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Abstract
Sulfur-containing compounds, H2S, SO2, allyl sulfide, and allyl isothiocyanate broke dormancy in gladiolus (Gladiolus x Tubergenii Hort., Gladiolus spp.), Platycodon grandiflorum A. DC., or tree peony (Paeonia suffruticosa Andr.). A 1% H2S treatment for 1-8 hr was most effective with the least phytotoxicity. Garlic paste/vapor, which included allyl sulfide, also was effective. H2S, allyl sulfide and garlic vapor increased the respiration rate of tubers in Platycodon grandiflorum within 15 hr after treatment.
Abstract
Volatiles from garlic and horseradish paste broke corm dormancy of springflowering gladiolus (Gladiolus × Tubergenii Hort. Effective substances in garlic were allyl sulfide, methyl disulfide, n-propyl disulfide, and those in horseradish were allyl sulfide, allyl isothiocyanate, and n-propyl sulfide. Monosulfide extracted from garlic paste, allyl sulfide, and allyl disulfide were effective in breaking corm dormancy of summer-flowering gladiolus (Gladiolus spp.). Methyl disulfide promoted sprouting and flowering of tree peony (Paeonia suffruticosa Andr.) and flowering of ornamental cherry (Prunus spp.) without phytotoxic symptoms.
Posidonia [Posidonia oceanica (L.) Delile] is a marine phanerogam endemic of the Mediterranean Sea that grows all along the coast forming extensive underwater meadows. Senescent posidonia leaves, together with fibers (residues of rhizomes and decomposed leaves), periodically accumulate along Mediterranean beaches, covering vast areas of coast. Removal and disposal of these large volumes of plant biomasses represent a high cost for local administrations. Therefore, in this experiment, beached residues of posidonia were composted with olive pruning and green wastes with the objective to assess the efficacy of posidonia-based compost (63% on a volume basis) as a peat replacement. The compost was then mixed with a peat-based commercial substrate at rates of 0% (C0, pure peat-based commercial substrate tested as control), 25% (C25), 50% (C50), 75% (C75), and 100% (C100, pure posidonia-based compost) v/v. Mixtures were used as growing media to produce lettuce seedlings for transplant. Two lettuce cultivars (8511RZ and Satine) were tested. Main physical and chemical properties of the five growing media, shoot and root fresh and dry weight, leaf area, root morphology, and elemental leaf tissue composition were studied. Growing media containing posidonia-based compost, C25 and C50 in particular, showed good physical properties. Increasing compost proportions in the mixtures resulted in enhanced: 1) availability of macro- and micronutrients in the growing media; and 2) overall growth parameters of lettuce seedlings, in particular for the cultivar Satine. In conclusion, posidonia-based compost shows a considerable potential as a peat substitute in horticultural substrates; posidonia residues are a low-cost renewable material. In growing media for lettuce seedlings production, posidonia-based compost could be used as a complement to peat at a rate of 25% or 50% to obtain optimal physical properties and to limit the negative effects of high B content, which are typical of posidonia residues.