*Corresponding Author C.S. Park: pcs89@jbnu.ac.kr

Root characteristics are important to increase water utilization rate in water-scarce environmental conditions due to climate change, but few studies have been conducted in Korean wheat. This study aimed to evaluate the root characteristics of 37 Korean wheat cultivars at early seedling stage and analyze the relationship between seedling growth and grain characteristics.

A total of six root traits and coleoptile length were evaluated from images captured seven days after seeding on germination paper, and grain characteristics, including embryo size, thousand kernel weight (TKW), and test weight (TW), were measured from dried seeds harvested over two years (2021 and 2022). Seminal root length showed a positive correlation with maximum depth and total root length, but a negative correlation with root number and seminal root angle.

Embryo length exhibited a significant positive correlation with the number of roots and coleoptile length, while TKW and TW have no correlation with root characteristics. We also conducted genotypic analysis of semi-dwarfing genes (RhtB1, Rht-D1) and grain size related genes (TaCWI-4A, TaCWI-5D, TaGW2-6A, TaSus2-2B). Rht-D1b was associated with decreased maximum depth, increased root angle, and reduced coleoptile length, indicating their negative impact on early seedling growth.

The alleles for large grain size (TaCwi-A1a, Hap-5D-C, Hap-L, and Hap-6A-G) at all four genes were associated with increased number of roots and maximum depth, indicating that cultivars with large grain size have favorable seedling growth. Korean wheat cultivars were clustered into three groups: Cluster I with fifteen cultivars, Cluster II with nine cultivars, and Cluster III with thirteen cultivars, based on root, grain, and coleoptile characteristics. Cluster II exhibited the largest grain size and TKW, as well as the longest coleoptile length and seminal root length, suggesting favorable early seedling conditions.

However, caution is required when developing cultivars with superior root characteristics to minimize the negative impact of large grain size on yield and quality, as it increases the risk of pre-harvest sprouting and insufficient grain filling in Korea due to the short maturation period. Our study provides valuable insights for selecting wheat cultivars with optimal root growth and grain characteristics to ensure stable wheat production.