Turnip growth,leaf yield,and leaf nutrient composition responses to nitrogen forms

’Shogoin’ turnip plants (Brassica rapa L.) were grown in sand culture under five nitrate:ammonium (NO₃:NH₄) ratios (N:N of 1:0, 3:1, 1:1, 1:3, 0:1). The leaves expressed symptoms of NH₄ toxicity (reduced growth and curly leaves with dark‐green areas surrounding yellow spots) when NH₄ was the dominant nitrogen (N) form. Increasing NO₃ in the nutrient solution significantly (p<0.01) increased leaf and root fresh weight and dry weight. Leaf nutrient concentration and composition of all elements analyzed, except N and calcium (Ca), responded quadratically (p<0.01) to NO₃:NH₄ ratios, and the highest values were observed with the 1:0 [for molybdenum (Mo)], 3:1 ([or magnesium (Mg)], 1:1 [for boron (B), coper (Cu), iron (Fe), manganese (Mn ), and zinc (Zn)] or 1:3 [for phosphorus (P) and potassium (K)] treatments. Nitrogen and Ca leaf concentration responses were linear and highest at 0:1 and at 1:0, respectively. Cultural practices and fertilizer applications should maintain NO₃ as the dominant N form in the root zone, and the continuous use of NH₄‐ based or NH4‐releasing fertilizers is not recommended for the production of high yields of turnip greens.     

Production of Chinese cabbage in relation to nitrogen source,rate, and leaf nutrient concentration

Abstract

Chinese cabbage (Brassica rapa L. Chinensis group) production is expanding in the U. S., and guidelines regarding its production under Western cultural practices are needed. The objectives of this study were to investigate the effects of N source and rate on Chinese cabbage yield, marketability, and wrapper leaf nutrient concentrations, and to estimate the critical wrapper leaf‐N concentration associated with maximum yield and marketability. Chinese cabbage was grown in five sequential plantings using raised‐bed, polyethylene mulch culture with subsurface irrigation on a sandy soil. Nitrogen fertilizer was applied at rates of 0, 67,112, and 157 kg/ha using the following sources: 1) ammonium nitrate. 2) calcium nitrate, 3) urea‐ammonium nitrate solution (Uram, 32% N), 4) urea, and 5) a urea‐calcium solution (18% N). Mature Chinese cabbage wrapper leaf concentrations of P, Ca, and Mg increased with increasing N rate, while leaf‐K concentration decreased. Leaf‐N concentration increased in response to N rate, but was not affected by N source or harvest date. Leaf‐P, K, Mg, and B concentrations were sufficient or high according to established standards, but leaf‐Ca was low. Leaf‐Ca and Mg concentrations were lowest with N sources containing only urea, and highest where at least part of the N was applied as NO₃ ^‐. Chinese cabbage head weight and percentage marketable heads increased as N rate increased. Yield and quality were highest with N sources which contained NO₃ ^‐, and were smallest where N was applied entirely as urea, which may have been due to plant sensitivity to NH₄ ⁺. The critical value of mature cabbage wrapper leaf‐N concentration above which yield or marketability was not limited was estimated to be 36 to 41 mg/g, which agrees well with established standards.     

The relationship of soil and leaf nutrients to rice leaf oranging

A symptom called leaf‐oranging, indicating a deficiency of many nutrients, occurs in paddy rice (Oryzasativa L.) when production expands into some upland soils. Rice (Gui Chou cv.) was grown in culture pots in a flooded, weathered, upland soil (Nacogdoches) and compared to rice growth in a flooded soil currently used for paddy rice production (Dacosta) in Texas to understand the soil and plant factors involved in leaf‐oranging. Fertilizer rates of 0, 10, and 100 mg N/kg as (NH₄)₂SO₄ were applied to each soil along with phosphorus (P) and potassium (K) fertilizer. The orange Leaf Index (OLI), a measure of leaf‐oranging, was determined weekly and increased to 60–70% for plants grown in the upland soil but its progression was delayed by higher N treatments. No leaf‐oranging was observed in the paddy soil. The soil evoking leaf‐oranging was low in silicon (Si) and high in iron (Fe). In addition, analysis of leaves from these plants showed 19–25% higher leaf ammonium‐nitrogen (NH₄‐N), 9–137% higher manganese (Mn) levels and lower total N:NH₄ concentration compared to normal rice leaves four weeks after transplanting. This inferred that leaf‐oranging probably was associated with some degree of NH₄‐N toxicity and antagonism with K. Leaf‐oranging was also associated with low calcium (Ca) assimilation or Ca uptake inhibition because of the heavy Fe‐oxide coating of the roots of the affected rice plants. In this experiment, leaf‐oranging was not associated with toxic levels of Fe or Mn.     

