Effect Of Stevia As Rootstock On The Growth, Development And Quality Of Chrysanthemum

Chrysanthemum(Chrysanthemum morifolium Ramat.)is one of the top ten traditional flowers in China and one of the top four cut flowers in the world.It has been cultivated in China for more than 3,000 years,and in addition to its ornamental and cultural values,it also has medicinal,edible and tea values.In recent years,people pay more and more attention to health,the market demand for tea chrysanthemum gradually increased,with the growing cultivation area of tea chrysanthemum,the accumulation of planting years,seed degradation and other factors lead to the decline of the yield and quality of tea chrysanthemum,sweetness is poor,flavonoids,amino acids and other nutrients content is low,it is difficult to meet the growing demand for tea chrysanthemum high quality.Changes in the market and demand.And stevia(Stevia rebaudiana Hemsl.)is a low-calorie,high-sweetness natural sugar crop whose leaves are rich in steviosides(SGs),flavonoids,amino acids,chlorogenic acid and other nutrients,and are widely used in edible and medicinal applications.If the sweet stevioside in stevia can be introduced into Camellia sinensis through grafting to increase the sweetness and improve the nutritional quality of camellia sinensis,it is of great significance for the sustainable development of camellia sinensis industry.Therefore,in this study,we selected the resistant and sweet stevia ’Shoutian No.3’ as rootstock and the tea chrysanthemum ’Jinsihuangju’ and ’Hangbaiju’ as scion for grafting between plants of different families.After grafting,the plant morphology,leaf chlorophyll content,soluble sugar content,soluble protein content,antioxidant enzyme activity,and endogenous hormone content of tea chrysanthemum grafted seedlings and cuttings were measured separately;the stevioside content of grafted tea chrysanthemum leaves and flowers were measured and analyzed.The results of the study were combined with the results of nutrient content(flavonoids,total phenols,chlorogenic acid,amino acids,VC)of grafted tea chrysanthemum seedlings to investigate the effect of stevia as rootstock on the nutritional quality of tea chrysanthemum.The main results of the study are as follows.1.Effect of stevia rootstock on the survival rate of tea-use chrysanthemumThe total survival rate of grafted ’Jinsihuangju’ ranged from 29.00% to 41.67%.41.67% of the grafted plants survived on May 1(J/T1),41.33% on May 8(J/T2),35.67% on May 15(J/T3),41.33% on May 22(J/ T4)was 41.33%,29.00% on May 29(J/T5)and 34.67% on June 5(J/T6),with the highest survival rate of ’Jinsihunagju’(J/T1)grafted on May 1.The total survival rate of grafted ’Hangbaiju’ ranged from 20.67% to 25.33%.24.67%survived on May 1(H/T1),25.33% on May 8(H/T2),20.67% on May 15(H/T3)and 21.67%on May 22(H/T4).The survival rate was 21.67%,24.00% on May 29(H/T5),and 24.33% on June 5(H/T6),with the highest survival rate of ’Hangbaiju’(H/T2)grafted on May 8.2.Effect of stevia rootstock on the morphological index of tea-use chrysanthemumThe plant height,stem thickness,crown width and number of branches of the grafted tea chrysanthemums were significantly reduced compared with the control,in which the grafted seedlings of ’Jinsihuangju’ were more significantly affected by the rootstock stevia than the grafted seedlings of ’Hangbaiju’.With the delay of grafting time,the decrease of height and crown width of grafted seedlings decreased.The inflorescence diameter size of grafted ’Jinsihuangju’ did not change significantly,and the flower diameter of grafted seedlings of ’Hangbaiju’ decreased significantly.Meanwhile,this study also found that stevia rootstocks could delay the flowering period of tea chrysanthemums,and the flowering period of ’Jinsihuangju’ grafted seedlings was 4-14 d later than