NaHCO3胁迫对紫根水葫芦形态学指标和光合参数的影响

Effects of NaHCO3 stress on morphological indices and photosynthetic parameters of purple root Eichhornia crassipes

关键词:  NaHCO₃胁迫, 紫根水葫芦, 形态学指标, 光合参数

Key words:  NaHCO₃ stress, purple root Eichhornia crassipes, morphological indices, photosynthetic parameters

摘要:

为研究NaHCO₃胁迫对紫根水葫芦的形态学指标及光合参数的影响,该文以紫根水葫芦为材料,采用不同浓度碱性盐NaHCO₃溶液处理成株紫根水葫芦,测定在NaHCO₃胁迫下紫根水葫芦的植株株高、根长、根冠比、生物量、含水量和光合参数[净光合速率(P_n)、胞间CO₂浓度(C_i)、蒸腾速率(T_r)、气孔导度(G_s)]。结果表明:紫根水葫芦在20 mmol·L^-1 NaHCO₃浓度下的水溶液pH值最为平缓; 在低浓度NaHCO₃溶液中(≤40 mmol·L^-1),相比CK,紫根水葫芦的形态学指标呈现增长或无显著影响情况,而在高浓度NaHCO₃溶液中(≥60 mmol·L^-1),随着NaHCO₃浓度的升高,紫根水葫芦形态学指标显著降低,且与NaHCO₃浓度呈负相关; NaHCO₃胁迫对紫根水葫芦的光合参数影响显著,随着NaHCO₃浓度的增加及试验处理时间的延长,紫根水葫芦的P_n呈持续下降的趋势,C_i、T_r和G_s整体呈上升趋势,其光合作用受到的主要是非气孔限制。综合分析显示,紫根水葫芦具有一定的耐NaHCO₃能力,能正常生存在不超过40 mmol·L^-1 NaHCO₃浓度的水体中,且能改善低NaHCO₃浓度下的水体pH值。

Abstract:

In order to study the effects of NaHCO₃ stress on the morphological indices and photosynthetic parameters of purple root Eichhornia crassipes, we used purple root E. crassipes as material, treated the adult purple root E. crassipes with different concentrations of the alkaline salt NaHCO₃ solution, and determined the morphological indices of purple root E. crassipes, including plant height, root length, root-shoot ratio, biomass, water content, and photosynthetic parameters of purple root E. crassipes, including net photosynthetic rate(P_n), intercellular CO₂ concentration(C_i), transpiration rate(T_r)and stomatal conductance(G_s). The results were as follows: The pH value of the water solution of purple root E. crassipes at 20 mmol·L^-1 NaHCO₃ concentration was the most gentle; In low concentration of alkaline salt NaHCO₃ solution(≤40 mmol·L^-1), compared with CK, the morphological indices of purple root E. crassipes showed an increase or no significant effect, while in high concentration alkaline salt NaHCO₃ solution(≥60 mmol·L^-1), with the increase of NaHCO₃ concentration, the morphological indices of purple root E. crassipes decreased significantly, and there was a negative correlation with the concentration of NaHCO₃; NaHCO₃ stress had a significant effect on the photosynthetic parameters of purple root E. crassipes, with the increase of the alkaline salt NaHCO₃ concentration and the extension of experimental treatment time, the P_n of purple root E. crassipes showed a continuously decrease trend, and C_i, T_r and G_s generally showed a continuously increase trend, and non-stomatal restriction was the main way to restrict photosynthesis in the purple root E. crassipes. Comprehensive analysis indicates that the purple root E. crassipes has a certain resistance to NaHCO₃, and the purple root E. crassipes can normally survive in water environment with an alkali concentration of no more than 40 mmol·L^-1 NaHCO₃, and the purple root E. crassipes can improve the pH value of water bodies in the low alkaline salt NaHCO₃ concentrations.