Intra-cultivar variation for seed weight and other agronomic traits within three elite soybean cultivars

Despite its importance, exploitation of intra-cultivar variation has been very limited due to the belief that elite cultivars are highly homogeneous. The main objective of this study was to investigate the presence of exploitable intra-cultivar variation for seed weight, maturity, and other agronomic traits within elite soybean cultivars released for their superior productivity and resistance to various diseases. Singleplant progeny lines, selected at very low plant density from within these cultivars, were evaluated for seed weight, maturity, plant height, lodging, and seed yield in row-plot replicated randomized complete block designs across years. For seed weight, the magnitude of intra-cultivar variation across years between the largest- and the smallest-seeded lines averaged 36 mg seed(-1) for Benning, 22 mg seed(-1) for Cook, and 45 mg seed(-1) for Haskell. For maturity, the magnitude of intra-cultivar variation was 5 d in Benning, 4 d in Cook, and 7 d in Haskell. Furthermore, we discovered intra-cultivar variation for plant height within Cook and Haskell, and for lodging within Haskell. This study is the first one to report evidence of significant intra-cultivar variation for seed weight, maturity, plant height, and lodging within soybean cultivars. The results suggest that cultivars may not be permanent records with nonexistent variation but genetic material that can be upgraded to maintain uniformity in the long term and further improve desirable agronomic or seed-trait characteristics.