title: Effect of delivery method and population size of Trichoderma harzianum on growth response of unrooted chrysanthemum cuttings.
abstract: In a previous study, addition of Trichoderma harzianum Rifai isolate T-12 to a propagative medium resulted in improved performance of chrysanthemum cuttings. However, root and shoot growth of one cultivar, 'Dark Bronze Charm', were more responsive to a lower (5 g T-12/kg medium) than higher (25 g T-12/kg medium) rate of fungal propagules, suggesting potential phytotoxicity at higher concentrations. The objectives of this study were to investigate higher rates of T-12 medium amendment for phytotoxicity, and to examine an alternative method of delivering the fungus to the propagative medium in order to obtain a more uniform response from cuttings. Isolate T-12 was added to the propagative medium as either a powdered peat-bran amendment (0, 5, or 50 g T-12/kg medium) or as alginate prills (80 or 800 g T-12/kg medium). There were no differences among treatments on day seven, but by day 21, shoot fresh weight and heights were significantly greater for plants treated with prills at 800 g T-12/kg medium. Both prill treatments resulted in greater shoot height on day 14 and 21 than all other treatments, which were similar to controls. Amendment with T-12 powder at 50 g/kg increased root length, but 80 g/kg medium added as prills decreased root dry weight compared to the control. The highest rate of T-12 (800 g prills/kg medium) had no effect on root growth. This suggests that moderate, rather than high rates of T-12 are more effective in promoting rooting of unrooted chrysanthemum, and that there is a potential for phytotoxic effects on root growth with higher rates.
authors.affiliation: Department of Ornamental Horticulture and Landscape Design, University of Tennessee, Knoxville 37996, USA.
authors.forename: A J
authors.initials: AJ
authors.lastname: MacKenzie
authors.forename: B H
authors.initials: BH
authors.lastname: Ownley
authors.forename: T W
authors.initials: TW
authors.lastname: Starman
authors.forename: M T
authors.initials: MT
authors.lastname: Windham
mesh_terms: D011723:Chrysanthemum cinerariifolium / Q000254:growth & development* / Q000382:microbiology*; D003470:Culture Media; D014242:Trichoderma / Q000254:growth & development*
chemical_list: D003470:Culture Media