Date of Graduation

Spring 2010


Master of Science in Plant Science (Agriculture)


College of Agriculture

Committee Chair

Martin Kaps


allelopathy, Narcissus, co-planting effects, alkaloids, companion planting

Subject Categories

Plant Sciences


This study investigates which plants can be grown successfully as follow-up crops after daffodils for small farmers or as landscape plantings to cover senescing daffodils. Other investigators have shown that Narcissi spp. have allelopathic effects due to alkaloids they produce. They identified narciclasine, a compound isolated in the mucilage of Narcissus bulbs, as one cause of inhibitory effects on growth and plastid development in excised radish cotyledons. In this study, four varieties of narcissi: N. tazetta ‘Paper-white', N. ‘Tripartite', N. ‘Ice Follies', N. tazetta ‘Thalia' were used. Greenhouse, field and seed germination studies were conducted to evaluate the effects of leaf leachates and plant residue on growth and development of landscape plants and herbs that included Snapdragon ‘Frosted Flames', Chine Aster ‘Powder-puff' (Chinese aster) , Coleus ‘Dragon Sunset' and ‘Volcano' hybrids, Cosmos‘Polidor', Basil‘Genovese' and ‘Lettuce Leaf', Italian parsley, Zinnia ‘Envy Double', and Alpine Strawberry ‘Mignonette'. Germination of snapdragon seed was reduced by 60 to 80% and delayed by 14 to 25 days when planted with N. tazetta ‘Paper-white'. Leaf residue of N.‘Tripartite' and N.‘Ice Follies' caused up to 50% stunting of the Coleus varieties, and chlorosis observed in the leaf blades of Coleus. In a field experiment co-planting of Narcissus with summer annuals and herbs, the greatest effects were observed on basil. Transplanted basil seedlings had reduced growth and fresh weight in the presence of N.‘Ice Follies' and N.tazetta ‘Thalia' bulbs, and several of the basil plants exhibited chlorosis. Transplanted seedlings of Cosmos and Zinnia were slow to reach flowering stage. No negative effects were observed on strawberry, and parsley. The evidence indicates that Coleus and basil would not be suitable as follow-up planting after Narcissus.


© Sonja Lallemand

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