Evaluation of Wheat’s (Triticum aestivum L.) Agronomic and Grain Traits and Protein and Starch Characteristics Under Cultivation Environments in Korea

This study was conducted to evaluate regional variation in wheat traits within the same genetic background using the Korean-bred cultivar ‘Saekumkang’, thereby minimising genetic effects. Field trials were conducted across six major wheat-growing regions in Korea: Gyeongsangnam-do (GN), Gyeongsangbuk-do (GB), Jeollanam-do (JN), Jeollabuk-do (JB), Chungcheongnam-do (CN), and Chungcheongbuk-do (CB). Regional grain-filling environments were characterised using temperature, vegetation indices, and photosynthesis-related traits measured at approximately 20 days after anthesis. Differences in grain-filling environments and leaf physiological status were accompanied by variation in grain morphology, starch composition, and protein-related traits. Grain area was highest in GN (17.92 ± 0.33 mm2) and lowest in CB (13.41 ± 0.49 mm2). Total grain protein concentration was highest in GB (12.39 ± 3.70 mg/g) and lowest in JN (5.40 ± 1.93 mg/g), whereas total grain starch content was highest in GN (45.09 ± 0.33%) and lowest in CB (36.48 ± 0.22%). Principal component analysis and partial least squares discriminant analysis showed that grain size- and starch-related traits were mainly associated with GN, whereas photosystem II energy flux and protein-related traits were associated with CB or GB. These results indicate that regional grain-filling environments are closely associated with coordinated changes in leaf physiology, grain development, and starch- and protein-related quality traits within a single cultivar, providing baseline information for region-specific wheat quality management.