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- Author or Editor: Carl E. Niedziela* Jr. x
Plug seedlings of lisianthus [Eustoma grandiflorum (Raf.) Shinn. `Mariachi'] and stock [Matthiola incana (L.) R.Br. `Cheerful White'] were planted on 20 Nov. 2003 followed by plug seedlings of snapdragon (Antirrhinum majus L. `Maryland') and seeds of sunflower (Helianthus annuus L. `Sunbrite') the next day. Each species was planted in four production systems (harvest lugs, lay-flat bags, pots, and polystyrene trays). Production systems were randomized in a Latin-square design with four replications of each system. Each treatment plot was 0.7 m × 1.1 m. Planting densities was 62 plants/m2 for stock and 31 plants/m2 for lisianthus, snapdragon, and sunflower. The harvest lugs were 55 cm × 37 cm × 16 cm. The lay-flat bags were 114 cm × 30 cm × 3 cm. The pots were 25 cm bulb pans. The polystyrene trays were 67 cm × 34 cm × 5 cm and contained 32 square cells. All of the containers were filled with the same tobacco germination media. The plants in the harvest lugs, lay-flat bags and pots were irrigated daily with 150 mg·kg-1 of N from 20N-4.4P-16.6K. The plants in the polystyrene trays were floated on a solution of 150 mg·kg-1 of N from 20N-4.4P-16.6K. Float solutions were monitored and adjusted weekly for volume and fertilizer concentration. Individual stems were harvested from each species at the appropriate stage of development for market. The weight and length of individual stems were recorded. Rate of growth and maturation differed between production systems and locations in the greenhouse. Detailed results will be presented.
Plug seedlings of Celosia cristata L. `Persimmon Chief' were planted in four production systems (harvest lugs, lay-flat bags, pots, and polystyrene trays) on 7 May 2004. Production systems were randomized in a Latin-square design with four replications of each system. Each treatment plot was 0.7 m × 1.1 m. Planting density was 31 plants/m2. The harvest lugs were 55 cm × 37 cm × 16 cm. The lay-flat bags were 114 cm × 30 cm × 3 cm. The pots were 25 cm bulb pans. The polystyrene trays were 67 cm × 34 cm × 5 cm and contained 32 square cells. All of the containers were filled with the same tobacco germination media. The plants in the harvest lugs, lay-flat bags and pots were irrigated daily with 150 mg·g-1 N from 20N–4.4P–16.6K. The plants in the polystyrene trays were floated on a solution of 150 mg·g-1 N from 20N–4.4P–16.6K. Float solutions were monitored and adjusted weekly for volume and fertilizer concentration. Individual stems were harvested at the appropriate stage of development for market. The fresh weight, stem length and flower diameter of individual stems were recorded. Stems produced in float trays had the lowest fresh weight (162.2 g). Stems grown in harvest lugs (363.5 g) weighed more than those in pots (298.4 g) but not lay-flat bags (338.4 g, lsd 0.05 = 42.7). Stems grown in float trays (88.8 g) were shorter than lay-flat bags (121.5 g), harvest lugs (120.5 g), and pots (113.5 cm, lsd 0.05 = 10.5). Flower diameter did not differ between production systems (mean diameter = 7.2 cm).
A new tube method for determining physical properties in container substrates was compared to an existing system. While both offer the advantages of undisturbed substrate and measurement of properties without altering the geometry of the substrate in the container, the tube method is easier to conduct. Both methods proved equally effective for determining air-tilled porosity, container capacity, total porosity, bulk density, and particle density.
This study investigated antimicrobial effects of guava products on the survival and growth of Escherichia coli O157:H7 in liquid medium. Seven strains of E. coli O157:H7 (944, 380, E0019, F4546, H1730, Cider, 9727) were tested. These strains were maintained in BHI broth. Guava fruits were sliced into small pieces and blended using a blender. Guava juice and leaves were then extracted using three solvents: water, methanol and hexane. Fruit extracts were dissolved in 10 ml BHI broth tubes to make a fruit solution of 5% (w/v). E. coli O157:H7 was inoculated into fruit solutions at 2 log cfu/mL. After incubation at 37 °C for 24 h, samples were serially diluted 10 folds. The proper diluent was spread-plated on TSA in duplicate. After incubation at 35 °C for 24 h, viable cell counts were obtained. The experiment was replicated three times in a randomized complete-block design. Results demonstrated that guava products (fruit, juice, and leaf extracts) significantly reduced survival and growth of the tested foodborne pathogen strains. Water extract showed the highest antimicrobial activity, followed by methanol and hexane. These results indicate guava extracts are a potential antimicrobial agent to ensure food safety.
