Studies On The Introduction And Cultivar Classification Of Canna

Canna is native to tropical and subtropical areas of America, now naturalized world widely. For the beautiful showy and colorful blossoms,Canna is a valuable ornamental plant and popular in gardening. At present the domestic cultivars of Canna are simple and outdated, the principle of cultivar classification is confused. To solve the mentioned problems, Canna germplasm world widely were introduced and the principle of cultivar classification was studied. Firstly, biological characteristics and growth habits were observed with cultivation experiments,to provide theoretical instruction in Canna production and management. Secondly, phylogenetic relationships and cultivars classification were studied with morphology method, RAPD molecular method and palynology techniques, the outcome will provide some academic instruction in breeding program. Finally, integrative valuation of the introduced accessions was carried out to screen some excellent cultivars suit to grow in Shenzhen and Zhujiang Delta area, the quantity of Canna cultivars in China was improved. The full results of the project are as following: 1. Biological and ecological characteristics of 57 accessions at growth stage of germination and emergence, Vegetative growth, flower formation, beginning of flowering, flowering , end of flowering, beginning of seed maturity and seed maturity were obtained. The adaptabilities of Canna in Shenzhen were evaluated. The influence of environmental factors at plant growth and flowering were discussed. Cultivation and propagation techniques were also summarized. 2. Based on the morphological characteristics, the goals of breeding and the common taste, 18 criterions at aesthetic characteristics and adaptabilities were selected in integrative evaluation. The weights of the 18 criterions were set up respectively based on the different requirement of three types of application on Canna, which established the system of integrative evaluation on Canna. Integrative evaluation result showed 11 cultivars behaved excellent in public green space and parterre, 9 cultivars in curtilage and 7 cultivars in pot. Seven cultivars, name'Jinbiancheng','En Avant','Extase','Zihong','Corail','Carnaval'and 'Picadore', are excellent in three types of application. The advantages and disadvantages of the integrative evaluation system were discussed. 3. Research advances on Canna taxonomy and cultivars classification were reviewed, cultivars origin and evolution process were discussed, the principles of Canna cultivars classification were proposed. The system of cultivar classification was set up, which content species, cultivar-group and cultivar. Morphological characteristics of petal, staminodes and folia were considered as the prerequisite criterion, and Canna cultivars were firstly classified into 5 species or hybrids, i.e. Canna indica L., C. flaccida Salisb. , C. x orchioides Bailey, C. x generalis Bailey and C. glauca L.(hydrophytic canna). Using height as the second degree criterion, two hybrids, C. x orchioides Bailey and C. x generalis Bailey were further divided into three groups respectively. According to this classification system, 66 accessions were divided into 5 species or hybrids, 6 cultivar-groups, 66 cultivars. 15 cultivars were recorded and described as new; 6 cultivars were translated from C. x generalis Bailey to C. x orchioides Bailey. 4. 56 accessions including four species and 52 cultivars were selected for RAPD analysis. There were specific amplified bands in three species and seven cultivars, these bands can be used in Canna individual identification. The dendrogram constructed by UPGMA grouped the 56 accessions into four clusters. The four species were grouped independently and 52 cultivars were grouped into Canna x generalis Bailey and C. x orchioides Bailey. The result is consistent with that of morphological method. Relationship of species, cultivars classification and cultivars evolution process were also discussed. 5. Pollen grain was studied by light microscope (LM) and scanning electron microscope (SEM), it shapes spheroidal or spherical, 63-113μm in diameter,radiate symmetry, homopolar, without aperture, with muri at exine surface. Appearance and exine ornamentation are similar within the genus. Muri and pollen abortion rate vary among species, they can provide some assistant evidence in species classification. Species sorted with pollen size in ascending order are C. x generalis Bailey,C. indica L,C. glauca L,C. flaccida Salisb and C. x orchioides Bailey. Pollen abortion rate of C. x orchioides Bailey and C. x generalis Bailey is the highest while that of Canna indica L. and C. glauca L. is lower, that of C. flaccida Salisb in the between.