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1.
Studies of the amino acids distribution in plants subjected to nutrient regimes are limited. The present study investigated the effect of NO 3‐N and FeSO 4‐Fe regimes on chlorophyll and total amino acids composition of tomato and wheat plants. Also the distribution of 17 amino acids between the different plant parts was studied. Increasing the NO 3‐N level up to 200 mg kg ‐1 greatly increased the total amino acids content of tomato plants. The total amino acids content of wheat plants continued to increase with addition of NO 3‐N up to 400 mg kg ‐1. The response of chlorophyll content to NO 3‐N supply was highly dependent on Fe level both in tomato and wheat plants. The interaction between NO 3‐N and FeSO 4‐Fe had a great effect on the total amino acids content and distribution. Iron increased the translocation of proline from roots to leaves. The overall amino acids contents of leaves was higher than that of stems or roots. 相似文献
2.
Studies on the effects of salinity and nitrogen (N) fertilization on ionic balance, biomass, and organic N production of annual ryegrass ( Lolium multiflorum Lam.) were conducted. Plants grown in sand were irrigated with nutrient solution with an electrical conductivity of 2 or 11.2 dS#lbm ‐1, and N in the form of sodium nitrate (NaNO 3), ammonium nitrate (NH 4NO 3), or ammonium sulfate [(NH 4) 2SO 4] ranging from 0.5 to 9.0 mM. Salinity increased the concentration of total inorganic cations (C) in plants and specifically sodium (Na) by more than 3‐fold higher in plants grown at high salinity as compared with plants at low salinity. Sodium (Na) concentration in roots was higher than in shoots irrespective of the salinity level, suggesting a restriction of Na transport from roots to shoots. The concentration of total inorganic anions (A) increased with salinity and when plants were supplied with nitrate (NO 3), salinity increased the concentrations of NO 3 and chloride (Cl) in plants. Increasing salinity and N concentration in the growth medium increased organic anions concentration in plants, estimated as the difference between C and A. The effect of different N sources on C‐A followed the order: NH 4NO 3 > NO 3 > ammonium (NH 4). The base of organic anions and inorganic ions with salinity contributed significantly to the osmotic potential of plants shoots and roots. Changes in C affected N and organic acids metabolism in plants, since C were highly correlated (p=0.0001) with C‐A and organic N (N org) concentrations regardless of the salinity level or N source in the nutrient solutions. A high and positive linear dependency was found between N org and C‐A in plants grown at high and low salinity levels and different N sources, pointing out the close relationship between N org and organic anions on metabolism under these conditions. The amount of biomass produced was correlated positively with organic anion concentration in plants exposed to different salinity levels. Plant biomass increased with N concentration in the nutrient solution regardless of the salinity level applied. Biomass accumulation decreased while N org concentration increased with salinity. Organic N content remained unaffected in plants exposed to salinity when grown in N less than 9.0 mM. 相似文献
3.
Pepper plants were hydroponically grown in a growth chamber with two levels of light intensity (300 and 240 w/m 2) and two NO 3:NH 4 ratios (100:0 and 80:20). Plants grown with both N forms (80:20) under high light regime displayed greater concentrations of free NH 4, organic soluble N and insoluble N than NO 3, treated plants, this effect was more pronounced for stem, petioles and root. By contrast, nitrate‐ammonium fed plants with light reduced over 25% presented similar concentrations of organic N (soluble and insoluble) as compared to plants supplied with NO 3 as sole source of N, however, the amount of free NH 4 in stem and root was increased. Results indicat that NH 4 supplied at low concentration was more deletereous for pepper plants grown under high light conditions, when light was reduced, plants presented an alleviation of toxic effect of NH 4 supply. Finally, nitrogen use efficiency is related to form of N nutrition and the light supplied to crop. 相似文献
4.
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 (NO 3?), ammonium (NH 4+) 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. NO 3? and NH 4+, 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
5.
