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1.
Plants show different growth responses to N sources supplied with either NH4+ or NO3-. The uptake of different N sources also affects the rhizosphere pH and therefore the bioavailability of soil phosphorus, particularly in alkaline soils. The plant growth, P uptake, and P availability in the rhizosphere of oat (Avena nuda L.) grown in hydroponics and in soil culture were investigated under supply with sole NH4+-N, sole NO3--N, or a combination. Sole NO3--fed oat plants accumulated more biomass than sole NH4+-fed ones. The highest biomass accumulation was observed when N was suppliedw ith both NH4+-N and NO3--N. Growth of the plant root increased with the proportion of NO3- in the cultural medium. Better root growth and higher root/shoot ratio were consistently observed in NO3--fed plants. However, root vigor was the highest when N was supplied with NO3-+NH4+. NH4+ supply reduced the rhizosphere pH but did not affect P uptake by plants grown in soils with CaHPO4 added as P source. No P deficiency was observed, and plant P concentrations were generally above 2 g kg-1. P uptake was increased when N was supplied partly or solely as NO3--N, similarly as biomass accumulation. The results suggested that oat was an NO3--preferring plant, and NO3--N was essential for plant growth and the maintenance of root absorption capacity. N supply with NH4+-N did not improve P nutrition, which was most likely due to the absence of P deficiency. 相似文献
2.
Salt-affected soils are agricultural and environmental problems on a global scale. Plants suffer from saline stresses in these soils and show nitrogen (N) deficiency symptoms. However, halophytes grow soundly under saline conditions. In order to clarify the N nutrition of the halophyte Salicornia bigelovii, it was grown at several N levels (1, 2, 3, and 4 mmol L-1), supplied in the form of NO3- or ammonium (NH4+), under high NaCl conditions (200 mmol L-1). NH4+-fed plants showed better growth than NO3--fed plants at 1-3 mmol L-1 N, and plants in both treatments showed the same growth at 4 mmol L-1 N. Nitrogen contents in NO3--fed plants increased with the N concentrations in solution; competitive inhibition of NO3- absorption by Cl- was observed under lower N conditions. In addition, shoot dry weight was significantly correlated only with shoot N content. Therefore, growth of NO3--fed plants was regulated by N absorption. Inc ontrast, N contents of shoots in NH4+-fed plants did not change with N concentration. Shoot Na content decreased with increasing N concentration, while K content increased. Dry weight was highly correlated only with K content in NH4+-fed plants. These observations indicated that growth of NH4+-fed plants was mainly regulated by K absorption. 相似文献
3.
Two experiments were conducted to determine the effects of various NH4(+)-N/NO3(-)-N percentages on growth and mineral concentrations in potato (Solanum tuberosum L.) plants using a non-recirculating nutrient film system in a controlled environment. The first experiment included six NH4(+)-N/NO3(-)-N percentages at 0/100, 20/80, 40/60, 60/40, 80/20, and 100/0 with the same total N concentration of 4 mM. The second experiment included six NH4(+)-N/NO3(-)-N percentages at 0/100, 4/96, 8/92, 12/88, 16/84, and 20/80 again with the same total N of 4 mM. In each experiment, plants were harvested 35 days after transplanting when tubers had been initiated and started to enlarge. Dry weights of shoots, tubers, and whole plant at the harvest were increased significantly with all mixed nitrogen treatments as compared with single NH4+ or NO3- form. The enhanced growth with mixed nitrogen was greatest at 8% to 20% NH4(+)-N. Also, the concentrations and accumulation of total N in the shoots and roots were greater with mixed nitrogen than with separate NH4+ or NO3- nutrition. With NH4+ present in the solutions, the concentrations of P and Cl in the shoots were increased compared to NO3- alone, whereas the tissue concentrations of Ca and Mg were decreased. It was concluded that nitrogen fertilization provided with combined NH4+ and NO3- forms, even at small proportions of NH4+, can enhance nitrogen uptake and productivity in potato plants. 相似文献
4.
