AVANCE GENÉTICO MEDIANTE SELECCIÓN RECURRENTE DE FAMILIAS DE MEDIOS HERMANOS MAZORCA POR SURCO, EN MAÍZ AMARILLO DURO (Zea mays), EN TROPICO

<p><strong>Background. </strong>Corn (<em>Zea mays</em> L.) is an allogamous plant in constant improvement through various selection methods, starting with mass selection towards the genetic improvement of populations.<strong> Objective: </strong>To evaluate the genetic advance in the Marginal 28T corn variety, using the recurrent selection method of ear-by-furrow half-siblings in the tropics.<strong> Methodology: </strong>Two selection periods (1996-2000 and 2018-2022) of the genetic core of the Marginal 28T variety were compared. With the remaining seeds from the period 2018-2022, performance evaluation plots were established in a randomized complete block design, and they were compared with the results reported in the period 1996-2000; To find out if there have been varietal changes since 1984, the year the variety was released, seeds from 2022 were used in five locations<strong>. Results: </strong>Between the genetic seed core selection periods 1996-2000 and 2018-2022 of Marginal 28T corn, seed yield improved 0.75 t·ha⁻¹, with a genetic gain of 0.042 t·ha⁻¹·year⁻ ¹. The evaluation of the agronomic performance of the genetic seed revealed a 6-day reduction in flowering, with an increase in grain yield of 0.86 t·ha⁻¹. The varietal characterization showed uniformity in key characteristics such as grain texture and notable changes in grain color from reddish yellow to orange-yellow, and an improvement in commercial grain yield, from 3.50 t·ha⁻¹ in 1984 to 5.57 t· ha⁻¹ in 2022.<strong> Implications: </strong>The importance of the continuous use of the recurrent selection method of ear-by-furrow half-sibling families is highlighted to maximize the yield and varietal stability of hard yellow corn cultivation in the tropics.<strong> Conclusion: </strong>The Marginal 28T corn variety has been genetically improved in yield and grain color since its release as an open-pollinated variety in 1996.</p>