Exogenous Salicylic Acid and Sodium Molybdate Increased Cold Tolerance and the Related Mechanism in Bougainvillea glabra

In order to comprehensively evaluate the effect of salicylic acid and sodium molybdate treatments on the cold resistance and provide a theoretical guidance for the landscaping maintenance management,the garden ornamental plant Bougainvillea glabra was used as test materials. After the single and composite treatment of 0.5 mmol/L salicylic acid and 2.0 mol/L sodium molybdate, related physiological indexes were determined of the five different temperatures at -3,0,3,6,25℃.The results showed that salicylic acid and sodium molybdate treatments could be reduced to a different degree under the stress of low temperature leaf relative conductivity and MDA content of B. glabra, and compound treatment effect was better; at 20 and 6℃, oxygen free radicals produced rate increased with temperature decrease, but in 3, 0 and 3℃, a downward trend; at 0 and -3℃, salicylic acid treatment made SOD activity lower than the others; chemical treatment increased POD activity, especially at 0℃, POD activity of T1, T2, T3 was significantly higher than CK.In addition, under low temperature stress, soluble sugar, starch, proline contents appeared first increased and then decreased trend, soluble sugar at 3℃, starch and proline at 0 and -3℃, theirs contents were significantly higher than CK. By the comprehensive evaluation, it was found that the salicylic acid and sodium molybdate treatments could improve cold resistance of B. glabra, and especially the effect of composite treatment was better.