Soybean plants (Glycine max [L.] Merr. cv Ransom) were grown for 21 days on 4 sources of N (1.0 mM NO3-, 0.67 mM NO3- plus 0.33 mM NH4+, 0.33 mM NO3- plus 0.67 mM NH4+, and 1.0 mM NH4+) in hydroponic culture with the acidity of the nutrient solution controlled at pH 6.0, 5.5, 5.0, and 4.5. Dry matter and total N accumulation of the plants was not significantly affected by N-source at any of the pH levels except for decreases in these parameters in plants supplied solely with NH4+ at pH 4.5. Shoot-to-root ratios increased in plants which had an increased proportion [correction of proporiton] of NH4(+)-N in their nutrient solutions at all levels of root-zone pH. Uptake of NO3- and NH4+ was monitored daily by ion chromatography as depletion of these ions from the replenished hydroponic solutions. At all pH levels the proportion of either ion that was absorbed increased as the ratio of that ion increased in the nutrient solution. In plants which were supplied with sources of NO3- plus NH4+, NH4+ was absorbed at a ratio of 2:1 over NO3- at pH 6.0. As the pH of the root-zone declined, however, NH4+ uptake decreased and NO3- uptake increased. Thus, the NH4+ to NO3- uptake ratio declined with decreases in root-zone pH. The data indicate a negative effect of declining root-zone pH on NH4+ uptake and supports a hypothesis that the inhibition of growth of plants dependent on NH4(+)-N at low pH is due to a decline in NH4+ uptake and a consequential limitation of growth by N stress. 相似文献
5.
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 increased NH4+ concentration. The NH4+ uptake system, which is saturated at less than 1mM NH4+, is able to regulate uptake of NH4+ at concentrations as high as 10 mM. 相似文献
6.
根系高效铵吸收系统是玉米获取氮素的重要补充机制 总被引:1,自引:0,他引:1
7.
Plants show different growth responses to N sources supplied with either NH4+ or NO3-.The uptake of different N sources also affects the rhizosphere pH and therefore the bioavailability of soil phosphorus,particularly in alkaline soils.The plant growth,P uptake,and P availability in the rhizosphere of oat (Arena nuda L.) grown in hydroponics and in soil culture were investigated under supply with sole NH4+-N,sole NO3--N,or a combination.Sole NO3-fed oat plants accumulated more biomass than sole NH4+-fed ones.The highest biomass accumulation was observed when N was supplied with both NH4+-N and NO3--N.Growth of the plant root increased with the proportion of NO3-in the cultural medium.Better root growth and higher root/shoot ratio were consistently observed in NO3--fed plants.However,root vigor was the highest when N was supplied with NO3-+NH4+.NH4+ supply reduced the rhizosphere pH but did not affect P uptake by plants grown in soils with CaHPO4 added as P source.No P deficiency was observed,and plant P concentrations were generally above 2 g kg-1.P uptake was increased when N was supplied partly or solely as NO3--N,similarly as biomass accumulation.The results suggested that oat was an NO3-prcferring plant,and NO3--N was essential for plant growth and the maintenance of root absorption capacity.N supply with NH4+-N did not improve P nutrition,which was most likely due to the absence of P deficiency. 相似文献
8.
Tobacco plants (Nicotiana tabacum L. cv NC82) were supplied with (NH4)2SO4 or NH4Cl at root-zone pH of 6.0 and 4.5 in hydroponic culture for 28 days. Dry matter accumulation, total N and C content, and leaf area and number were not affected by the NH4+ source or root-zone pH. Plants supplied with NH4Cl accumulated up to 1.2 mM Cl g DW-1, but accumulated 37% less inorganic H2PO4- and 47% less SO4(2-) than plants supplied with (NH4)2SO4. The large Cl- accumulation resulted in NH4Cl- supplied plants having a 31% higher inorganic anion (NO3-, H2, PO4-, SO4(2-), and Cl-) charge. This higher inorganic anion charge in the NH4Cl-supplied plants was balanced by a similar increase in K+ charge. Plants supplied with NH4Cl accumulated greater concentrations of Cl- in leaves (up to 5.1% of DW) than plants supplied with (NH4)2SO4 (less than -% DW). Despite the high Cl- concentration of leaves in NH4Cl supplied plants, these plants showed no symptoms of Cl- toxicity. This demonstrates that toxicity symptoms are not due solely to an interaction between high Cl- concentration in tissue and NH4+ nutrition. The increase in root-zone acidity to pH 4.5 from 6.0 did not induce toxicity symptoms. 相似文献
9.
