This study aimed to measure the effects of rates of plant growth regulator trinexapac-ethyl on the development of the aerial, root parts and yield components of corn. The experiments were conducted in a greenhouse: one assay was aimed at evaluating the growth and development of the plant, in a 4 x 4 factorial arrangement, with four rates of trinexapac-ethyl (0, 125, 250 and 375 g of i.a. ha-1) and four assessment periods (14, 21, 28 and 35 days after application), and the other was aimed at assessing the yield productions for corn in response to the same four rates of the regulator. The present study demonstrates that grain yield per plant was reduced with the use of trinexapac-ethyl, due to decrease in spike length, number of kernels in each row and hundred grain mass. The use of trinexapac-ethyl does not change the cycle of corn, but increases stem diameter and chlorophyll index, and reduces the plant height and spike insertion height, leaf area, dry mass of aerial part, dry mass and volume root system. The trinexapac-ethyl changes the size of the corn plants, enabling new spatial arrangements. Key words: Leaf architecture, yield components, plant growth, plant growth regulator, Zea mays L.