On the breeding of Rhododendron for landscape effect

Abstract

Crosses were carried out on the among R. Omurasaki and eight other species (including garden species) for the purpose of breeding of Rhododendron, which have color of flower, form of flower and type of tree that adapt to new garden style, and also high resistant for drought, cold and disease as materials of public garden plant.
The following nine species (including garden species) were used of the present experimement; Rhododendron japonicum var, glaucophyllum, R. japanicum f, flavum, R. luteum, R. lateritlium, R. linearifolium var, macrosepalum, R. obtsusum, R. Oomrasaki, R, scabrum, Azalea.
In reciplocal crosses between each species of Rhododendron and R. Oomurasaki, R. obtsusum, R. linearifolium var, macrosepalum, R. scabrum and R. laterium, the seeds fertility is good. And also in among each species are the same result to reciplocal crosses. Generally in cross combinations the fructification rate, germination and growth is both good.
F₁ seedling of Azalea (nine species) X. R. Oomu-rasaki, R. obtsusum flower in four years (three years old) after sowing, and show growth resem-blance to father plant, and also was good both form of tree, size of flower, color of flower of double petals and corolla types.
F₁ were obtained from the mating between Azaleaa (each species) and R. scabrum and other species are not reach to period of flower, but growth is good.
Crosses was made among the Rhododendron and Azalea, R. scabrum, R. lateritium and R. japon-icum f, flavum for make evergreen Rhododendron that have flower of yellow-orange color. From the result F obtained were mostly albino, and could not grow for insect injure.
F₁ (young seedling) were obtained by X-rays irradiation of bud-flower or pollen grains, are growing now.