Influence of Nitrate:Ammonium Ratios on Growth and Elemental Concentration in Two Azalea Cultivars

Abstract

Rooted cuttings of Rhododendron canescens “Brook” and Rhododendron austrinum were grown in sand culture with a modified Hoagland's solution under greenhouse conditions. The effect of varying ammonium:nitrate (NO₃ ^?:NH₄ ⁺) ratios (100:0, 75:25, 50:50, 25:75, 0:100) on growth, chlorophyll content, plant quality, and elemental tissue concentration were determined. With NO₃ ^? as the nitrogen (N) form, both azalea cultivars exhibited less vegetative growth, lower overall plant quality, with leaves showing visual chlorotic symptoms in comparison to plants receiving NH₄ ⁺ as the N‐form. Leachate pH was highest with NO₃ ^? as the predominate N‐form and decreased significantly with each increment of NH₄ ⁺. With both azalea cultivars, N‐form significantly influenced uptake and utilization of essential plant nutrients. Leaf concentrations of N, potassium (K), calcium (Ca), sulfur (S), boron (B), and molybdenum (Mo) were highest with NO₃ ^?‐N. Leaf elemental concentrations of phosphorous (P), magnesium (Mg), copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn) increased as NH₄ ⁺ supplied more of the N‐ratio. Significant differences in Mg, Mn, and Zn were observed between species. Results from this study show that foliar N concentration is not an accurate indicator of plant growth response. Further investigations are needed to determine if foliarchlorosis and low growth rates observed with NO₃ ^? fed plants due to an Fe deficiency, to low nitrate reductase (NR) activity in the leaves, or to a combination of these factors.     

Comparison of hydroponic solutions for poinsettia nutritional studies 1

Poinsettia cultivars Supjibi and Freedom were grown in eight hydroponic solutions to develop a baseline solution for further nutritional studies. Four solutions contained nitrogen (N) from Ca(NO₃)₂‐4H₂O and KNO₃ (denoted as ‐NH₄) and four contained Ca(NO₃)₂‐4H₂O, KNO₃, nitric acid, and NH₄NO₃ as the N sources (denoted as +NH₄). The four ‐NH₄ and +NH₄ solutions were further divided by an IX or 2X rate of micronutrients [boron (B), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), and zinc (Zn)] (denoted as IX or 2X). A factorial of these four solutions at 2 concentrations (100 mg L¹ of N and potassium (K) and 15 mg L¹ phosphorus (P), or 300 mg L¹ of N and K and 46 mg L^‐1 P) was studied. Greater leaf and stem dry weight for both ‘Supjibi’ and ‘Freedom’ was observed in plants grown with the +NH₄ solutions, with a larger increase occurring with’ Supjibi’. Leaf NH₄‐N content for both cultivars was higher for both the 100 and 300 mg L^‐1 N and K fertilization rates when NH₄‐N was included. The leaf K content was highest for the plants grown with the +NH/2X solution for ‘Supjibi’, for both fertilization rates, and leaf K content increased as the K application rate increased. Results indicate that for nutritional studies with poinsettias, hydroponic solutions should include between 12.5% to 33% of the N in the NH₄ form, a calcium magnesium (Ca:Mg) ratio of 2:1, and a micronutrient concentration of (mg I/¹) 0.5, 0.02, 6.6, 0.5, 0.1, and 0.05, respectively, for B, Cu, Fe, Mn, Mo, and Zn, for adequate plant growth.     

