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Dormant-budded `Gloria' azaleas (Rhododendron sp.) were used to observe the effect of forcing irradiance, temperature, and fertilization on postproduction performance after flower bud dormancy had been broken. Four experiments were conducted during forcing, the treatments for each experiment were: Expt. 1, three forcing irradiances (200,460, and 900 μmol·m-2·s-1) and three postproduction irradiances (4, 8, and 16 μmol·m-z·s-1); Expt. 2, three forcing irradiances (320, 560, and 1110 μmol·m-2s-l); Expt. 3, three controlled day/night temperatures (18/16C, 23/21C, and 29/27C); Expt. 4, fertilizer applied for 7, 14, or 28 days at either 150 or 300 mg N/liter (12% nitrate, 8% ammoniacal) 20N-4.8P-16K soluble fertilizer at every watering, control plants did not receive fertilizer. Days to harvest (time until plants had eight individual open flowers) was less at the high forcing irradiances and temperatures and when fertilizer was applied during forcing. Flower color was less intense at the low forcing irradiance levels, high temperatures, and when duration of fertilization was prolonged and concentration was high. There were more open flower inflorescences at week 2 of postproduction at high forcing irradiance levels, but their number was not affected by forcing temperature or fertilization. Postproduction longevity was shorter when forcing was at 29/27C (day/night) and when plants were fertilized for 28 days at 300 mg N/liter, but was not affected by forcing or postproduction irradiance.

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containers has been increasing because container production enables the large-scale production of plants with an intact root system and uniform dimensions in all seasons. However, the lack of information about precision fertilization during the growing season

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Abstract

Growth and development of the pistillate flower and fruit in Corylus avellana L. cv. Barcelona, was studied from anthesis (January) to maturity (September). Ovary growth is very slow for about 4.5 months, proceeds very rapidly for about 6 weeks, during which time 90% of the increase in diameter occurs, and then abruptly ceases. Ovule development, megasporogenesis, megagametogenesis, and fertilization are described. At the time of pollination (January) the pistillate flower consists of a pair of stigmatic styles joined at their bases by a minute ovarian meristem. Pollen tubes reach the base of the style in 4 to 7 days. The sperm nucleus remains in the pollen tube tip in a resting stage until mid-June (about 5 months). During this period the basal meristematic cells develop into a mature ovary. Multiple megasporocytes, derived directly from archesporial cells, give rise to several megaspores, partly developed embryo sacs, and one normal embryo sac. When the sac is mature a secondary pollen tube, bearing the sperm, grows basipetally from the resting site in the upper tip of the ovary. It proceeds through the funiculus of the anatropous ovule, along the single integument, enters the nucellus through the chalazal end, and penetrates the micropylar end of the embryo sac where the sperm is ejected. While pollination is necessary to initiate ovary development, only a small percentage of the pollinated pistils develop into a full size nut. Fertilization is necessary for the formation of normal nuts with embryos. Full size nuts which are empty at maturity result from pollination without fertilization or from embryo abortion.

Open Access

Abstract

Rate of coverage from plugs of ‘A-20’ Kentucky bluegrass (Poa pratensis L.) planted in Flanagan silt loam and treated with oxadiazon at 3.4 kg/ha increased as mowing height increased from 1.9 to 3.8 to 7.5 cm and with fertilization at 25 kg N/ha per growing month or higher. Sod strength measurements taken 2 years after planting were highest in plots receiving 25 kg N/ha per growing month compared to 0, 50, and 100 kg. Where plugs of 48 cultivars of Kentucky bluegrss received the same oxadiazon treatment, phytotoxicity ranged from no injury to complete necrosis.

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Abstract

Termination of liquid fertilizer application at the visible bud stage or 2 weeks later during production of potted Lilium longiflorum Thunb. ‘Nellie White’ increased foliar chlorosis development relative to fertilization until harvest on plants stored for 3 weeks at 2C in the dark. Drenches of ancymidol applied during early production increased poststorage foliar chlorosis and bud abortion. Polyethylene (PE) lining of boxes used for cold storage and simulated shipment of potted lilies reduced water loss but did not affect subsequent floral longevity, but abortion, or foliar chlorosis. Spermidine application before boxed storage did not influence foliar chlorosis.

