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Nirit Bernstein, Marina Ioffe, Moshe Bruner, Yair Nishri, Gideon Luria, Irit Dori, Eli Matan, Sonia Philosoph-Hadas, Nakdimon Umiel, and Amir Hagiladi

The form of N supplied to the plant (NH4 + or NO3 ) affects growth, morphology and a range of physiological processes in the plant. Little information is available concerning the effects of N form on development, production or quality of cut-flowers. The present study investigated for the first time the effects of N form and quantity on growth, flower production and flower quality of Ranunculus asiaticus L. The plants were cultivated in an inert mineral soilless medium (perlite) and were exposed to two levels of nitrogen fertilization (50 or 100 ppm) and three levels of NH + 4 (10%, 20%, or 30%, under 100 ppm nitrogen fertilization). Larger shoots and increased shoot/root ratios were obtained in the lowest (50 ppm) N treatment. This treatment also excelled in flower yield production, resulting in higher numbers of total flower produced as well as higher numbers of long flowers. The results demonstrate an effect of N ferlilization treatments on cut-flower quality. Flowers grown under 50 ppm N application characterized by almost double vase life duration compared to flowers grown under the various 100 ppm N treatments. However, flower quantity and quality were not affected by the level of NH4 applied. The R. asiaticus L. root was less sensitive to the N fertilization treatments than its shoot. Contents of organic N, NO 3, P, K, Ca, Mg, Na, Cl, Fe, Cu, Zn, B, and Mo in the leaves were not affected by the fertilization treatments. Taken together, our results suggest a low requirement of R. asiaticus L. for N fertilization, and insensitivity to ammonium concentrations in the range of 10 to 30 ppm, 10% to 30% of the total N supplied. Detrimental effects in terms of growth, production and cut flower quality were apparent already under 100 ppm N supply.

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Mary C. Stevens, Rui Yang, and Joshua H. Freeman

of EDN. The deposition of ammonium by EDN could be beneficial, because ammonium is commonly used as a source of nitrogen in fertilizer blends applied by vegetable producers. However, toxicity to some vegetable crops can occur because of an

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Y.C. Li, P.J. Stoffella, A.K. Alva, D.V. Calvert, and D.A. Graetz

Compost amendment to agricultural soils has been shown to either reduce disease incidence, conserve soil moisture, control weeds or improve soil fertility. Application of compost can range from 5 to 250 Mt·ha–1 (N content up to 4%). Large application of compost with high N and P levels may result in excessive leaching of nitrate, ammonium, and phosphate into groundwater. It could be a serious concern on the east coast of Florida with its high annual rainfall and shallow water table. In this study, five composts (sugarcane filtercake, biosolids, and mixtures of municipal solid wastes and biosolids) were collected from different facilities throughout Florida. Composts were applied on a surface of 15-cm sandy soil columns at the rate of 100 Mt·ha–1 on the surface basis and leached with deionized water by 300 ml·d–1 for 5 days (equivalent to 34 cm rainfall). The concentrations of NO3-N, NH4-N, and PO4-P in leachates reached as high as 246, 29, and 142 mg·L–1, respectively. The amount of N and P leached following 5-day leaching events accounted for 3.3% to 15.8% of total N and 0.2% to 2.8% of total P as inorganic forms.

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Hitoshi Ohara*, Marom Ungsa, Katsuya Ohkawa, Hiroyuki Matsui, and Martin J. Bukovac

The effects of ammonium nitrate (AMN) on the penetration of Gibberellin A3 (GA3) into berries of `Kyoho' (Vitis labruscana Bailey) grape during berry development were studied. Treatment solutions of GA3 (100 ng·μL-1) and GA3 + AMN (20 millimolar concentration) were applied to the surface of grape berries under field conditions. The amount of GA3 penetrated was assayed using dwarf rice (Oryza sativa L., cv. Tan-ginbozu). At full bloom, the addition of AMN significantly enhanced GA3 penetration 24, 48 ad 72 hours after application by 13%, 16% and 21% of the applied GA3, respectively, representing a 1.7- to 2.4-fold increase over GA3 alone. At 4 weeks after full bloom (WAFB) at 24 hours after application, 20% of the applied GA3 penetrated in the presence of AMN compared to 15% in the absence of AMN. From varaison (7 WAFB) to maturity (10 WAFB), GA3 penetration decreased, from 6% to 2%, respectively, in the presence of AMN, and from 3% to 1% in the absence of AMN. The addition of AMN to the GA3 solution increased GA3 penetration relative to GA3 alone at all berry developmental stages. On the other hand, Cuticular wax density on the berry surface at 4 WAFB was 1.10 μg·mm-2, 5.8-fold greater than at full bloom (0.19 μg·mm-2). The thickness of the epidermal tissue doubled during the first 2 WAFB, but was maintained almost constant over the next 6 weeks. GA3 penetration was more closely related to the cuticular wax levels than the epidermal tissue thickness.

