Studies on Geographical Diversity of Floral Morphology of Tea Plant (Camellia sinensis (L.) O.KUNTZE) using the Method of Numerical Taxonomy

Numerical taxonomy was conducted to discuss the intraspecific classification of tea plant based on the variations of floral morphology. Experimental materials were main clonal cultivars (Experiment 1) and stock populations (Experiment 2) in Makurazaki; NIVOT, belonging to geographical sources of tea species.<BR>Experiment 1: The 103 clonal cultivars selected from the different sources; Japan(numbers of Cv; 44), China (14), Assam (14), Assam hybrid (20) and Others (11) were investigated for the diversity of the 13 flower characters, such as flower size, number of petals, traits of pistil and stamen, and hairiness of ovary. Principal component analysis (PCA) and discriminant analysis were performed using the data of chosen 11 characters.<BR>Large variation was shown among the cultivars for 6 characters. They are relative length of pistil to stamen (character code no. 4), splitting point of the style (8), constriction of the splitting arms (9), hairiness of the ovary (10) and number of stamens (11). Typical Japanese originated cultivars were with the same length of pistil as of stamen (Code M; according TAKEDA et al. 1980) or shorter one (Code S). Almost of all the Chinese originated cultivars had a longer pistil than stamen (Code L) with distinct constriction of splitting arms. Many Assam group cultivars generally had a longer pistil (L), but some cultivars were the same length of pistil and stamen (M). The cultivars with glabrous or less hairy ovary were observed in Assam plants.<BR>The first component of PCA was loaded with primarily morphological characters of pistil such as relative length of pistil to stamen and constriction of style arm. Principal component score 2 mainly correspond to the characteristics of flower size and number of petals. The first three cumulative contributions accounted for a total 62% of the variation in the traits measured. In the discriminant analysis, taxonomic distance estimates based on morphological flower characters were significantly different between each group. This showed that the Japan, China and Assam groups of cultivars were clearly classified. Flower characteristics of the Assam hybrids resembled the China and Assam cultivars so their taxonomic distances were generally narrow.<BR>Experiment 2: The 1, 356 accessions of 42 populations which belongs to the source of Japan (number of populations ;17), China (10), Assam (11) and others(4) were examined for the 6 characters of the flower morphology to clear the variations within and between groups of tea plant populations.<BR>Distinct differences among the groups in the pistil characters, such as relative length of pistil to stamen and constriction of style arm were detected as the same results of Exp. 1 . The plants having long pistil with distinct constriction were found more frequently in the China and in the Assam populations than in the Japan ones. Glabrous or less hairy ovary was sometimes found in Assam accessions, but none in Japanese plants. It was recognized that the diversity of all characteristics within the Assam group was wider than in the Chinese or in the Japanese plants, and a 'cline'of the character diversity of floral morphology from the Assam to the China and to the Japan. It suggests that the origin of the tea plant is near and surrounding the area where the Assam groups of plants are distributed in the Southwest districts of China.<BR>Principal component analysis and cluster analysis were carried for the 6 flower characters of 42 populations of 5 groups in Exp. 2. The 1st component score of PCA was loaded with the traits of the style which was like as Exp.1. Contribution of the 1st component mostly related to the characters, i.e. relative length of pistil to stamen and constriction of style had a score as high as 50%. The 2nd component mainly related to the flower size and hairiness of ovary, and their contribution ratio was 22%.