REDUCTION OF CONTAMINATION IN BULB-EXPLANT CULTURES OF NARCISSUS BY A HOT-WATER TREATMENT OF PARENT BULBS

After disinfestation of explants with 1% sodium hypochlorite for 30 min, 40-60% of twin-scale cultures of Narcissus 'Golden Harvest' remained contaminated, mainly by Fusarium spp. Extension of the disinfestation time in hypochlorite from 30 min to 2h or a double disinfestation treatment did not reduce the contamination, suggesting that the fungus may be located inside the tissue. Hot-water treatment of bulbs prior to treatment with sodium hypochlorite resulted in contamination being reduced to 5%, while the regeneration was not affected. Similar results were obtained when experiments were repeated with five other cultivars of Narcissus.