Effect of Exogenous Salicylic Acid on the Physiological and Biochemical Processes of Ligustrum lucidum during Natural Cold Acclimation

Abstract

The evergreen Ligustrum lucidum (glossy privet) suffers from freezing injury in northern China, where there are short growing seasons and early fall frost events. To investigate the influence of exogenous salicylic acid (SA) application on the natural cold acclimation of glossy privet, physiological and biochemical changes in glossy privet seedlings subjected to SA treatments at four concentrations (0, 150, 250, and 350 mg·L−1) were evaluated from Sept. to Dec. 2016. The optimum application concentrations were between 250 and 350 mg·L−1, which led to better freezing tolerance during natural cold acclimation. The improved freezing tolerance under exogenous SA application was associated with the accumulation of chlorophyll, proline, soluble protein, and soluble sugar, and the regulations of gibberellic acid (GA) and abscisic acid (ABA). Salicylic acid treatments started a cascade of steps for advancing the cold acclimation process of glossy privet. We suggest that exogenous SA application may be used on glossy privet grown in northern China.