硝态氮和铵态氮供应比例对雷竹碳、氮、磷化学计量的影响 总被引:3,自引:1,他引:2
10.
Tomato (Lycopersicon esculentum L. Mill. 'Vendor') plants were grown for 21 days in flowing solution culture with N supplied as either 1.0 mM NO3- or 1.0 mM NH4+. 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 NO3- or NH4+ can be used efficiently by tomato. Uptake of K+ and Ca2+ were not altered by N source, but uptake of Mg2+ was reduced in NH4(+)-fed plants. This indicates that uptake of Mg2+ was regulated at least partially by ionic balance within the plant. 相似文献
11.
生境因子作用下NO_3~-/NH_4~+吸收及硝酸还原酶活性变化 总被引:1,自引:0,他引:1
土壤中的氮素因土壤类型和季节变化产生异质性。在长期的进化过程中,植物适应各自的氮营养生境,形成了对NO3-/NH4+吸收的分子机制。饱和高亲和传输系统(HATS)中,植物在不同的转录基因控制下吸收NO3-/NH4+,表现出对两种氮源的偏选性。这种偏选性主要取决于植物种的特性,但是NO3-/NH4+的吸收受光照、介质N强度、pH值、外源氨基酸和温度等生境因子的影响,同时植物的营养生境也因NO3-/NH4+的吸收被深刻改造。硝酸还原酶(NR)在氮同化过程中作用于NO3-还原阶段,其活性受各种生境因子的制约,影响植物对NO3-吸收利用。 相似文献
12.
An investigation was conducted to determine the effect of potassium (K) nutrition on alfalfa (Medicago sativa L.) growth and metabolism of root total nonstructural carbohydrates (TNC) and proteins, and to study whether nitrogen (N) fertilization overcomes N deficiency and low root protein concentrations caused by K deficiency. In Experiment 1, nodulated alfalfa plants were grown in plastic pots containing washed quartz sand and provided minus‐N Hoagland's solution containing 0, 0.6, or 6.0 mM K. Shoot and root K concentrations increased with increasing solution K. Root N concentrations were higher in plants receiving 6.0 mM K than in plants receiving 0.6 or 0 mM K, but shoot N concentrations were similar for all treatments. Plant persistence, shoots per plant, and shoot mass increased as solution K levels increased. Root starch concentration and utilization were positively associated with K nutrition. Total amylase activity was higher, but endoamylase activity was lower in roots of plants receiving 6.0 mM K compared to plants receiving 0.6 or 0 mM K. Root soluble protein concentrations were significantly higher in plants receiving 6.0 mM K than in plants receiving 0 or 0.6 mM K. In Experiment 2, plants were supplied with Hoagland's solution containing 10 mM N as ammonium (NH4 +) or nitrate (NO3) with 0,3, or 6.0 mM K. The addition of N increased root N concentrations only in plants receiving 0 mM K. Plant persistence was reduced by NH4 + application, especially in plants receiving 0 or 3 mM K. Root starch concentrations were markedly reduced in plants receiving NH4 + at all K levels. The addition of NO3 ‐ had little effect on alfalfa root carbohydrate and protein metabolism and subsequent shoot growth. Potassium deficiency reduced starch and protein concentrations in roots; factors that were associated with poor persistence and slow shoot regrowth of alfalfa. 相似文献
13.
