Estratificação ambiental, controle genético e heterose para maturação e produtividade de milho safrinha

Abstract

The objective of this work was to stratify the crop environments of west and central western Paraná, in order to complement the information obtained in each location, to evaluate the potential per se of the genitors, to demonstrate heterosis in hybrids and to obtain genetic control information for attributes related to productivity and maturation. Productivity and harvest moisture information of 16 commercial hybrids, conducted in DBC with two replicates, present in the Coodetec VCU trials in the seasons of 2014 and 2015, sown in the micro regions of Cascavel, Toledo, Foz do Iguaçu for representation of the West and in the microregion of Campo Mourão and in Mariluz, representing the Caiuá sandstone, for the representation of the central western Paraná, were used for environmental stratification, using the factor analysis methodology. For the study of heterosis, potential per se and genetic control, we selected 13 elite strains from the Coodetec breeding program, from which leaf discs were collected for genotyping with SNP molecular markers. The 78 hybrids, recorded in a half-diallel table, the 13 parents and 9 commercial hybrids were planted in Mariluz, Palotina and São Pedro do Iguaçu, in a 10x10 square lattice with three repetitions. Male and female blooms, crop moisture, yield and the weight of one thousand seeds were evaluated. For the grouping based on the dissimilarity matrix, the modified Tocher (sequential) method was used, and the methodologies of Gardner and Eberhart (1966) and Hayman (1954) were used for evaluation of the diallel. The environmental stratification showed that the municipalities of Cascavel, Palotina, Mariluz, Campo Mourão and São Pedro do Iguaçu are vital selections for yields, and Campo Mourão, Cascavel, Mariluz, Santa Terezinha do Itaipu, Palotina and São Pedro do Iguaçu for crop moisture. The cluster analysis formed three heterotic groups based on genetic distance, and the mean heterosis showed the possibility of exploiting the group of strains for precocity and yield. The combinations CD008 x CD038 and CD072 x CD070 stood out for population synthesis and CD010 x CD034 for direct synthesis of the hybrid. The CD034 strain stood out as more divergent among the strains studied for testing potential. The genetic information showed that the dominant strains are found more frequently in the parents, except for yield, which is predominantly recessive. Dominant gene effects are predominant in the control of the variables studied with an overdominant interaction between the alleles. The CD069 strain shows a higher number of dominant genes for maturation and the CD038 strain had a higher number of dominant genes for yield.