Effects of Soil Covering on Growth and Physio-Biochemical Indices of Sugar Beet Seedlings Under Short-Term Low-Temperature Stress

Frequent extreme weather incidents can seriously affect the growth and yield of sugar beet. In this study, a simple solution was explored to alleviate the damage from short-term low-temperature stress to sugar beet seedlings. The growth status and physiological indices of sugar beet were examined using an artificial climate chamber simulating short-time low-temperature adversity with 4 temperature gradients − 3, − 4, − 5, and − 6 °C under two treatments of bare and covering soil. The results showed that compared with the bare state, soil covering significantly decreased the frost damage to seedlings and increasing survival rate by 30.8, 92.8, and 63.8% at − 4, − 5, and − 6 °C, respectively. Also, at − 3 and − 4 °C, soil covering significantly improved the root activity, effectively reduced damage to the leaf cell membrane, reduced proline (Pro) and soluble protein (SP) contents, and decreased the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) enzymes. Results suggested that soil covering alleviated the cold stress. Notably, the short-term low temperature of above − 3 °C for 3 h did not significantly affect the survival rate of sugar beet seedlings in the bare state, while all the seedlings died below − 5 °C in 3 h. However, soil covering improved the short-time freezing resistance of sugar beet seedlings. Our study showed a remarkable impact of soil covering on alleviation of low-temperature freezing damage and can promote sugar beet yield.