The objective of this study was to identify the linear relationships between the morphological variables of corn hybrids, associated with grain yield and fungicide use in subtropical environments. Seven experiments were conducted in three locations: santa maria - rs, são vicente do sul - rs, and frederico westphalen - rs, brazil. The design used was a randomized block design with subdivided plots and three replications, where the main factor was the use or not of fungicide and the subplots corresponded to six corn hybrids. The following traits were evaluated: leaf angle, stem diameter, ear insertion height, ear length, ear diameter, number of rows, grain length, thousand-grain mass, percentage of damaged grains, and grain yield. The characters were subjected to pearson correlation analysis and path analysis using r software. It can be concluded that there is a difference in the magnitudes of the linear relationships depending on whether or not fungicides are used on corn hybrids in subtropical environments, with cultural management influencing the results of the linear relationships. The characters ear diameter, grain length, ear length, and thousand-grain mass are positively related, while leaf angle and the percentage of damaged grains are negatively related to grain yield in corn hybrids.