The influence of N form on xylem exudate and the guttation fluid concentration in cucumber plants was studied under greenhouse conditions. Plants were hydroponically grown with three NO 3:NH 4 ratios (100:0, 80:20, and 60:40) at a constant pH of 6.0 in the nutrient solutions. Plants supplied with 60:40 NO 3:NH 4 ratio displayed a significant decrease of NO 3‐N, total‐N, organic‐P, and Mn concentrations in the xylem sap and an increase of H 2PO 4‐P, SO 4‐S, Cl, B, and Zn concentrations. Potassium and Ca uptake in these plants was slightly reduced, indicating that pH control was an important factor for cationic nutrition in cucumber plants fed with NH 4. The major ions present in the nutrient solutions are concentrated in the xylem sap, particularly for NO 3, K, Ca, and Na. The NO 3:NH 4 ratio had a small effect on the ionic levels of the guttation fluid. The concentrations of all nutrients in the guttation fluid were substantially reduced, except for Cl, showing that the leaf tissues of cucumber plants remove the excess of Cl ion. Finally, in this study, secondary effects of N source on ion uptake and release were minimized by controlling nutrient solution pH. 相似文献
6.
Abstract Tomato and watermelon plants were grown in nutrient solutions in which nitrogen (N) was supplied as NO 3 ? (6 mM‐N) or NH 4 + (6 mM‐N). The experiments were conducted to evaluate the effect which different N sources exert on iron (Fe) uptake and accumulation, on the enzymatic activities of aconitase (Aco), chelate reductase (FeCH‐R), peroxidase (POD), catalase (CAT), and Fe‐superoxide dismutase (FeSOD), and on biomass production. For both species of plants, fertilization with NH 4 + caused the total Fe concentration to be lower, in the roots and in the leaves in relation to the concentrations recorded in plants fertilized with NO 3 ?. The response of the enzymes related to Fe correlated with their concentration. The plants treated with N?NO 3 ? registered the highest activities in Aco, FeCH‐R, POD, and CAT for both tomato and watermelon. On the other hand, only in the tomato plants was the superoxide dismutase (SOD) activity appreciably influenced primarily by NH 4 +, due possibly to the toxic effect of this N source. Finally, in relation to biomass production, fertilization with NH 4 + drastically reduced growth in the tomato plants, while in watermelon plants, no significant alteration was detected in dry‐matter production, regardless of the N form used. It was concluded that the response of the parameters analyzed to NH 4 + fertilization, in tomato and watermelon, compared to fertilization with NO 3 ? was similar. By contrast, tomato plants, but not watermelon plants, were negatively influenced by NH 4 +. 相似文献
7.
The combined effects of NaCl and N nutrition (NO 3 ‐ and NH 4 ++NO 3 ‐) on nitrate reductase activity (NRA) in intact tomato ( Lvcopersicum esculentum) and cucumber ( Cucumis sativus) seedlings were studied. NRA decreased in leaves of both plant species as salinity increased. Within each salinity level, NRA increased with the external NO 3 ‐ concentration. An interference of C1 ‐ on NO 3 ‐ uptake was observed. Based on these results, it appears that the NRA was affected directly by the presence of excessive NaCl in the root media at least in two ways, by either interfering with the uptake of NO 3 ‐ by roots, or by inhibiting the transport of NO 3 ‐ from vacuole to cytosol. The effects were accentuated by the presence of NH 4 + as N source. 相似文献
8.
The influence of three potassium:rubidium (K:Rb) ratios (6:0, 5:1, and 4:2) on the xylematic transport of solutes in cucumber plants cv. Medusa supplied with both nitrate (NO 3 ‐) (60%) and ammonium (NH 4 +) (40%) was studied in greenhouse conditions. In the xylem sap of plants grown with a K:Rb ratio of 4:2, there was an increase in the transport of NO 3 ‐, phosphate (H 2PO 4 ‐), calcium (Ca 2+), magnesium (Mg 2+), sodium (Na +), manganese (Mn) and boron (B) while that of organic‐N, organic‐P, K +, zinc (Zn), organic acids, and carbohydrates decreased, if compared with the sap of the plants supplied with K alone. The translocation of NO 3 ‐, H 2PO 4 ‐, Ca 2+, Mg 2+, and Mn was enhanced and that of K + and organic acids decreased when the plants were supplied with a K:Rb ratio of 5:1. The K:Rb ratio detected in the xylem sap was the same K:Rb ratio as in the solutions. However, in the cucumber plant substituting 33% of total K by Rb resulted in an alteration in the transport of solutes, probably due to a competition between Rb and K rather than between the latter two and NH 4 +. 相似文献
9.