Plug seedlings of delphinium (Delphinium elatum L. `Guardian') were planted on 19 Nov. 2004 in four production systems (harvest lugs, lay-flat bags, pots, and polystyrene trays). Production systems were randomized in a Latin-square design with four replications of each system. Each treatment plot was 0.7 × 1.1 m. Planting density was 31 plants/m2. The harvest lugs were 55 × 37 × 16 cm. The lay-flat bags were 114 × 30 × 3 cm. The pots were 25 cm bulb pans. The polystyrene trays were 67 × 34 × 5 cm and contained 32 square cells. All of the containers were filled with the same tobacco germination media. The plants in the harvest lugs, lay-flat bags and pots were irrigated daily with 150 mg N/kg from 20N–4.4P–16.6K. The plants in the polystyrene trays were floated on a solution of 150 mg N/kg from 20N–4.4P–16.6K. Float solutions were monitored and adjusted weekly for volume and fertilizer concentration. Individual stems were harvested at the one-third bloom stage of development. The final harvest was on 1 Apr. 2005. Fewer stems were harvested from float trays and lay-flat bags than from pots and harvest lugs. The stems harvested from float tray plots were shorter than those from the other three systems. Stem fresh weight from greatest to least was lay-flat bags, harvest lugs, pots, and float trays. Stem dry weight was less for float trays than the other three systems.
This research was initiated to study different culture media and plant growth regulators for their influences on callus initiation and production, with a research goal of developing an efficient in vitro callus regeneration protocol for guava (Psidium guajava L.). Guava is an important tropical fruit species that is rich in vitamins and vitamin precursors, minerals, organic acids, and pectins. Seventy-nine phytochemicals provide guava with many unique properties and actions, including anti-microbial, astringent, bactericidal, cicatrizant, emmenagogue, hypoglycemic, laxative, nutritive, and spasmolytic. Different concentrations of various plant growth regulators (PGR), such as 6-benzyladenine (BA), kinetin, or 2,4-dichlorophenoxyacetic acid (2,4-D), and naphthaleneacetic acid (NAA) were added to basic Murashige and Skoog (MS) and woody plant medium (WPM) and tested for their influences. Differences in callus initiation and morphology were noticed between MS and WPM, and among PGR concentration treatments.
Plug seedlings of Tagetes erecta L. `Gold Coin Mix' were planted in four production systems (harvest lugs, lay-flat bags, pots, and polystyrene trays) on 5 May 2005. Production systems were randomized in a Latin-square design with four replications of each system. Each treatment plot was 0.7 m × 1.1 m. Planting density was 31 plants/m2. The harvest lugs were 55 cm × 37 cm × 16 cm. The lay-flat bags were 114 cm × 30 cm × 3 cm. The pots were 25-cm bulb pans. The polystyrene trays were 67 × 34 × 5 cm and contained 32 square cells. All of the containers were filled with the same tobacco germination media. The plants in the harvest lugs, lay-flat bags, and pots were irrigated on alternate days with 150 mg·kg-1 N from 20N–4.4P–16.6K. The plants in the polystyrene trays were floated on a solution of 150 mg·kg-1 N from 20N–4.4P–16.6K. Float solutions were monitored and adjusted weekly for volume and fertilizer concentration. Individual stems were harvested at the appropriate stage of development for market. The fresh weight, stem length, and dry weight of individual stems were recorded. The rate of growth and maturation differed between production systems and locations in the greenhouse. Detailed results will be presented.
