Selection Of Factors Affecting The Survival Rate Of Grafted Rose Cuttings

Rosa hybrida is one of the most popular flowers in the world and has a high ornamental value.Market value of modern roses is not limited for using it as cut flowers,potted plants,and landscaping plants,but it is also be processed into flower cakes,fragrant dried flowers,cosmetics and medicinal products.By virtue of huge market demand,a huge number of seedlings are needed for production.As a new method of reproduction,the rootless grafting technology not only have the advantages of grafting and cuttings at the same time,but also save labor load and reduce production costs.Although the rootless grafting technology of rose has been applied in production,there is still a lack of systematic theoretical research.Therefore,in this study,the rootless grafted seedlings were first compared with cutting seedlings of rose,and on this basis,studies on related factors affecting the survival and growth of grafted rose seedlings were carried out.The results of this study are given below;1.Comparing rose grafted seedlings with cutting seedlings,there were significant differences in cutting survival rate,root index,grafted growth index and growth rate.Besides,the survival rate of‘Riany Blue’rose cuttings was slightly higher,and the overall growth status of‘Riany Blue’and‘Queen of Sweden’from good to bad was in order of hetero-root grafted seedlings,cutting seedlings,and self-rooted grafted seedlings.It is specified that grafted seedlings have the advantage over cutting seedlings for promoting growth.2.Comparing rose grafted seedlings with cutting seedlings,there were some prominent differences in physiological indicators.The leaf color value of the‘Riany Blue’rose from higher to lower was in order of hetero-root grafted seedlings,cutting seedlings,and self-rooted grafted seedlings,and that of the‘Queen of Sweden’rose from higher to lower was in order of hetero-root grafted seedlings,self-rooted grafted seedlings,and cutting seedlings.The photosynthetic efficiency of the two rose varieties from higher to lower was in order of hetero-root grafted seedlings,self-rooted grafted seedlings,and cutting seedlings.It is indicated that different root grafted seedlings have obvious photosynthetic advantages.3.There were significant differences in cutting survival rate,root callus rate,rooting number,and root length in cuttings of 10 species of Rosa plants.The‘thornlessness’appeared to be the most efficient rootstock for cutting roots,and its cutting survival rate,average rooting number,average root length,and longest root length reached to 98.33%,14.63,8.78 cm,and 14.05 cm,respectively.Therefore,the‘thornlessness’was chosen for the follow-up experiment as a rootstock.4.Among the 10 kinds of scions grafted with‘thornlessness’,the scion varieties with better compatibility were‘Parade Gigi’,‘Fragrance King Terrazza’,‘Claude Monet’,and‘Cherry Brandy’.In the follow-up experiments,‘Claude Monet’,‘Fragrance King Terrazza’,and‘Parade Gigi’were selected as scions.5.The best growth status for the grafted seedlings of‘Claude Monet’was when the thickness of the rootstock was 0.8-1.0 cm,followed by the thickness of the rootstock being0.5-0.8 cm.The cutting rooting effect of the grafted seedlings of‘Claude Monet’on the rootstock at the middle node was the best.6.The use of peat and coconut bran at ratio of 8:2 had better effect on growing the grafted seedlings of‘Fragrance King Terrazza’with 95.00%of survival rate.The survival rate of transplanting reached to 86.67%,and the rooting number,root length,grafting callus rate and branch length were higher,and most suitable substrate ratio.The physical and chemical properties of the matrix of this ratio were having dry bulk density of 0.19 g·cm^-3,saturated bulk density of 0.85 g·cm^-3,total porosity of 78.92%,pH=5.84,and electrical conductivity of 0.43 m S·cm^-1.7.Application of different plant growth regulators significantly promote the grafting growth of‘Parade Gigi’,especially the rooting number,root length,and branc length,as compared with the control.The commercial rooting fluid handling of grafting growth was better than other hormonal treatments,regarding average root number（15.29）,root length（4.30 cm）,and shoot length（1.05 cm）.8.Different types of fungicides promote the growth of grafted seedlings of‘Parade Gigi’to varying degrees,but they all inhibit the formation of root callus to variable degrees.Among them,the growth status of the grafted seedlings of‘Parade Gigi’under hymexazol treatment was the best.It’s cutting survival rate,root number,average root length,longest root length and branch length was 86.67%,7.08 and 3.29 cm,4.79 cm,1.69 cm respectively.