Abstract:
【Objective】 To explore the residual digestion patterns of different plant growth regulators such as gibberellic acid (GA
3), brassinolide (BR), and thidiazuron (TDZ) on jujube and their effects on fruit flavonoids and phenolic compounds in the hope of providing a theoretical basis for the scientific and standardized use of some plant growth regulators.
【Methods】 18 g/hm
2 and 36 g/hm
2 GA
3 were applied by foliar spray at the full bloom stage of jujube, and they were sprayed simultaneously with BR (45 mg/hm
2) and TDZ (1.8 mg/hm
2). Meanwhile, ultra-high performance liquid chromatography tandem mass spectrometry were used to determine the residual levels of GA
3 and TDZ in leaves after application, and analyzed the changes in flavonoid and phenolic acid content in fruits based on extensive targeted metabolomics analysis.
【Results】 The residual amounts of GA
3 at two kinds of doses on junjube were 0.10 mg/kg and 0.20 mg/kg, respectively, 14 days after application. The residual amount of TDZ was 0.01 mg/kg, which was lower than the MRL value. The digestion rates of GA
3 and TDZ on junjube were both above 90%. The half-lives of the two doses of GA
3 were 3.73 days and 4.26 days, respectively, while the half-lives of TDZ was 1.63 days. After treatment with GA
3, BR, and TDZ, the flavonoid compounds such as catechin gallate, epicatechin gallate, isoquercetin, rutin, and quercetin in junjube fruit were upregulated; Phenolic acid compounds such as benzoic acid, phenyl salicylate, phenylethyl caffeic acid, cinnamic acid were upregulated, too.
【Conclusion】 GA
3 and TDZ degrade rapidly on junjube, and the application of appropriate amounts of GA
3, BR, and TDZ helps to increase the content of flavonoids and phenolic acids in the fruit.