Physiological status, rooting and bulb yield of leaf cuttings of Eucomis comosa (Houtt.) H.R. Wehrh. 'Sparkling Burgundy' as affected by chitosan

Breeding efforts within the Eucomis genus has resulted in the global availability of attractive cultivars with decorative leaves and inflorescences. A cultivar that is particularly valuable and attractive, but rarely cultivated due to its low propagation rate is 'Sparkling Burgundy'. In our research, we considered it advisable to check the possibility of intensifying the reproduction of the investigated cultivar by means of leaf cuttings. This study, conducted in the years 2016-2018, involved leaf cuttings collected from plants growing in an unheated polytunnel. The cuttings were soaked, watered or sprayed with 0.4% chitosan with a molecular weight of 7 000 or 10 000 g/mol. The control plants were not treated with chitosan. During the rooting period that followed, the cuttings were assessed for their chlorophyll a fluorescence and the intensity of their greenness, and for their root growth and bulb yield after five months. Chitosan applied during rooting improved some chlorophyll fluorescence parameters and the greenness index of the cuttings. Moreover, the compound with a molecular weight of 7 000 g/mol more efficiently increased the number and length of the roots and the number and weight of the adventitious bulbs than that with a molecular weight of 10 000 g/mol. Soaking the cuttings prior to rooting was more effective in terms of the number, length and weight of the produced roots and the number, diameter and weight of the daughter bulbs than watering or spraying.