Tomato plants were grown in sand culture with NO 3 or NH 4 N at two levels of light. Foliar sprays at three levels of N as well as combinations of foliar and root feeding were used. Shade increased NH4 toxicity in plants sprayed with NH4 but decreased the toxicity in plants receiving NH4 through the roots. NH4‐N greatly reduced growth and cation uptake when supplied through the roots but not with foliar application. Plants sprayed with NH4 showed better growth, higher K, Ca, and Mg content and lower free NH4 in shoot, compared to plants receiving NH4 through the roots. The overall free amino acid contents of shoots was higher for NH4‐fed plants regardless of how the N was applied. Plants sprayed with NH4 incorporated a greater amount of N into insoluble compounds compared with NO3 nutrition. The N uptake per unit of leaf area was higher for plants grown under full sun light whereas N content was higher for plants grown under hade. N content in tissue increased with N concentration in foliar spray, although plants supplied with N through the roots had higher levels of free amino acids and total nitrogen. 相似文献
10.
The influence of two N sources, NO 3 alone and NH 4+NO 3 (2:1) in the external medium on fluxes of Cl, N, Na and K calculated from the total nutrient content per unit root dry weight, were investigated using cucumber (Cucumis sativus) seedlings grown in saline conditions. The N source affected the fluxes of the above ions very differently: (a) when only NO 3 was added, the rate of Cl uptake was inhibited whereas the rate of K absorption was stimulated; and (b) by contrast, the presence of NH, in the N source enhanced Cl uptake and inhibited K uptake. The effect on the rates of Na and N uptake was more complex and salinity dependent. The potassium: sodium ratios (K:Na) and potassium: sodium selectivity ratio (S., ) in roots and shoots in relation with the treatments are also presented. Possible reasons of the N source effect on the processes implicated with the response of plants to salinity are also discussed. 相似文献
11.
Tomato ( Lycopersicon esculentum L. Mill. ‘Vendor') plants were grown for 21 days in flowing solution culture with N supplied as either 1.0 mM NO 3 ‐ or 1.0 mM NH 4 +. Acidity in the solutions was automatically maintained at pH 6.0. Accumulation and distribution of dry matter and total N and net photosynthetic rate were not affected by source of N. Thus, when rhizosphere acidity was controlled at pH 6.0 during uptake, either NO 3 ‐ or NH 4 + can be used efficiently by tomato. Uptake of K + and Ca 2+ were not altered by N source, but uptake of Mg 2+ was reduced in NH 4 +‐fed plants. This indicates that uptake of Mg 2+ was regulated at least partially by ionic balance within the plant. 相似文献
12.
Although most plants can use ammonium (NH 4) or nitrate (NO 3) as a source of N, the degree of effectiveness of these two N forms on tomato growth was found to be dependent on the NH 4: NO 3 ratio. The addition of small amounts of NH 4 to NO 3 solutions, up to 14 ppm, improved plant growth but did not significantly change the uptake of K, Ca, and Mg as compared to NO 3 alone. However, with 28 ppm NH 4‐N and above, dry weights and cation accumulations decreased in amounts of about 35 to 50% and in a 12‐day period. The decreased dry weight and cation uptake with 77: 77 ppm NH 4: NO 3 ratio was comparable to that obtained with a O N treatment for the same interval. 相似文献
13.
It is often thought that the most important source of nitrogen for plants and microorganisms comes from amino acids and amino sugars when they are hydrolysed in acid conditions. We did a microcosm experiment to test the hypothesis. In the experiment spruce seedlings ( Picea abies L. Karst) were grown for 145 days in soil taken from a podzol Oa horizon under a long-term nitrogen fertilization experiment (control and N-treated soil). Net changes in different pools of organic N were determined using standard fractionation (acid hydrolysis and pyrophosphate extraction). During the experiment the amino acid and amino sugar pools decreased significantly (14% and 15% for the control and 10% and 17% for the N treatment), whereas no significant change was observed in the non-amino acid plus non-amino sugar fraction. On a per organic C basis there was even a significant increase in the non-amino acid plus non-amino sugar fraction of 11% for the control and 8% for the N treatment. Pyrophosphate extractions suggest that amino acids or amino sugars associated with the humin fraction were more accessible to microbes and plants than those associated with the humic acid, fulvic acid and hydrophilic substances. The long-term N fertilization (about 73 kg N ha −1 was added annually as NH 4NO 3 during a 24-year period) resulted in an enrichment of all major fractions of organic N, i.e. amino acids, amino sugars and non-amino acids plus non-amino sugars. This enrichment was largely the result of small increases in all of the amino acids rather than large increases in just a few. 相似文献
14.
