Under the changed watering condition of progressive soil water stress-rewater, the betaine content and the betaine aldehyde dehydrogenase (BADH) activity were the highest while the tissue relative water content (RWC) of winter wheat seedling was in the range of 80 % to 70%. The betaine content and the BADH activity reduced when the seedling RWC was higher than 80% or lower than 70%. And the change of both was synchronous. Under the water stress winter wheat seedlings rapidly accumulated betaine. Betaine content of genotypes with drought resistance increased sixfold to eightfold, while susceptible genotypes fourfold. Accumulated betaine correlated to drought resistance, and play a main role in maintenance of osmotic balance of cytoplasm with cellular internal (vecuole) and external environment. The time that maximum betaine content appeared was earlier than proline and soluble sugar do during water stress. Genotypes that betaine content were higher and the maximum betaine content appeared later were drought resistance.
Acta Agronomica Sinica