Significance of Nickel Supply for Growth and Chlorophyll Content of Wheat Supplied with Urea or Ammonium Nitrate

ABSTRACT

Nickel (Ni) is an essential element for activation of urease in higher plants. The effects of Ni as an essential micronutrient on growth and chlorophyll content of wheat plants grew in nutrient solutions supplied either with ammonium nitrate or urea as two different nitrogen (N) sources were investigated. Plants were allowed to grow for six weeks, then leaf chlorophyll content, shoot and root fresh and dry weights, and Ni concentration in shoots and roots were determined. Shoot and root Ni concentration in both urea and ammonium nitrate-fed plants increased significantly with the increase in Ni concentration. Growth and chlorophyll content in leaves of the urea-fed plants increased when Ni concentration in the solution was as high as 0.05 mg L^?1 and decreased at 0.1 mg Ni L^?1. In ammonium nitrate-fed plants, these parameters increased up to 0.01 mg Ni L^?1 and started to decrease with further increase in Ni concentration. Plants that grew in nutrient solutions containing urea had more shoots and roots fresh and dry weight at third and fourth Ni levels (0.05 and 0.1 mg L^?1) than those that grew in media containing ammonium nitrate with similar Ni levels. Total chlorophyll content was also higher in plants supplied with urea plus Ni. The amount of Ni required for optimum wheat growth was dependent on the forms of N used. When supplied with ammonium nitrate or urea, the amount of Ni needed was 0.01 and 0.05 mgL^?1 of nutrient solutions, respectively.     

Effects of Seasonal Nitrate Flush on Nitrogen Metabolism and Soluble Fractions Accumulation in Two Rice Varieties

ABSTRACT

Two rice varieties, ‘Piaui’ (a landrace) and ‘IAC-47’ (an improved variety), were grown in nutrient solution containing 20 mg nitrate (NO₃ ^?)-nitrogen (N) L^{? 1} up to 32 days after germination (DAG). After this, a group of plants received 200 mg NO₃ ^?NL^{? 1}, while the other was kept at 20 mg NO₃ ^?NL^{? 1} up to 42 DAG. From 42 until 56 DAG, all plants received 5 mg NO₃ ^?NL^{? 1}. Plants were collected at 42 and 56 DAG, soluble fractions, nitrate reductase (NR) and GS enzymatic activities were determined. The nutritional history of the plants affected significantly the uptake and use of nitrogen (N), and should be taken into consideration in the studies of N-use efficiency. The variety ‘Piaui’ was more efficient than ‘IAC-47’ in N-uptake use, accumulating more NO₃ ^? in its tissues at the initial phases of its cycle for subsequent utilization.     

Effects of Molybdenum,Nickel, and Nitrogen Sources on the Mineral Nutrition and Growth of Rice Plants

Upland rice plants, cultivar ‘IAC 202,’ were grown in nutrient solution until full tillering. Treatments consisted of ammonium nitrate (AN) or urea (UR) as nitrogen (N) source plus molybdenum (Mo) and/or nickel (Ni): AN + Mo + Ni, AN + Mo ? Ni, AN ? Mo + Ni, UR + Mo + Ni, UR + Mo ? Ni, and UR ? Mo + Ni. The experiment was carried out to better understand the effect of these treatments on dry‐matter yield, chlorophyll, net photosynthesis rate, nitrate (NO₃ ^?‐N), total N, in vitro activities of urease and nitrate reductase (NR), and Mo and Ni concentrations. In UR‐grown plants, Mo and Ni addition increased yield of dry matter. Regardless of the N source, chlorophyll concentration and net photosynthesis rate were reduced when Mo or Ni were omitted, although not always significantly. The omission of either Mo or Ni led to a decrease in urease activity, independent of N source. Nitrate reductase activity increased in nutrient solutions without Mo, although NO₃ ^?‐N increased. There was not a consistent variation in total N concentration. Molybdenum and Ni concentration in roots and shoots were influenced by their supply in the nutrient solution. Molybdenum concentration was not influenced by N sources, whereas Ni content in both root and shoots was greater in ammonium nitrate–grown plants. In conclusion, it can be hypothesized that there is a relationship between Mo and Ni acting on photosynthesis, although is an indirect one. This is the first evidence for a beneficial effect of Mo and Ni interaction on plant growth.     

