General and specific combining abilities and partial diallel analysis of hop genotypes for traits of agronomic interest in the highlands of Santa Catarina

ABSTRACT: Hops (Humulus lupulus L.) are of particular economic importance in the highlands of the state of Santa Catarina, Brazil, by virtue of the number of breweries in the region. However, since the cultivars currently available in the country present poor qualitative attributes and low cone productivity, there is considerable demand for improved genotypes. The results of diallel crossing experiments help to increase our understanding of inheritance processes and the mechanisms controlling the transfer of alleles with additive or non-additive action, thereby allowing breeders to explore the benefits of heterosis. The present study evaluated the general and specific combining abilities (GCA and SCA, respectively) of four hop genotypes and to obtain F1 hybrids with agronomic traits superior to those of the parents and the ability to adapt to the environmental conditions in the Santa Catarina highlands. Partial diallel crosses were performed using a randomized complete block design involving 14 treatments, namely two male parents (Cascade and Hallertauer), four female parents (Columbus, Chinook, Cascade and Hallertauer) and eight hybrid combinations, with three repetitions each. The results showed that SCA was the predominant controlling mechanism for the manifestation in hybrids of the traits length of the lateral branch, height of insertion of the first cone, plant green mass and cone productivity. Some parental combinations also exhibited high GCA, indicating the presence of favorable alleles with additive action. The best combination was Hallertauer × Cascade, a finding that highlights the importance of choosing parents from different gene pools (American × European) to obtain genetically enhanced hybrids.