水培条件下不同pH值对香根草幼苗形态和生理特性的影响

在pH2.0-pH11.0的1/2Hoagland培养液水培条件下，对培养20d后香根草也Vetiveriazizanioides（Linn.）Nash页幼苗形态、叶片和根系部分生理指标的变化进行了研究。结果表明：在强碱性（pH11.0和pH10.0）及强酸性（pH2.0和pH3.0）条件下，香根草幼苗的部分叶片枯黄，茎干枯，须根数量明显减少且长度趋短；而在弱碱性（pH9.0和pH8.0）及弱酸性（pH5.0和pH4.0）条件下，仅可见部分叶尖出现轻度失绿现象，根系形态无明显变化仅颜色有差异。随培养液pH值的增大（碱性增加）或减小（酸性增加），叶片含水量和叶绿素含量均逐渐降低且均小于对照（pH6.5），而相对电解质外渗率和MDA含量均逐渐增加并高于对照；各指标在强碱性（pH11.0和pH10.0）及强酸性（pH2.0和pH3.0）条件下总体上与对照差异显著（P〈0.05），而在弱碱性（pH9.0和pH8.0）及弱酸性（pH5.0和pH4.0）条件下总体上与对照差异不显著（P〉0.05）。随培养液pH值的增大（碱性增加）或减小（酸性增加），幼苗的最大根长和根系活力均逐渐降低；在弱碱性（pH8.0）和弱酸性（pH5.0）条件下，最大根长略小于对照、根系活力略大于对照，但差异均不显著；而在pH9.0-pH11.0及pH4.0-pH2.0条件下最大根长及根系活力均显著小于对照，其中，在pH11.0条件下根系最短、根系活力最小，分别仅为对照的60.50%和9.52%。研究结果揭示：香根草对环境酸碱性的适应范围较广，可适应pH4.0-pH9.0的土壤生境。

Effects of different pH values on seedling morphology and physiological characteristics of Vetiveria zizanioides under hydroponic culture

Under hydroponic culture with 1 / 2 Hoagland solution of pH 2. 0-pH 11. 0, seedling morphology, changes of some physiological indexes of leaf and root of Vetiveria zizanioides （Linn.） Nash were researched after cultured for 20 d. The results show that V. zizanioides seedling appears a part of leaves firing, stem withering, fibrous root number decreasing obviously and its length shortening under conditions of strong alkalinity （pH 11. 0 and pH 10. 0） and strong acidity （pH 2. 0 and pH 3. 0）, and the seedling only appears a part of leaf apexes with a little chlorosis and root morphology without obvious change except color under conditions of weak alkalinity （ pH 9. 0 and pH 8. 0） and weak acidity （pH 5. 0 and pH 4. 0）. With pH value of solution increasing （ alkalinity increasing） or decreasing （acidity increasing）, both leaf water content and chlorophyll content decrease gradually and are lower than those of the control （pH 6. 5）, while both relative electrolytic leakage and MDA content increase gradually and are higher than those of the control. In general, there are significant （P〈0. 05） differences in all indexes under conditions of strong alkalinity （pH 11. 0 and pH 10. 0） and strong acidity （pH 2. 0 and pH 3. 0） with the control, while generally without significant （P〉0. 05） difference in all indexes under conditions of weak alkalinity （pH 9. 0 and pH 8. 0） and weak acidity （pH 5. 0 and pH 4. 0） with the control. With pH value of solution increasing （ alkalinity increasing ） or decreasing （ acidity increasing）, both the maximum root length and root activity decrease gradually. Under conditions of weak alkalinity （pH 8. 0） and weak acidity （pH 5. 0）, the maximum root length is slightly lower than that of the control and root activity is slightly higher than that of the control without significant difference. Under pH 9. 0-pH 11. 0 and pH 4. 0-pH 2. 0, both the maximum root length and root activity are significantly lower than those of t