Inheritance of resistance to Fusarium ear rot in popcorn
Crop Breeding and Applied Biotechnology
To date, no studies on the inheritance of Fusarium spp. ear rot resistance in popcorn are available. The purpose of this paper was to investigate the additive-dominance model to estimate the genetic components of variance, heritability and the inheritance pattern in a diallel for popcorn, by Hayman's approach. The experiment was carried out in two environments, using eight parent lines. The following traits were measured: grain yield (GY), popping expansion (PE), incidence of ears infected by
... ears infected by Fusarium (FusIE), total number of kernels infected by fungi (FunIK) and total number of kernels infected by Fusarium spp. (FusIK). The results indicated that the incidence of FusIK (Fusarium-infected kernels), FunIK (fungus-infected kernels), and FusIE (Fusarium-infected ears) is controlled by dominant genes. Parent L77 had a high number of favorable alleles for all resistance-related traits, as well as for PE. The strategy recommended for reduction of FunIK, FusIK, and FusIE consists of exploiting hetorosis using inbred lines with favorable alleles. Crop Breeding and Applied Biotechnology -18: 81-88, 2018 IA Schwantes et al. breeders in the choice of the best selection procedures and the most efficient methods to optimize gains in segregating populations (Schuelter et al. 2010 , Cruz et al. 2014 . To this end, diallel crosses are highly efficient to provide valuable information, such as the discrimination of parents for hybridization, identification of more efficient selection methods, and knowledge of the genetic basis controlling traits (Nascimento et al. 2010 , Cruz et al. 2014 ). Among the diallel analysis methods, the Hayman (1954) procedure is particularly interesting, for providing highly relevant genetic information for the definition of the most recommendable breeding strategy. The Hayman (1954) method is founded on knowledge about the environmental and genetic nature of statistics (means, variances, and covariances), obtained from a diallel table, which provides information on the mean trait dominance, the distribution of alleles between parents, the theoretical limit of selection, the relationship between favorable alleles and dominance, the proportion between dominant and recessive genes, and the estimates of genotypic determination coefficients (Cruz et al. 2014) . Despite its potential, the methodology of Hayman (1954) has rarely been used in the generation of genetic information for popcorn breeding. The only example is a study developed by Silva et al. (2010) , in which the authors determined the inheritance of traits of economic interest for the crop, e.g., popping expansion, grain yield, and ear weight. With regard to the diseases attacking the crop, to this date, no studies are available. This research was developed using the Hayman (1954) approach, aiming to investigate the additive-dominance model in order to determine the adequacy of data and of the experimental design, the genetic component of variance, the heritability, and inheritance patterns (additivity vs. dominance) for resistance to Fusarium spp. ear rot in diallel crosses of popcorn, and finally determine the best strategy to obtain superior genetic gains.