| In this study,two varieties of tea plants,Baicha and Zhirenzaocha were tested for their tolerance to aluminum(Al) and fluorine(F) interaction.Hydroponic culture experiments were carried out to characterize the mechanism on quality and physiology by means of a series of chemical and biochemical methods.The major results were summarized as follows:1.The spectra of root,stem,leaf of tea plants(Camellia sinensis L.) with 0,30,90 mg·L-1Al3+ and 0,4,12 mg·L-1F interaction was determined by Fourier Transform Infrared (FTIR) spectrometry with OMNI-sampler directly,fast and accurately.Results from the comparison of the spectra showed some differences in their FTIR spectra among root,stem and leaf of tea plants.Moreover,the results showed that the FTIR spectra of Zhirenzaocha indicated much more observable differences than Baicha with different concentrations of Al and F interaction,comparing with their spectra,implying Zhirenzaocha was evidently affected, especially.Little difference was found between the spectra of control leaves of two tea plants, except the indices of wave number-absorbance from 928 cm-1 to 1200 cm-1,and similar results were also observed in stem and root samples of two tea plants.Compared with Zhirenzaocha,the intensity and the shape of absorption peaks of root of Baicha were higher under Al alone.The same results were to stem under F alone and to leaves under Al and F interaction.It suggested that the material metabolize of root,stem and leaf of tea plants produce some distinguishable differences under Al and F alone or Al and F interaction. Meanwhile,Baicha got maximum absorbance with 12 mg·L-1 F and Zhirenzaocha reached the peak absorbance with 4 mg·L-1 F at wave number of 1034,1519,1645 and 3351 cm-1, representing that F stress alone was more relativity than Al alone on increase of protein, amino acids and so on.Further,the figures of FTIR proved there is a critical problem of endurance of tea plants to Al and F interaction stress.2.After 30 d in hydroponic culture,the contents of polyphenols,caffine,free amino acids,vitamin C and chlorophyll in tea leaves were increased with 30 mg·L-1 Al alone.But when the concentration of Al was 90 mg·L-1,the contents of above components in tea leaves were decreased.These components in tea leaves increased under the treatment of 4 mg·L-1 F alone and decreased with treatment of 12 mg·L-1 F alone.In the process of Al and F interaction,the contents of these components in tea leaves of Baicha enhanced when the ratios of Al/F were 30/4,30/12,90/4 and 90/12.However,Zhirenzaocha reduced.The results showed that tea quality improved in low concentration of Al and F alone stress.Meanwhile, the variance effect of interaction was correlated to different proportion of Al/F,which played different impact on Baicha and Zhirenzaocha indicating there existed a varietal difference.3.RA in roots and the activity of SOD in leaves were enhanced with 30 mg·L-1 of Al alone,but MP and activity of POD and CAT in leaves declined.When the concentration of F alone was 4 mg·L-1 and 12 mg·L-1,enzymes of tea leaves increased and MP and RA in roots decrease compared with control(0 mg·L-1 Al and 0 mg·L-1 F),all which implied 30 mg·L-1 Al alone and 4 mg·L-1 F alone were not the optimum concentration.RA,content of Pro and activity of POD,CAT and SOD were lower under high Al and low F interaction compared with 90 mg·L-1Al alone.Maybe Al and F cooperated with each other during growth of tea plants.When proportion of Al and F were from 30/4 to 30/12,activity of POD,CAT and SOD showed an obvious upward tendency,as was inferred that the range of proportion strengthened the ability of reactive oxygen species(ROS) scavenging.In comparison with control,activity of POD,CAT and SOD of tea plants increased,but MP and RA fell under high Al and high F interaction,indicating that tea plants injured in some degree.Therefore,Al and F interaction has a significant effect on physiological and biochemical characteristics of young tea plants,and the proportion of interaction exist some range.The sensibilities between Baicha and Zhirenzaocha are different resulting from Al and F interaction and order is Zhirenzaocha＞Baicha,which is suggested that there may be correlation with variety.4.The values of maximum fluorescence(Fm),PSII maximum fluorescence efficiency (Fv/Fm) and photochemical quench(qP) for Zhirenzaocha were higher than Baicha. Compared with control,qP and the PSII actual fluorescence efficiency(ΦPSII) of tea plants increased under 30 mg·L-1 Al alone.With the concentration of Al was up to 90 mg·L-1, Minimal fluorescence(Fo) and Fm of Baicha and qP and Fm of Zhirenzaocha appeared the lower values than control.At the same time,these indexes except non-photochemical quench (qN) for Zhirenzaocha with 4 mg·L-1 F alone were all below control.Fo,Fm,qP and qN of Zhirenzaocha displayed descending trend with the increasing of concentration of Al.But all same indexes of Baicha showed a robust negative relation.It suggested that low concentration of Al and F alone was advantage to protect or alleviate PSII photosystem from the damage of surplus of light energy.When the concentration of Al and F interaction was low,the values of Fo,Fm,Fv/Fm,qP andΦPSII of Baicha were higher than that of 4 mg·L-1 F alone.Fo,Fv/Fm andΦPSII of tea plants still increased under the concentration of Al increasing,which implied the two ratios of F/Al resulted in augment of membrane lipid peroxidation,but couldn't induce the dead of tea leaves.When the ratio of F/Al was from 12/30 to 12/90,the values of Fm,Fv/Fm,qP and qN showed a descending trend for tea plants,which revealed the effects increased with increasing Al concentration,reducing the ability of elimination of active oxygen and damaging PSII in degree.5.In the study about addition of phosphate(P) under Al and F interaction,compared with the four non-P treatments,an obvious upward tendency of soluble protein,chlorophyll and polyphenol contents and SOD,POD and CAT activity was observed in the treatment of 0.2 mmol/L P under Al or F alone.Meanwhile these indexes reached maximum values except content of chlorophyll under 5.0 mmol·L-1 Al and 1.0 mmol/L F interaction for Zhirenzaocha. This suggested proper concentration of P can weaken oxidative injury-caused by Al and/or F and inhibit lipid peroxides by increasing antioxidative enzyme activities.With the increasing concentrations of P,the soluble protein,chlorophyll and polyphenol content and SOD,POD, CAT activities were all fell to the minimum level,which were all below non-P and control. The fact that the treatment of 1.0 mmol·L-1 P can not alleviated the toxonosis-caused by Al and F interaction implies detoxication depended on concentration of P and beyond the concentration range,it restrains detoxication.The sensibilities between Baicha and Zhirenzaocha according to the P stress were differed and order was sorted as follows: Zhirenzaocha＞Baicha.Therefore,the concentration of P plays a high impact on physiological and biochemical characteristics of young tea plants and detoxication of P is associated with variety under Al and F interaction. |
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