Aluminum tolerance,mineral nutrition,and growth of ‘Helleri’ holly in solution culture

‘Helleri’ holly (Ilex crenata Thunb. ‘Helleri') plants were grown in solution culture at aluminum (Al) concentrations of 0, 6, 12, 24, and 48 mg.L^‐1 for 116 days. Aluminum did not affect root or crown index, stem length growth, plant dry weight, or leaf area. Aluminum treatments significantly increased Al uptake and reduced nutrient uptake of magnesium (Mg), calcium (Ca), zinc (Zn), and copper (Cu) on some sampling dates. Iron (Fe) and manganese (Mn) uptake decreased on most sampling dates but increased on some with Al treatments. Potassium (K), phosphorus (P), and boron (B) uptake were significantly affected by Al, decreasing and increasing at different sampling dates. Although plants preferentially took up ammonium‐nitrogen (NH₄ ⁺‐N) in all treatments (including 0 Al controls), neither NH₄ ⁺‐N nor nitrate‐nitrogen (NO₃ ‐N) uptake were affected by Al. Tissue concentrations of P, K, B, Zn, and Al increased with Al treatment; whereas tissue Ca, Mg, and Cu concentrations decreased with increasing Al. Iron and Mn tissue concentrations exhibited increases and decreases in different tissues. Results indicated that ‘Helleri’ holly was tolerant of high concentrations of Al.     

Effect of nitrogen form during the flowering period on zucchini squash growth and nutrient element uptake

Zucchini squash (Cucurbita pepo L. cv. Green Magic) plants were grown hydroponically with nitrate (NO₃):ammonium (NH₄) ratio of 3:1 until the onset of flowering when the plants were assigned to four NO₃:NH₄ ratio (1:0, 1:1, 1:3, or 3:1) treatments. Changing the original nitrogen (N) form ratio significantly affected plant growth, fruit yield, nutrient element, and water uptake. Growth of plants was better when NO₃‐N (1:0) was the sole form of N than when NH₄‐N was part of the N treatment. Fruit yields for plants fertilized with 1:0 or 1:3 N‐form ratio were double those of plants grown continuously with 3:1 N ratio. The largest leaf area and plant water use were obtained with 1:0 N ratio treatment Total uptake of calcium (Ca), magnesium (Mg), and potassium (K) decreased with increasing NH₄‐N proportion in the nutrient solution which suggest NH₄‐N was competing with these cations for uptake. The results also demonstrated that growers may increase fruit yield by using a predominantly NO₃‐N source fertilizer through the vegetative growth stage and by shifting the NO₃:NH₄ ratio during the reproductive phase.     

Sodium bicarbonate‐DTPA test for macro‐and micronutrient elements in soils

Abstract

Individual soil tests are used to assess plant nutrient element needs. Separate soil tests, however, are time consuming and costly. Our objective was to develop a 0.5M sodium bicarbonate (NaHCO₃) soil phosphorus (P) test in combination with 0.005M diethylenetriaminepentaacetic acid (DTPA) so macronutrient dements: ammonium‐nitrogen (NH₄‐N), nitrate‐nitrogen (NO₃‐N), P, potassium (K), calcium (Ca), and magnesium (Mg); and micronutrients: iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu) could be quantified in one extraction. The NaHCO₃‐DTPA extracting solution is a combination of 0.5M NaHCO₃ and 0.005M DTPA and has a pH of 7.60±0.05. Sodium in the solution enhances the NH₄, K, Ca, and Mg extraction; bicarbonate (HCO₃) is for P extraction; DTPA chelates Ca, Mg, and micronutrients; and the water is for NO₃ extraction. Soil samples (0–15 cm depth) came from two sources. The first set was from 12 N x P dryland proso millet (Panicum miliaceum L.) experiments, conducted from 1985 through 1987 in eastern Colorado. These soils were extracted with potassium chloride (KCl), NaHCO₃, ammonium acetate (CH₃‐COONH₄), DTPA, ammonium bicarbonate DTPA (AB‐DTPA), and with the NaHCO₃‐DTPA solutions. The second set included 25 soils from Alabama, Georgia, North Carolina, and South Carolina and were analyzed only for available P with the NaHCO₃ and NaHCO₃‐DTPA methods. Simple linear correlations for macronutrient elements and micronutrients were highly significant. Critical levels for the macronutrient elements: NO₃‐N, P, and K were 27, 11, and 144 mg kg^‐1, respectively; and the critical levels for the micronutrients: Fe, Mn, Zn, and Cu were 3.9, 0.35, 0.97, and 0.24 mg kg^‐1, respectively.     