Marandu Palisadegrass Mineral Nutrition and Production Related to Nitrogen and Potassium Supply

Nitrogen (N) and potassium (K) fertilization play a key role in forage crops and can significantly increase yields of ‘Marandu’ palisadegrass [Brachiaria brizantha (Hochst. exA. Rich.) Stapf.], one of the most important forage crops in Brazil. This study aimed to identify the concentrations of total N and K, nitrate (NO₃^?), and ammonium (NH₄⁺), chlorophyll meter readings (SPAD), and nitrate reductase activity (At-RNA) required to maximize yield. Plants were grown in quartz substrate and treated with nutrient solutions that ranged from 2 to 33 mmol L^?1 for N and 0.5 to 11 mmol L^?1 for K. Dry matter production and At-RNA increased with increasing N and K supplies. SPAD readings correlated strongly with N leaf concentration and dry matter production and can be used to assess the N status of this species. The supply of N and K in the fertilization promoted high yield and adequate N and K concentration for plant metabolism.     

Comparative Effect of Nitrogen Forms on Nitrogen Uptake and Cotton Growth Under Salinity Stress

The effects of nitrogen (N) forms (ammonium- or nitrate-N) on plant growth under salinity stress [150 mmol sodium chloride (NaCl)] were studied in hydroponically cultured cotton. Net fluxes of sodium (Na⁺), ammonium (NH₄⁺), and nitrate (NO₃^?) were also determined using the Non-Invasive Micro-Test Technology. Plant growth was impaired under salinity stress, but nitrate-fed plants were less sensitive to salinity than ammonium-fed plants due mainly to superior root growth by the nitrate-fed plants. The root length, root surface area, root volume, and root viability of seedlings treated with NO₃-N were greater than those treated with NH₄-N with or without salinity stress. Under salinity stress, the Na⁺ content of seedlings treated with NO₃-N was lower than that in seedlings treated with NH₄-N owing to higher root Na⁺ efflux. A lower net NO₃^? efflux was observed in roots of nitrate-fed plants relative to the net NH₄⁺ efflux from roots of ammonium-fed plants. This resulted in much more nitrogen accumulation in different tissues, especially in leaves, thereby enhancing photosynthesis in nitrate-fed plants under salinity stress. Nitrate-N is superior to ammonium-N based on nitrogen uptake and cotton growth under salinity stress.     

Nitrogen Source and Concentration Affect Growth and Performance of Bedding-Plant Impatiens

ABSTRACT

Impatiens (Impatiens wallerana Hook. f.) is the most important annual bedding plant in the United States, based on wholesale dollar volume. Production of high-quality plants requires optimization of the nutrition regimen during growth, especially the total nitrogen (N) concentration and the ratio of N sources. The objective was to determine the N concentration and the nitrate (NO₃ ^??N):ammonium (NH₄ ⁺?N) ratio of N source that optimized bedding-plant impatiens growth and flower development. Four N concentrations (3.5, 7, 10.5, and 14 mmol N · L^?1) were used in factorial combination with four ratios of NO₃ ^??N:NH₄ ⁺?N (4:0, 3:1, 1:1, and 1:3). Application of treatments was made for 30 d. Then for 10 d only deionized water was applied to reduce salt buildup. Substrate pH was lowest (4.9) with the NH₄ ⁺?N source and electrical conductivity (EC) highest, but never > 2.4 dS m^?1. Nitrogen concentration and N source displayed an interaction for most growth parameters. Shoot fresh and dry weights and flower bud number were maximized at the 1:3 NO₃ ^??N:NH₄ ⁺?N ratio with a N concentration of 10.5 mmol L^?1. However, plant diameter, leaf number, and leaf chlorophyll content responded quadratically to N form ratio, with the 1:1 ratio optimum at a concentration of 10.5 mmol N· L^?1.     

