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1.
Nitrogen is taken up by most plant species in the form of nitrate and ammonium. The objective of this study was to investigate the effect of different nitrogen forms on the growth of watermelon seedlings. Plants were grown in hydroponic culture with five nitrate (NO3?)/ammonium (NH4+) ratios (100/0, 75/25, 50/50, 25/75, 0/100). When the proportion of NH4+ was increased, the leaf number, leaf area, shoot height, net photosynthesis, biomass, and root growth were significantly decreased. Higher concentrations of nitrogen (N) and phosphorus (P) were observed when plants were supplied with mixed NO3? and NH4+ compared to NO3? or NH4+ alone, whereas the concentrations of potassium (K), calcium (Ca), and magnesium (Mg) were decreased with increasing NH4+. The microelements concentrations were generally increased with more NH4+ added. In addition, plants fed with higher NO3?/NH4+ ratios resulted in more minerals accumulation.  相似文献   

2.
ABSTRACT

A pot experiment was conducted to study the influence of four nitrogen (N) fertilizer forms [Urea; calcium nitrate, Ca(NO3)2; ammonium sulfate, (NH4)2SO4; and organic N] on growth, photosynthesis, and yield of rice under two cadmium (Cd) levels (0 and 100 mg Cd kg?1 soil). Cadmium addition significantly reduced photosynthetic rate, and the reduction varied with N fertilizer form, with ammonium (NH4 +)-N and urea treated plants having more reduction. Nitrogen form had a distinct effect on SPAD value, and the effect was also dependent on Cd level and growth stage. Cadmium-stress significantly reduced flag leaf area, but for the second leaf, only the plants supplied with organic N showed the reduction. There was a significant difference in plant height among four N forms, with NH4 +- and nitrate (NO3 ?)-treated plants having the highest and lowest height, respectively. Cadmium stress caused significant reduction in grains per panicle and total plant weight, and the reduction varied with N form, with organic N treatment showing more reduction. There were significant differences among N forms in N and Cd concentrations of the plants subjected to Cd stress, with NH4 +-N treated plants having highest N and lowest Cd concentrations and NO3 ?-treated plants having lowest N and highest Cd uptake. The results showed that the inhibition of Cd stress on growth and yield formation of rice is closely related to N fertilizer form.  相似文献   

3.
Although retranslocation or nitrogen (N) derived from plants (NDFP) may account for more than 50% of the annual N demand in new growth of conifer seedlings, the proportional contribution of NDFP vs. current uptake or N derived from fertilizer (NDFF) in new growth of hardwood seedlings is relatively unknown. The current uptake was labeled with ammonium sulfate [(15NH4)2SO4] at the rate of 1.56 g N plant?1 and reared for 90 days in sand culture under greenhouse conditions, and NDFP vs. NDFF was quantified in new growth of half‐sib bareroot black walnut (Juglans nigra L.) seedlings. Nitrogen derived from plants accounted for 68 to 83% of the total N demand in new shoot growth of black walnut seedlings vs. NDFF (17 to 32%). Recovered applied fertilizer was 43% in soil and 9% in plants. The greater proportion of NDFP in new growth demonstrates the importance of retranslocation in meeting early N demand of transplanted black walnut seedlings.  相似文献   

4.
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.  相似文献   

5.
The aim of this study was to evaluate the sustainability of an agro-industry sludge as a nitrogen (N) fertilizer in perennial crops by assessing its dynamics of release of: 1) N as ammonium (NH4+)- and nitrate (NO3?)-N, and 2) carbon as soil respiration. In incubation assay, application of agro-industry sludge promoted the maximum NH4+-N concentration (50 mg kg?1) 2 h after application, then it decreased with time until day 26. NO3?-N increased, reaching the maximum between day 60 and day 100, according to a second degree function. Agro-industry sludge showed a slower release of NO3?-N compared with urea. Soil basal respiration and cumulative amount of carbon dioxide were higher in sludge from day 71 on. In field, soil NO3?-N increased after fertilization treatments and was higher in Calcari Stagnic Cambisols soil. Sludge showed a potential lower environment impact in terms of mineral N release, than urea.  相似文献   