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Nader Soltani and George Lazarovits

Ammonium lignosulfonate (ALS) is a liquid waste by-product of pulp and paper industry that may be a source of organic fertilizer. Four plots each of tomato, pepper, broccoli, and corn were set up in a randomized block design on the AAFC-SCPFRC farm in the Spring 1998. Treatments were untreated control, 0.5% (v/w) ALS, and 1% (v/w) ALS. Soil samples were taken at 0, 2, 4, 8, and 22 weeks after amendment incorporation and analyzed for pH, microbial population, and water soluble ions. Soil temperature was measured at 8-cm depth. Leaf chlorophyll content was measured at four sampling dates. Tomato and pepper fruit were evaluated for symptoms of diseases. Soil temperature in 0.5% and 1.% ALS treatments were 2 and 7 °C warmer, respectively, than the control. Soil pH was lower in ALS-treated plots. 1% ALS caused more than 10-fold increase in bacterial population. Fungal populations in both 0.5% and 1% ALS treatments were 10- to 100-fold higher than control soil and continued to be higher to the last sampling date. Weeds were reduced by more than 50% by 0.5% or 1% ALS treatments. Both ALS rates caused an initial increase in NH4, NO3, NO2, K, Na, Cl, PO4, Ca, and SO4. NH4 and SO4 remained elevated for 22 weeks in both ALS treatments. ALS slightly increased chlorophyll content in tomato, pepper, and corn, but not in broccoli plants. The number of diseased tomato fruit in ALS plots were reduced by 50% to 70%. Bacterial spot decreased by more than 50% in both ALS-treated plots, while anthracnose declined by 50% to 75%. There were no significant differences in early and total yield of tomato, peppers, and corn. Early broccoli yield decreased in ALS treatments, while total yield increased over that of control in both ALS treatments.

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Royal G. Fader and Martin J. Bukovac

The plant cuticle is the prime barrier to penetration of foliar-applied plant growth regulators (PGR). Spray additives of various chemistries are frequently included in a tank mix to increase performance of PGRs. We have reported that urea and ammonium nitrate (AN) enhance transcuticular penetration of 14C-labeled NAA (pKa 4.2) from aqueous droplets (pH 5.2) and their subsequent deposits through enzymatically isolated tomato fruit cuticular membranes (CM). Studies on effects of Triton × surfactants on AN-enhanced NAA penetration showed an additional 25% increase in NAA penetration and the AN:surfactant interaction was significant. Also, some alkylamine hydrochlorides increased NAA penetration. Studies comparing NAA penetration through tomato and pepper fruit and Citrus leaf CM in the presence of 8 mM AN or 8 mM ethylamine HCl showed that all three species exhibited the same trend for penetration at 120 h: ethylamine HCl > AN > NAA only. Comparative NAA penetration for CM of the three species was pepper > Citrus > tomato, with significant differences (P > 0.006) in NAA penetration, as indexed by initial slope and penetration after 120 h. On addition of AN, NAA penetration was greater (range 3% to 40%) for Citrus and pepper CM than tomato CM. When ethylamine HCl was added, NAA penetration through Citrus and pepper CM was less (–37 and –27%, respectively) than tomato CM as measured by the initial slope, but 6% and 11%, respectively, more than tomato CM for penetration after 120 h. The differences in NAA penetration among the three species cannot be explained by cuticle thickness, since pepper and tomato CM are 2.5- to 3.5-fold thicker than Citrus CM. We have suggested that the enhanced NAA penetration mediated by AN and ethylamine HCl (and other alkylamine HCl examined) may be related to their hygroscopic properties leading to greater deposit hydration. The significance of the differences among the species CM and surfactant-enhanced NAA penetration will be discussed, in relation to diffusion in the non-living, non-metabolic plant cuticle.

