Abstract
Plants grown in small containers often show limited growth due to low levels of aeration and water holding capacity in the medium. These levels can be changed by management practices such as medium compaction, medium wetness at time of container filling, container height and volume, peat : vermiculite ratio, particle size, and the use of a wetting agent. A modified equilibrium capacity variable model was applied to an investigation of media-container interactions for short containers (<5 cm tall). Predicted volume percentages for total porosity (TP), container capacity (CC), air space (AS), unavailable water (UW), and available water (AW) were developed from measured moisture retention data and container geometry. AS increased with: 1) increased particle size, 2) increased media moisture at time of container filling, 3) decreased medium compaction, 4) increased wetting agent concentration, 5) decreased ratio of peat : vermiculite, and 6) increased container height. Increased percent AW resulted from smaller particle size, increased media moisture at time of container filling, decreased container compaction, decreased wetting agent concentration, increased ratio of peat : vermiculite and decreased container height.
The annual bedding plants `Dazzler Rose Star' impatiens (Impatiens wallerana), `Cooler Blush' vinca (Catharanthus roseus), `Orbit Cardinal' geranium (Pelargonium × hotorum), `Janie Bright Yellow' marigold (Tagetes patula) and `Bingo Azure' pansy (Viola tricolor) were grown on germination papers treated with deionized water (DI), 2500 or 5000 mg·L-1 (ppm) humic acid (HA) or nutrient control (NC) solutions. Seedlings grown on HA-treated germination papers had higher dry root weights than those grown on DI or NC-treated germination papers. Except for impatiens, seedlings germinated on HA-treated germination papers had higher lateral root numbers and higher total lateral root lengths than those grown on DI and NC-treated germination papers. Impatiens grown on NC-treated germination papers had higher lateral root numbers than those grown on DI or HA-treated germination papers. Overall, lateral root numbers for impatiens were higher for seedlings germinated on HA-treated papers than DI or NC-treated papers and highest lateral root numbers occurred on those impatiens germinated on papers treated with 5000 mg·L-1 HA. Except for geranium, seedlings grown in HA-amended sphagnum-peat-based substrates had similar dry root and dry shoot weights as those grown in unamended substrates. Geranium seedlings grown in HA-amended sphagnum peat-based substrates had significantly higher dry root weights than those grown in unamended substrates. However, dry shoot weights of geranium grown in HA-amended sphagnum peat-based substrates were similar to those grown in unamended substrates.
Tomato (Lycopersicon esculentum Mill) seedlings given 0.3 to 0.4 L/tray per day of a mineral solution containing (in mg·L-1) 150N-47P-216K-64Ca-40Mg maintained optimal height at 10 to 13 cm for Ontario processing tomato transplants. Seedlings given greater fertigation volumes were too tall and spindly to use as transplants. Transplants given 0.2 L of water per tray per day were very short (6 cm) compared to those receiving 0.3 to 0.4 L. As fertigation volume was increased from 0.2 to 0.7 L, shoot N remained constant while root N increased. Shoots had about a 3-fold higher level of N, P, and K than the roots. Calcium and magnesium were similar in roots and shoots. Mineral leaching from the trays was 1% of the total volume applied for the 0.4-L and 4% for the 0.7-L treatment.
Sweetpotato [Ipomoea batatas (L.) Lam., `Beniazuma'] plantlets were grown photoautotrophically (without sugar) for 12 days in an improved forced ventilation system designed with air distribution pipes for uniform spatial distributions of carbon dioxide (CO2) concentration. Enriched CO2 conditions and photosynthetic photon flux (PPF) were provided at 1500 μmol·mol-1 and 150 μmol·m-2·s-1, respectively. The forced (F) ventilation treatments were designated high (FH), medium (FM), and low (FL), corresponding to ventilation rates of 23 mL·s-1 (1.40 inch3/s), 17 mL·s-1 (1.04 inch3/s), and 10 mL·s-1 (0.61 inch3/s), respectively, on day 12. The natural (N) ventilation treatment was extremely low (NE) at 0.4 mL·s-1 (0.02 inch3/s), relative to the forced ventilation treatments. Total soluble sugar (TSS) and starch content were determined on day 12. Total soluble sugars (sucrose, glucose, fructose) of FH plantlets were lowest in leaf tissue and highest in stem tissue as compared to other ventilation treatments. Starch concentration was higher in leaf tissue of FH or FM plantlets as compared to that of FL or NE plantlets. Plantlets subjected to FH or FM treatments exhibited significantly higher net photosynthetic rates (NPR) than those of the other treatments; and on day 12, NPR was almost five times higher in the FH or FM treatment than the FL or NE treatments. Carbohydrate concentration of plantlets was also influenced by the position of the plantlets in the vessel. Within the forced ventilation vessels, leaf TSS of FH and FM plantlets was similar regardless of whether plantlets were located near the inlet or outlet of CO2 enriched air. However, under FH or FM conditions, leaf starch concentration was higher in plantlets located closest to the CO2 inlet as compared to the outlet.
artificial shade conditions. Materials and Methods Experiments were conducted in 2006 and 2007 at the Texas Tech University Horticulture Greenhouse in Lubbock, TX. Plugs measuring 2.5 cm 2 of six zoysiagrass genotypes [ Zoysia japonica Steud. genotype
osmotic regulation resulting in higher turgor pressures. The present study was conducted to evaluate the recuperative potential of transplanted plugs of 24 commonly grown cultivars of three species of warm-season turfgrasses subjected to varying amounts of
) compared the establishment rate and stolon growth characteristics of five Z. japonica lines, ‘Emerald’, and a Z. matrella cultivar in Maryland. When planted as 5-cm diameter plugs on 30-cm centers, ‘Midwest’, a Z. japonica , and Bel-Zrt-1, an
strawberry industry. However, early planting in Florida exposes strawberry transplants to heat stress. The use of strawberry plug transplants is proposed as a means of reducing or eliminating the high sprinkler irrigation requirement for bare-root transplant
the existing sod and replacing sod of a warm-season species would be the ideal remedy, but this may be cost prohibitive for many homeowners and facilities. An alternative approach would be to seed or plug the warm-season species directly into the
1 E-mail blackb@ba.ars.usda.gov . The author gratefully acknowledges student intern Michele Sumi for technical assistance, Davon Crest Farms for supplying strawberry plug plants, and BASF Corp. for providing prohexadione-Ca. Mention of a trademark