6.
Under conditions of limited nutrient supply, plant nutrient uptake is controlled by the external concentration of the ions. Limited information exists about the whole-plant regulation of nutrient uptake when the supply is adequate. To study the relationship between growth rate and carbon dioxide (CO2) assimilation with nutrient uptake, growth chamber experiments were conducted with temperatures ranging from 10 to 35°C at medium (600 µmol m?2 s?1) and high (1200 µmol m?2 s?1) light intensities. Nutrient solution samples were collected every 24 hours and the concentration of ions was analyzed by Inductively coupled plasma -atomic emission spectroscopy (ICP-AES) and nitrate and ammonium (NO3?/NH4+) conductivity. Leaf photo-synthesis was measured using a closed gas exchange system and the total amount of CO2 assimilated was calculated from dry weight increases. The daily absorption of NO3?, Total nitrogen (N), dihydrogen phosphate (H2PO4?) and potassium (K+) responded linearly to plant growth, while ammonium (NH4+) and sulfate (SO42?) uptake showed a curvilinear response. All the ions studied showed a curvilinear relation with CO2 assimilation.  相似文献   

7.
The objective of the experiment was to identify the most favorable nitrogen (N) source ratio of ammonium (NH4 +) and nitrate (NO3 ?) for aeroponically-grown Douglas-fir when pH was maintained at pH 4.0. Seedlings were grown in controlled environments with solutions containing 0:100, 20:80, 40:60, 60:40, 80:20 or 100:0 NH4 +:NO3 ? ratios. Nutrient additions in the aeroponic culture units were controlled by solution conductivity set points. Seedling growth and nutrient allocation was observed for 45 days. Different NH4 +:NO3 ? ratios resulted in significant differences in the rate of N addition, growth, morphology, and nutrient allocation. Seedlings grown in solutions containing 60 or 80% NO3 ? were characterized by a combination of high growth and photosynthetic rates, high and stable internal plant N concentrations, and sufficient levels of other essential nutrients. High proportions of NH4 + in solution resulted in low rates of N addition, stunted lateral root growth, and may have been toxic.  相似文献   

8.
Results are presented from a 3-year investigation into nitrate leaching from grassed monolith lysimeters treated with double (15NH415NO3) or single (15NH4NO3) labelled ammonium nitrate at three rates, 250, 500 and 900 kg N ha?1 a?1. Over the 3 years of the experiment, 0.14%, 3.1% and 18.1% of the applied fertilizer was recovered in the leachate at 250, 500 and 900kg N ha?1 respectively. This represented 9%, 39% and 75% of the overall nitrate leaching at the three application rates. A significant proportion of the fertilizer leached as nitrate at the three application rates was derived, via nitrification, from the fertilizer ammonium. Increasing fertilizer applications caused a rise in the leaching of both soil and fertilizer derived nitrogen, although whether the increase reflected a true priming effect was not clear.  相似文献   

9.
Due to the high levels of crude protein in the achene, sunflower (Helianthus annuus L.) is one of the main oilseeds grown worldwide, particularly for the oil and meal production for animal feed. Despite these advantages, there are few studies on nutrient use efficiency under tropical conditions, especially nitrogen (N). The experiment was conducted in greenhouse conditions to evaluate the effects of N sources and rates on sunflower achene yield (AY), yield and physiological components, and nutritional status of sunflower. The five N sources (calcium nitrate (Ca(NO3)2), potassium nitrate (KNO3), ammonium nitrate (NO3NH4), ammonium sulfate ((NH4)2SO4), and urea (CO(NH2)2)), and four N rates (0, 50, 100, and 200 mg kg?1) were studied. AY was reduced with the ammonia sources application from the 100 mg N kg?1. Plant height and capitulum dry weight (CDW), capitulum diameter, shoot dry weight (SDW), and chlorophyll content were significantly related with N sources and rates. Except for potassium (K), the N rates changed the N, P, Ca, Mg, and S concentration in the leaves and N concentration in achene. In the comparison of sources, on the average of N rates, urea application was more effective than the other N fertilizers in the AY.  相似文献   