Nitrogen Levels Influence Biomass,Elemental Accumulations,and Pigment Concentrations in Spinach

ABSTRACT

Spinach (Spinacia oleracea L.) has one of the highest United States per capita consumption rates among leafy vegetable crops, and also ranks second for lutein and β-carotene carotenoid concentration. The objectives of this study were to determine the effects of nitrogen (N) concentration on elemental and pigment accumulation in spinach. Two spinach cultivars (‘Melody’ and ‘Springer F1’) were greenhouse grown in nutrient solution culture under N treatments of 13, 26, 52, and 105 mg L^{? 1}. Leaf tissue biomass increased from 45.6 to 273.2 g plant^{? 1} and from 127.0 to 438.6 g plant^{? 1} as N increased from 13 to 105 mg L^{? 1} for ‘Springer F1’ and ‘Melody’, respectively. Leaf tissue N, phosphorus (P), calcium (Ca), magnesium (Mg), copper (Cu), and zinc (Zn) responded to N treatments. Lutein accumulations, expressed on a fresh weight basis, responded quadratically to increasing N treatments for ‘Springer F1’. Maximum lutein values were 110 and 76 μ g g^{? 1} on a fresh weight basis, and maximum β-carotene values were 85 and 57 μ g g^{? 1} on a fresh weight basis for ‘Springer F1’ and ‘Melody’, respectively. Interestingly, N levels had a significant effect on carotenoid accumulation in both ‘Springer F1’ and ‘Melody’ when the pigments were expressed on a dry weight basis. Leaf tissue lutein increased from 0.59 to 1.06 mg g^{? 1} and from 0.59 to 0.90 mg g^{? 1} on a dry weight basis with increasing N treatments for ‘Springer F1’ and ‘Melody’, respectively. Reporting lutein and β-carotene on both a fresh and dry weight basis may be the most accurate way to express the carotenoid values of spinach.     

Nitrogen-Metabolizing Enzymes: Effect of Nitrogen Sources and Saline Irrigation

Abstract

Indian mustard (Brassica juncea L. cv. RH-30) was grown under different types and levels of nitrogen (N) sources, i.e. nitrate, ammonical, and nitrate plus ammonical, at 40, 80, and 120 kg ha^{? 1} under green house conditions. The plants were salinized with 8 and 12 dSm^{? 1} at 35 and 55 days after sowing. A progressive inhibition of the activity of enzymes of N metabolism, i.e., nitrate reductase (NR), nitrite reductase (NiR), glutamine synthetase (GS), glutamate synthase (GOGAT), and glutamate dehydrogenase (GDH), was observed with increasing level of salinity. However, the magnitude of such reductions was lowest at the highest level of N (120 kg ha^{? 1}) as compared with the lowest level (40 kg ha^{? 1}) irrespective of N source. The activity of nitrate-assimilating enzymes (NR and NiR) was maximum with nitrate fertilizer, and minimum with the ammonical form. The alleviation of detrimental effects of salinity on NR and NiR was better with the highest level of N (120 kg ha^{? 1}) in nitrate form as compared with the lowest level of N (40 kg ha^{? 1}). In contrast, the maximum activity of ammonium-assimilating enzymes (GS, GOGAT, and GDH) was observed with the highest level of N (120 kg ha^{? 1}) and the minimum with the nitrate form of N under salinity. These results indicate that despite the high salinity, an increase in the concentration and uptake of N stimulates the activities of nitrate-assimilating enzymes (NR and NiR) as well as of the ammonia-assimilating enzymes (GS, GOGAT, and GDH).     

EFFECT OF PETUNIA STOCK PLANT NUTRITIONAL STATUS ON FERTILIZER RESPONSE DURING PROPAGATION

Fertilization strategies during stock plant and cutting production are linked in terms of cutting nutrient levels and quality. Objectives were to evaluate (1) the effect of stock plant nutrition on tissue nutrient concentration and growth during vegetative propagation and (2) response to fertilizer during propagation for cuttings with 4 different initial tissue nutrient concentrations. ‘Supertunia Royal Velvet’ petunia stock plants were grown under constant fertigation of 0, 50, 100 or 200 mg nitrogen (N)^.L^?1 for 21 days. The 200 mg N^.L^?1 solution contained 150 nitrate (NO₃-N), 50 ammonium (NH₄-N), 24 phosphorus (P), 166 potassium (K), 40 calcium (Ca), 20 magnesium (Mg), 0.7 sulfur (S), 1.0 iron (Fe), 0.5 manganese (Mn), 0.5 zinc (Zn), 0.24 copper (Cu), 0.24 boron (B), and 0.1 molybdenum (Mo). Providing a complete fertilizer during propagation of petunia, beginning immediately after sticking of cuttings, reduces the risk of nutrient deficiency. Particularly in situations where fertilizer is not applied early during propagation, stock plants should be managed to ensure unrooted cuttings have adequate nutrient reserves.     

