Nitrate and ammonium nutrition of plants: Effects on acid/base balance and adaptation of root cell plasmalemma H+ ATPase

The increase of rhizosphere pH in the course of nitrate nutrition results from H⁺ consumption in the external medium during uptake of NO₃^? in a H⁺ co-transport and from internal OH^? production during nitrate reduction. Synthesis of organic acids for NH₄⁺ assimilation as well as strong partial depolarization of membrane potential with NH₄⁺ uptake are the important reasons for rhizosphere acidification during ammonium nutrition. Despite differences in proton balance depending on N form, cytoplasmic pH changes are small due to physico-chemical buffering, biochemical pH regulation, H⁺ inclusion in vacuoles, and H⁺ release into the rhizosphere. Because of the large capacity for proton excretion the plasmalemma H⁺ ATPase of root cells plays an essential role during ammonium nutrition. An increase of the kinetic parameter V_max after ammonium nutrition relative to nitrate nutrition suggests that the capacity of H⁺ release may be adjusted to the particular requirements of ammonium nutrition. Moreover, H⁺ ATPase is adjusted not only quantitatively but also qualitatively. The increase of the kinetic parameter k_m as well as the capability of the plasmalemma vesicles in vitro to establish a steeper pH gradient favours the supposition that H⁺ ATPase isoforms are formed which allow H⁺ release into the rhizosphere under conditions of low pH or poor H⁺ buffering of the soil. In this respect species differences exist, e.g. between maize (efficient adaptation) and faba bean (poor adaptation).     

Nitrate and ammonium nutrition in chicory and rocket salad plants

To evaluate chicory (Cichorium intybus L.) and rocket salad [Eruca vesicaria (L.) Cav.subsp. sativa (Mill.)] capability to use ammonium‐nitrogen (NH₄‐N) even in the absence of nitrate‐nitrogen (NO₃‐N) in the nutrient solution, and the chances they offer to reduce leaf NO₃ content, cultivated rocket and two cultivars of chicory ('Frastagliata’, whose edible parts are leaves and stems, and ‘Clio’, a leaf hybrid) were hydroponically grown in a growth chamber. Three nutrient solutions with the same nitrogen (N) level (4 mM) but a different NH₄‐N:NO₃‐N (NH₄:NO₃) ratio (100:0, 50:50, and 0:100) were used. Rocket growth was inhibited by NH₄ nutrition, while it reached the highest values with the NH₄:NO₃ ratio 50:50. Water and N‐use efficiencies increased in rocket with the increase of NO₃‐N percentage in the nutrient solution. In the best conditions of N nutrition, however, rocket accumulated NO₃ in leaves in a very high concentration (about 6,300 mg kg^‐1 fresh mass). For all the morphological and yield features analyzed, chicory resulted to be quite unresponsive to N chemical forms, despite it took more NO₃‐N than NH₄‐N when N was administered in mixed form. By increasing NO₃‐N percentage in the nutrient solution, NO₃ leaf content increased (5,466 mg kg^‐1 fresh mass with the ratio NH₄:NO₃ 0:100). On average, both chicory cultivars accumulated 213 mg NO₃ kg^‐1 fresh mass with the ratio NH₄:NO₃ 100:0 and, differently from rocket, they showed that by using NH₄ produce can be obtained very low in NO₃ content.     

Influence of ammonium: Nitrate ratios on the growth and nitrogen uptake of pearl millet

Pearl millet [Pennisetum glaucum (L.) R. Br.] is a potentially high‐yielding grain crop for the Southern Coastal Plain region of the USA. Information on the growth and N nutrition of pearl millet is limited; therefore, this study was initiated with the objective of studying pearl millet growth, N content, N uptake patterns and N‐form preference. Plants were grown in solution culture using a modified Hoagland's solution. Solutions were changed weekly and transpirational losses replaced daily. The N‐form ratios were 1:0, 3:1, 1:1, 1:3 and 0:1 NH₄ ⁺ to NO₃ ^‐ Uptake was determined by difference between the initial and final solutions. Nitrate and NH₄ ⁺ uptake patterns were different from each other and were influenced by the ratio of NH₄ ⁺ to NO₃ ^‐. After the plants had been transferred to the solutions, ammonium was preferred for the first two weeks, with NO₃ ^‐ preferred thereafter. Nitrate uptake was highest during the grain filling period. Plant growth as measured by leaf, stem, root, and seed weight, plant height, average seed weight, and head length was generally reduced as NH₄ ⁺ increased. The largest reduction was observed between the 3:1 and 1:0 ratios. Ammonium nutrition had an overall negative effect on pearl millet growth. Ammonium fertilization of pearl millet under conditions that increase absorption of NH₄ ⁺ over NO₃ ^‐ may have a negative effect on pearl millet growth and development.     