Effects of ammonium nitrate encapsulated with coal combustion byproducts on nutrient accumulation by corn and rye

Ammonium nitrate is a fertilizer and an explosive. Encapsulation of ammonium nitrate (NH₄NO₃) with coal combustion byproducts (fly ash or flue gas desulfurization gypsum) reduces the explosiveness of NH₄NO₃. A field study was conducted to determine the effects of encapsulated NH₄NO₃ on corn (Zea mays L.) and rye (Secale cereal L.) yield and accumulation of nitrogen (N), arsenic (As), cadmium (Cd), iron (Pb), copper (Cu), manganese (Mn), and zinc (Zn). Nitrogen rates were 56 and 112 kg ha^?1. Yields and concentrations of N and metals in corn grain, ear-leaf, and stover and in rye shoots were not affected by N source. Increased N rate resulted in increased corn ear-leaf, grain, and stover N, ear-leaf Cu, Mn, and Zn, and rye shoot yield, Cu, and Zn. For both species, metal levels did not exceed normal ranges. Coal byproduct-encapsulated NH₄NO₃ is as effective as non-encapsulated NH₄NO₃ for corn or rye production, without increasing plant metal concentrations above normal levels.     

Effect of different composts on growth and nitrogen composition of Chinese mustard in an acid red soil

Abstract

A pot experiment was conducted to assess the effect of different kinds of composts on the growth and nitrogen (N) composition of Chinese mustard in acid red soil. There were six treatments including a lime‐chemical fertilizer treatment and a control plot of conventional chemical fertilizer. The plants were harvested 37 days after transplanting and the growth and N composition of these plants were measured. The soil was also sampled, and selected chemical properties were determined after harvesting the plants. The results show that different composts affected the growth and soil chemical properties significantly. The pH, nitrate nitrogen (NO₃‐N), ammonium N (NH₄‐N), electrical conductivity (EC), and 1 N ammonium acetate exchangeable potassium (K), calcium (Ca), magnesium (Mg), aluminum (Al), manganese (Mn), and iron (Fe) were all significantly affected by the compost treatment. The growth of plants in the control treatment was significantly lower than that of the compost‐treated and lime‐treated plants, suggesting that the acid Oxisol is unfavorable for the growth of Chinese mustard. Some composts could increase the growth of Chinese mustard. The lime‐treated plants had higher concentrations of chlorophyll a and chlorophyll b than those of the compost‐treated plants. There were no significant differences between treatments in the concentrations of chlorophyll a and chlorophyll b, however, there was a close correlation between the total chlorophyll concentrations and the shoot yield of the plants. The NO₃‐N, soluble reduced N, and insoluble N concentrations in leaf blades and petioles of Chinese mustard varied significantly according to the compost applied. The hog dung compost B could adequately supply nutrients especially N for plant growth and caused little NO₃‐N accumulation in plant tissues.     

Pecan leaf analysis: I. Varietal,fertilizer, and seasonal effects

Abstract

Differences in elemental content of pecan [Carya illinoensis (Wang.) K. Koch] leaves among cultivars were found for N, P, K, Ca, Mg, Mn and Zn. Of the 7 elements studied, only leaf K indicated a date by cultivar interaction. Differences in leaf K among cultivars became greater as the season progressed. Increasing rate of application of N‐P‐K fertilizer increased leaf N, Ca, Mn, and Al, but had very little or erratic effect on leaf P, K, Fe, B, Cu, Zn, and Sr. There were very few consistent significant fertilizer rate by date interactions for the 13 elements tested. Seasonal trends for element leaf contents from mid‐May through October were generally downward for N, upward for Ca, Mn, Fe, B, Cu, Al, and Ba and changed very little for Mg, Zn, and Sr. Leaf P and K responses to sampling date varied with year. Large year to year variations in leaf trends over dates suggests difficulty in selecting a period for leaf sampling where little change in leaf levels consistently occurs.     

Assessment of the Nitrogen and Potassium Fertilizer in Green Bean Irrigated with Disinfected Urban Wastewater

Green bean Helda in autumn cycle (118 days) was grown under greenhouse conditions in sand-mulched sandy loam soil. The crop was irrigated with disinfected urban wastewater (DUW) obtained from ozone from the Almería Purifying Plant. The average nutrient parameters of DUW were 0.4 mM of nitrate (NO₃ ^?), 2.1 mM of ammonium (NH₄ ⁺), 0.8 mM of potassium (K⁺), and electrical conductivity (EC) 1.6 dS m^?1. Three different treatments were established: DUW without additional fertilization (F_DUW), DUW with fertilization until the recommended rate was obtained (10.0 mM of N and 3.4 mM of K) (F_NK), and DUW with fertilization until 1.5 F_NK rate (15.0 mM of N and 5.1 mM of K) (F_1.5NK) was obtained. The dry-matter production was not conditioned by the fertilizer level. Treatments F_NK and F_1.5NK showed the greatest yield and uptake of N and K independent of the fertilizer level. The most nitrogen (N), calcium (Ca), and magnesium (Mg) were in the leaf, phosphorus (P) was high in fruit, and K was similar in leaf and fruit. With regard to the macronutrient absorption efficiency, the F_1.5NK treatment showed the least N and K efficiency and the greatest soil salinity.     

