Registration of ‘R18C‐13665’: A high‐yielding conventional soybean cultivar

Abstract ‘R18C‐13665’ (Reg. no. CV‐568, PI 708976) is a high‐yielding, conventional soybean [ Glycine max (L.) Merr.] cultivar developed and released by the University of Arkansas System Division of Agriculture Research & Extension Center in 2024. It is a maturity group (MG) IV late with a relative maturity of 4.8. The plants feature an indeterminate growth habit, white flowers, light tawny pubescence, brown pod walls, and a black hilum. From 2019 to 2024, R18C‐13665 was evaluated across 55 environments in seven Mid‐Southern states, achieving an average grain yield of 4389 kg ha −1 , which corresponds to 100% of the non‐Xtend checks and 94% of the Xtend checks. Its seed weighs an average of 14.5 g per 100 seeds and contain 387 g protein kg −1 and 216 g oil kg −1 on a dry‐weight basis. R18C‐13665 is resistant to stem canker (caused by Diaporthe phaseolorum var. aspalathi ) and frogeye leaf spot (caused by Cercospora sojina Hara). R18C‐13665 addresses the limited availability of high‐yielding, indeterminate MG 4 public cultivars in Arkansas and the Mid‐South—an ideotype in high demand due to the region's shift toward earlier planting. As a public release, R18C‐13665 provides growers with a cost‐effective, nonproprietary option that allows seed saving and access to niche or premium markets. Beyond its agronomic and economic value, R18C‐13665 represents an important genetic resource for breeding programs aiming to strengthen the indeterminate MG 4 class and broaden the genetic base of Mid‐South soybean production.