A copper hydroxide formulation (0%, 3.5%, 7%, 11% Cu) was applied to plug trays before sowing seeds of Impatiens ×hybrida L. `Accent Red', Pelargonium ×hortorum Bailey `Scarlet Elite', and Petunia ×hybrida Hort.Vilm.-Andr. `Ultra White' to investigate the influence of the formulations on ease of transplant, root growth, and shoot growth. These factors also were investigated in Cu-treated seedling plugs held past optimal transplanting stage. Root spiraling and seedling height at transplant were reduced for all taxa grown in Cu-treated trays, regardless of concentration, compared to seedlings from nontreated trays. Root weight and shoot weight responses to Cu treatments at transplant and at flowering varied among taxa. Mature heights of all taxa were unaffected by Cu treatment; however, flowering date was delayed for impatiens and geraniums transplanted at optimal time from Cu-treated trays. In general, petunias displayed little response to Cu treatment. Root spiraling was reduced and plugs were removed more easily from Cu-treated than from control trays stored for 2 weeks in the greenhouse, but flowering time was delayed for 12 days for impatiens and petunias and 21 days for geraniums, regardless of Cu concentration.
Capillary mat subirrigation provides uniform water in the growing medium to optimize seedling growth in plugs. It also offers a closed system that allows the grower to regulate the amount of water available to seedlings and to reduce water runoff. However, root outgrowth into the capillary mat can be a significant problem. Copper hydroxide (Spin Out) was painted on the bottom, outside surface of the plug container to control root outgrowth into the capillary mat. Three square and two octagonal plug sizes were treated with copper. Regardless of the plug size or shape, copper treatment was an effective treatment to control root outgrowth in marigold seedlings. Copper treatment reduced overall root outgrowth by 80% to 92%. Marigold and geranium seedlings in copper-treated square plug containers showed some reduced shoot and root development during plug production, but there were no differences in copper-treated plants compared to nontreated plants following transplanting to cell packs.
A greenhouse hydroponic system, which uses suspended plastic troughs, was found to be an efficient system for the production of high quality strawberry (Fragaria ×ananassa) plantlets. In this system micropropagated mother plants of `Oso Grande' and `Sweet Charlie' produced an average of 84 and 80 daughters per mother plant, respectively, in 1996, at a plant density of 3 mother plants/ft2 (32 mother plants/m2). Nearly 100% of the plantlets harvested from the system were successfully rooted in plug trays, and showed no symptoms of leaf or crown diseases.
Seed of Viola × wittrockiana `Majestic Giant Yellow' were germinated in #406 plug trays at ambient CO2, 25 C and a light intensity of 100 μmol s-1m-2 with an 18 hr photoperiod. At emergence and at successive one week intervals, seedlings were exposed to CO2 levels of 500, 1000 or 1500 μl l-1 and irradiances of 100, 225, 350 μmol s-1m-2 for 7 to 35 days, after which seedlings were transplanted into 10 cm pots and grown to flower in the greenhouse. CO2 at 1000 μl l-1 was as effective as 1500 μl l-1 in accelerating growth in the plug stage. 500 μl l-1 at all irradiances did not accelerate growth significantly. Plants grown at 1000 μl l-1 and 225 μmol s-1m-2 intensity reached the 5 leaf stage up to 14 days earlier than the control, as well as decreasing time to flower during the growing on phase.
Shoot stretching in plug production reduces quality and makes mechanized transplanting difficult. The objectives of this study were to measure seedling emergence and shoot height of plugs as affected by paclobutrazol application during seed soaking, priming, or coating on seedling emergence and height. Verbena (Verbena ×hybrida Voss. `Quartz White'), pansy (Viola wittrockiana L. `Bingo Yellow Blotch'), and celosia (Celosia cristata L. `New Look') seeds were soaked in water solutions of paclobutrazol and subsequently dried on filter paper at 20 °C for 24 h. Soaking seeds in paclobutrazol solutions before sowing reduced growth and percentage seedling emergence of verbena and pansy but had little effect on those of celosia. Verbena seeds soaked in 50, 200, or 500 mg paclobutrazol/L for 5, 45, or 180 min produced fewer and shorter seedlings than controls. Osmopriming verbena seeds with 10 to 500 mg paclobutrazol/L reduced seedling emergence. Seedling height and emergence percentage of pansy decreased with increasing paclobutrazol concentrations from 2 to 30 mg·L–1 and with soaking time from 1 to 5 min. The elongation of celosia seedlings was reduced by soaking seeds in 10, 50, 200, or 500 mg paclobutrazol/L solutions for 5, 180, or 360 min. However, these reductions were negligible and without any practical application.
