From Hokkaido to Okinawa Prefecture, 52 clones of
Imperata cylindrica were collected and the data of sprouting of new shoots, heading and death of aerial parts were recorded. A total of 260 ramets (5 ramets×52 clones) were planted in clay pots (20 cm diameter, 19 cm depth) individually and plant height, number of shoots, number of rhizomes and dry weight of each organ were determined.
Principal component analysis based on the correlation matrix of the ten characters was applied using 47 clones except for five clones from Hokkaido, Akita, Amami and Ryukyu Islands for which the phenological characters could not be assessed.
The accumulated contribution from the first to the third components reached 84.4%. The first principal component (Z
1), the second (Z
2) and the third (Z
3) refer to plant height and phenology, rhizome length and number, and dry matter partitioning ratio to rhizomes, respectively.
The 47 clones were divided into three groups corresponding to the adaptive characteristics to their original habitats. Group A consisted of clones of
I. cylindrica var.
genuina from the northern part of the Tohoku district, which exhibited a low value for plant height and emerged late in spring. Group B which contained clones of var.
koenigii from the southern part of the Tohoku to northern part of the Kyushu districts showed characteristics intermediate between those of groups A and C. Group C consisted of clones of var.
koenigii from the southern part of the Kyushu district with a high value for plant height and in which the aerial parts died in late winter.
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