在缓慢土壤水分胁迫-复水的变水处理条件下,小麦幼苗地上部分相对含水量在80％～70％时,甜菜碱含量及甜菜碱醛脱氢酶活性最高,相对含水量大于80％或小于70％,甜菜碱的含量和甜菜碱醛脱氢酶活性都降低,并且两者变化是“同步”的。水分胁迫时,小麦幼苗迅速积累甜菜碱,抗旱型小麦增加6～8倍,水分敏感型增加4倍。积累甜菜碱与小麦抗旱性密切相关,积累的甜菜碱在维持细胞质与其内（液泡）外环境的渗透平衡中起主要作用。小麦幼苗中甜菜碱的最大含量比脯氨酸和可溶性糖最大含量出现得早;甜菜碱含量高、最大含量出现较晚的小麦基因型,幼苗抗旱性较强。 Under the condition of slow soil water stress and rewatering, the content of betaine and the activity of betaine aldehyde dehydrogenase were the highest when the relative water content of wheat shoots was 80% ~ 70%, the relative water content was more than 80% Less than 70%, betaine content and betaine aldehyde dehydrogenase activity are reduced, and both changes are “synchronized.” When water stress, the wheat seedlings rapidly accumulate betaine, drought-resistant wheat increased by 6 to 8 times, water-sensitive increased by 4 times. Accumulation of betaine is closely related to the drought resistance of wheat, and the accumulated betaine plays a major role in maintaining the balance of cytoplasm with its internal (vacuolar) environment. The maximum content of betaine in wheat seedlings appeared earlier than the maximum content of proline and soluble sugar. The content of betaine was high, and the content of betaine appeared later in wheat genotype. The seedling had stronger drought resistance.