the highest-yielding population cross (GO-B/GN-03; 7567 kg ha −1 ).…”

“…This can quickly increase yield and useful genetic diversity in OP populations (e.g., Rincon‐Sanchez and Ruiz‐Torres, 2005; Miranda Filho and Vencovsky, 1984; Castro et al, 1968; Gardner and Paterniani, 1967), though attention must be paid to how composites are formed to achieve the highest yields (Marquez‐Sanchez, 1992b). In some cases, composite populations have yielded as well as the best varietal hybrids and nearly as well as commercial double cross hybrids (Silva and Miranda Filho, 2003; dos Santos et al, 1994; Naspolini Filho et al, 1981). A composite of Mexican OP populations and a few early generation inbred lines, formed in the 1940s, outyielded the best local OP populations by 15% and more (Matchett, 2006).…”