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Wlodzimierz Bres and Leslie A. Weston

Experiments were conducted to evaluate the effect of incorporated hydrogel amendments to a soilless growth medium on ammonium, nitrate, and water retention and tomato (Lycopersicon esculentum Mill.) seedling growth. HydroSource and Agri-gel were incorporated into a 1 peat: 1 perlite: 1 vermiculite soilless medium at rates of 1, 2, or 3 g·liter-1 with 0.88 g of ammonium nitrate fertilizer. Water retention by the growth medium increased linearly with gel application; HydroSource generally was more effective than Agri-gel. Between 90% and 96% of the applied nitrate-N was recovered in the resulting leachate of the gel-amended media, while 33% to 55% of the ammonium-N was recovered. Nitrate-N and ammonium-N retention was higher when 3 g·liter-1 of either gel was added to the growth medium than when lower amounts or no gel was added. Gel amendment did not affect tomato seedling growth. Total foliar N concentration in tomato leaves was significantly higher in the HydroSource treatments than in the control or Agri-gel treatments.

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T.R. Roper, A.R. Krueger, C.J. DeMoranville, N. Vorsa, J. Hart, and A.P. Poole

Nitrogen fertilizer application is a universal practice among cranberry growers. Cranberries only use ammonium nitrogen sources. This study was undertaken to discover how quickly cranberries in the field would take up fertilizer-derived ammonium nitrogen. Ammonium sulfate labeled with 15N was applied in field locations in Oregon, Massachusetts, New Jersey, and Wisconsin. Samples of current season growth were collected daily for 7 days beginning 24 hours after fertilizer application. In all cases 15N was detectable in the plants from treated plots by 24 hours following application. Additional nitrogen was taken up for the next 3 to 5 days depending on the location. With the exception of Oregon, the maximum concentration of 15N was found by day 7. Oregon was the coolest of the sites in this research. To determine a temperature response curve for N uptake in cranberry, cranberry roots were exposed to various temperatures in aeroponics chambers while vines were at ambient greenhouse temperatures. The optimum temperature for N uptake by cranberry vines was 18 to 24 °C. This research suggests that ammonium fertilizers applied by growers and irrigated into the soil (solubilized) are taken up by the plant within 1 day following application. Soil and root temperature is involved in the rate of N uptake.

Full access

Timothy K. Broschat

Container-grown Bougainvillea Comm. Ex Juss. `Brasiliensis' were fertilized with ammonium sulfate, sodium nitrate, or ammonium sulfate plus sodium nitrate as N sources. Plants fertilized with sodium nitrate were stunted, extremely chlorotic, and produced few flowers compared to those receiving ammonium sulfate. In a second experiment bougainvilleas were fertilized with 12 different controlled-release or soluble ammonium, urea, or nitrate fertilizers as N sources. Plants grown with only nitrate N were chlorotic, stunted, and produced fewer flowers compared to those receiving N from urea or ammonium salts. High substrate pH, associated with nitrate fertilization, was believed to be a cause of the chlorosis, but possible toxicity symptoms (small necrotic lesions and premature leafdrop) were also observed on nitrate-treated plants. Plants receiving controlled-release urea or potassium nitrate were of higher quality than those receiving similar uncoated fertilizers.

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Douglas T. Linde and Lawrence D. Hepner

Using composted biosolid waste as a soil amendment for turfgrass is becoming a common method for disposing of municipal waste. This study was conducted to evaluate turfgrass seed and sod establishment on subsoil amended with various rates of biosolid compost. To a soil that had its A-horizon removed, biosolid compost derived from sewage sludge was incorporated at rates of 0, 132, 270, and 402 yard3/acre. A fifth treatment included a single application of fertilizer at time of sowing. Kentucky bluegrass (Poa pratensis) was seeded immediately after treatment application. The treatments were repeated on an adjacent area using kentucky bluegrass sod. For 1.5 years, turfgrass percent cover, color, density, and weeds were evaluated. Overall, the compost performed well as a soil amendment for turfgrass. A 2- to 3-inch depth of compost appeared to be the best incorporation rate for the soil and compost used in this study. High salinity and excessive ammonium nitrogen (NH4-N) levels in the compost-amended soil at the time of establishment caused a 2- to 3-week delay in seed and sod establishment. After the 2 to 3 weeks, the compost-amended plots outperformed the one-time fertilized plots in turfgrass color and density. Turf managers may want to account for the delay in establishment when incorporating a 60-day-cured compost.