Effects Of LaCl₃ And COS On Physiological Characteristic Of Blueberry Seedlings

In this paper,four months old blueberry cutting seedlings were used as materials. Adopting the method of spraying leaf surface,the experiment was to study the effect of LaCl₃ and chito-oligosaccharide(COS) on the gas exchange parameters and the influence on such indicators as the relative conductivity,chlorophyll fluorescence and protective enzyme activities under low temperature stress at 0℃.The effects of LaCl₃ and COS on physiological characteristic and the mechanism in relieving the low temperature injury were elucidated, which could provide guidance for the safe use during cultivation and production.The results showed that 10-40mg/L LaCl₃ could significantly improve net photosynthetic rate,stomatal conductance,intercellular CO₂ concentrations,20-110 mg/L COS had no significant effects on the gas exchange parameters.LaCl₃ treatment with different concentration could significantly increase photosynthetic pigmen content and ch1a/ch1b, promote the activity of Ca²⁺ ATPase and Mg²⁺ ATPase in chloroplast membrane,which 20 mg/L(La20) treatment had the best effect.The values of various indexes showed that LaCl₃ and COS could decrease the relative conductivity of blueberry leaves under 0℃stress,in which 10-40 mg/L LaCl₃ had no significant effects and 50mg/L COS(COS50) had the best effect.The content of Chla,total chlorophyll,Car and chla/chlb were increased significantly,the increase amplitude of F_o,qNP and the decrease amplitude ofΦPSâ…¡,Fv/Fm,qP were decreased significantly with La20 and COS50.Moreover,La20 has better effect than COS50.Results indicated that the activity of SOD and POD were improved significantly,the content of proline and soluble sugar were increased significantly,while the accumulation of MDA were reduced with COS50. Moreover,the SOD activity was improved and the accumulation of MDA was reduced with La20,but there were no significant effects on the other indexes.Based on the results obtained,LaCl₃ could improve the photosynthetic of blueberry seedling;LaCl₃ and COS could reduce the damage of photosynthetic organs and membrane system,relieve the adverse effects of low temperature on physiological activities of blueberry promising cold resistant.Under low temperature stress,LaCl₃ had better effect on photosynthetic system and COS50 had better effect on inducing self defense.