Abstract:

Paclobutrazol(PP₃₃₃)is a gibberellin inhibitor that can regulate plant physiological processes and enhance their stress tolerance.In order to investigate the physiological responses of Corethrodendron fruticosum seedlings to PP₃₃₃,potted method was used to study the effects of root inoculated PP₃₃₃ with different mass concentrations(150,300,450,and 600 mg/L)on photosynthesis,antioxidant and osmotic regulation abilities of C.fruticosum seedlings.The results showed that root irrigation treatment with 150~600 mg/L mass concentration of PP₃₃₃ improved photosynthesis,antioxidant and osmotic regulation abilities of C.fruticosum seedlings.With the increase of PP₃₃₃ mass concentration,the photosynthetic gas exchange parameters such as net photosynthetic rate(P_n),transpiration rate (T_r),stomatal conductance(G_s),photosynthetic pigment content,antioxidant enzyme activity and osmotic adjustment substances of C.fruticosum seedlings showed a trend of increasing first and then decreasing,and decreased after reaching the optimal inflection point under the treatment of 450 mg/L PP₃₃₃,while intercellular CO₂ mole fraction(C_i)and malondialdehyde content(MDA)showed the opposite trend under the same conditions.In conclusion,root irrigation treatment with 150~600 mg/L mass concentration of PP₃₃₃ could improve photosynthesis,plasma membrane protection and antioxidant capacity,accumulate osmotic substances,and enhance the stress resistance of C.fruticosum seedlings by alleviating non-stomatal photosynthesis and reducing the accumulation of membrane lipid peroxidation products on C.fruticosum seedlings,450 mg/L of PP₃₃₃ root irrigation treatment showed the best effect.

Key words: Corethrodendron fruticosum seedlings, paclobutrazol(PP₃₃₃), physiological characteristics, stress resistance