10.
Field experiments were conducted to determine the effect of nitrogen (N) fertilizer forms and doses on wheat (Triticum aestivum L.) on three soils differing in their ammonium (NH4) fixation capacity [high = 161 mg fixed NH4-N kg?1 soil, medium = 31.5 mg fixed NH4-N kg?1 soil and no = nearly no fixed NH4-N kg?1 soil]. On high NH4+ fixing soil, 80 kg N ha?1 Urea+ ammonium nitrate [NH4NO3] or 240 kg N ha?1 ammonium sulfate [(NH4)2SO4]+(NH4)2SO4, was required to obtain the maximum yield. Urea + NH4NO3 generally showed the highest significance in respect to the agronomic efficiency of N fertilizers. In the non NH4+ fixing soil, 80 kg N ha?1 urea+NH4NO3 was enough to obtain high grain yield. The agronomic efficiency of N fertilizers was generally higher in the non NH4+ fixing soil than in the others. Grain protein was highly affected by NH4+ fixation capacities and N doses. Harvest index was affected by the NH4+ fixation capacity at the 1% significance level.  相似文献   

11.
ABSTRACT

The present study was performed to characterize the interaction between nitrogen (N) form and availability with respect to growth, water relations, and mineral nutrition of wild swiss chard (Beta macrocarpa Guss). Plants were cultured hydroponically with two levels of N concentrations, high-N (2.5 mM) or low-N (0.5 mM), added as nitrate (NO? 3) or ammonium (NH+ 4). At high N, growth was affected significantly by N form. If the NO? 3 medium was considered as control, the use of NH+ 4 decreased dry matter production and leaf area by ca. 35%. Use of NH+ 4 led to water economy and did not affect the nutrient content of the plant tissues. Compared to growth with high N, plants growth fell in either low- NO? 3 or low- NH+ 4 medium. In this case, the difference between the two N sources was not significant. Our results showed that the replacement of NO? 3 by NH+ 4 as the N source decreased the NO? 3 concentration in consumable leaves and increased the water use efficiency.  相似文献   

12.
ABSTRACT

Aspects of ammonium (NH4 +) toxicity in cucumber (Cucumis sativus L.) were investigated following growth with different N sources [nitrate (NO3 ?), NH4 +, or NH4NO3] supplied in concentrations of 1, 5, 10, or 15 mM. Plant dry weights and root: shoot ratios were lower with NH4 +-fed plants than with NO3 ?-fed plants. Ammonium accumulated strongly in leaves, stem, and roots when the concentration in the growth medium exceeded 1 mM. The increase in tissue NH4 + coincided with saturation of glutamine synthetase activity and accumulation of glutamine and arginine. Low tissue levels of calcium and magnesium in the NH4 +-fed plants constituted part of the NH4 +-toxicity syndrome. Additions of small amounts of NH4 + to NO3 ? -grown cucumber plants markedly increased the growth.  相似文献   

13.
Nitrogen (N), ammonium (NH4+) and nitrate (NO3?), is one of the key determinants for plant growth. The interaction of both ions displays a significant effect on their uptake in some species. In the current study, net fluxes of NH4+ and NO3? along the roots of Picea asperata were determined using a Non-invasive Micro-test Technology (NMT). Besides, we examined the interaction of NH4+ and NO3? on the fluxes of both ions, and the plasma membrane (PM) H+-ATPases and nitrate reductase (NR) were taken into account as well. The results demonstrated that the maximal net NH4+ and NO3? influxes were detected at 13–15?mm and 8–10.5?mm from the root apex, respectively. Net NH4+ influx was significantly stimulated with the presence of NO3?, whereas NH4+ exhibited a markedly negative effect on NO3? uptake in the roots of P. asperata. Also, our results indicated that PM H+-ATPases and NR play a key role in the control of N uptake.  相似文献   

