Genetic variation in fruitfulness in a hinoki (Chamaecyparis obtusa Endl.) seed orchard and its impact on the maintenance of genetic diversity in seedlots |
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Authors: | Ding-Qin Tang Yuji Ide |
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Institution: | (1) Asian Natural Environmental Science Center, The University of Tokyo, 113-0032 Tokyo, Japan;(2) Faculty of Forest Resources and Environment, Northeast Forestry University, 150040 Harbin, China;(3) Graduate School of Agricultural and Life Sciences, The University of Tokyo, 113-8657 Tokyo, Japan |
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Abstract: | Genetic variation in seed/cone production among clones was studied in a hinoki (Chamaecyparis obtusa Endl.) seed orchard containing 25 plus-trees by analyzing the number of cones, the yield of cones and seeds of individual
ramets for 5 successive years (1982 to 1986). There was significant variation among clones each year and parental contribution
in the seed orchard. Specifically, in the years 1982, 1983, 1984, 1985, and 1986, 20% of the clones produced 37.2, 60.6, 36.0,
44.3, and 44.8% of the total cones, respectively. The size of the crop greatly influenced the parental balance in the resulting
seed/cone crops. The product moment correlation coefficients and Spearman’s coefficients of rank correlation were small and
insignificant between consecutive years, but large and highly significant between alternate years, suggesting the presence
of carry-over effects in seed/cone production. The broad-sense heritability on a clone mean basis was 0.74 ± 0.15 for the
number of cones, 0.72 ± 0.14 for the yield of cones, and 0.68 ± 0.13 for the yield of seeds. The corresponding heritabilities
from analyses combined over all years were 0.24, 0.558, and 0.724, respectively. These results indicate that seed/cone production
in hinoki is under strong genetic control. Several managerial measures are discussed that maintain the genetic diversity in
seedlots used for reforestation, by reducing the variation in seed/cone production among clones and producing seed crops with
equal contributions from all parents. |
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Keywords: | Chamaecyparis obtusa clones genetic diversity parental balance seed orchard |
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