Scion-rootstock relationships in hybrid tea cut roses on Rosa canina 'Inermis'.

In 2 successive years, 11-month-old cut rose clones grown in greenhouses were uprooted in December. Highly significant correlations occurred between the girth at the graft union and the root weight or the number of bottom-breaks, between the root weight and the number of bottom-breaks, and between the number of bottom-breaks and the number of harvested shoots. Plant vigour in clones was mainly determined by the scion. Rootstock-scion relations in rose were similar to those in apples and cherries. The equilibrium between aerial and underground parts in composite plants is discussed. Breeding of rose rootstocks that promote scion vigour under various glasshouse conditions is recommended. (Abstract retrieved from CAB Abstracts by CABI’s permission

Hybrid tea-roses under controlled light conditions. 3. Flower and blind shoot production in the glasshouse of seedlings selected for flowering or flower bud abortion at low irradiances in a growth room.

Seedlings of hybrid tea roses, previously selected in a growth room for flowering or flower bud abortion at low light intensities were grown in a greenhouse for periods of at least 14 months. Previously flowering seedlings whether grown on their own roots or on a rootstock yielded more flowers, particularly in winter, than previously aborting ones. This was due to a lower percentage of blind shoots and a tendency to produce more shoots. It was shown that selection for better winter performance under glass could be made in young seedlings. [For part 2 see HcA 48, 7528.] (Abstract retrieved from CAB Abstracts by CABI’s permission

Hybrid tea-roses under controlled light conditions. 4. Combining ability analysis of variance for percentage of flowering in F1 populations.

F1 populations of the hybrid tea-roses Sonia, Baccara, Ilona, Prominent and Zorina were grown in a growth room under 8 W/m2 at 20 deg C with an 8 h day. The inheritance of flowering ability under low irradiance was mainly controlled by additive gene action. Prominent and Zorina had a good general combining ability for flowering under low irradiance. [For part 3 see HcA 49, 5235]. (Abstract retrieved from CAB Abstracts by CABI’s permission

Rose breeding: past, present, prospects

In this review the PAST, PRESENT and PROSPECT will be considered as three separate periods in the history of the breeding and development of rose cultivars. The recurring theme is the genetic variation. This theme was chosen because there is justified doubt as to sufficient genetic variation available among current progenitors to ascertain the vitality and productivity of future cultivars in cross-breeding. This seems particularly true for glasshouse cultivars. The above three periods are defined as follows. PAST: the era from pre-history until about the year 1875, the PRESENT era from about 1875 until 1967, and the PROSPECT (future) from 1967 onwards. With probably over 5000 years, the PAST covers the longest time lapse. It ended around the year 1875, with the discovery of aimed cross-breeding. Not accidentally, Mendel published his famous laws about inheritance about simultaneously. It is remarkable that many rose breeders still like to think in terms of Mendelian or qualitative inheritance. Quantitative inheritance or additive gene action, seems either little known or not used. The PRESENT period started with the knowledge about aimed cross-breeding, and ended with the introduction of biotechnology in rose breeding in 1967. This period has covered about 90 years only. The PROSPECT, which in fact is the FUTURE era, has already begun in 1967, and is about 28 years on the way. To start with, the breeding and genetic variation occurring in the PAST period will be considered. It is assumed that early horticulturists sampled desirable rose species from the wild and planted them in collections. According to Wiley (1955) and Krussmann (1987), several species and most likely cultivars of them too, were grown in gardens in China, Persia, Mesopotamia, Egypt, Greece and in Italy, long before the beginning of the Christian era. It is uncertain, however, whether all the roses of ancient horticulture were seedlings, or that certain strains were already vegetatively propagated. A fact is, that during this whole period, new cultivars exclusively arose by sowing the seeds that resulted from open-pollination. Particularly in the beginning, domestication of species and their probable inter-specific hybrids supposedly was a slow process. However, as unsuitable primitive forms were discarded and propagation methods improved, progress towards tame forms was more rapid. Introduction of new genotypes and exchange of species and cultivars by travellers, considerably broadened the genetic variation available to horticulturists. It should be noted, by the way, that domestication of a species, any species in fact, necessarily involves a narrowing of the genetic variation available. In a few cases only, early breeders kept record of the female parent and the year of introduction of a new cultivar. These records, however, have enabled to ascertain part of the descent of later cultivars Although it was instinctively felt that neighbouring plants in collections had a relation to the new forms obtained, breeders did not yet realize that characters of the male parent could be turned over by pollination. Afterwards, it was established that from initially mainly diploid, gradually new cultivars were and later tetraploids. Particularly nowadays, important cultivars are almost exclusively tetraploid. Modern research demonstrated that in crossing diploid an

The direct regeneration of adventitious buds on leaf explants of glasshouse grown cut rose cultivars

Leaf explants from glasshouse-grown cut rose cultivars were highly regenerative on media containing TDZ and NAA. Particularly the basis of leaflets and leaf sheaths produced adventitious buds in 14–20 days