Urea as an organic nitrogen source for hydroponically grown tomatoes in comparison with inorganic nitrogen sources

Tomato (Lycopersicon esculentum Mill., cv. Momotaro) plants were grown in nutrient solutions with several levels of urea, nitrate, and ammonium alone or in combination to evaluate the role of urea as an organic nitrogen source compared with that of nitrate and/or ammonium as inorganic nitrogen sources. Nitrogen deficiency and excess symptoms were detected in the urea-fed plants at lower (28 mg N L^-1) and higher nitrogen levels (336, 504 mg N L^-1), respectively. The effect of urea on plant growth and leaf elemental composition was intermediate between that of nitrate and ammonium. Solution pH under urea nutrition slightly increased or remained stable. When plants were cultured with the solution containing 168 mg N L^-1, the total dry weight of the plants which received urea+nitrate was significantly higher than that of the plant which received urea and was almost equal to that of the plants which received nitrate or nitrate+ammonium. Both absorption and utilization of nitrogen in the plants fed with urea decreased compared with those of the plants fed with nitrate or ammonium. The insufficient absorption and utilization of nitrogen were estimated to be the main factors associated with the growth reduction of tomato plants under urea nutrition. However, combined application of urea and nitrate is useful for adequate plant growth without a reduction of the cation absorption in tomato while maintaining a stable solution pH.     

Visible injury and growth responses of tomato and soybean to combinations of nickel,copper and ozone

Tomato (Lycopersicon esculentum Mill.) plants were grown in silica sand in controlled environments. In the first experiment Ni was added as NiSO₄ · 6 H₂O to the nutrient solution at 0, 1.5, 7.5, or 37.5 mg L^?1 for 6 day beginning 14 day from seeding, them plants were exposed to 0, 0.15, or 0.30 μL L^?1 O₃, and harvested 3 day later. Visible symptoms of Ni injury developed rapidly and there was distinctive O₃ injury. Growth variables were markedly reduced by Ni but O₃ response depended on Ni level. In the second experiment 0, 0.3, or 1.5 mg L^?1 Ni was provided from the 5th or 14th day onward. There was little effect of duration of Ni treatment on growth. Increasing Ni and increasing O₃ decreased growth but there was no interaction. In the third experiment 0, 1.5, and 3.0 mg L^?1 Ni treatments were combined with 0, 3.0, and 6.0 mg L^?1 Cu prior to 0 or 0.25 μL L^?1 O₃ treatment. There were complex interactive effects of all three factors on plant growth. Soybean (Glycine max Merr.) plants exposed to Ni and O₃ were only slightly affected by Ni or O₃ and there was no interaction.     

Characterization of nutrients uptake and enzymes activity in Khatouni melon (Cucumis melo var. inodorus) seedlings under different concentrations of nitrogen,potassium and phosphorus of nutrient solution

A nutrient solution experiment was done to evaluate effects of different concentrations of nitrogen (N), phosphorus (P) and potassium (K) on leaf mineral concentrations and some enzymes activity of melon seedlings (Cucumismelo var. inodorus subvar. Khatouni). Different levels of these nutrients including 0, 53, 105, 158 and 210?mg L^?1 N; 0, 8, 16, 23 and 31?mg L^?1 P; 0, 59, 118, 176 and 235?mg L^?1 K, all corresponding to 0, 25, 50, 75 and 100% of their concentrations in Hoagland nutrient solution, were applied to plants. The results showed that the highest leaf nitrate reductase (NR) activity was observed at highest N and P levels, whereas the three highest K levels showed the highest NR activity. The highest leaf peroxidase activity was observed at 8?mg L^?1 P, 59?mg L^?1 K and 158?mg L^?1 N. The leaf catalase activity was highest at zero concentration of P, 158?mg L^?1 N and 176?mg L^?1 K; however, catalase activity was decreased by increasing P levels. Leaf protein content showed an increasing trend with increasing N, P and K levels of nutrient solution, while there was no significant difference between 158 and 210?mg L^?1 N. The highest leaf concentrations of N, P, K and Mg were observed at highest nitrogen, potassium and phosphorus levels of nutrient solution, whereas the highest leaf concentration of Ca were obtained at 53 or 105?mg L^?1 N, 176?mg L^?1 K and 23–31?mg L^?1 P. The highest iron concentration of leaves was obtained from 23 to 31?mg L^?1 P, 176?mg L^?1 K and 210?mg L^?1 N.     

