The influence of intermittent and continuous irrigation on the growth, substrate nutrient accumulation and leaching from container-grown marigolds was determined. During a three week period. Tagetes erecta L. `Apollo' in a pine bark substrate received 12 irrigations. Each irrigation allotment was applied intermittently (multiple applications) or continuously (single application). Irrigation occurred when bark reached a targeted water content; irrigation water contained a complete nutrient solution. Leachates were cumulatively collected for each container and analyzed for N; plant dry weight. size, and nutrient composition were determined. Compared to continuously irrigated plants, intermittently irrigated plants had 43% greater root dry weight, 0.7% greater N concentration, and 43% more N leached from the substrate. Shoot mass. size. K, and P concentrations, substrate (pour-through extraction) and leachate N concentration were unaffected by irrigation method. Results demonstrated that. compared to conventional irrigation practices, intermittent irrigation was an effective method to reduce fertilizer effluent and increase N absorption for container-grown plants.
Nabila S. Karam and Alexander X. Niemiera
R.A. Mirabello, A.E. Einert, G.L. Klingaman, and R.W. McNew
To examine the effects of mulching and fertilization on nutrient availability and plant growth in landscape beds, plots were established using four mulches (cottonseed hulls, cypress wood, pine bark, pine straw) and three fertilizer application methods (granular, liquid, time-release). Fertilizer was applied either below the mulch on the soil surface or over the mulch surface. Marigolds, Tagetes erecta L., were planted during the summer, followed by pansies, Viola×wittrockiana Gams, during the winter. Applied fertilizers, existing soil nutrients, and water-soluble nutrients from the new mulch provided an adequate supply of nutrients for marigold growth. Placement of fertilizer above or below the mulch did not affect marigold growth. Pansy growth was limited by depletion of soil N during the marigold season and by leaching of applied nutrients in the winter while plants were not actively growing. Mulch lowered soil temperatures and slowed pansy recovery in the spring. Pine straw allowed soil temperatures to rise earlier in the spring and improved pansy growth.
Joyce G. Latimer and Ronald D. Oetting
Two weeks after planting, plugs of New Guinea impatiens (Impatiens × hybrida), marigold (Tagetes erecta), or ageratum (Ageratum Houstonianum) were subjected to eight conditioning treatments: untreated, low N (50 ppm), high N (500 ppm), ebb/flow watering, drought, brushing (40 strokes twice daily), daminozide (5000 ppm), or paclobutrazol (45 ppm). Fertilizers were applied three times per week at 250 ppm N for all plants not treated with high or low N. Five adult twospotted spider mites were placed on each plant 1 week after treatment. New Guinea impatiens height was reduced by low N, brushing, or paclobutrazol at 4 weeks after treatment. Spider mite populations were reduced only by brushing. Marigold height was reduced by low N, drought, or brushing, but spider mite counts were reduced by brushing or paclobutrazol. Height of ageratum was reduced by low N, daminozide, or paclobutrazol, but spider mite counts were reduced by ebb/flow or brushing at 4 weeks after treatment.
Carl E. Niedziela Jr., Stephen A. Emerson, and Guochen Yang
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.
Jonathan M. Frantz*, Dharmalingam S. Pitchay, James C. Locke, and Charles Krause
Silica (Si) is not considered to be an essential plant nutrient because without it, most plants can be grown from seed to seed without its presence. However, many investigations have shown a positive growth effect if Si is present, including increased dry weight, increased yield, enhanced pollination, and most commonly, increased disease resistance, which leads to its official designation as a beneficial nutrient. Surprisingly, some effects, such as reduced incidence of micronutrient toxicity, appear to occur even if Si is not taken up in appreciable amounts. The literature results must be interpreted with care, however, because many of the benefits can be obtained with the counterion of the Si supplied to the plant. Determining a potential benefit from Si could be a large benefit to greenhouse plant producers because more production is using soilless media that are devoid of Si. Therefore, Si must be supplied either as a foliar spray or nutrient solution amendment. We investigated adding Si to New Guinea Impatiens (Impatiens hawkeri Bull), marigold (Tagetes erecta), pansy (Viola wittrockiana), spreading petunia (Petunia hybridia), geranium (Pelargonium spp.), and orchid (Phalaenopsis spp.). Using SEM, energy dispersive X-ray analysis, and ICP analysis, Si content and location was determined. This information and other growth characteristics will be used as a first step in determining the likelihood of using Si as a beneficial element in greenhouse fertilizer solutions for higher quality bedding plants with fewer agrochemical inputs.
David A Gilbertz
Seven to 9 cvs each of Begonia semperflorens, Tagetes erecta, T. patula, and Petunia hybrida (grandiflora and multiflora types) were sown into seedling trays. One to 3 weeks after transplanting to flats (75 cm3/cell), paclobutrazol (PB) was sprayed at concentrations of 10 (begonia), 60 (marigold) or 100 (petunia) mg liter-1 at a 200 ml m-2 rate. Uniconazole (UC) was applied at one-half the PB concentrations. Plant height was measured before planting in the field May 17 and monthly through July. Species were analyzed separately and generally, there were no cultivar by triazole interactions. During the greenhouse phase, the triazoles controlled height of both marigold species compared to control, but in July the PB and UC treated plants were 100 and 91%, respectively, of control plant height. Flowering was delayed up to 4 days for UC treated T. patula plants. Height of triazole-treated petunias was 60-67% of control height during the greenhouse phase and 84-95% after 2 months in the field. Begonia height was reduced by triazoles during both phases. After 2 months in the field, PB and UC treated begonias were 72 and 44%, respectively, of control plant height.