14.
Two hydroponic experiments were carried out to investigate the effects of nitrogen (N) levels and forms on the oxalate concentrations of different form in edible parts of spinach. Nitrogen was supplied at five levels (4, 8, 12, 16, 20 mM) in Experiment 1 and five ratios of nitrate (NO3 ?) to ammonium (NH4 +) (100/0, 75/25, 50/50, 25/75, 0/100) at a total N of 8 mM in Experiment 2. Biomass of spinach increased markedly from 4 mM to 8 mM N and reached the flat with further increase in N. The total oxalate and soluble oxalate in leaves and shoots (edible parts) increased significantly with increasing N levels from 4 to 12 mM, while the total oxalate and insoluble oxalate decreased markedly when N level was further increased from 12 to 20 mM. Oxalates of different forms in petioles increased first and then decreased and elevated again with increasing nitrogen levels. In the second experiment, decreasing NO3 ?/NH4 + ratios markedly increased at first and then significantly decreased the biomass of spinach plants and the maximum biomass was recorded in the treatment of the NO3 ?/NH4 + ratio of 50:50. The oxalate concentrations of different form in leaves and shoots were all decreased obviously as the ratio of NO3 ?/NH4 + decreased from 100:0 to 0:100. Concentrations of total oxalate and soluble oxalate in petioles could be reduced by increasing ammonium proportion and were the lowest as the ratio of NO3 ?/NH4 + was 50:50 and insoluble oxalate decreased as nitrate/ammonium ratio decreased. The concentrations of oxalate forms in leaves were all higher than those in petioles and soluble oxalate was predominant form of oxalates in both trials. It is evident that high biomass of spinach can be achieved and oxalate concentrations of different forms can be reduced by modulating N levels and NO3 ?/NH4 + ratio, so this will benefit for human health especially for those people with a history of calcium oxalate kidney stones.  相似文献   

15.
It is well known that plants are capable of taking up intact amino acids. However, how the nitrogen (N) rates and N forms affect amino acid uptake and amino acid nutritional contribution for plant are still uncertain. Effects of the different proportions of nitrate (NO3?), ammonium (NH4+) and 15N-labeled glycine on pakchoi seedlings glycine uptake were investigated for 21 days hydroponics under the aseptic media. Our results showed that plant biomass and glycine uptake was positively related to glycine rate. NO3? and NH4+, the two antagonistic N forms, both significantly inhibited plant glycine uptake. Their interactions with glycine were also negatively related to glycine uptake and glycine nutritional contribution. Glycine nutritional contribution in the treatments with high glycine rate (13.4%–35.8%) was significantly higher than that with low glycine rate (2.2%–13.2%). The high nutritional contribution indicated amino acids can serve as an important N source for plant growth under the high organic and low inorganic N input ecosystem.  相似文献   

16.
Co-composting of chicken slurry and rice straw with clinoptilolite zeolite and urea as additives was conducted to determine the characteristics of a compost and their effects on controlling ammonium (NH4+) and nitrate (NO3?) losses from urea. Quality of the compost was assessed based on temperature, moisture content, ash, pH, electrical conductivity, carbon/nitrogen (C/N) ratio, NH4+, NO3?, macronutrients, heavy metals, humic acid, microbial population, germination index, and phytotoxicity test. Moisture content and C/N ratio of the compost were 43.83% and 15, respectively. Total N, humic acid, ash, NH4+, NO3?, phosphorus (P), calcium (Ca), magnesium (Mg), potassium (K), and sodium (Na) increased after co-composting rice straw and chicken slurry. Copper, iron (Fe), manganese (Mn), zinc (Zn), and microbial biomass of the compost were low. The germination rate of Zea mays on distilled water and Spinacia oleracea growth on peat-based growing medium (PBGM) and compost were not significantly different. Urea amended with compost reduced N loss by retaining NH4+ and NO3? in the soil.  相似文献   

