Effect Of Light Intensity On Celery Growth And Main Study On The Influence Of Flavonoids

Light is a necessary prerequisite for crop growth,and suitable light intensity plays an important role in plant morphogenesis and nutrient accumulation.Therefore,it is of great significance to screen out the optimum light intensity for celery growth and accumulation of main flavonoids.In this study,the effects of different light intensities on the growth of celery,the distribution of basic nutrients in leaves and petioles,and the physiological mechanism of the accumulation of apigenin and anthocyanin,the main flavonoids,were studied by hydroponics.The main results are as follows:（1）The effects of light intensity(40μmol·m^-2·s^-1,100μmol·m^-2·s^-1,200μmol·m^-2·s^-1,300μmol·m^-2·s^-1)on red celery（HQ）and Bao Qin（BQ）were studied through hydroponic experiments.The results showed that with the increase of light intensity,the shoot growth of celery was promoted,but it was inhibited at 300μmol·m^-2·s^-1 compared with other treatments.The root growth of celery was inhibited at 40μmol·m^-2·s^-1,and the root dry weight decreased significantly,but the root length increased significantly.At 200μmol·m^-2·s^-1,the aboveground and underground growth and photosynthesis of celery were better than other treatments.Therefore,200μmol·m^-2·s^-1 is more beneficial to the morphogenesis and photosynthesis of celery.（2）Red celery（HQ）and Bao Qin（BQ）were used as materials to study the effects of light intensity on the basic nutrients in celery.The results showed that the nitrate content was the lowest at 300μmol·m^-2·s^-1,and the contents of five other nutrients were the highest at200μmol·m^-2·s^-1.At the same time,it was found that the contents of soluble sugar,soluble protein,total phenol and VC in celery leaves were higher than those in petioles,while the contents of nitrate and cellulose in leaves were lower than those in petioles.Therefore,200μmol·m^-2·s^-1 is the most helpful to promote the formation of basic nutrients in celery,and the nutritional quality of celery leaves is higher than that of petioles.（3）The effects of different light intensities and different periods（15 d,30 d and 45 d）on the contents of apigenin and anthocyanin were studied.The results showed that the content of apigenin in BQ leaves and petioles increased with the extension of cultivation time,but decreased with the extension of cultivation time in HQ,but the content was the highest at 200μmol·m^-2·s^-1.Anthocyanin content was not detected in leaves and petioles of BQ in three periods,but increased in leaves and petioles of HQ with the extension of cultivation time and the enhancement of light intensity.Therefore,the content of apigenin was the highest when BQ was treated at 200μmol·m^-2·s^-1 for 45 d,and the products containing higher apigenin and anthocyanin could be obtained when HQ was treated at 200μmol·m^-2·s^-1 for 30 d.（4）Enzyme-linked immunosorbent assay（ELISA）and q RT-PCR were used to analyze the activities of related enzymes and the related expressions of key genes during the biosynthesis of apigenin and anthocyanin at different light intensities and different periods.The results showed that with the increase of light intensity,the activities of phenylalanine ammonia-lyase（PAL）and anthocyanin synthase（ANS）increased,while the activities of chalcone synthase（CHS）,chalcone isomerase（CHI）and flavone synthase（FNS）were inhibited at 300μmol·m^-2·s^-1.The expression of Ag3GT,a key gene in anthocyanin synthesis,was positively correlated with light intensity in HQ,which increased anthocyanin content and ANS activity,but negatively correlated with light intensity in BQ,which decreased ANS activity.The expression of Ag FNS,a key gene in apigenin synthesis,increased with the increase of light intensity,but was inhibited at 300μmol·m^-2·s^-1.（5）The light intensity has different regulating factors on the content of apigenin and anthocyanin in celery.Through correlation and principal component analysis,the results showed that photosynthesis and enzyme activity were the main regulating factors of light intensity on apigenin content in celery leaves and petioles.The regulation factors of anthocyanin content in celery leaves and petioles are mainly photosynthesis and key gene expression.At the same time,the comprehensive evaluation found that 200μmol·m^-2·s^-1treatment was the most suitable for celery cultivation.