The effects of sodium chloride (NaCl) salinity (0 and 200 mM) and ammonium (NH 4):nitrate (NO 3) ratios (100:0, 25:75, 50:50, and 75:25) on growth, photosynthesis, fatty acids and the activity of antioxidative enzymes were investigated in canola plants. Leaf area and fresh and dry weights of leaves were significantly reduced by the salinity. The reduction in vegetative characteristics varied in both salinized and unsalinized plants according to the NH 4:NO 3 ratios so that the lowest reduction was observed with the 50:50 (NH 4:NO 3) ratio. Increased NH 4 up to 50 percent (50:50) of total N, promotes the yield at both salinized and unsalinized plants. In both salinized and unsalinized plants, the increased NH 4 and NO 3 ratio in the nutrient solution reduced the photosynthetic (Pn) rate and stomatal conductance; however, the reduction in Pn rate was severely impaired at a higher ratio of NH 4 in the nutrient solution. In both salinized and unsalinized plants, the 75:25 ratio had the lowest potassium (K) and sodium (Na) content; however, the K/Na ratio was the highest in 50:50 ratio. An increase of NH 4 in the solution led to a significant increase in NH 4 content in both salinized and unsalinized plants. Salinity increased NH 4 content so that the salinized plant had nearly twice as high NH 4 content in the leaves. The activity of nitrate reductase was increased by increasing NH 4 from 0 to 50% and then reduced at a higher ratio of NH 4 in the solution. The activities of antioxidative enzymes increased in salinized plants regardless of the NH 4:NO 3 ratios. In salinized plants, the activities of superoxide dismutase and catalase enzymes were increased by 44.4 % and 97.5%, respectively. Within salinized and unsalinized treatments, the highest activities of all antioxidant were observed in 75:25 ratio, while they remained unchanged for all NH 4:NO 3 ratios. The increased NH 4 content in the solution increased the oil content and the maximum oil content in both salinized and unsalinized plant was obtained in both 50:50 and 75:25 ratios. The percentage of oleic acid was affected by both salinity and NH 4:NO 3 ratios. The ratios of NH 4:NO 3 had no effect on the protein content; however, salinity reduced the protein content by 20%. 相似文献
15.
Pepper plants were hydroponically grown in a growth chamber with two levels of light intensity (300 and 240 w/m 2 ) and two N0 3:NH 4 ratios (100:0 and 80:20). Plants supplied with both N forms (80:20) under high light conditions showed a decrease of nutrient uptake and produced low plant weight and yield compared to the all NO 3 treated plants. By contrast, plants receiving both N forms (80:20) with light reduced over 25% showed a growth and yield slightly superior to plants supplied with N0 3 as sole source of N. This suggests a significant light intensity‐N form interaction that favors all NO 3 nutrition for pepper at high light intensities. 相似文献
16.
The availability of inorganic N has been shown to be one of the major factors limiting primary productivity in high latitude ecosystems. The factors regulating the rate of transformation of organic N to nitrate and ammonium, however, remain poorly understood. The aim of this study was to investigate the nature of the soluble N pool in forest soils and to determine the relative rate of inorganic N production from high and low molecular weight (MW) dissolved organic nitrogen (DON) compounds in black spruce forest soils. DON was found to be the dominant N form in soil solution, however, most of this DON was of high MW of which >75% remained unidentified. Free amino acids constituted less than 5% of the total DON pool. The concentration of NO 3− and NH 4+ was low in all soils but significantly greater than the concentration of free amino acids. Incubations of low MW DON with soil indicated a rapid processing of amino acids, di- and tri-peptides to NH 4+ followed by a slower transformation of the NH 4+ pool to NO 3−. The rate of protein transformation to NH 4+ was slower than for amino acids and peptides suggesting that the block in N mineralization in taiga forest soils is the transformation of high MW DON to low MW DON and not low MW DON to NH 4+ or NH 4+ to NO 3−. Calculated turnover rates of amino acid-derived C and N immobilized in the soil microbial biomass were similar with a half-life of approximately 30 d indicating congruent C and N mineralization. 相似文献
17.
