Genotypic Variation in Coleoptile Length of Turkish Winter Barley (Hordeum vulgare L.) Varieties

Abstract

Coleoptile length (CL) plays a crucial role in seedling establishment and determining optimal sowing depth in cereals, particularly under environmental stress conditions. This study investigated CL in 51 Turkish winter barley (Hordeum vulgare L.) varieties to identify long-coleoptile sources for breeding programs and to guide optimal sowing depths. The experiment was carried out in the greenhouse of the Central Research Institute for Field Crops during the 2025 growing season, and coleoptile length variation was studied in eight-day-old seedlings on a sand-based growing medium. Statistically significant genotypic variation in CL was observed (P<0.05), ranging from 48.6 mm in Kıral-97 to 85.2 mm in Cacabey varieties. A substantial proportion of the evaluated varieties exhibited CL within the 60 to 80 mm range. Nine varieties exhibited long CL, exceeding 80 mm, indicating their potential as genetic resources for enhanced early vigor and improved drought tolerance. Conversely, short-coleoptile varieties, with CL less than 60 mm, necessitate careful sowing depth management to mitigate emergence failure. The varieties with the longest coleoptiles were the tall varieties developed for dry conditions, while the varieties with the shortest coleoptiles were the short varieties developed for the high-yielding areas. However, a direct correlation between plant height and coleoptile length was not consistently observed across all varieties. A significant and positive correlation was established between CL and thousand-grain weight (r=0.6033) and grain length (r=0.5931). Furthermore, the study demonstrated that the effect of genotype (85.7%) on CL was more pronounced than that of grain size, underscoring the strong genetic control of this important agronomic trait. Further field trials with varied sowing depths and emergence rates are needed to refine and validate these findings.