Physiological response of sugar beet (Beta vulgaris L.) to water deficit at sugar accumulation stage under drip irrigation

Understanding the effects of water deficit on the physiological characteristics of sugar beet is essential for the determination of the minimum soil water content during sugar accumulation stage. Thus a field experiment was conducted to study the changes in leaf photosynthetic characteristics, water stress index, recovery degree, yield and technological sugar yield under drought resistance and rehydration cultivation. The study included three soil water content levels in the 0-40 cm depth-70% of field capacity (T1), 50% of field capacity (T2) and 30% of field capacity (T3). The results showed that the yield and technological sugar yield under T3 were significantly higher than those under T1 and T2 by 51.34%, 51.47%, and 36.72%, 39.48%, respectively. Leaf proline and soluble sugar contents were sensitive to water deficit before rehydration. Moreover, both leaf proline and soluble sugar contents were positive correlated with the degree of water deficit. Rehydration after water stress showed positive compensation effect on membrane permeability, antioxidant enzyme activities and osmotic adjustment substances contents of sugar beet. The enhancements were observed in leaf malondiadehyde content, peroxidased and catlase enzyme activities, proline and soluble sugar contents which favored increased osmotic adjustment. Therefore, prompt supplemental irrigation was needed when soil water content dropped to 30% of field capacity during sugar accumulation stage, which had a compensation effect on sugar beet under water deficit cultivation. It was helpful to work toward high yield and quality of sugar beet under drip irrigation in arid areas.