Two cultivars of lettuce plants ( Lactuca sativa L. cvs Berlo and Kirsten) were grown for two months in late fall in NFT under three different nitrogen (N)‐regimes but with the same total N concentration (13.4 mM). A reference treatment with a nutrient solution containing 94% nitrate (NO 3) and 6% ammonium (NH 4) was compared with urea and proteinate treatments in which 20% of the NO 3 of the reference treatment was replaced by either of these two N sources. Proteinate is a fertilizer produced in Turkey containing 8% amino acid N and 8% NO 3‐N. For both cultivars the fresh weights of the harvested plants were unaffected by the N source as was also the total N uptake. Nitrate content, however, was considerably lower in the urea and proteinate plants, values for the three treatments ranging from 3314 to 4579 mg NO 3/kg fresh wt making up from between 44.3% to 55.4% of the total plant N. Of the two cultivars, Berlo accumulated greater concentrations of NO 3 than did Kirsten. The accumulation of chloride (Cl) was in the reverse order of that of NO 3 with greatest concentrations occurring in the proteinate plants. 相似文献
18.
ABSTRACT A pot experiment was conducted to study the influence of four nitrogen (N) fertilizer forms [Urea; calcium nitrate, Ca(NO 3) 2; ammonium sulfate, (NH 4) 2SO 4; 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 (NH 4 +)-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 NH 4 +- and nitrate (NO 3 ?)-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 NH 4 +-N treated plants having highest N and lowest Cd concentrations and NO 3 ?-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
19.
ABSTRACT Understanding how plants use of various nitrogen (N) sources is important for improving plant N use efficiency in organic farming systems. This study investigated the effects of farming management practices (organic and conventional) on pakchoi short-term uptake of glycine (Gly), nitrate (NO 3 ?) and ammonium (NH 4 +) under two N level conditions. Results showed that plant N uptake rates and N contributions from the three N forms in the low N (0.15 μg N g ?1 dry soil) treatment did not significantly differ between the organic and conventional soils, except the significantly greater Gly contribution in organic soil at 24 h after tracer addition. Under high N (15 μg N g ?1 dry soil) conditions, the N uptake rates, uptake efficiencies, and N contributions of Gly and NH 4 +-N were significantly greater in pakchoi cultivated in the organic soil compared to conventional soil, whereas the N uptake rates and N contributions from NO 3 –-N decreased in pakchoi cultivated in the organic soil. The greater Gly-N uptake in plants grown in high-N treated organic soil may be related to the greater gross N transformation, Gly turnover rate and the increased expression of an amino acid transporter gene BcLHT1. Intact Gly contributed at most 6% to Gly-derived N at 24 h after tracer additions, which accounting for about 1.24% of the total N uptake in organic soil. Our study suggested that Gly-N and other organic source N might serve as a more important compensatory N source for plants in organic farming. 相似文献
20.
ABSTRACT Aspects of ammonium (NH 4 +) toxicity in cucumber ( Cucumis sativus L.) were investigated following growth with different N sources [nitrate (NO 3 ?), NH 4 +, or NH 4NO 3] supplied in concentrations of 1, 5, 10, or 15 mM. Plant dry weights and root: shoot ratios were lower with NH 4 +-fed plants than with NO 3 ?-fed plants. Ammonium accumulated strongly in leaves, stem, and roots when the concentration in the growth medium exceeded 1 mM. The increase in tissue NH 4 + coincided with saturation of glutamine synthetase activity and accumulation of glutamine and arginine. Low tissue levels of calcium and magnesium in the NH 4 +-fed plants constituted part of the NH 4 +-toxicity syndrome. Additions of small amounts of NH 4 + to NO 3 ? -grown cucumber plants markedly increased the growth. 相似文献
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