Study On The Classification Of Hydrangea Cultivars

Hydrangea is the general name of the genus Hydrangea in the family Saxifragaceae.It has the advantages of large and colorful flowers,various varieties,long flowering period.It has extremely high ornamental value and ecological value.Hydrangea originated in the south of Qinling Mountains in China and widely distributed in the temperate zone of the northern hemisphere.It is an important material for modern potted flower production,landscaping,and commercial flower cutting.As the resource distribution center of Hydrangea in China,most of the original species of Hydrangea used for hybridization in foreign countries originated in China,but the cultivation of Hydrangea caltivars in China started late,which led to the lack of comprehensive utilization of the germplasm resources of Hydrangea plants.Most of the potted and cut varieties of Hydrangea in China were introduced from abroad,and there was little research on the breeding of new varieties of Hydrangea in China The origin of new caltivars is unknown,and the naming and classification of new caltivars are confused.Therefore,it is of great significance to study the genetic relationship among different caltivars of Hydrangea for promoting the development,utilization and protection of the germplasm resources.In addition,due to the serious drought phenomenon in China in recent years,the growth and development of Hydrangea and its application and promotion in the garden are seriously restricted,and the leaf anatomical structure can reflect the adaptability of plants to the drought environment.By studying the anatomical characteristics of the leaves of Hydrangea,drought tolerance classification can promote the application and promotion of Hydrangea.Therefore,this paper conducted a classification study of 28 Hydrangea cultivars based on phenotypic traits,leaf anatomical structure and ISSR molecular marker technology,and analyzed the anatomical structure of 28 Hydrangea leaf anatomical structures by comparative analysis to discuss the tolerance of different Hydrangea cultivars.Drought structure was classified,and its drought tolerance was classified and studied.The main results were obtained as follows:.1.42 morphological and leaf anatomical structure traits were investigated.Through R-type clustering and principal component analysis,screen out trait indexes with small correlation and large cumulative contribution rate.Q-type clustering.The R-type clustering results show that in addition to stomatal length and stomatal width(r = 0.916),corolla width and corolla length(r = 0.924),corolla width and small petal length(r = 0.684),leaf surface hair and petiole length(r=0.791),sponge tissue thickness and leaf shape ratio(r=0.873)are more correlated,and other traits are relatively independent.The results of principal component analysis showed that the cumulative contribution rate of the first 7 principal components was 80.258%,and the cumulative contribution rate of the first 15 principal components reached 96.571%.Flowering period,inflorescence morphology,corolla width,petal,leaf tip,and leaf surface hair,The cumulative contribution rate of characteristic traits such as leaf shape ratio has a great influence on the variety classification.The Q-type clustering results show that the 28 hydrangea varieties can be classified into 2 categories according to the presence or absence of leaf surface hair,and 3 categories according to the inflorescence type,and finally can be classified into 7 categories according to the number of small petals,flowering period,and color group.2.Genetic relationship of 14 cultivars of Hydrangea was assessed using inter-simple sequence repeat marker.8 primers with good amplification effect were selected from 49 UBC primers,and a total of 149 gene loci were amplified,including 138 polymorphic loci.The percentage of polymorphic loci was 92.62%.According to the data calculated by the POPGENE software,the effective allele is 1.6894,the Nei 's gene diversity index is 0.4679,and the Shannon 's information index is 0.4486,indicating that there is a high genetic diversity among the 28 Hydrangea.The UPGMA cluster analysis of 28 varieties showed that the genetic similarity coefficient of about 0.38 can be clearly divided into 2 major groups.At the genetic similarity coefficient of about 0.53,the 2 groups are divided into 4 subgroups.3.16 anatomical structures of Hydrangea leaves were selected,and the index system was simplified to stomatal density,midrib thickness,lower epidermis length,looseness of leaf spongy tissue and palisade tissue and spongy tissue ratio indexes by coefficient of variation and cluster analysis.The function value method was used to rank the early tolerance of 28 Hydrangea cultivars.According to the average degree of membership,the drought tolerance of different varieties was divided into four types: drought resistance type,moderate drought resistance type,low drought resistance type and sensitive type.‘Endless Summer Bride',‘Magical Moonstone',‘Rose',‘Classic Rood'and‘Pillnitz'are drought-resistant types;‘Magical Diamond',‘Magical Amethgst'and‘Magical Opalare'moderately drought-resistant types;‘Schneeball'and ‘Glowing Alps' are low drought-resistant types;the remaining 64.29% of the cultivars are not sensitive to drought.