The Different Effect Of Na～+ And K～+ On Photosynthetic Activities In Rumex Leaves Under Iso-osmotic Stress

Rumex was used as a material in this study. Iso-osmotic stress was created by adding NaCl and KCl and PEG to culture solution. The effects of iso-osmotic solution of KCl and NaCl on Rumex were investigated by measuring and analyzing photosynthesis, chlorophyll fluorescence, oxygen-evolution, water potential, osmotic potential, proline , chlorophyll content and ion content in leaves of the Rumex. The effect of additon of Na⁺,Ca²⁺ on KCl stressed Rumex was also studied. The possible mechanisms of K⁺, Na⁺ and Ca²⁺ on salt stress were discussed and the main results are as follow:1.Effect of iso-osmotic NaCl and KCl stesses on PSII activities in Rumex leavesThe effects of salt treatment with different iso-osmotic NaCl and KCl (100-300mmol/L) on photosynthetic activity and osmotic adjustment in leaves of Rumex were studied. The results showed that the maximum PSII photochemistry, the actual PSII photochemistry, the CO2 assimilation rate, the stomatal conductance , the oxygen evolution, the PIabs,PIcso,PIcsm,ET0/RC and chlorophyll content were all increased slightly with the treatment of <100mmol/L iso-osmotic NaCl and KCl, , which indicated that Rumex is a kinds of salt-tolerant plants.But Rumex were damaged when the concentration of NaCl and KCl solution above 100mmol/L.The inhibition of the photosynthetic activities in Rumex leaves caused by KCl stress was slighter than that caused by NaCl stress under the concentration of 200mmol/L. However, the inhibition caused by KCl stress was more severer than that caused by NaCl under concentration of 300mmol/L.The Na⁺ content was decreased in the 300mmol/L KCl stressed Rumex leaves, but both the Na⁺ content and the K⁺ content kept in a high level when treated with the 300 mmol/L NaCl.The results indicated that the increased...