Heterosis and genetic distance in intervarietal corn hybrids

Abstract

The objective of this work was to evaluate the performance of intervarietal corn (Zea mays) hybrids with topcross crosses between landrace populations, and to confirm whether genetic dissimilarity between populations is correlated with the heterosis of the intervarietal hybrids in the field. Nine topcross hybrids were evaluated with their tester 'BRS Planalto', and the following landrace populations were used as parents: Argentino Branco, Dente de Ouro, Amarelão, Criolão, Caiano Rajado, Branco Oito Carreiras, Branco Roxo Índio, Cateto Branco, and Argentino Amarelo. The tester 'BRS Planalto' and the topcross hybrids Branco Oito Carreiras x 'BRS Planalto' and Criolão x 'BRS Planalto' showed higher per se potential for grain yield. The topcross hybrid Branco Oito Carreiras x 'BRS Planalto' showed a better performance for number of grains per row, grain weight, and ear diameter, whereas Criolão x 'BRS Planalto' displayed a better performance for the number of grains per row and ear length. Greater estimates of genetic distance did not necessarily result in greater heterosis values and were exclusively correlated with grain ear length. Therefore, it is not possible to predict the effects of high heterosis on grain yield, based on the genetic distance between the populations involved in the crosses.

Maize genetic breeding for tolerance to abiotic stress with focus on sustainable use of environmental resources

“…Varieties, on the other hand, are characterized by exhibiting greater phenotypic stability in the face of environmental variations due to their broad genetic base, as observed by Troyjack et al (2019). It can be understood that in a context of climate change, plants that have a wide genetic diversity, such as open-pollinated and creole varieties (Baretta et al, 2019), tend to manifest a more pronounced phenotypic stability, resulting in greater resilience in the face of extreme weather conditions. Therefore, it is essential to preserve these genetic bases, since they are sources of desirable alleles to minimize negative impacts from the environment.…”