Effect Of Salt Stress On Photosynthesis Of Lonicera Japonica Thunb. And Quality Of Flos Lonicerae

Objective:To analysis the effect of salt stress on photosynthetic parameters including net photosynthetic rate, stomatal conductance, intercellular CO2 concentration, transpiration rate of Lonicera japonica var. chinensis and Lonicera japonica Thunb. and on quality of Flos Lonicerae. To discuss the decisive stress factor affecting the photosynthesis of Lonicera japonica Thunb., and provide theoretical basis for Lonicera japonica Thunb. cultivation in salt-affected soil.Methods:Using Na Cl solution、neutral salt solution(Na Cl:Na2SO4)、alkaline salt solution(Na HCO3:Na2CO3) and mixed salt solution(Na Cl、Na2SO4、Na HCO3、Na2CO3) to culture the Lonicera japonica var. chinensis and Lonicera japonica Thunb. young cutting plants. The photosynthetic parameters were determined by photosynthetic apparatus. The effect of salt stress on photosynthesis of Lonicera japonica var. chinensis and Lonicera japonica Thunb. were evaluated with variance analysis, correlation analysis, stepwise regression analysis. Ten active components(loganin, rutin, green original acid, chlorogenic acid, implicit chlorogenic acid, luteolin, caffeic acid, isochlorogenic acid B, isochlorogenic acid A and isochlorogenic acid C) were determined by HPLC.Results:(1)The net photosynthetic rate of Lonicera japonica var. chinensis treated with 0.1% and 0.3% Na Cl solution were higher than that of control, the net photosynthetic rate of Lonicera japonica Thunb. treated with 0.3% Na Cl solution was lower than that of control in the fourth day. The active components in Flos Lonicerae were the highest under 0.5 % Na Cl solution treated.(2)The net photosynthetic rate of Lonicera japonica Thunb. rised first, then declined along with the increasing concentration of neutral salt solution and alkaline salt solution. The photosynthesis of Lonicera japonica Thunb. showed the highest under the condition of 15 mmol·L-1 neutral salt solution and 5 mmol · L-1 alkaline salt solution. The flavonoids accumulation first raised then declined along with the increasing concentration of neutral salt solution. The neutral salt stress and alkaline salt stress are not good for flavonoids accumulation in Flos Lonicerae. Under the condition of 12.5、25、50 mmol·L-1 neutral salt solution, the content of loganin was significantly higher than that of the control group, while the content of loganin for the other treatment group were lower than that of the control. The accumulation of phenolic acids first decreased then increased along with the increasing neutral salt concentration, while first increased then decreased under the condition of alkaline salt stress, and for each treatment, the phenolic acids contents was lower than that of the control.(3)Correlation analysis and regression analysis showed that the salinity, p H and buffer capacity were the three major stress factors, and salinity was the main factor inhibiting the photosynthesis of Lonicera japonica Thunb.. p H became the secondary factors affected the photosynthesis of Lonicera japonica Thunb., along with the extension of stress time.Conclusions:Under Na Cl stress condition, the salt resistance of Lonicera japonica var. chinensis was higher than that of Lonicera japonica Thunb.. The active components in Flos Lonicerae were the highest under 0.5 % Na Cl solution treated. The neutral salt stress and alkaline salt stress are not good for flavonoids accumulation in Flos Lonicerae, and suitable salt concentration is beneficial to the accumulation of cyclic iridoid glycoside components, high concentration of neutral salt stress was conducive to the accumulation of phenolic acids, alkaline salt stress was not conducive to the accumulation of phenolic acids. Under the mixed salt stress, salinity as the decisive factor affecting the photosynthesis of Lonicera japonica Thunb.