Nitrogen Uptake,Leaf Nitrogen Concentration,and Growth of Saskatoons in Response to Soil Nitrogen Fertility

ABSTRACT

Nutrient requirements of the saskatoon (Amelanchier alnifolia: Rosaceae), a relatively new horticultural crop on the Canadian prairies, are unknown. In this study, two-year old saskatoon plants of the cultivar ‘Smoky’ were grown in a greenhouse in pots under four different soil nitrogen (N) regimes (20, 40, 60, and 80 mg N L^?1). Half the plants were harvested after one growing season. After a five-month period of dormancy, the remaining plants were grown for a second growing season under the same soil N regimes. At harvest, plant growth, dry weight biomass, and leaf N concentration were measured, and soil N uptake was calculated. In both years, leaf N concentration and plant N uptake were strongly positively correlated (first year r = 0.93; second year r = 0.95) and increased linearly with an increase in soil N. Stem diameter and new shoot growth increased in both years of the study in response to additional N. The soil N treatments had no significant effect on plant biomass during the first growing season. In the second year, stem, root, total shoot and total plant biomass increased with increasing soil N.     

Interactive Effect of Sulfur and Nitrogen on Nitrogen Accumulation and Harvest in Oilseed Crops Differing in Nitrogen Assimilation Potential

ABSTRACT

Field experiments were conducted to determine the interactive effect of sulfur (S) and nitrogen (N) on nitrogen accumulation, its distribution in various plant parts, and nitrogen harvest of oilseed crops viz. rapeseed (Brassica campestris L. cv. ‘Pusa Gold’) and taramira (Eruca sativa Mill.) differing in their N-assimilation potential. Two combinations of S and N (in Kg/ha): 0S + 100N (?S+N) and 40S + 100N (+S+N) were used. The results showed that combined application of S and N (+S+N) significantly (P < 0.05) increased the nitrogen accumulation in both the genotypes at all the growth stages compared with N applied alone (?S+N). This increase in nitrogen accumulation was due to the improvement in the reduction of nitrate into reduced nitrogen as evident from higher nitrate reductase (NR) activity in the leaves of plants grown with both S and N, compared with N alone. Nitrate-N content in the leaves of plants grown with only N (?S+N) was higher compared to those grown with both S and N (+S+N), showing that combined application of S along with N (+S+N) appreciably reduced the nitrate content in the leaves due to higher NR activity. This decline in nitrate (NO₃ ^?) was followed by an overall increase in N-accumulation in the plants. Consequently, the nitrogen content in the plant was increased by 29–148% in rapeseed and 38-166% in taramira with +S+N treatment. Combined application of S along with N (+S+N) also increased seed protein content and nitrogen harvest index of both the genotypes. It is concluded that combined application of S along with N (+S+N) not only increased the N-accumulation, but also its mobilization towards economic sinks.     

