Underlining rose varieties potential as genitors through the study of hybrid combinations.

摘要

Despite the impressive number of rose cultivars and hybrids currently available in the market place, there is an unlimited desire to continue breeding to increase their range or assortment. The principal method to create new rose cultivars is through hybridization. Unfortunately, not all genotypes make suitable genitors because some are sterile, intersterile or incompatible. Furthermore, seed germination rates are either poor or produce descendents with limited value. In this research, two groups of hybrid combinations were studied to establish the suitability of several rose cultivars as genitors. Group one contained 13 combinations selected from 21 different Polyantha cultivars whilst in group two, 18 hybrid combinations were made from Hybrid Tea and Floribunda cultivars selected from 36 different lines. Following crossing of the Polyantha genotypes, 'Bella Rosa' x 'Golden Fiesta' and 'Bella Rosa' x 'Lichtkonigin Lucia' no seeds or fruits resulted. In the other combinations, the number of seeds produced per pollinated flower ranged from a mean of 0.1 for 'Heidekind' x 'Golden Fiesta' to 9.9 for 'Nobilia' x 'Super Excelsa'. The number of seeds per fruit ranged between 2.0 to 10.7 ('Simina' x 'Nostalgica'). The mean seed germination rate in nine combinations was 66.8%. It was found that from a population of 1441 seedlings; seven elites were selected from which just two have the potential to become new cultivars. When different combinations with Hybrid Tea and Floribunda cultivars were used as genitors, the number of seeds obtained per pollinated flower ranged from 1.7 for the 'Romstar' x 'Chrisler Imperial' to 23.0 for the 'Carina' x 'Golden Fiesta' crosses respectively. Mean seed germination arising from 12 combinations was 55.1% and from 510 seedlings (0.4%) two have the potential to be released as new varieties. Among the Polyantha roses, good genitors seem to be the cultivars 'Simina', 'Nostalgica', 'Nobilia', 'Super Excelsa', 'Bonica', 'Lavender Dream', and from Hybrid Tea and Floribunda progenies 'Montana', 'Rosagold', 'Dalli-Dalli', 'Las Vegas', 'Monica', 'Alec's Red', 'Friesia', 'Landora', 'Splendid', 'Akito' had valuable characteristics when used as genitors.