Genetic distances between popcorn populations based on molecular markers and correlations with heterosis estimates made by diallel analysis of hybrids

Diallel analysis was used to obtain information on combining ability, heterosis, estimates of genetic distances by random amplified polymorphic DNA (RAPD) and on their correlations with heterosis, for the popcorn varieties RS 20, UNB2, CMS 43, CMS 42, Zelia, UEM J1, UEM M2, Beija-Flor, and Vicosa, which were crossed to obtain all possible combinations, without reciprocals. The genitors and the 36 F-1 hybrids were evaluated in field trials in Maringa during two growing seasons in a randomized complete block design with three replications. Based on the results, strategies for further studies were developed, including the construction of composites by joining varieties with high general combining ability for grain yield (UNB2 and CMS 42) with those with high general combining ability for popping expansion (Zelia, RS 20 and UEM M2). Based on the RAPD markers, UEM J1 and Zelia were the most genetically distant and RS 20 and UNB2 were the most similar. The low correlation between heterosis and genetic distances may be explained by the random dispersion of the RAPD markers, which were insufficient for the exploitation of the popcorn genome. We concluded that an association between genetic dissimilarity and heterosis based only on genetic distance is not expected without considering the effect of dominant loci.