Dry matter and nitrogen accumulation are not affected by superopt1mal concentration of ammonium in flowing solution culture with pH control

Abstract

While it is known that superoptimal concentrations of the nitrate (NO₃ ^?) ion in solution culture do not increase NO₃ ^? uptake or dry matter accumulation, the same is not known for the ammonium (NH₄ ⁺) ion. An experiment was conducted utilizing flowing solution culture with pH control to investigate the influence of superoptimal NH₄ ⁺ concentrations on dry matter, nitrogen (N), potassium (K), calcium (Ca), and magnesium (Mg) accumulation by nonnodulated soybean plants. Increasing the NH₄ ⁺ concentration in solution from 1 to 10 mM did not affect dry matter or N accumulation. Accumulations of K, Ca, and Mg were slightly decreased with the increased NH₄ ⁺ concentration. The NH₄ ⁺ uptake system, which is saturated at less than 1 mM NH₄ ⁺, is able to regulate uptake of NH₄ ⁺ at concentrations as high as 10 mM.     

Chemical soil properties and bromegrass hay composition as affected by 23 annual fall and spring applications of ammonium nitrate and urea

Abstract

The influence of nitrogen (N) fertilization on grass forage yield and quality as well as soil properties may vary with type of N fertilizer and time of application. The effects of 23 annual applications (from 1974 to 1996) of ammonium nitrate (AN) and urea (112 kg N ha^‐1) applied in early fall, late fall, early spring and late spring on chemical soil properties and composition of bromegrass hay were evaluated in a field experiment on a thin Black Chernozemic soil located near Crossfield, Alberta, Canada. The influence of N addition, fertilizer type and application time on the soil properties was most pronounced in the 0–5 cm layer and declined in deeper soil layers. Application of N increased extractable ammonium (NH₄)‐N, zinc (Zn), and iron (Fe) in the 0–5 cm layer; and sodium (Na), aluminum (Al), and manganese (Mn) in the 0–10 cm layer. But, N addition reduced extractable phosphoras (P) in the 0–30 cm; potassium (K) in the 0–60 cm; and pH, calcium (Ca), and magnesium (Mg) in the 0–5 cm soil layers. There was little effect of N fertilization on nitrate (NO₃)‐N in soil. Soil pH, and extractable Ca and Mg in the 0–5 cm layer and Zn in the surface 15‐cm soil depth were lower with AN compared to urea, whereas the opposite was true for Fe, Mn, and Cu in the 0–5 cm layer and Na and Al in the top 15‐cm soil depth. Most of the changes in chemical soil properties due to N fertilization were reflected in elemental concentration of bromegrass hay, except for the increase of P concentration in bromegrass with N fertilization. In bromegrass hay for example, N addition increased total N and Cu with both N fertilizers and Mn and Zn with AN, but it lowered K and Ca with both fertilizers. There was more N and less Na with AN than urea in bromegrass hay. The effect of application time on chemical soil properties and composition of bromegrass hay was much less pronounced than N addition and fertilizer type. In conclusion, both N fertilizers changed chemical soil properties and composition of bromegrass hay, but the effects of 23 annual applications on soil properties were confined to shallow soil layers only. The greater lowering of soil pH with AN than urea may have implications of increased liming costs with AN.     

The acidulation effects of nitrogenous fertilizers on selected chemical and microbiological properties of soil

Abstract

The acidulation effects of the prolonged use of nitrogenous fertilizers on selected chemical and microbiological properties of a silt loam soil (Typic Ochraqualf) were assessed.

Soil samples were collected from experimental plots initially established in 1971 that were annually treated with ten N fertilizer treatments and planted to corn. Residual soil acidity found to be associated with 9 annual applications of the N fertilizers was of the order: (NH₄)₂ SO₄ > NH₄C1 > anhydrous NH₃ (at 300 kg N/ha) = NH₄NO₃ > urea = ureaform = anhydrous NH₃ (at 150 kg N/ha) > Ca(NO₃)₂ NaNO₃. Extractable P, Fe, Mn and Al followed a pattern of increasing availability with a decrease in soil pH. Exchangeable Ca and Mg levels were significantly higher in those treatments that did not show a significant decrease in soil pH over the 9‐year duration.

