Branching Characteristics of Primary Branch and Primary Roots of Sugi (Cryptomeria japonica D. Don) Cultivars

Shirota Tetsuo, Tashiro Naoaki, Gyokusenn Koichiro, Saito Akira

doi:10.15017/10880

Branching characteristics of primary branches and primary roots were studied in three types of sugi (Cryptomeria japonica D. Don) differed in their growth patterns and crown form; two cultivars (cv. Ayasugi and cv. Shakain) and a seedling. Primary branches and roots were cut into pieces of 20cm in length, Each piece was classified as a branch unit or root unit. Top cross-sectional areas (T), bottom cross-sectional areas(B), and divergence cross-sectional areas (S) of the units were measured. The simple pipe model relation (T+S=B) was applied to branch units. The pipe model of tree form (T+S≦B)was applied to root units. The results indicated that fine root death occurs more frequently than branch death. Rates of fine root death calculated from 1-(T+S)/B, were high in seedling, and small in cv. Ayasugi and cv. Shakain. Relationships between T/S ratio and B of branch and root units were analyzed in order to compare the strength of apical domillance among the sample trees. T/S ratio of branch units increased proportionally to growth of the primary branch. Differences of the increase rates among sample trees indicated that the decreasing order of strength of apical dominance is as fol1ows:Shakain> seedling>Ayasugi. Apical dolninance was not significant in the root system, as the T/S ratio was not related to the growth of the primary root.

Branching Characteristics of Primary Branch and Primary Roots of Sugi (Cryptomeria japonica D. Don) Cultivars

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