【Objective】 Variations in physiological indexes between scions and rootstocks of different grafting combinations were analyzed in Cyclocarya paliurus, and the relationship between the physiological characteristics of rootstocks and grafting survival was studied. This will allow the early prediction of grafting compatibility of rootstock-scion and the selection of C. paliurus stock. 【Method】 Three grafting combinations were designed, with Pterocarya stenoptera, Carya illinoinensis and C. paliurus as rootstocks to graft C. paliurus (as scions). The contents of soluble sugar, soluble protein, starch and tannin, peroxidase (POD) and polyphenol oxidase (PPO) activity in rootstocks and scions of the grafting combinations were measured at 0, 40 and 70 days after grafting, respectively, while the grafting survival was determined at 70 days after grafting. 【Result】 The graft survival rate with C. paliurus as the rootstock was 53.49%, which was significantly higher than that of the P. stenoptera and C. illinoinensis grafting combinations. With the increase in time after grafting, soluble sugar and starch in the rootstock-scion initially decreased and then rose. The tannin content increased initially and then decreased, and the higher content of tannin in the rootstock-scion was not conducive to the survival of grafting. The increase in POD activity was beneficial for improving the defense response of affinity grafts, while a high PPO activity was not conducive to the survival of grafting. The correlation analysis showed that the soluble sugar, starch, tannin content, and PPO activity of stocks measured at 40 days were significantly negatively correlated with the graft survival rate (P <0.05), while POD activity was significantly positively correlated with the graft survival rate (P <0.05). The soluble sugar, tannin content, and PPO activity of the stocks measured at 70 days were significantly negatively correlated with the graft survival rate (P <0.05), but the POD activity of the scion was significantly positively correlated with the graft survival rate (P <0.01). The absolute value of the PPO activity difference between the scion and rootstock showed a significant negative correlation with the graft survival rate at 40 days (P <0.05), while the absolute value of the POD activity difference at 70 days showed a very significant negative correlation with the graft survival rate (P <0.01). 【Conclusion】 The graft compatibility was strong using C. paliurus as a grafting stock, while the grafting compatibility was weak when P. stenoptera and C. illinoensis were used as rootstocks. The content of soluble sugar, starch, tannin content, POD and PPO activity, and the absolute value of POD and PPO activity can be used as physiological indicators for the early evaluation of the grafting compatibility of rootstock and scion.
【Objective】 Based on two-round selections for phenotypic characteristics of Cyclocarya paliurus (first-round) and the content of bioactive substances in their leaves (second-round), the superior individuals were screened out through an evaluation of annual stability of bioactive substance contents over two consecutive years. These individuals would be taken as good planting materials for the production of bioactive materials of C. paliurus.【Method】Superior individuals were selected in the first-round in March 2017 based on phenotypic traits, including leaf color, shape and size; angle of the first lateral branch; crown shape (flat and round) and superior provenance. The total flavonoids, triterpenoids, and water-soluble polysaccharides in the leaves of the selected trees were determined in September 2017. After the improvement potential of the selected individuals was evaluated, these selected trees were taken as the basis of the second-round selection. In September 2018, the content stability of bioactive substances was assessed for the second-round selected trees to determine the final elite individuals.【Result】The contents of the main bioactive substances in leaves of 36 selected individuals were significantly different in the first-round selection phase, and the improvement potential of the total flavonoids, total triterpenoids and water-soluble polysaccharides was 34.3%, 43.43% and 36.41%, respectively. In the second-round selection, ten individuals were screened based on the combination of single and multiple indexes from the first-round selected individuals. Finally, three elite individuals with stable contents, including LC1, LC4 and CP3, were determined by comparing the contents of the main bioactive substances in the leaves over two consecutive years. The correlation analysis indicates that tender leaves in red are positively correlated with high contents of the total flavonoids and triterpenoids, while the total triterpenoids are significantly correlated with the larger branch angle and round crown. However, the content of water-soluble polysaccharides is no correlated with the observed phenotypic traits.【Conclusion】Owing to the positive correlation of phenotypic traits with a high content of main bioactive substances in the leaves, tender leaves in red, plant with a large branching angle and round crown were taken as the selection basis of the superior individuals for medicinal use of C. paliurus. The contents of the main bioactive substances in three final selected elite individuals (LC1, LC4 and CP3) were higher than those of others, and kept stable over two consecutive years. To ensure the high and stable yield of the bioactive substances in the selected plants, it is necessary to study the interaction effects between the genetic and environment in multiple habitats for further selecting suitable planting areas and corresponding cultivation strategies.
【Objective】 In order to explore the main factors that affect the regeneration of natural Cyclocarya paliurus forests and a provide a scientific strategy and theoretical basis for the protection and sustainable utilization of natural resources, the diversity of plants, species composition and structure of different geographical distributions of C. paliurus communities were investigated. 【Method】 A typical sample-plot survey method was used to investigate species composition, species diversity characteristics, flora characteristics, and community similarity in different geographically distributed communities of C. paliurus. Their population structure and regeneration status were evaluated using a diameter grade approach, instead of age. 【Result】 There were 70 species belonging to 50 genera and 32 families in the Muchuan community of Sichuan Province (M community), 96 species belonging to 79 genera and 50 families in the Jinzhongshan community of Guangxi Province (J community), and 126 species belonging to 100 genera and 59 families in the Hefeng community of Hubei Province (H community), respectively. However, the floristic characteristics were not significantly different among three communities investigated, all of which showed obvious subtropical and temperate elements. The dynamic trends of species diversity and species richness were similar among the three communities, all of which showed the order of tree indexes was tree layers > shrub layers > herb layers. The species diversity and richness of three communities were generally represented as H community > J community > M community. The structures of communities were moderately dissimilar, where the similarity among three communities was M and J > M and H > J and H. 【Conclusion】 Overall, the species composition of the communities in different geographical locations was obviously different, and the similarity level was low, but its structural characteristics were similar. The tree layer species were dominant in all communities, which led to stand closure and reduced understory light, and eventually affected the regeneration of C. paliurus populations. There were more plant species in the shrub layers, and their distribution was more uniform, but the herb layers (mainly ferns) took up less space. From the viewpoint of the natural generation, properly opening forest gaps would be helpful to promote the growth and uniform distribution of C. paliurus seedlings in the forest in order to complete the natural regeneration of the population, and develop a stable community.
