RHA Newsletter 9(2):
Rosa Rugosa Hybrids x Miniatures
Studying progress or lack of progress in rose breeding with our native winter hardy and disease resistant roses in the ARS Annuals, we are struck by the very few generations achieved in any one line of our native species x species or garden roses. A breeder may soon possess acres of roses to weed and care for while waiting for them to blossom. He must then evaluate them and if he hasn't already come to a dead end due to sterility or some other reason, must do it all over again before he can even get some repeat bloomers in many cases. Methods are needed to speed up the process, ideally to achieve a generation in one year...to cross blooming plants, plant the seed, and have blooming plants to cross again in one year.
Needed are strains of winter hardy roses that will blossom in 6 to 8 weeks from the time the seed germinates; an environment where they get sufficient natural or artificial light to equal a 16-hour day and temperatures from 65 to 70 degrees at night and up to 75 or 80 during the day; to conserve space, such of the work could be done with miniatures. Careful study of work already done should be made to help avoid problems of sterility and to take advantage of work already done by others.
I admit it has taken me more than 20 years for that which started out as a long-range breeding program to crystalize and for as to acquire the plant material and controlled environment that I now have; a basement setup of 440 square feet of bench space, with 88-8 foot fluorescent tubes mixed 1/2 warm white and 1/2 cool white plus a new 32 x 96' double poly inflated greenhouse.
A number of years ago, I had a large plant of 'Thérèse Bugnet' (R. acicularis x R. rugosa kamtchatica) x (R. amblyotis x R. rugosa plena) x 'Betty Bland', also 'George Will' (R. rugosa x R. acicularis) x garden roses, and 'Will Alderman' (R. rugosa x R. acicularis) x a Hybrid Tea, all in a group. 'Thérèse Bugnet' set abundant hips that year and I planted the seed that fall and grew the seedling under fluorescent lights. One seedling and one only blossomed when about 6 weeks old. The flower was semi-double pink, very fragrant, and had plenty of pollen. The plant was upright growing with red stems, thorny at the base and thornless near the top. I started more plants from cuttings as fast as possible and in the spring set then out in a row. Sometime previous to this I had a row of Edward Baker Risley's climbing 'White Mountains', a derivative of Rosa maximowicsiana, alternating with his 'Durham Pillar' nailed on the barn. Open pollinated seed of 'White Mountain' surprisingly gave me, among others, one very miniature everblooming plant which has since had such influence in miniaturizing our smallest roses. All of our miniature roses with flowers that turn green as they age, show this influence.
Pollen from the 'Thérèse Bugnet' quick-blooming seedling, which we call 'Pink Seedling', was used on the diploid miniature and polyantha-like roses that we were working with. We were plagued with poor fertility and poor seed germination and it hasn't been until now that we appear to have obtained the breaks we need. A very hardy 'Pink Seedling' derivative crossed on 'Merry Christmas' and 'Red Can Can' has given us several fertile red flowered seedlings. These and 'Merry Christmas' and 'Red Can Can' are again being crossed with pollen from several quick blooming seedlings of 'Pink Seedling' with improved fertility.
Fertility and quick everblooming habit will be of the greatest importance. Much seed must be produced and many plants grown to select from. One generation must follow another as quickly as possible. Under lights we have eternal spring, so breeding can continue all year. We will of course take advantage of our severe winter season to test promising seedlings and our summer season to produce such seed from selected plants isolated, in an area where the bees can inter-cross them. These plants will all be on their own roots. We have found that cuttings will root in 8 to 10 days in No-3 vermiculite, watered with 1/4 strength fertilizer, with a thin plastic covering them, under 16 hours daily of artificial light at temperatures around 70 or a little higher, and will be blossoming in 6 to 8 weeks. Much larger cuttings can be rooted outdoors under sprinklers, if taken in June, and will make blooming plants by fall. This breeding program has developed considerable urgency. If we do not succeed in the use of these rugosa-blanda hybrids, I doubt if any one ever will, judging from previous attempts. Most work of this nature is now being done with tetraploids. However, if we come up with plants of sufficient merit and fertility, crosses with tetraploids might eventually produce tetraploids, as they have many times in the past.
Elements in this breeding program that differ from efforts in the past to combine native rugosa roses and garden roses are the use of quick everblooming hardy stock, everblooming miniatures, and a controlled environment.