Eight bedding plant species were grown from plugs obtained from two sources. The plugs were transplanted into jumbo six packs and sprayed with a solution of chlormequat/daminozide with concentrations of 1000/800, 1250/1250, or 1500/5000 mg·L-1 when new growth was ≈5 cm in height or width. Three different species were grown in the fall (Dianthus chinensis L., `Telstar Mix', Petunia ×hybrida Hort. Vilm.-Andr., `Dreams Red', and Viola ×wittrockiana Gams., `Bingo Blue'), winter [Antirrhinum majus L., `Tahiti Mix', Matthiola incana (L.) R. Br., `Midget Red', and P. × hybrida, `Dreams Mix'], and spring [Catharanthus roseus (L.) G. Don, `Cooler Pink', Salvia splendens F. Sellow ex Roem. & Schult., `Empire Red', and Begonia ×semperflorens-cultorum Hort., `Cocktail Mix']. The treatments significantly reduced finished plant size of all species for each season. There was a significant difference in finish size between sources for Dianthus, Antirrhinum, Matthiola, Catharanthus, Salvia, and Begonia. The efficacy of chlormequat/daminozide also differed for each source of Dianthus, Matthiola, and Begonia, but the treatments minimized the differences in finish size between sources for Petunia and Viola. Chemical names used: (2-chlorethyl) trimethylammonium chloride (chlormequat); (N-dimethylaminosuccinamic acid) (daminozide).
Seed of Petunia × hybrida `Ultra White' were germinated in #406 plug trays at 2.5 C and at a light intensity of 100 μ mol s-1m-2 using a 24 or photoperiod. At germination, seedlings were grown under natural light conditions for 8 hrs (SD) or for 8 hrs with the photoperiod extended to 16 hrs (LD) using incandescent bulbs. At approximately the 6th leaf stage, seedlings were stored at 5 C in the dark or at 12 μ mol s-1m-2 and a 24 hr photoperiod for 0 to 21 days. After storage, plants were potted n 10 cm pots and grown to flowering in a greenhouse. Plants grown under SD to the 6th leaf stage with no cold treatment were shorter. flowered later and had more lateral branching than unstored LD plants. Storage at 5 C decreased time to flower of SD plants and increased branching of LD plants regardless of photoperiod during storage.
Pelargonium×hortorum L.H. Bailey `Scarlet Elite' seedlings were grown in plugs from seed to transplant size. About 14 days before attaining transplant size, seedlings were exposed to various fertility or temperature regimes (preconditioning treatments), then stored for 1 to 3 weeks at 5C. Seedlings receiving 150 mg N/liter before storage flowered sooner and required less crop time (days to flower – days in storage) than those receiving 0, 75, or 300 mg. Temperature preconditioning at 10 or 15C delayed flowering compared to preconditioning at 20C. Final plant height and dry weight were not adversely affected by varying N levels or temperature during preconditioning. Preconditioning seedlings with 300 mg N/liter resulted in seedling mortality rates up to 16% after 7 days' storage. Low temperature or fertility were not effective preconditioning treatments. Best results were attained by preconditioning seedlings with 150 mg N/liter.
Plug-grown Pelargonium × hortorum `Pinto Red' seedlings were grown under natural daylight (average of 4.7 mol/day) or with supplemental irradiance from high-pressure sodium lamps. Seedlings were grown under 8-, 16-, or 24-h photoperiods with supplemental irradiances of 2.5, 3.75, or 5.0 mol/day at each photoperiod. Supplemental irradiance was provided for 7, 14, 21, and 28 days beginning 7, 14, 21, 28, and 35 days after sowing. Seedlings were transplanted 63 days after sowing to 8-cm containers (121 plants/m2) and grown to flower. Leaf number at time of transplant was not affected by photoperiod, but increased as daily irradiance and weeks of supplemental irradiance increased. Seedlings were more responsive to supplemental irradiance applications beginning 28 and 35 days than at 7 to 21 days after sowing. Ninety-two percent of seedlings receiving 28 days of 5.0 mol/day supplemental irradiance under a 24-h photoperiod starting 35 days after sowing had initiated flower buds at time of transplant; 75% of those receiving 3.75 mol/day were initiated. Plants receiving less than 3 weeks of supplemental irradiance or with an irradiance period beginning less than 28 days after sowing had not initiated flowers at transplant.
Tomato `Marglobe' seed were sown on germination paper in enclosed plastic dishes in a growth room Ammonium was more toxic when applied as the single salt, ammonium sulfate, than when applied as part of a complete Hoagland solution. The lowest toxic ammonium levels were for the single salt 1.5 mM and for the complete solution 4.5 mM. Symptoms included reduced length of primary and particularly lateral roots, reduced numbers of root hairs, and chlorosis, distortion, and slower development of cotyledons. Tomato `Marglobe' seedlings were also grown in 288 cell plug trays in a substrate of 3 sphagnum peat moss and 1 perlite containing no N, P, or K but amended with dolomitic limestone to pH 6.0 They were fertilized every third watering with 4 mM NH4 + NO3, 0.4 mM PO4, and 1.2 mM K from 15 to 28 days after sowing and at double this concentration from 29 to 42 days. A zero leaching percentage was practiced. Ammoniacal-N comprised 25, 50, or 75% of total N. There were no effects of ammonium on root or shoot weights, height or appearance of plants through this period. Plant growth was limited throughout this period by N stress in accordance. with commercial practice. After 42 days N stress was alleviated by again doubling the nutrient solution concentration and applying it with every watering. Ammonium toxicity developed with symptoms of shorter plant height, general chlorosis of lower leaves, and necrosis of the base of lower leaves.