Abstract:

Objective: This study aims to investigate the differences in wax content and composition in pericarp at various picking periods, and explore the relationship between meteorological factors and wax accumulation in pericarp of Lycium barbarum during different picking periods, in order to provide a theoretical basis for the selection of suitable drying methods for different picking periods. Method: The fruits of L. barbarum ‘Ningqi No. 1’ and L. barbarum ‘Ningqi No. 5’ in three picking periods (old eye branch period, seven-inch branch period and autumn fruit period) were used as materials. GC-MS technology was used to measure and analyze the wax content and components. The meteorological factors in different picking periods were monitored by JL-18 air temperature, humidity and light recorder. The relationship between wax content and components in pericarp and meteorological factors was analyzed by regression analysis. Result: 1)There were significant differences in fruit wax content between the two L. barbarum varieties during the three picking periods of green fruit stage, color change stage and red fruit stage. The wax content of the fruit at the red fruit stage was significantly different from that at the green fruit stage and color change stage. However, the difference in wax content between green stage fruit stage and color change stage was not significant. 2) The wax composition analysis showed that the wax of ‘Ningqi No.1’ peel was mainly composed of hexacosane, octacosane, 1-iodoctacosane, 1-iodotriacontane, docosanol and β-amyrin, while the wax of ‘Ningqi No. 5’ peel was mainly composed of hexacosane, heptacosane, 1-iodoctacosane, 1-iodotriacontane, docosanol and 2-hexyl-1-decanol. 3) During the old eye branch period, the peel wax content of the two cultivars was significantly negatively correlated with light intensity, with correlation coefficients of ?0.759 (P<0.05) and ?0.838 (P<0.01). For ‘Ningqi No.1’, esters were significantly negatively correlated with daily average temperature, with a correlation coefficient of ?0.712. For ‘Ningqi No.5’, acids and esters were significantly positively correlated with daily average humidity, with correlation coefficients of 0.728 (P<0.05) and 0.739 (P<0.05), ketones were significantly positively correlated with night average temperature, and significantly negatively correlated with light intensity, with correlation coefficients of 0.717 (P<0.01) and -0.649 (P<0.05), alkanes were significantly negatively correlated with daily average humidity and night average temperature, with correlation coefficients of ?0.772 (P<0.01) and 0.637 (P<0.05), iodinated alkanes were significantly positively correlated with night average humidity, with the correlation coefficient of 0.820 (P<0.01). During the seven-inch branch period, for ‘Ningqi No.1’, the alkanes were significantly positively correlated with the average night temperature, with the correlation coefficient of 0.779 (P<0.05), the iodinated alkanes were significantly negatively correlated with the average daily temperature, with the correlation coefficient of -0.724 (P<0.05), the acids were significantly negatively correlated with the average daily humidity, with the correlation coefficient of -0.680. For ‘Ningqi No.5’, the wax content was significantly positively correlated with night average humidity and light intensity, with the correlation coefficients of 0.795 (P<0.01) and 0.748 (P<0.01), the ketones and iodoalkanes were significantly negatively correlated with daily average temperature, with the correlation coefficients of -0.887 (P<0.01) and -0.749. During the autumn fruit period, for ‘Ningqi No.1’, the alkanes and iodoalkanes were significantly positively correlated with night average temperature, with correlation coefficients of 0.887 (P<0.01) and 0.767 (P<0.05). Conclusion: The meteorological factors during different picking periods have differents effects on wax content and components. Temperature is mainly related to the accumulation of iodoalkanes, ketones and alkanes. Humidity is related to the accumulation of esters, acids and alkanes. Light intensity is related to the accumulation of esters and alcohols. The results provide a theoretical basis for the suitable dewaxing agent pretreatment in the drying of L. barbarum fruits at different picking periods.

Key words: Lycium barbarum, different picking stages, wax accumulation, wax component, meteorological factors