Investigation and Characterization of Grain Size Variation in Barley (Hordeum vulgare L.) Landraces Using Conventional and Image Processing Techniques

Abstract: Barley (Hordeum vulgare L.) is the fourth most cultivated cereal globally, with 60-70% used for animal feed and 20- 30% for the malt and brewing industries. Grain size is a critical factor for yield and market value, influenced by both genetic and environmental factors. This study aimed to identify grain characteristic differences among barley landraces stored in the Osman Tosun Gene Bank using conventional analysis methods and image processing techniques. The study included 51 two-row and six-row barley landraces (102 genotypes), alongside three two-row and three six-row control varieties. Grain analyses were conducted on samples obtained from two continuous field trials between 2021 and 2023. Grains were evaluated using sieve analysis, thousand-grain weight, and an image processing software, GrainScan, to determine grain area, perimeter, length, diameter, and color values. In the two- row control varieties, the percentage of plump grains (>2.5 mm) was 95%, with 11 genotypes showing similar sizes. In the six-row controls, the percentage of plump grains ranged from 63% to 81%, while 31 genotypes exceeded these values. Thousand-grain weight ranged from 46.15 to 64.60 g in two-row barley and 35.80 to 58.61 g in six-row barley. A strong correlation was found between plump grains (>2.8 mm) and high thousand-grain weight with grain diameter and area in two-row barley, and with grain area, perimeter, and length in six-row barley. In conclusion, there is significant variation in grain size among barley genotypes, and image processing techniques effectively detect these differences.