JARS v39n1 - ARS Seed Exchange Plants in Bloom in Japan

ARS Seed Exchange Plants in Bloom in Japan
Kentaro Tanii
Miyagi, Japan

It has been 13 years since I was admitted to the ARS. From the first Seed Exchange in 1972 until 1978, I received seed each year of hybrid crosses with seeds of Japanese origin such as R. yakushimanum , during which time I have seeded 350 packets.

Since 1978 when some of those seeds bloomed, I have started double crosses in order to have better hybrids and also crosses with R. degronianum of wild growth around nearby Mt. Zao (5,790 ft.), besides re-crosses with R. degronianum hybrids. Consequently they are coming into bloom with several nice flowers similar to those of Japanese R. metternichii group. These have thick indumentum and are of dwarf type. I'm pleased to present slides of some of the Seed Exchange plants that I think are excellent. I remember I was deeply moved when I first saw the ARS Seed Exchange catalog in 1972. I was impressed by the enormous distribution of R. yakushimanum hybrids which were rare in Japan and also by the ARS members' open-minded good intentions. I'll never forget that I was very encouraged to continue breeding hybrids. I hereby wish to express my sincere thanks especially to Messrs Cecil Smith, Jacob Rosenthal and Robert Furman, as I have received a lot of seeds given originally by them, and also to Mrs. Robert Berry for all her kind attention given at that time.

I have seeds which have already come into blossom, and also I have many not yet in bloom. The majority of the R. yakushimanum and R. degronianum types on which I place my hope are, in the case of an average of their parents with respect to indumented or dwarf types. Therefore I think I have to proceed to F2 or double crosses. A successful case of such double crosses is shown in slides nos. 1, 2, and 3.

As to the flower, generally speaking its corollas have less petals, and just a few of them take spherical shapes. As to the flower color, in case of red, the majority become, in principle, pink, an average of their parents. Although there are some excellent reds depending upon combination. The biggest problem is a persistent influence of discoloration deriving from R. yakushimanum , by which excellent red buds become discolored into pink four or five days after they bloom. It's a great disappointment to me and, ironically, nice compact hybrids of R. yakushimanum type with thick indumentum often can be seen in them.

On the contrary, R. degronianum has a smaller influence on discoloration, largely inherited early blossom (April 15 - May 10) at a time of year when the temperatures aren't usually high in the daytime. The difference between the two types appears to be in the extended time of flowering.

I'm thus trying to make crosses mainly of R. degronianum and I expect this spring to have some blossoms of such hybrids. On the next opportunity, I will repay the ARS Seed Exchange and the seed distributors for their good intention by reporting that the descendants of the Seed Exchange are very active here in Japan. I'd be very glad if I could have some comments on this from the seed distributors.