The chrysanthemum × Artemisia vulgaris intergeneric hybrid has better rooting ability and higher resistance to alternaria leaf spot than its chrysanthemum parent

Abstract The rooting ability and resistance to alternaria root spot of the chrysanthemum ( Chrysanthemum grandiflorum (Ramat.) Kitamura) variety ‘Zhongshanjingui’, the mugwort ( Artemisia vulgaris L.) variety ‘Variegata’ and ten independent ‘Zhongshanjingui’ × ‘Variegata’ intergeneric hybrids were compared. Although the rooting ability of the hybrid cuttings was not as high as those taken from mugwort itself, it was higher than that of chrysanthemum with respect to the rate of initiation of both adventitious and lateral roots. By 15 d after cutting, the hybrids produced a mean of ∼22 adventitious roots per cutting (mean length 23.4 mm), whereas ‘Zhongshanjingui’ produced only ∼14 (14.5 mm). The ability of the cuttings to recover from dehydration also differed: hybrid cuttings were able to form ∼9 lateral roots per adventitious root, while those from ‘Zhongshanjingui’ could form only 4.1. ‘Zhongshanjingui’ was susceptible to alternaria leaf spot infection, the hybrid was moderately resistant and ‘Variegata’ was highly resistant. An assay based on essential oils extracted from the leaf showed that both the hybrid and ‘Variegata’ leaves possessed more antifungal activity than extracts from ‘Zhongshanjingui’ leaf.