Commercial recommendations exist for using short-term salt-shocks on tomato (Lycopersicon esculentum Mill.) to improve fruit quality. Six experiments were conducted to 1) assess the influence of nutrient concentration and short-term salt-shocks on fruit quality and yield and 2) identify a vegetative predictor of subsequent fruit quality. The first objective was addressed in three nutrient film technique (NFT) experiments (Expts. 1-3). Four treatments were applied: two maintained constant at two baseline concentrations (0.25X and 1X-commercial level) and two provided salt-shock periods of 30 min, twice daily. There were no effects of baseline concentration or salt-shocks on total number and weight of marketable fruit. Fruit quality was better at the 1X baseline concentration as observed by higher titratable acidity (Expt. 2), higher percent dry matter (Expts. 2 and 3), higher soluble solids concentration (Expt. 2), and lower pH (Expts. 2 and 3), however, weight per marketable fruit was lower (Expt. 2). Salt-shocks had little effect on fruit quality, refuting its commercial potential. Salt-shocks decreased fruit pH (Expts. 1 and 3). However, titratable acidity increased at the 0.25X level and decreased at the 1X level (Expt. 3). In Expt. 2, but not in Expt. 3, citrate concentration in the fifth leaf from the apex of young vegetative plants was correlated with subsequent fruit quality. Three additional experiments in static hydroponics with vegetative plants showed no significant differences in leaf citrate levels due to a single, short-term salt-shock. Thus, citrate is not a good predictor of fruit quality.
The objective of this study was to determine how plant species, fertilizer potential acidity/basicity rating (PABR), and fertilizer concentration affect root substrate pH. Three experiments were conducted. In the first experiment, 13 herbaceous species were grown in a root substrate of three sphagnum peatmoss: one perlite (v/v) with deionized water and a neutral fertilizer (NF) with a PABR of 0 for 78 days to determine species relationships to substrate pH. The decrease in substrate pH ranged from 0.14 to 2.45 units, depending on species. In the second experiment, four of the 13 species from the previous trial representing the range of pH suppression were grown under similar growth conditions as the first experiment for 70 days. Substrate pH was lowered in the range of 0.47 to 2.72 units. In the third experiment, three fertilizers with PABRs of 150 kg·t−1 CaCO3 equivalent alkalinity, 0 neutral, and 193 kg·t−1 CaCO3 equivalent acidity were applied in a factorial design at 100 and 200 mg·L−1 N at each irrigation to kalanchoe (the species with the greatest pH suppression from the previous experiments) for 56 days. When applied at the lower fertilizer rate (100 mg·L−1 N), the PABRs resulted in the final substrate pH levels of 4.68, 5.60, and 6.11 for the acidic fertilizer (AF), NF, and basic fertilizer (BF), respectively. At the high fertilizer rate (200 mg·L−1 N), substrate pH declined continuously to 3.97, 4.03, and 4.92 for the AF, NF, and BF, respectively. Expression of PABR depended on the balance between the abiotic (chemical) effect of the fertilizers vs. the biotic (physiological) effects of the fertilizers on microbes and plants. The PABR was best expressed when the fertilizer supply was just adequate or lower indicating a closer connection to the biotic effect.
Fertilizers with a high proportion of nitrogen (N) in the nitrate (NO3 –) form are used in the ornamental industry to promote compactness in plants. Although the common belief is that it is the high proportion of NO3 – that causes compactness, these formulations also contain no or a low level of phosphate, which can also cause compactness. This study was conducted to assess the relative effects of NO3 – to ammonium (NH4 +) ratio and phosphate supply, as found in high NO3 – fertilizers, on seedling shoot growth. A series of fertilizers was formulated in which the level of phosphate and proportion of N in the NO3 – form were varied factorially. Additionally, commercial fertilizers varying in these same two nutrient components were tested to verify the results obtained using the formulated fertilizers. Test plants included gomphrena (Gomphrena globosa L.), impatiens (Impatiens wallerana Hook. F.), petunia (Petunia ×hybrida Juss.), marigold (Tagetes erecta L.), and tomato (Solanum esculentum Mill.) grown as plug seedling crops. A strong inverse relationship occurred between the supply of phosphate and extent of compactness. The relationship between proportion of N in the NO3 – form and compactness was comparatively small. In most comparisons within the study, shoot size increased with increasing proportion of NO3 –, contrary to common belief. These data indicate that it is the limited phosphate level in high NO3 – fertilizers that accounts for compactness rather than the high proportion of N in the NO3 – form.