不同氮效率水稻品种增硝营养下根系生长的响应特征 总被引:3,自引:0,他引:3
试验采用两室分根盒和溶液培养方法,研究了在增硝营养下不同氮效率水稻品种根系生长的响应特征。结果表明,在本试验条件下,与全铵培养下的根系相比,氮高效水稻品种南光在铵硝混合培养下的根系干重和氮积累量显著增加,增幅达33%和41%;同时其根系表面积、根系体积和侧根数增幅均达到显著水平,但根系长度却无明显增加。氮低效水稻品种Elio在铵硝混合培养下的根系生长差异均不显著。这表明氮高效水稻品种南光的根系生长对增硝营养的响应度强,进而促进了根系对氮素的吸收利用。从本试验的结果可推论,水稻对增硝营养的强响应度可能是水稻氮素高效吸收利用的生理机制之一。 相似文献
14.
在氮素供应水平一致的条件下,采用基质栽培盆栽试验,设置5个NH_4~+-N比例(0、10%、20%、30%、40%),探究增铵营养对基质栽培西葫芦产量、品质与N、K素吸收的影响,为高效优质的西葫芦栽培模式提供理论依据。结果表明,在12.6 mmol/L的N素供应量下,20%增铵比例能促进西葫芦植株的生长发育,株型粗壮。10%~20%的NH_4~+-N比例能促进N素在果实部分积累,且过量的铵供应会明显抑制植株地上部对K素的吸收。同时随着NH_4~+-N比例的增加,西葫芦中NO_3~--N含量与可溶性固形物呈下降趋势,可溶性糖含量不断增加。30%NH_4~+-N比例处理下单株产量最高,相对于全硝处理增产29.6%,且N素偏生产力与收获指数水平最高。当NH_4~+-N比例30%以上时,西葫芦结瓜率低于60%,且地上部生物量呈现下降趋势。因此,30%增铵比例下西葫芦产量、品质以及水肥效率最能实现西葫芦在基质栽培中的高产优质高效。 相似文献
15.
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. 相似文献
16.
适量施氮增强盐胁迫下高羊茅生长和抗氧化能力 总被引:2,自引:0,他引:2
为土壤盐渍地区高羊茅(Festuca arundinacea)草坪的合理施肥,该研究用NaCl浓度为0,70,140mmol/L和不同NH4NO3水平(质量浓度为0.01,0.6,1.2g/L)对盆栽高羊茅植株进行交互处理,并测定处理后其生长量和抗氧化能力。结果表明,同一水平NH4NO3相比,NaCl胁迫下高羊茅鲜质量、干质量、含水率均低于无NaCl处理;而根系脱氢酶活性、硝酸还原酶(nitratereductase,NR)活性、超氧化物歧化酶(superoxidedismutase,SOD)同工酶活性NO3-含量、质膜透性和丙二醛(malonicdialdehyde,MDA)含量均强于或高于无NaCl处理;CAT(catalase,CAT)同工酶活性及蛋白表达量发生改变。同一浓度NaCl胁迫下,随NH4NO3水平增加,其鲜质量、干质量、含水率呈上升趋势;NO3-含量、质膜透性和MDA含量呈下降趋势;SOD同工酶增强;根系脱氢酶活性、NR活性、CAT同工酶活性和蛋白表达量增强幅度明显减弱。因此,与NH4NO30.01g/L相比,NH4NO30.6g/L改善了同浓度盐胁迫下高羊茅氮素营养、抗氧化能力和蛋白质表达量,增强了其耐盐性;而NH4NO31.2g/L能一定程度上改善其氮素营养,但根系主动吸收离子能力、清除H2O2能力和蛋白质表达量增强有限,引起根际环境NH4NO3积累,严重导致土壤次生盐渍化。该研究为盐渍土壤上的高羊茅草坪合理施用NH4NO3提供参考。 相似文献
17.
