Evaluation of Frost Tolerance in Sugar Beet Cultivars During Early Growth Stages

Late spring frost is the most hazardous abiotic stress affecting the survival of sugar beet seedlings. Therefore, it is very important to identify frost-tolerant cultivars during the early seedling development stage. In the study, the physiological and morphological responses of ten sugar beet cultivars (Ernestina, Isabella, Orthega, Serenada, Kuno, Taurus, Tuna, Mohican, Rodeo, and Smılodon) to frost stress at different growth stages (V1.1, V2.1, and V3.1) were evaluated. Seedlings were exposed to − 3 °C for 2 h at all stages. Percent damage (%), leaf chlorophyll content (SPAD), leaf surface temperature (°C), electrolyte leakage (%), leaf relative water content (%), and turgidity loss (%) were examined. The results showed that higher damage percentages were observed in earlier growth stages of sugar beet, with recorded values of 29.7% in V1.1, 15.4% in V2.1, and 3.6% in V3.1. A great genotypic variation was observed among the cultivars; electrolyte leakage increased from 15.6% in control to 52.6% in frost stress, and higher electrolyte leakage was obtained from frost-stressed plants. The relative water content of leaves increased only at stage V2.1, although frost decreased turgor loss. Sugar beet showed sensitivity to frost in earlier seedling growth stages, but their tolerance levels increased in later growth stages. The study revealed that electrolyte leakage is a reliable indicator for identifying sugar beet cultivars that exhibit tolerance to frost stress during early development.