Natural cold acclimation of Ligustrum lucidum in response to exogenous application of paclobutrazol in Beijing

Abstract

To investigate the influence of exogenous paclobutrazol (PBZ) application on the natural cold acclimation of Ligustrum lucidum, 1-year-old L. lucidum seedlings were conducted with PBZ at four concentrations (0, 100, 300, and 500 mg L−1) from September to December 2016, and leaves were collected to measure physiological and biochemical parameters. Results showed that 500 mg L−1 was the optimum concentration, which led to stronger freezing tolerance during natural cold acclimation. The enhanced freezing tolerance induced by exogenous PBZ application was attributed to the accumulation of chlorophyll, proline, soluble protein, and soluble sugar, and the regulation of gibberellic acid and abscisic acid. PBZ treatments initiated a cascade of steps for advancing the cold acclimation of L. lucidum. It appears that exogenous PBZ application may be applied to L. lucidum grown in northern China, where the growing periods are short and there are early fall frost events and low mid-winter temperatures.