Significant differences by N treatment among selected microbial groups were also determined. The annual mean counts of soil fungi were significantly higher for the most and least acidifying treatments, namely ammonium sulfate and sodium nitrate. However, the mean counts of soil bacteria and actinomycetes were non‐significant for any of the fertilizer treatments although the counts of both microbial groups declined with the addition of N. Significant differences in the mean counts of nitrifying and denitrifying bacteria were obtained with the ammonium sulfate treatment showing the greatest reduction in MPN counts. Microbial diversity (H') indices were also determined and correlated with soil pH. A quadratic relationship was determined for phyleal diversity (the total population of bacteria, actinomycetes and fungi) with soil pH, while a linear function best described physiological diversity (the nitrifying and denitrifying bacteria) versus soil pH.     

Nitrate/ammonium ratio effects on mineral element uptake by sorghum 1

Abstract

Experiments were conducted using different NO₃ ^–/NH₄ ⁺ ratios to determine the effects of these sources of N on mineral element uptake by sorghum [Sorghum bicolor (L.) Moench] plants grown in nutrient solution. The NO₃ ^–/NH₄ ⁺ ratios in nutrient solution were 200/0, 195/5, 190/10, and 160/40 mg N L^–1. Nutrient solutions were sampled daily and plants harvested every other day during the 12‐day treatment period.

Moderately severe Fe deficiencies were observed on leaves of plants grown with 200/0 NO₃ ^–/NH₄ ⁺ solutions, but not on the leaves of plants grown with the other NO₃ ^–/NH₄ ⁺ ratios. As plants aged, less Fe, Mn, and Cu were translocated from the roots to leaves and leaf/root ratios of these elements decreased dramatically in plants grown with 200/0 NO₃ ^–/NH₄ ⁺ solutions. Extensive amounts of Fe, Mn, and Cu accumulated in or on the roots of plants grown with 200/0 NO₃ ^–/NH₄ ⁺ solutions. Manganese and Cu may have interacted strongly with Fe to inhibit Fe translocation to leaves and to induce Fe deficiency. As the proportion of NH₄ ⁺ in solution increased, K, Ca, Mg, Mn, and Zn concentrations decreased in the leaves, and Ca, Mg, Mn, and Cu concentrations decreased in roots. Potassium and Zn tended to increase in roots as NH₄ ⁺ in solution increased.     

Effect of soil pH and nitrogen source on nutrient status in peach: I. Macronutrients

Following 13‐year treatments of soil pH and nitrogen (N) source in a peach orchard of North Carolina, the concentration of calcium (Ca), magnesium (Mg), N, phosphorus (P), and potassium (K) in leaves, shoots, trunks and roots, as well as soil pH, soil exchangeable Ca, Mg, and K content, were determined. Through liming, higher soil pH treatment enhanced soil Ca and tissue Ca level. Among six N sources examined, the highest values of soil pH and soil Ca, Mg, and K were detected following poultry manure application. Compared to ammonium sulfate [(NH₄)₂SO₄], calcium nitrate [Ca(NO₃)₂] increased soil pH and soil Ca and K content, but reduced soil Mg. For most of macronutrients examined in peach tissues, the highest levels were found in manure treatment. Mineral N sources containing Ca(NO₃)₂ resulted in high tissue Ca and low tissue N. In the above‐ground tissues, Mg concentration was relatively low following application of mineral N materials containing Ca, K, or sodium (Na). Acid‐ forming N, especially (NH₄)₂SO₄, reduced tissue Ca and P. The magnitude of impact of liming and N source on macronutrients was tissue‐type dependent, with leaves and other new growth the most sensitive ones while trunks seldom responded to the treatments.     

