Palms (Arecaceae) are perhaps the most important tropical plant family for human use, both for utility and ornamental horticulture. The wide diversity of palm species with different seed germination characteristics necessitates tailoring horticultural practices to the needs of each. This is crucial for production and conservation horticulture. In this study, wild-collected seeds of yarey palm (Copernicia berteroana) and buccaneer palm (Pseudophoenix sargentii) were germinated in a variety of organic (standard nursery container mixes) and inorganic substrates. The yarey palm seeds were sown at two different depths, 0.5 inch and at the surface (seed half exposed). Mean maximum germination across all treatments for yarey palm was 79% and for buccaneer palm 60%. The standard nursery mixes generally fostered the best germination and long-term survival. This is likely due to a combination of the lower water availability at the surfaces of the more porous inorganic substrates (sand and perlite) and greater difficulty for coarse palm roots to penetrate the denser inorganic substrates, including fired ceramic, which otherwise had similar water-holding capacity (WHC) and even lower air space than the organic substrates. Difficulty of penetration caused roots of some seedlings to either dry up early in germination as in the surface sown yarey palm, or to “push up” the seed (buccaneer palm) rather than penetrating the substrate and this was often fatal. Thus, inorganic substrates are not recommended for germination and early seedling growth of these palm species and planting the seeds slightly below the surface may be preferable to surface sowing. For conservation horticulture of wild-collected palm seeds, this information can help prevent further genetic bottlenecks while under protective cultivation.
Germination studies indicated that increasing priming duration (-1.0 MPa at 20 °C for 7, 14, or 21 days) increased `Moss Curled' parsley [Petroselinum crispum (Mill.) Nyman ex A.W. Hill] germination rate quadratically and seed moisture content linearly. A histological and anatomical study was conducted to identify and/or quantify principle mericarp organ or tissue volume changes influenced by priming duration. Embryo volume increased as priming duration increased from 7 to 21 days (0.014 to 0.034 mm3), and this was due more to radicle (0.007 to 0.022 mm3) than to cotyledon (0.006 to 0.011 mm3) growth. Concomitant with increased embryo volume was increased volume of the depleted layer (space formation, surrounding the embryo), from 0.038 after 7 days to 0.071 mm3 after 21 days, and increased hydrolysis of central endosperm (a thick-walled endosperm type). In nonprimed mericarps, central endosperm cells constituted 97% of the endosperm volume. The remaining 3% was comprised of 1% depleted layer and 2% distal endosperm (small, thin-walled, and irregularly shaped endosperm cells). During 7 or 21 days of priming, ≈10% or 40%, respectively, of central endosperm cells were hydrolyzed centrifugally around the embryo with a corresponding decrease in volume of central endosperm with thick cell walls. In addition, distal endosperm cells adjacent to the depleted layer, containing reserve materials, were digested of contents following 21 days priming, and sometimes, following 7 days priming. A long priming duration resulted in degradation of pericarp tissues, as indicated visually and by a decline in pericarp volume. We hypothesize that priming duration of parsley primarily influences radicle growth and centrifugal digestion and utilization of central and distal endosperm, resulting in a larger depleted layer required for embryo volume increases. Secondary events influenced by priming duration include cotyledon growth and degradation of pericarp tissues.
Tomato (Lycopersicon esculentum Mill.) and asparagus (Asparagus officinalis L.) seeds were primed for 1 week in –0.8 MPa (20C, dark) polyethylene glycol 8000 (PEG), synthetic seawater (INO), or combinations of Ca+2, K+, or Na+ with Cl–,
Seeds of `Ace 55' tomato (Lycopersicon esculentum Mill.) and `Mary Washington' asparagus (Asparagus officinalis L.) were primed in -0.8 MPa (20C, 1 week, dark) polyethylene glycol 8000 (PEG), synthetic seawater (INO), or NaNO3. Primed seeds of both species had a higher percentage of germination than untreated seeds only at 10C in nonsaline (– 0.05 MPa) medium, while in saline medium (– 0.6 MPa) priming increased the percentage of germination of tomato seeds at 10 and 30C, and of primed asparagus seeds at 10 and 20C. Sodium nitrate was superior to PEG or IN0 for priming tomato seeds since it resulted in fewer days to 50% germination and higher final germination percentage in saline media at all temperatures. IN0 was a satisfactory alternative to PEG or NaNO3 for priming asparagus seeds since priming agent had little or no effect on germination. Seedling emergence from NaNO3-primed seeds of both species sown in a seedbed provided saline (– 0.39 MPa) irrigation was faster than from untreated dry-sown seeds. In the saline seedbed, priming increased final emergence percentage (FEP) from asparagus seeds, provided they were not subsequently dried, but had no effect on the percentage emergence of tomato seeds. Fluid-drilling primed or germinated seeds of either species enhanced seedling establishment in the saline seedbed by reducing time to 50% emergence and/or increasing FEP relative to primed, dried-b&k or untreated seeds.
Tomato seedling hypocotyls elongate rapidly after germination resulting in weak seedlings. The effects of 0, 250, 500, 750, or 1000 mg paclobutrazol (PB)/L seed soak and soaking times from 1 to 12 hours on tomato (Solanum lycopersicum L.) seed germination, seedling growth, and plant growth were tested. Adequate height control was obtained with 250 mg PB/L while soaking time did not affect seedling growth. In a second experiment, PB was tested at 0, 50, 100, 150, 200, or 250 mg PB/L soaking the seed for 1 hour. A concentration of PB at 100 mg·L–1 provided optimum control of hypocotyl elongation with minimal residual effect on subsequent plant growth. In a third experiment, seed soaked at the different PB concentrations were germinated and grown under light intensities of 0.09, 50, 70, or 120 μmol·m–2·s–1. Seedlings grown under 0.09 μmol·m–2·s–1 were not affected by PB treatment and did not develop an epicotyl. PB seed soak treatment gave greater growth suppression under 50 μmol·m-2·s-1 than under the two higher light levels. Soaking tomato seeds in 100 mg PB/L for 1 hour prevented early hypocotyl stretch of tomato seedlings with no long term effects on plant growth. This treatment effectively prevented excessive hypocotyl elongation when seeds were germinated under low PAR while not over controlling elongation under high PAR conditions.
Abstract
Germinated spinach (Spinacia oleracea L.) seed (radicle length 3 to 12 mm) were subjected to dehydration under uncontrolled room conditions for 3 to 25 days before planting. Although diminishing over time, some seedlings emerged after all dehydration periods. Seedling height and dry weight responded similarly. Dehydration of germinated seed for ≥15 days was required before seedling emergence was reduced by 50% of that produced by undehydrated germinated seed. Three cultivars responded similarly to length of dehydration period in respect to seedling emergence and vigor.
partially supported from grants by the New York Onion Growers Association, Syngenta Crop Protection-Seed treatment group and by other industry funds. The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal
Seed treatments are widely used in agriculture and have desirable properties as pesticides, disinfectants, or plant growth regulators ( Taylor, 2003 ). Many seed treatment active materials have systemic activity providing protection of the
200% to ≥5000%. By contrast, seed coating or encrusting is a minimal application of inert materials resulting in a smaller seed size increase of just 20% to 200% ( Taylor, 2003 ). Seed coatings and seed treatments may be grouped into different classes
Baskin, 1998 ). A buffalograss seed, called a bur, consists of 1–5 caryopses tightly wrapped in a bur coat. When planted without any seed treatment, bur germination rates are <30%, making stand establishment from seed a difficult task. However, nontreated