the control.The flowering stage of ’Hangbaiju’ grafted seedlings were 2-14 d later than the control,respectively.3.Effect of stevia rootstock on on chlorophyll,soluble sugar and soluble protein content in leaves of tea-use chrysanthemumAfter grafting,the leaf chlorophyll,soluble sugar and soluble protein contents of grafted seedlings of Chrysanthemum for tea increased significantly.The leaf chlorophyll content of’Jinsihuangju’ grafted seedlings increased by 8.25%～15.16%,soluble sugar content increased by 41.98%～66.29% and soluble protein content increased by 34.88%～52.41%.The chlorophyll content of leaves of grafted seedlings of ’Hangbaiju’ increased by 28.08%～40.31%,and the soluble sugar and soluble protein increased by 22.24%～39.86% and 23.60%～50.31%,respectively.Among them,J/T1,J/T2,H/T1 and H/T2 had the highest chlorophyll,soluble sugar and soluble protein contents among all grafted chrysanthemums.4.Dynamic changes of antioxidant enzyme activities of tea chrysanthemum grafted for 28dThe SOD activity of grafted seedlings of ’Jinsihuangju’ showed a rising-declining-rising trend within 28 d of grafting;the POD activity showed a rising and then declining trend,and reached the peak at 21 d of grafting;the CAT activity showed an "M" trend.The SOD and CAT activities of grafted seedlings of ’Hangbaiju’ showed an "M" trend within 28 d of grafting,and the POD activity showed an upward and then downward trend,and reached the peak at 21 d of grafting.5、Dynamic changes of endogenous hormone content of tea chrysanthemum grafted for28 dThe IAA content of the grafted seedlings of ’Jinsihuangju’ showed a decreasing-risingdecreasing trend within 28 d of grafting,with a trough value at 7 d of grafting and a peak value at 21 d of grafting;the ABA content reached a peak value at 7 d of grafting,and then declined rapidly;The overall GA3 content showed a "W" trend,which was at the trough on the 7th and21 st d of grafting and at the peak on the 14 th d.The ZR content showed a rising and then declining trend and reached the peak on the 14 th d of grafting.The trends of IAA,ABA,GA3 and ZR contents of leaves of ’Hangbaiju’ grafted seedlings were the same as those of’Jinsihuangju’ grafted seedlings.6、The effect of stevia rootstock on the content of steviol glycosides(RA and ST)of Camomile for teaThe leaves and flowers of grafted Camomile contain stevioside A(RA)and stevioside(ST),the main components of SGs,among which the leaves of grafted seedlings of’Jinsihuangju’ contain 0.21%～0.29% of RA and The RA and STV contents of the grafted seedling leaves of ’Hangbaiju’ ranged from 0.12% to 0.18% and 0.05% to 0.09%,respectively.Among the six grafted seedlings of ’Jinsihuangju’,the flowers of J/T1,J/T2 and J/T3 contained0.01%～0.03% of RA and about 0.01% of ST.Among the six grafted seedlings of ’Hangbaiju’,the flowers of H/T2 and H/T4 contained about 0.01% of RA and about 0.01% of ST.7.Effect of stevia rootstock on the nutritional quality of tea-use chrysanthemumStevia rebaudiana as rootstock increased the flavonoids,total phenols and chlorogenic acid content of chrysanthemum flowers for tea,and reduced the formation of amino acids and VC.The flavonoids,total phenols and chlorogenic acid in the flowers of grafted seedlings of’Jinsihuangju’ increased by 6.49%～9.63%,0.25%～1.19% and 2.42%～6.94%,respectively,and the amino acid and VC contents decreased by 5.57%～9.45% and 12.57%～14.70%.The flavonoids,total phenols and chlorogenic acid contents of flowers of grafted seedlings of’Hangbaiju’ increased by 5.45%～6.68%,0.29%～0.80% and 2.04%～5.13%,respectively,while amino acid and VC contents decreased by 2.53%～6.48% and 3.50%～6.35%.The results of the above study showed that the sweetness and nutritional quality of Stevia rebaudiana were superior compared with cuttings when grafted onto Stevia rebaudiana as rootstock.