Nitrogen losses from outdoor pig farming systems

Abstract. Nitrogen losses via nitrate leaching, ammonia volatilization and nitrous oxide emissions were measured from contrasting outdoor pig farming systems in a two year field study. Four 1‐ha paddocks representing three outdoor pig management systems and an arable control were established on a sandy loam soil in Berkshire, UK. The pig management systems represented: (i) current commercial practice (CCP) ‐ 25 dry sows ha^?1 on arable stubble; (ii) ‘improved’ management practice (IMP) ‐ 18 dry sows ha^?1 on stubble undersown with grass, and (iii) ‘best’ management practice (BMP) 12 dry sows ha^?1 on established grass. Nitrogen (N) inputs in the feed were measured and N offtakes in the pig meat estimated to calculate a nitrogen balance for each system. In the first winter, mean nitrate‐N concentrations in drainage water from the CCP, IMP, BMP and arable paddocks were 28, 25, 8 and 10 mg NO₃ l^?1, respectively. On the BMP system, leaching losses were limited by the grass cover, but this was destroyed by the pigs before the start of the second drainage season. In the second winter, mean concentrations increased to 111, 106 and 105 mg NO₃‐N l^?1 from the CCP, IMP and BMP systems, respectively, compared to only 32 mg NO₃‐N l^?1 on the arable paddock. Ammonia (NH₃) volatilization measurements indicated that losses from outdoor dry sows were in the region of 11 g NH₃‐N sow^?1 day^?1. Urine patches were identified as the major source of nitrous oxide (N₂O) emissions, with N₂O‐N losses estimated at less than 1% of the total N excreted. The nitrogen balance calculations indicated that N inputs to all the outdoor pig systems greatly exceeded N offtakes plus N losses, with estimated N surpluses on the CCP, IMP and BMP systems after 2 years of stocking at 576, 398 and 264 kg N ha^?1, respectively, compared with 27 kg N ha^?1 on the arable control. These large N surpluses are likely to exacerbate nitrate leaching losses in following seasons and make a contribution to the N requirement of future crops.     

Nitrate leaching from short-rotation coppice

In the UK, short‐rotation coppice (SRC) is expected to become a significant source of ‘bio‐energy’ over the next few years. Thus, it is important to establish how nitrate leaching losses compare with conventional arable cropping, especially if SRC is grown in Nitrate Vulnerable Zones. Nitrate leaching was measured using porous ceramic cups in each of the three phases in the lifespan of SRC, establishment, harvest and removal and was compared with conventional arable cropping. Nitrogen concentrations were increased in drainage water as soon as the crop cover was destroyed to plant the SRC (peak 70 mg L^?1 nitrate‐N) and increased further (peak 134 mg L^?1 nitrate‐N) on cultivation. Once the coppice crop was established, concentrations returned to a smaller level (average 18 mg L^?1 nitrate‐N). Concentrations were not affected by the harvesting operation, and annual applications of nitrogen (40, 60 and 100 kg ha^?1 N in the first, second and third years, respectively) had little effect. By contrast, concentrations in the arable rotation showed a regular pattern of increase in the autumn, and the average peak value over the 4 years was 54 mg L^?1 nitrate‐N. When the SRC was ‘grubbed up’ and roots removed, the soil disturbance resulted in a flush of mineralization which, combined with a lack of crop cover, led to increased nitrate‐N in leachate (peak 67 mg L^?1 nitrate‐N). In a normal life‐span of SRC (15–30 years), the relatively large nitrate losses on establishment and at final grubbing up would be offset by small losses during the productive harvest phase, especially when compared with results under the arable rotation.     

Elevational Patterns of Acid Deposition into a Forest and Nitrogen Saturation on Mt. Oyama, Japan

Virgin fir trees have been dying on Mt. Oyama, which is located in the southwestern part of Kanto Plain, although the frequency of death seems to be reducing recently. We report elevational patterns of acid deposition in precipitation and throughfall under fir and cedar canopies and nitrogen saturation in the forest ecosystem on Mt. Oyama. The deposition fluxes of major inorganic ions in precipitation were nearly constant regardless of elevation except for hydrogen and ammonium ions, whereas the deposition fluxes of all major inorganic ions in throughfall among cedar increased. The 5-year average of annual nitrate deposition in precipitation from 1994 to 1998 showed 19.3 – 23.5 kg ha^?1 yr^?1 (annual inorganic total N deposition: 9.6 – 10.7 kgN ha^?1 yr^?1) at four sites ranging in elevation from 500 to 1252 m, whereas the deposition in both cedar and fir throughfall was over 6 times greater than that in precipitation. The average soil surface nitrate concentration in 1998 was 140 µg g^?1 (the range: 21.1 – 429 µg g^?1, n=80) and the 7-year average of nitrate concentration in stream water from 1992 to 1998 was 4.81 mg L^?1 (the range: 2.38 – 20.6 mg L^?1, n=317). Our results indicate that nitrogen saturation is occurring in the forest ecosystem because of high N deposition, probably via acid fog, on Mt. Oyama.     

