Tecnologia de duplo haploide na determinação da herança da resistência à podridâo de colmo (Fusarium moniliforme) em linhagens de milho

Abstract

The second-crop corn has become the most important in Brazil is responsible for most of the corn grain produced in the country. The state of Mato Grosso is one of the largest producers of this culture, just by the use of second-crop corn cultivation in succession to soybean crop cultivation. This growing season has favorable conditions for the development of diseases, especially stalk rot. Corn seed companies in recent years are using in their breeding programs to double haploid technique, this allows the generation of large amount of inbred lines in a shorter period of time compared to the conventional method. The objective of this study was to determine the genetic inheritance of stalk rot caused by F. moniliforme in maize inbred lines derived from double haploid technology. Four cross between the contrasting lines were synthesized as tolerance to F. moniliforme, with the use of double-haploid technology which inbred lines were obtained 70 days after planting were inoculated with F. moniliforme spores suspension and after 70 days of inoculation reaction was evaluated, the stalk of the plants were longitudinally sectioned for evaluation and obtained the density of stalks, percentage of the pathogen lesion size and the grain weight. There was a significant difference between strains for agronomic characteristics. It was observed variance between plants of the same inbred line, which was not expected by the use of double-haploid technology. The variance due to dominant genetic effects was greatest magnitude, and the heritability in the narrow sense was 0.28. The observed frequency distribution may indicate epistatic effects involved in the genetic control of resistance to F. moniliforme. The biggest gains expected with the selection were achieved with the use of selection among families and mass selection