Effects Of Na₂SeO₃ On Physiological And Photosynthetic Characteristics Of Grape Under NaCl Stress

Objective: To investigate the effects of Na₂SeO₃ on physiological and photosynthetic characteristics of “Huozhouheiyu” grape under NaCl stress and provide a theoretical basis for the production practices. Method:The two-year cutting seedlings of “Huozhouheiyu” grape cultured in nutrient solution were used as experimental material. Then they were treated with NaCl at 4g/L and Na₂SeO₃ of three concentrations. When the height of grapevines was about 50 cm, stem diameter, plant height, free water, bound water, relative conductivity, MDA content, soluble sugar content, proline content and protein content were measured on the day before treatment and on the 4, 8, 12 day after treatment. Then chlorophyll content, chlorophyll fluorescence parameters, gas exchange parameters, SOD activity, POD activity and CAT activity were measured on the 12 day after treatment. Result:（1） With increasing concentration of Na₂SeO₃, plant height and stem diameter of “Huozhouheiyu” firstly increased and then decreased.（2） With increasing concentration of Na₂SeO₃, bound water, soluble sugar content, proline content and protein content in leaves of “Huozhouheiyu” firstly increased and then decreased, but free water, free water/bound water, relative conductivity and MDA content in leaves of “Huozhouheiyu” firstly decreased and then increased. With the increase of processing time, free water firstly decreased and then increased, and free water/bound water gradually decreased. While relative conductivity and MDA content firstly increased and then decreased, and bound water, soluble sugar content, proline content and protein content gradually increased.（3） With increasing concentration of Na₂SeO₃, net photosynthetic rate（Pn）, stomatic conductance（Gs）, transpiration rate（Tr）, water use efficiency（WUE）, maximum photochemical efficiency of photosystem Ⅱ（PSⅡ）（Fv/Fm）, actual photochemical efficiency of photosystem Ⅱ（PSⅡ）（ФPSⅡ）, PS Ⅱ potential activity（Fv/Fo）, SOD activity, POD activity and CAT activity in leaves of “Huozhouheiyu” firstly increased and then decreased, while intercellular CO2 concentration（Ci）, stomatal limitation value（Ls） and non-photochemical quenching（NPQ） in leaves of “Huozhouheiyu” firstly decreased and then increased.（4） All values reached the extreme value at Na₂SeO₃ concentration of 10 mg/L. Conclusion:The treatment at Na₂SeO₃ 5-10 mg/L alleviated NaCl stress in grape and the optimal Na₂SeO₃ treatment was 10 mg/L Na₂SeO₃.