Influence of agronomic and kernel‐related properties on popping expansion in popcorn

Knowledge about relationships between traits can contribute to raising the efficiency of selection of superior genotypes. The objective of this study was to estimate the correlations, direct and indirect effects of agronomic, chemical and physical traits of kernels on popping expansion (PE) in popcorn (Zea mays L.). The trial was carried out in the 2017/2018 growing season, in Maringá ‐ PR, with 49 treatments, which consisted of 43 popcorn, four flint, and two sweet corn. The trial was arranged in a randomized complete block design with three replications. Multiple agronomic, chemical, physical, and popcorn quality traits were evaluated. Analysis of variance was performed to estimate the coefficients of phenotypic and genotypic correlations and the direct and indirect effects of path analysis. The genotypes were partitioned into genotype within each kernel type (popcorn, flint, and sweet corn) and two more contrasts (popcorn vs. [flint + sweet corn]) and flint vs. sweet corn. Positive phenotypic (.76) and genotypic correlations (.81) between popping expansion and pericarp thickness were detected. Kernel length had negative phenotypic (−.75) and genotypic correlations (−.78) with PE. Path analysis indicated that pericarp thickness has a direct and positive effect on PE and that the observed positive correlation with thermal diffusivity of the kernel pericarp and kernel length can be explained by indirect effects of the pericarp thickness. Evaluating kernel length may be most prudent considering economical and practical constraints to popcorn breeding programs. Core Ideas Pericarp thickness is relevant in the selection of genotypes with greater popping expansion. Pericarp thickness has a direct and positive effect on popping expansion. Thermal diffusivity of kernel pericarp are indirectly related to popping expansion. Kernel length is indirectly related to popping expansion. It is more economical and easy to evaluate the kernel length.