Nitrogen application rates for greenhouse tomato based on real-time diagnosis of petiole sap: Effects of soil nitrate contents before cultivation

(pp. 825–831)

This study was carried out to clarify the effects of soil nitrate before cultivation and amounts of basal-dressed nitrogen on additional N application rate and yields of semi-forced tomato for three years from 1998 to 2000. The amounts and timing of additional N dressing were determined based on diagnosis of petiole sap nitrate. The top-dressing was carried out with a liquid fertilizer when the nitrate concentration of a leaflet's petiole sap of leaf beneath fruit which is 2–4 cm declined below 2000 mg L^?1.

For standard yield by the method of fertilizer application based on this condition, no basal-dressed nitrogen was required when soil nitrate before cultivation was 150 mg kg^?1 dry soil or higher in the 0–30 cm layer; 38 kg ha^?1 of basal-dressed nitrogen, which corresponds to 25% of the standard rate of fertilizer application of Chiba Prefecture, was optimum when soil nitrate before cultivation was 100150 mg kg^?1 dry soil; 75 kg ha^?1 of basal-dressed nitrogen, which corresponds to 50% of the standard, was optimum when soil nitrate before cultivation was under 100 mg kg^?1 dry soil. A standard yield was secured and the rate of nitrogen fertilizer application decreased by 49–76% of the standard by keeping the nitrate concentration of tomato petiole sap between 1000–2000 mg L^?1 from early harvest time to topping time under these conditions.     

Influence of Salt Stress on the Nutritional State of Cordyline fruticosa var. Red Edge: Chloride,Nitrogen, and Phosphorus

This trial was carried out to study the nutritional and productive behavior generated by modifications in the salt concentration in the nutrient solution for Cordyline fruticosa var. Red Edge plants. The anions studied were chloride (Cl), nitrogen (N), and phosphorus (P). Four treatments were tested: T₁ [control, 1.5 dS m^?1, 14.3 mmol L^?1 sodium chloride (NaCl)], T₂ (2.5 dS m^?1, 22.2 mmol L^?1 NaCl), T₃ (3.5 dS m^?1, 32.7 mmol L^?1 NaCl), and T₄ (4.5 dS m^?1, 38.2 mmol L^?1 NaCl). At the end of the cultivation, leaf, petiole, shoot and root fresh and dry weights, elemental extractions, and elemental concentrations were determined. Nutrient concentrations and total plant uptake (extraction) were calculated from the dry matter. The treatment T₂ induces a blade protection mechanism, which consists on the accumulation of chloride (Cl^?) in root and vessels; so, leaf storage is reduced, avoiding damages. Petiole also contributes to this protection, acting as a salt pool. As NaCl concentration in the nutritive solution arises, N plant concentration increases significantly although there are no significant differences between T₁ and T₂. With high salinity levels, P in vessels is reduced, whereas root extraction and concentration increases. The greatest N and P extractions are observed in T₂, which is due to its higher dry matter. Chloride extractions are lower in T₁ than in the other treatments.     

Growth,Nutrition, and Photosynthetic Response of Black Walnut to Varying Nitrogen Sources and Rates

ABSTRACT

Black walnut (Juglans nigra L.) half-sib 1+0 seedlings were exponentially fertilized with ammonium (NH₄ ⁺) as ammonium sulfate [(NH₄)₂SO₄], nitrate (NO₃ ^?) as sodium nitrate (NaNO₃), or a mixed nitrogen (N) source as ammonium nitrate (NH₄NO₃) at the rate of 0, 800, or 1600 mg N plant^?1 and grown for three months. One month following the final fertilization, N concentration, growth, and photosynthetic characteristics were assessed. Compared with unfertilized seedlings, N addition increased plant component N content, chlorophyll content, and photosynthetic gas exchange. Net photosynthesis ranged from 2.45 to 4.84 μmol m^?2 s^?1 for lower leaves but varied from 5.95 to 9.06 μmol m^?2 s^?1 for upper leaves. Plants responded more favorably to NH₄NO₃ than sole NH₄ ⁺ or NO₃ ^? fertilizers. These results suggest that N fertilization can be used to promote net photosynthesis as well as increase N storage in black walnut seedlings. The NH₄NO₃ appears to be the preferred N source to promote black walnut growth and physiology.