Open Access

Seedlings of processing tomato `H 2653' (Lycopersicon esculentum Mill.) were cultured in 288-cell (< 6 cm3 volume) plug trays in a soilless growing medium. Pretransplant fertilization with nutrient solutions containing 10 or 20 mm N and 2 or 5 mm P for 10 days altered the total ammoniacal-N and P, and the soluble NO3-N and PO4-P concentrations in the shoot tissue at transplanting. Post-transplanting shoot and root growth were more rapid in late May plantings than in earlier plantings. The 20-mm N and 2-mm P pretransplant treatment caused the most rapid shoot growth following early season plantings in the field. Rapid seedling establishment after transplanting was generally not a good indicator of potential fruit yield. The 5-mm P pretransplant treatment produced higher marketable fruit yields in early plantings but not in later. Culture of seedlings under a low fertilization regime (5.4 mm N, 1.0 mm P, and 1.6 mm K) before pretransplant treatment produced as high or higher fruit yields than did seedlings from a higher regimen. Withholding fertilizer temporarily before transplanting resulted in a depletion in tissue N and P concentrations, slow post-transplanting shoot growth, and lower yields.

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Soils were fertilized with gypsum (CaSO4·2H2O) at rates up to 4 t·ha-1, and Ca2+ concentrations in pods of 12 snap bean (Phaseolus vulgaris L.) cultivars were determined, with the intention of improving snap beans as a source of Ca2+ for human nutrition. The addition of gypsum to the soil did not affect the Ca2+ concentration of pods, even though Ca2+ in the soil solution increased from 4 to 15 mmol·L-1. Calcium concentrations of pods of the various snap bean cultivars ranged from 4.1 to 5.7 mg·g-1 dry mass. `Top Crop', `Astrel', `Tenderlake', and `True Blue' had the highest Ca2+ concentration in the pods and `Labrador' and `Roma II' had the lowest. The results suggest that factors other than Ca2+ supply influenced the Ca2+ concentration of the snap bean pod. Therefore, increased Ca2+ concentration of pods may be better achieved through breeding and selection rather than Ca2+ fertilization when Ca2+ levels in soil are sufficient.

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Pine bark-filled containers periodically fertilized with NH4-N were heated from 21C to 28, 34, 40, 46, or 52C for daily exposures of 1, 2, 4, 6, or 24 hours over 20 days. Concentrations of NH4-N and NO3-N in medium solution extracts were determined every 5 days. Medium solution NH4-N concentration was higher at constant (24 hours) exposure to 40C than at lower temperatures or exposure times. There was a similar increase in NH4-N concentration for a 2-hour·day–1 exposure to 46C, with further increases in NH4-N for longer exposure times. By day 10, NH4-N concentration was highest after 1 hour·day–1 exposure to 52C. Decreases in medium solution NO3-N concentration generally coincided with the increases in NH4-N. These results indicate that container medium thermal periods, similar to those observed in nurseries of the southern United States, may inhibit nitrification, thereby influencing NH4-N: NO3-N ratios in the medium solution of plants fertilized with predominantly ammoniacal N sources.

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irrigation rate, calcium fertilization, and the incidence of BER, however, are still not fully understood. Soils in the Coastal Plain, where most Georgia bell peppers are grown, have low water-holding capacity ( Smittle et al., 1994 ). Excessive irrigation

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Dendrobium Linnapa `No. 3' plants were potted one per 1.75-liter pot with large or small fir bark with or without 30% peatmoss (by volume before mixing). Plants in each medium were fertilized at each or every third irrigation with 1 g·liter−1 of 20N-8.6P-16.6K fertilizer. Neither medium nor fertilization frequency affected flowering date of the first pseudobulb. Adding peatmoss to both types of bark resulted in taller first pseudobulbs. Peatmoss in the large bark promoted the production of more inflorescences and flowers (20) compared to the bark alone (11). Constant fertilization promoted the early emergence and development of the second pseudobulb and resulted in more inflorescences and flowers (21) than intermittent fertilization (12). Vegetatively propagated Phalaenopsis Taisuco Kochdian were planted in 0.5-liter pots with 1) equal volumes of no. 3 perlite, Metro Mix 700, and charcoal (PMC); 2) 100% large fir bark; or 3) 40% medium fir bark, 20% peatmoss, 10% each of no. 3 and no. 2 perlite, 10% vermiculite, and 10% ParGro rockwool (RM). Plants in PMC produced twice the number of new leaves and 1.5 -fold more leaf area than those in the large bark. PMC and RM resulted in similar shoot weights, but the latter enhanced flower count due to more lateral inflorescences. Most (80%) of the roots on plants in the bark were hanging out of the pots, whereas nearly all the roots remained in the pots with PMC. Although medium had no effect on flowering date, flowers on plants produced in PMC and RM were 10% larger than in those on plants produced in bark.

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