增硝营养对不同基因型水稻苗期硝酸还原酶活性及其表达量的影响 总被引:2,自引:0,他引:2
利用控制条件下的溶液培养方法,研究了增硝营养(NH4+∶NO3-比例为100∶0和50∶50)对两种不同的基因型水稻南光和云粳苗期生长和硝酸还原酶(NR)活性及基因表达量的影响。结果表明,不同基因型水稻在增NO3-营养下生物量、氮素含量、氮积累量的增幅南光大于云粳。NO3-的存在增强了水稻硝酸还原酶的活力和NR基因OsNia1、OsNia2的表达。不同基因在水稻幼苗中,两个品种OsNia2的相对表达量均高于OsNia1。就品种而言,无论叶片还是根系,增硝后南光OsNia2mRNA表达量都高于云粳;南光叶片OsNia1mRNA表达量也较云粳叶片高。增硝营养提高了水稻NR基因的表达,增加了NR活性,促进了水稻NO3-的同化利用,从而增加了氮素在植株地上部的积累同化。南光和云粳相比,前者对NO3-的响应更为强烈。 相似文献
18.
We measured the growth, nutrition, and N assimilation of arbuscular-mycorrhizal and non-mycorrhizal lettuce (Lactuca sativa L.) as affected by forms of N and drought. Moisture was maintained at 80% water-holding capacity, and N was applied as NO
inf3
sup-
, NH
inf4
sup+
, or NO
inf3
sup-
/NH
inf4
sup+
(3:1, 1:1, or 1:3). The growth of Glomus fasciculatum-colonized plants was comparable to that of uncolonized P-supplemented plants when N was provided as NH
inf4
sup+
or combined NO
inf3
sup-
/NH
inf4
sup+
. When N was supplied solely as NO
inf3
sup-
, G. fasciculatum-colonized plants produced a higher yield than P-fertilized plants, suggesting that the uptake and/or assimilation of NO
inf3
sup-
was particularly affected by mycorrhizal status in this water-limited situation. Nutrient availability, except Ca, was less limited for mycorrhizal plants than for P-fertilized plants. P fertilization increased the growth, glutamine synthetase activity, and protein content of lettuce to the same extent that G. fasciculatum colonization did when N was applied as NH
inf4
sup+
. With NO
inf3
sup-
-fertilization, G. fasciculatum-colonized plants showed increased growth, nitrate reductase activity, and protein content compared to P-fertilizer treatment. Plants colonized by G. mosseae showed increased photosynthetic activity and proline acumulation, and these mechanisms may be important in adaptation by the plant to drought conditions. The present results confirmed that under drought conditions, the uptake or metabolism of N forms is particularly affected in mycorrhizal fungi-colonized plants, depending on the mycorrhizal endophyte and the N source added. Thus the significance of arbuscular-mycorrhizal fungus selection for plant growth in drought conditions is a consideration for management strategy. 相似文献
19.
Tobacco (Nicotiana tabacum L., cv. 'Coker 319') plants were grown for 28 days in flowing nutrient culture containing either 1.0 mM NO3- or 1.0 mM NH4+ as the nitrogen source in a complete nutrient solution. Acidities of the solutions were controlled at pH 6.0 or 4.0 for each nitrogen source. Plants were sampled at intervals of 6 to 8 days for determination of dry matter and nitrogen accumulation. Specific rates of NO3- or NH4+ uptake (rate of uptake per unit root mass) were calculated from these data. Net photosynthetic rates per unit leaf area were measured on attached leaves by infrared gas analysis. When NO3- [correction of NO-] was the sole nitrogen source, root growth and nitrogen uptake rate were unaffected by pH of the solution, and photosynthetic activity of leaves and accumulation of dry matter and nitrogen in the whole plant were similar. When NH4+ was the nitrogen source, photosynthetic rate of leaves and accumulation of dry matter and nitrogen in the whole plant were not statistically different from NO3(-) -fed plants when acidity of the solution was controlled at pH 6.0. When acidity for NH4(+) -fed plants was increased to pH 4.0, however, specific rate of NH4+ uptake decreased by about 50% within the first 6 days of treatment. The effect of acidity on root function was associated with a decreased rate of accumulation of nitrogen in shoots that was accompanied by a rapid cessation of leaf development between days 6 and 13. The decline in leaf growth rate of NH4(+) -fed plants at pH 4.0 was followed by reductions in photosynthetic rate per unit leaf area. These responses of NH4(+) -fed plants to increased root-zone acidity are characteristic of the sequence of responses that occur during onset of nitrogen stress. 相似文献
20.