Abstract

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.

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