34. グイマツとカラマツの雑種各種の耐鼠性(会員研究発表講演)

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Resistance against vole-gnawing of Kurile larch (Larix gmelinii var japonica;Gk:ex Kurile;Gs:ex Saghlien), Japanese larch (L. laptolepis;L) and several hybrid families between them was put to test in the Winters cf 1971-'72 and '72-'73. Some of the hybrids were newly produced from the intercrossing of individuals of F_1 hybrid families and the back-crossing of them to trees of parental species since the last report of the senior author and his colleague. The degree of resistance was measured by the loss amounts of the test pieces which, in every pair or whole set of 8 hybrid families, were subjected to the gnawing of voles kept under isolated (1 vole in each of 14 chambers) or aggregate (7 voles in a chamber) conditions. Through the repeated and variously. combined experiments using young seedlings and saplings, through observation on a test plantation, and partly through comparison of the results of the present study and the former reports, the following facts are confirmed newly or again. (i) Among these hybrids, newly tested [(Gk×L)×(Gk×L)] and [(Gk×L)×L] are ranked in the resistance beside Korean larch. (Korean larch was of intermediate-class and praetically sufficient resistance and therefore used as a criterion (or standard) for its comparison in the former studies.) Their growth is also as good as that of F_1 hybrid families. (ii) Every interspecific hybrid inclines toward the parent with larger resistance against vole-gnawing, as mentioned formerly, and the back-crossed family gets so much close to the parental species. (iii) Within the variation of Kurile larch, two geographical races, i.e., Gk and Gs, should be kept separated from each other on the basis of the difference of their vole-resistance The former(GK) is doubtlessly of greater resistance than the latter. Naturally, there is still remained some possibility of detecting difference of resistance among provenences or populations within each race. (iv) One of the conclusions of the former report, that unilateral inclination or resistance toward maternal parent (usually considered in the rank of species or varieties) is recognizable between the families of reciprocal crossings of these two species, seems thus to be denied, with reservation of partial possibility of distinguishing such inclination among combinations of some races, provenances or individuals of parental species in the future studies. As a general conclusion, the hybrids of these two species are ranked according to their resistance as follows: L×L≫(Gk×L)×(Gk×L), (Gk×L)×L, L×Gs, Ga×L)>L×Gk, Gk×L>Gs×Gs, (Gk×L)×Gk>Gk×Gk
北方森林学会の論文

34. グイマツとカラマツの雑種各種の耐鼠性(会員研究発表講演)

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