Physiological responses of flue-cured tobacco under the high chloride to chloride channel inhibitors
[Objectives] High Cl-content in soil is one of the main factors for high Cl-content in tobacco leaves,which plagues tobacco production in some tobacco-growing area of China.Studying the effect of Cl channel inhibitors on the physiological and biological indexes of flue-cured tobacco would provide reference for approaching reasonable way of relieving the adverse impaction in tobacco production.[Methods] Three Cl-inhibitors,Zn2+,NFA and 9-AC,were tested in a pot experiment,in which the used soil Cl-content was 50 mg/kg.All the three Cl-inhibitors were made into water solution of 200 μmol/L,each time irrigated 1 L per pot and consecutively for 3 days after the tobacco plants were transplanted for 30,45,60 and 75 days.The expression of CLC-Nt2 gene,photosynthetic pigments content,chlorophyll fluorescence parameters,the related elements accumulation and plant biomass were measured in maturing leaves.[Results] 1) There was no significant difference in the expressions of CLC-Nt2 gene in tobacco leaves among the Zn2+,NFA and 9-AC treatments,but they were all significantly lower than those in control,which were 82.22％,75.39％ and 72.19％ respectively.2)Inhibitor treatments could obviously raise the content of chlorophyll,with the increasing rate of 20.15％ (Zn2+),29.10％ (NFA) and 45.52％ (9-AC) separately compared with CK.The chlorophyll fluorescence in each treatment was higher than the control to a certain degree,which had remarkable benefit to decrease the damage of the PS Ⅱ photosynthetic apparatus in tobacco leaves.3) Compared with control,the leaf Cl-contents were significantly decreased by 18.17％～33.48％,while the K+ and NO3 were apparently increased by 5.28％-10.20％ and 12.19％-25.24％,with the best effect in 9-AC.4) Tobacco biomass were significantly affected by the use of inhibitors.Compared with CK,the dry weight of leaf,stem and the total biomass were significantly promoted and increased by 17.02％-32.45％,10.54％-20.66％ and 13.21％-25.50％,while the root dry weight increased only by 5.94％-11.43％.Therefore,the root-shoot ratio was comparatively lower.The biomass was showed in the order of 9-AC ＞ NFA ＞ Zn2+ ＞ CK.[Conclusions] Irrigation of chloride channel inhibitors can alleviate chloride damage to tobacco plants planted in soil with relatively higher Cl-content,because of the positive reactions to growth and physiological activities of flue-cured tobacco.200 μmol/L 9-AC shows the best performance in the experimental condition,200 μmol/L Zn2+ could meet the needs of reduction of chlorine ion in tobacco leaves with low cost in practice.
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