滴灌甜菜对糖分积累期水分亏缺的生理响应

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

  • 摘要: 滴灌条件下,于甜菜糖分积累期设置0~40 cm土层含水量下限分别为70%、50%、30%田间持水量的3种土壤水分处理,从叶片光合特性、水分胁迫指数、恢复度、产量及产糖量方面分析复水前后甜菜的生理响应,明确甜菜糖分积累期可忍受最大程度的水分亏缺下限。结果表明:30%田间持水量处理甜菜产量及产糖量都显著高于70%田间持水量和50%田间持水量,分别比70%田间持水量提高51.34%和51.47%,比50%田间持水量提高36.72%和39.48%。复水前30%田间持水量处理的甜菜叶片净光合速率显著低于其他处理,复水后处理间的叶片净光合速率的差异随时间推移减小,胞间CO2浓度表现出相反的趋势。当土壤水分下降到既定下限时,叶片脯氨酸和可溶性糖含量变化最为灵敏,且与缺水程度呈正相关;复水后叶片的细胞膜透性、抗氧化防御体系以及渗透调节物质均产生了正补偿效应,表现为丙二醛含量降低,抗氧化性酶活性增强,控制渗透调节的脯氨酸和可溶性糖含量增加。因此,在糖分积累期,土壤含水量下降至田间持水量的30%时进行补充灌溉,在一定程度上补偿水分亏缺对甜菜产生的负面影响,实现干旱区滴灌甜菜节水高产优质的目的。

     

    Abstract: 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.

     

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