Jillene R. Summers, Gail R. Nonnecke, Cynthia A. Cambardella, Richard C. Schultz, and Thomas M. Isenhart
Improving soil quality and suppressing weeds are two challenges facing strawberry growers. Cover crops, such as perennial ryegrass (Lolium perenne) and sorghum-sudangrass (Sorghum sudanense), have been used in rotation with strawberry in the Midwest. The objective of the field study was to investigate the effects of various cover crops on soil quality and weed populations for strawberry production. The experiment was established in 1996 at the Iowa State Univ. Horticulture Station, Ames, in plots that previously were planted continuously in strawberry for 10 years. Nine treatments were arranged in a randomized complete-block design with three replications. Treatments included cover crops of Indian grass (Sorghastrum avenaceum), switchgrass (Panicum virgatum), big bluestem (Andropogon gerardii), black-eyed susan (Rudbeckia hirta), marigold (Tagetes erecta `Crackerjack'), sorghum-sudangrass, perennial ryegrass, strawberry (Fragaria ×ananassa `Honeoye'), and bare soil (control). Data from 1998 showed that both annual and perennial cover crops were established more readily (higher treatment-plant populations and less weed populations) than in 1997. Water infiltration rates were highest in bare soil plots and lowest in P. virgatum plots. Bare soil plots and S. sudanense plots had the lowest percent soil moisture.
Lynn Burney and Richard L. Harkess
Maintaining annual color throughout the long summer season in warm temperate regions has become an interest to landscapers and nursery operators. Some colorscaping companies have begun implementing a second summer planting season. There is little information available concerning suitable cultivars and species of bedding plants for establishment in late summer. This study examined plant establishment in two container sizes and three dates of transplanting to determine late season establishment in Starkville, Miss. (33°27' latitude, 88°49' longitude). Seeds of 27 different cultivars were grown in plug flats in the greenhouse and transplanted into jumbo 606 or 10-cm square containers. The plants were grown in the greenhouse until transplanting on 16 Aug., 30 Aug., or 13 Sept. 1996. The plants were transplanted into plots containing nine plants with three replications per planting date. The plants were spaced on 20-cm centers among and between plots. The earliest two plantings resulted in better plant establishment and floral display. Some of the cultivars and species were more tolerant of the late season temperature and humidity establishing and providing a good color display from 6 weeks after transplanting until frost, 2 Nov. 1996. Cultivars that performed well included: Impatiens wallerana `Deco Crystal', `Expo Lavender Blush', `Dazzler Salmon', Begonia semperflorens `Varsity Bronze Scarlet', Zinnia `White Pinwheel', Tagetes erecta `Marvel Gold', and Tagetes patula `Bonanza Harmony'. Cultivars that did not establish well under these conditions included: Verbena hybrida `Romance Pink' and Salvia splendens `Salsa Salmon'. The container size did not significantly affect plant establishment.
Douglas A. Cox
`First Lady' marigold (Tagetes erecta L.) and `Selenia' New Guinea impatiens (NGI; Impatiens sp. hyb.) were grown in solution culture for 60 days. At 10-day intervals, plants received low N for 10 days (marigold) or 20 days (NGI). Low-N treatment was 5% and 10% of the control, respectively, for marigold and NGI. After each low-N period, FW of treated and control plants was measured and N uptake by the controls was determined by solution depletion. Nitrogen uptake by marigold reached a peak 40 days after planting, and then decreased somewhat during the final 20 days of the experiment. In contrast, N uptake by NGI increased gradually after planting, reaching its highest level at the end of the experiment (60 days). Low-N periods 10 to 20 and 20 to 30 days after planting reduced the FW of marigold about 35% vs. control. FW reductions resulting from earlier or later low-N periods were much smaller or did not occur. Reductions in NGI FW resulted from low-N periods 20 to 40, 30 to 50, and 50 to 60 days after planting. While short periods of low N reduced the growth of both species, these reductions were desirable and not excessive, and no foliar symptoms of N deficiency were apparent at any time. Results of these experiments have implications for efficient fertilizer use and growth suppression using short periods of low nutrition.
John M. Dole
Three cut-flower species, Ageratum houstonianum `Tall Blue Horizon', Antirrhinum majus `Spring Giants Mix', and Helianthus annuus `Sunrich Orange' were grown in 806, 1801, or 1001 bedding plants flats resulting in 32 (85), 86 (280), and 156 (620) cm2 (mililiter medium)/plant, respectively. Plants were sown Sept. 1997 (fall), Dec. 1997 (winter), or Mar. 1998 (spring). Increasing area per plant decreased number of stems harvested but increased percent of stems harvested for all species. Increasing area per plant increased stem length and selling price for Antirrhinum and Helianthus; no significant difference was noted for Ageratum. Days to anthesis decreased with later planting for Antirrhinum and Helianthus; however, for Ageratum winter planting had the longest crop time and spring planting the shortest. Gross profit per square meter and square meter per week increased with decreasing area per plant for Ageratum and Helianthus; no significant difference was noted for Ageratum. Gross profit per square meter per week increased with later planting for all species. With all species 806 flats or spring planting required frequent irrigation, which would best be supplied by an automated irrigation system. Experiment was repeated in 1998/1999 using Carthamus tinctorius `Lasting Yellow', Celosia argentea `Chief Mix', Cosmos bipinnatus `Early Wonder', Helianthus annuus `Sunbright, Tagetes erecta `Promise Orange' and `Promise Yellow', and Zinnia elegans `Giant Deep Red' and `Oklahoma Mix'.