17.
In this paper, the uptake kinetics of various nitrogens (nitrate (NO3?), ammonium (NH4+), urea, amino acid) by Chinese kale (Brassica oleracea L. var. Bailey) were studied under hydroponic condition. The results indicated that the uptake kinetics of organic and inorganic nitrogen (N) by Chinese kale conform to the Michaelis–Menten equation, and the maximum uptake rate (Vmax) and affinity index (1/Km) showed nitrate (NO3—N) > ammonium (NH4+-N) > urea-N > Gly-N, with significant differences between treatments (p < 0.05). Adding different types of N to NO3? nutrient solution had little impact on its affinity, but significantly decreased the NO3? Vmax, which showed NO3–N > NO3? + NH4+ > NO3? + urea > NO3? + Gly. Chinese kale preferred inorganic N to organic N, with NO3? preceding NH4+. Adding organic and NH4+ N to nutrient solution reduced the NO3? uptake capacity by the plant.  相似文献   

18.
The effect of elevated nitrate [(NO3‐nitrogen (N)] or ammonium (NH4)‐N on the response of nonmycorrhizal (NM) and ectomycorrhizal (ECM) pitch pine (Pintis rigida Mill.) seedlings to aluminum (Al) was determined in experiments in which N was increased three times above ambient levels. Seedlings with and without the mycorrhizal fungus Pisolithus tinctorius (Pers.) Coker & Couch were grown in sand irrigated with nutrient solution (pH 3.8) containing 0, 10, or 20 mg Al L‐1 (0, 370, or 740 μM Al). The nutrient solution simulated that for the sandy, nutrient‐poor soil of the New Jersey Pine Barrens. Elevated NO3‐N had no significant effect on Al toxicity in NM seedlings, but Al toxicity at ambient NH4‐N was ameliorated by elevated NH4‐N. Symptoms of Al toxicity in roots (thick and stunted) of ECM seedlings at ambient N levels were reduced by elevated NH4‐N and absent at elevated NO3‐N. When N was elevated by an increase in NO3‐N or NH4‐N, uptake of N and relative increases in total biomass were greater in ECM than in NM seedlings.  相似文献   

19.
Fate of fertilizer nitrogen.   总被引：3，自引：0，他引：3  
Results are presented from a three year lysimeter investigation, employing single (15NH4NO3) and double (15NH415NO3) labelled ammonium nitrate to study the uptake of soil and fertilizer nitrogen by cut ryegrass at 250, 500 and 900 kg N ha?1 a?1. Average annual recoveries of nitrogen were equivalent to 99,76 and 50% of the nitrogen added at 250, 500 and 900 kg N ha?1, respectively. At 250 kg N ha?1 the difference between the overall nitrogen recovery and the fertilizer recovery was almost entirely attributable to pool substitution resulting from mineralization/immobilization turnover (MIT). At 900 kg N ha?1 both the low overall recovery of nitrogen and the low fertilizer recovery reflected the large excess of available nitrogen over crop requirements. No evidence of ‘priming’ was obtained. Analysis of the results from single and double labelled lysimeters using simultaneous equations indicated that at 250 kg N ha?1,～70% of the nitrogen in the crop was derived from the ammonium pool. At 500 kg N ha?1 this dropped to 64%, while at 900 kg N ha?1 the figure was 59%. There was a suggestion that at the lower application rates, preferential uptake of ammonium was occurring but that as N supply exceeded crop requirements, nitrate was the major N source. Despite the preferential exploitation of the ammonium pool, at 250 and 500 kg N ha?1 pool substitution resulting from MIT resulted in lower recoveries of fertilizer ammonium compared with fertilizer nitrate.  相似文献   

20.
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