Morphoagronomic characterization and production gain after two mass selection cycles in Nawa Sheki landraces maize originated from the Western Brazilian Amazon

Abstract

Intensive breeding and artificial selection of the desired traits in maize landraces through domestication have created modern maize, which needs a great technological contribution for optimal productive development. However, the narrowing of the genetic bases of maize made it difficult for traditional farmers to access productive genetic material that maintains the genotypic and phenotypic diversity capable of ensuring productive sustainability. Thus, objective of the study was to evaluate the variability and production gain in morphoagronomic characters of Nawa Sheki landraces maize after two mass selection cycles. The work was carried out in the experimental area of the Federal University of Acre, where two cycles of mass selection were applied on variety Nawa Sheki, in periods 2018/2019 and 2019/2020. The characteristics evaluated were: plant height, ear insertion height, ear length, ear diameter, number of rows of grains, number of grains per row, ear mass and grain mass. Data were submitted to descriptive analysis, with presentation of the histogram of frequency, asymmetry, kurtosis and Shapiro-Wilk test for the general population in both cycles. For the selected population, the following were obtained: mean, coefficient of variation, amplitude, minimum and maximum values and population variance in each cycle. The genetic parameters were selection differential for both cycles, production gain with selection and realized heritability of the first cycle. The choice of individuals in both cycles of mass selection was based on the ranking of the best values of the evaluated characteristics. The two cycles of mass selection provided high variability in the traits with the presence of superior phenotypes. Still, mass selection stabilized values for plant height, ear insertion height, followed by production gains for number of grains per row and ear mass.