Inoculation of ‘Golden Delicious’ Apple Trees on M9 Rootstock with Azotobacter Improves Nutrient Uptake and Growth Indices

ABSTRACT

Roots of young ‘Golden Delicious’ apple on M9 rootstock were inoculated with four strains of Azotobacter chroococcum, which were isolated from various soils. Effects of these strains in combination with different levels of nitrogen (N) fertilizer and compost on plant growth and nutrient uptake were studied over two seasons. Therefore, a factorial arrangement included four strains of A. chroococcum, two levels of N-fertilizer (0 and 35 mg N kg^?1soil of ammonium nitrate) and two levels of compost (0 and 12 g kg^?1 soil of air-dried vermicompost). Among the four strains, AFA₁₄₆ was the most beneficial strain, as it increased leaf area, leaf potassium (K), magnesium (Mg), iron (Fe), manganese (Mn), zinc (Zn), and boron (B) uptake and root N, phosphorus (P), potassium (K), Mn, and Zn. The combination of AFA₁₄₆ strain, compost and N fertilizer increased leaf uptake of Ca, Mg, Fe, Mn, Zn, and B, and root uptake of P, K, Ca, Mg, Mn, and copper (Cu), and root dry weight.     

Elemental leaf content and deficiency symptoms in rabbiteye blueberries: 1. Nitrogen

Rabbiteye blueberries grown in sand culture were subjected to varying levels of N fertilization (0 ‐ 81 mg N/liter) applied in aqueous solution at the rate of 250 ml/plant daily. Essential elements other than N were kept constant. Shoot growth and leaf concentration of N, P, K, Mg, Ca, Mn, Fe, Cu, B, Zn, Co, and Al were determined. Shoot growth and percent leaf N increased with increased N levels. Shoot growth increased little at N fertilization levels of 0 ‐ 9 mg/ liter but increased rapidly at higher rates. N content in leaves followed a quadratic curve, with % N in leaves increasing more rapidly from 0 to 27 mg N/liter than from 27 to 81 mg N/liter fertilization levels. Leaf concentration of K, Ca, Mg, Mn, B, and Ca decreased linearly as N levels increased. Total content of all elements increased as N fertilization increased. Visual N deficiency became increasingly evident as % N content decreased below 1.4% N.

Nitrogen, the most utilized element in plants, is usually the first to become deficient in sandy soils low in nutrient content (1). Rabbiteye blueberries (Vaccinium ashei Reade) are often grown on acidic, sandy, upland coastal plains soils that are low in cation exchange capacity, organic matter content, and available nutrients. In these acidic soils, NH₄N is more available than in neutral soils (2). The NH₄N source appears to be more suitable for blueberry growth, resulting in greater nutrient uptake, plant growth, and % N of leaf tissue than did the NO₃N sources (5,6).

Nitrogen deficiency symptoms in rabbiteye blueberries are characterized by small, yellow and/or red leaves and stunted plants (3). Since young rabbiteye plants are very sensitive to fertilizer, similar chlorosis symptoms (yellowing or reddening of leaves) can be associated with over‐fertilization, possibly due to root damage (7). Cain (2) found that leaves from healthy container‐grown highbush (V. corymbosum L.) blueberry plants contained about 2% N and higher levels of K and Ca than field‐grown plants. Greenhouse and Field studies indicate that leaf N content in rabbiteye blueberries is usually lower, ranging from about 1.5 to 1.8 (3,7,8). Increased N fertilization decreased the nutrient uptake of other essential elements (Ca and Mg) in rabbiteye blueberries (6). In highbush, Popenoe (4) indicated that a depression of P and K might occur under conditions of high N levels.

This study was initiated to ascertain the effect of NH₄N fertilization levels on uptake patterns of essential elements and to determine the relationships of N fertilization, leaf N content, plant growth, and visible deficiency symptoms.     

Effect of nitrogen on growth,flower yield,oil composition,and yield in boronia megastigma nees

Four forms of nitrogen (N), isobutylidene diurea (IBDU), urea, ammonium nitrate (NH₄NO₃), and calcium nitrate [Ca(NO₃)₂] were applied to boronia plants at three rates of application (25, 50, and 100 kg N/ha) either as a single application in late October or in two equal applications, one in October and the other in early January. Two sites and two clones were investigated, growth measurements were taken on one site on a regular basis throughout the year, and flowers were harvested in September. Leaf N, flower N number of nodes, and flower and oil yields as well as the percent volatiles and ß‐ionone content of the oil were positively correlated with increased rates of N application. Ammonium nitrate and Ca(NO₃)₂ gave the highest yields for both clones. IBDU and urea were partially toxic to Clone 5 at 100 kg N/ha which was thought to be due to an inability to detoxify ammonium (NH₄) rather than a low nitrate reductase activity. This results of this experiment provides guide lines for N management in the future.