Effects Of Exogenous GA₃ On Growth And Medicinal Components Of Densely Planting Young Phellodendron Chinense Schneid

Phellodendron chinense Schneid(PC)is one of the three species of woody medicinal plants in China.Its dried bark is Cortex phellodendri,one of traditional Chinese medicinal material.At present,artificial plantation is its mainly way of cultivation,but with a long utilization cycle.Here,it is found that,in the early experiment,exogenous GA3 had a greater effect on the content of the main medicinal components in seedlings of PC by laboratory personnel.On this basis,1-5-year-old densely planting PC was used as the research material,and the influence and regularity of exogenous GA3 on their growth,physiology and medicinal components,as well as the accumulation rule of medicinal components were systematically studied in this paper.And the feasibility of using the densely planting young PC to form effective resources was explored.The results appear as shown below:1.According to the growth of plant height and ground diameter of 1-year-old densely planting PC after 5 months continuous treating(September),the optimal treatment was selected as follows:spraying 100 mg·L-1 GA3 every 10 days(GA3-10-100),its plant height and ground diameter in September were 156.76 cm and 14.33 mm,respectively,which were increased by 40.44%and 20.65%compared with the control,with significant differences in plant height(P<0.05).GA3-10-100 had the highest absolute growth and multiple of plant height and ground diameter(compared with September and April),150.68 cm and 12.89 mm,24.79 and 8.99 times respectively.Three high concentrations of GA3-10-200,GA3-30-200 and GA3-60-200 also promoted the growth obviously.In the next year,the best GA3 treatment was used in the experiment of 1-year-old and 2-year-old densely planting PC after adjusting the density.After 1 months continuous treating,the plant height,ground diameter and stem fresh weight of the 1-year-old GA3 treatment increased by 19.49%,25.40%and 80.67%respectively compared with the control(P<0.05).After 3 months continuous treating,aboveground fresh weight,leaf fresh weight and bark fresh weight of the 2-year-old GA3 treatment by 15.43%,38.07%and 28.09%,respectively,with significant differences compared with control(P<0.05),and the diameters of the middle and lower parts also increased to some extent.2.The content of soluble sugar and protein in the leaves of the 1-year-old densely planting PC was increased by exogenous GA3 from May to July.Their content was positively correlated with the spraying concentration and negatively correlated with the spraying period in May before the PC was not closed,but no obvious regularity after the canopy.Otherwise,the content and activity of osmoregulation substance(soluble sugar and protein)and antioxidant index(SOD,POD,CAT and GSH)in the leaves of PC that under water and high temperature and drought stress were increased by exogenous GA3.3.The best GA3 spraying increased the content of medicinal components in 1-year-old densely planting PC and most parts of 2-year-old densely planting PC,which was positively related to its effect on promoting the growth of different parts of tree diameter.In addition,exogenous GA3 had no effect on the distribution of medicinal components in the whole plant.Among them,the content of the medicinal components in the main root bark and the basal stem bark of the 1-year-old plants sprayed with GA3 was higher than that of the control,and GA3 spraying increased the expression level of the gene THBO in the basal stem bark of the 1-year-old densely planting PC.The content of medicinal components in the main root bark,lateral root bark,basal stem bark,middle stem bark and top stem bark of the two-year-old plants sprayed with GA3 was higher than that of control.There was significant difference between lateral root bark and middle stem bark(P<0.05).The content of Phellodendrine-Berberine in lateral root bark treated with GA3 was 4.16-41.02 mg/g,29.60%and 28.51%higher than that of the control,and that in middle Stem bark was 4.64-39.03 mg/g,18.07%and 15.64%higher than that of the control.The 2-year-old PC that began to form bark yield,its contents of medicinal components were as follows:Main root bark>Basal Stem bark>Middle Stem bark>Lateral root bark>Upper Stem bark>Top Stem bark.And the contents of medicinal components of the bark below the middle part met the standards of Phellodendrine≥3.4 mg/g and berberine≥30 mg/g.And the content of the medicinal components decreases upward along the main stem.In different years of PC,the accumulation of medicinal components in the early(1-year-old)is faster,and later(4-year-old and 5-year-old)is slower.The accumulation of the medicinal components in branch bark was similar to that in the stem bark,it is higher at basal and lower gradually upward.Generally,the content of medicinal components increases with the diameter of branches and growth year.In all parts of PC,the accumulation of berberine is faster than that of Phellodendrine.In conclusion,exogenous GA3 can effectively promote the growth of the densely planting young PC,improve the adaptability to the environment,enhance the content of the medicinal ingredients in the medicinal parts,shorten the time for PC to reach the standard of medicinal ingredients,which provides scientific and technology basis for the densely planting young PC to become a medicinal resource.