不同浓度硒酸钠对茶树的生长和生理指标的影响.

Using hydroponie experiments with one-year-old cutting seedlings, we investigated the effects of sodium selenate (Se concentration of 0, 0. 15, 0.3, 1.5, 3, 5 and 8 mg L) on selenium accumulation, plant growth, physiological index, and microscopic structure of tea tree. The results were as follows: The selenium contents in the roots and shoot of tea seedlings were positively correlated with the selenium level in the nutrient solution; With the increase of selenium level, the plant growth indexes including the fresh weight of tea seedling, the number of lateral roots, the root biomass, the contents of photosynthetic pigments, and root activity tended to increase initially and then decrease, and the tea quality indexes such as tea polyphenols, soluble protein and soluble sugar contents also presented the similar trend; However, the contents of malondialdehyde, hydrogen peroxide, and proline decreased in treatments of low selenium levels, and then increased in treatments of high selenium levels. Anatomical analysis of the root tips revealed different effects on the microscopic structure of roots under low and high selenium concentration. The cortex parenchyma cells of root treated with the low Se concentration (0.15, 0.3 and 1.5 mg L') were intact and well-shaped, and the root epidermal cells were smaller; Treatments at high selenium level (Se >3 mg • L') demonstrated larger root epidermal cells and damaged parenchyma cells with irregular shape, which showed stress responses. All together, the findings revealed that Se (IV) induced dual effects on tea seedlings. Se-supplementation with appropriate level (0.3 mg. L') showed beneficial effects on plant growth and tea quality by improving root activity and photosynthetic efficiency, minimizing the accumulation of peroxide and proline, and increasing both of the biomass and tea polyphenols contents. While excessive-Se (especially at 8 mg• L' Se) showed opposite effects on the parameters mentioned above and led to the reduction of plant growth and tea quality. These data might be helpful to explore the mechanism of dual effects of selenate on the growth of tea tree and provide reference for cultivation of Se-enriched tea. [ABSTRACT FROM AUTHOR]