Crossability among modern roses and heterosis of quantitative and qualitative traits in hybrids

Abstract

Nine divergent popular hybrid rose cultivars and 22 of their F1 hybrids were studied to determine the extent of crossability and heterosis effects for several quantitative and qualitative traits in the climatic conditions of Faisalabad, Pakistan. The percentage of pollen germination differed across cultivars. Gruss-an-Teplitz exhibited the maximum value for pollen germination (46.5%), followed by Autumn Sunset (38.9%). Iceberg, being triploid, presented the lowest percentage of germination. All cultivars exhibited a strong correlation between pollen germination percentages in the lab and crossing success under field conditions. The cultivar Handel showed remarkable fruit-set and crossing success. In contrast, the cultivar Iceberg exhibited very poor crossing success rates. The setting of hips after crossing was maximal in the crosses Handel × Louise Odier and Autumn Sunset × Casino (83% each). The number of seeds in a single hip varied among cultivars. The potential for heterotic and heterobeltiotic was also variable and showed contrasting performance between F1 progenies for various qualitative and quantitative traits. The parent cultivars and progenies were sorted into five major groups by cluster analysis based on phenotypic variation. Phenotypic and genotypic coefficients of variability and heritability percentages varied among all parent cultivars for all morphological traits.