Influence of phosphorus nutrition and root zone temperature on growth and mineral uptake of peach seedlings 1

Siberian C peach seedlings (Prunus persica L. Batsch) were grown for 35 days in all combinations of Long Ashton nutrient solution containing P concentrations of 0.05, 0.5, or 5.0 mM and root zone temperatures (RZT) of 8°C, 16°C, and 24°C. At harvest, a significant interaction between solution P concentration and RZT occurred for shoot and root dry weight, root length, shoot P concentration and shoot P uptake. At 8°C RZT, P concentration and uptake but not growth were increased by P. At 16°C and 24° C RZT, growth was depressed at the 5.0 mM P level with shoot P concentration and uptake lower at 24°C than 16°C. The inflow of P to the peach shoot per unit root length was increased at high P concentration and low temperatures but was lower than whole plant inflow rates for apples. The growth depression at high temperature‐high P was related to increased young leaf chlorosis, reduced shoot Fe and a possible P/Zn imbalance.     

Effect of ammonium or nitrate nutrition on photosynthesis,growth, and nitrogen assimilation in tomato plants

Nitrogen (N) is taken up by most plant species in the form of nitrate (NO ) or ammonium (NH ). Plant response to continuous NH nutrition is species‐dependent. In this study, we compare the responses of tomato (Solanum lycopersicum L. cv. Rio Grande) plants to N source (NO or NH ). To this end, early plant growth, photosynthesis, chlorophyll, carbohydrate, and N‐compound concentrations as well as the activities of main enzymes involved in N metabolism (nitrate reductase, nitrite reductase, glutamine synthetase, and glutamate dehydrogenase) were analyzed. Early plant growth was remarkably ameliorated under NH ‐ in comparison to NO ‐based nutrition. Concomitantly, photosynthetic activity, total chlorophyll, and carbohydrate concentrations were significantly increased. With increasing external NH concentration, NH accumulated mainly in roots. In addition, root protein concentration was significantly increased, reflecting high NH incorporation into organic nitrogen. Root glutamine synthetase (GS) activity was enhanced by NH for concentrations below 5 mM, whereas root glutamate dehydrogenase (GDH) activity increased in parallel to NH availability. Together with the positive effect of NH on tomato plant cv. Rio Grande growth, these results reveal that GDH could have, in addition to GS, a possible role in NH detoxification and tolerance of NH ‐based nutrition.     

根区温度对黄瓜生长和土壤养分利用的影响

采用盆栽试验,研究了不同土壤温度（对照不加温10?2℃、加温到18?2℃、加温到26?2℃）和不同盐分含量土壤（1#>2#>3#）对黄瓜干物质积累、矿质元素吸收与分配特征的影响,并对土壤性状、酶活性的影响进行了研究。结果表明：与对照不加温10℃相比,加温到18℃和26℃可以克服冬季土壤低温对黄瓜生长的限制作用,促进黄瓜苗的正常生长,为黄瓜开花结果提供保障。随着土壤温度升高,黄瓜果实干物重增加;加温到26℃与加温到18℃相比,三种盐分含量土壤1#、2#、3#黄瓜果实干物重分别增加了41.84%、15.49%、3.59%,同时反映了盐分含量高的土壤加温对提高黄瓜产量更明显。与对照不加温相比,土壤加温使黄瓜单株N、P、K的总摄取量增加,促进黄瓜根系吸收的养分向地上部转移,使土壤中速效养分（碱解氮、速效磷、速效钾）含量降低。土壤加温使土壤脲酶活性明显升高,对磷酸酶和过氧化氢酶影响不大。因此,冬季升高土壤温度可增加黄瓜产量,促进土壤养分转化,提高土壤养分利用率。     

增铵营养对生菜根系生长发育影响的研究

矿质养分中以氮素的供应对根系生长、形态、以及根系在介质中的分布影响最为明显[1-3]。增施氮肥可以提高根系的干重、根系的活力及硝酸还原酶活性[4]。在一定范围内,增加氮素供应可以促进地上部和根系的生长,但往往对地上部生长的促进作用大于根系,导致随施氮量的增加根/冠比降低。但此时根系变得纤细根表面积增加[1]。在春小麦上的试验表明[5],适量施氮(尿素600 kg/hm2)可以增加总根重和深层土壤中的根重,过量施氮(尿素1500 kg/hm2)可以增加上层土壤中的根重。但也有研究认为增加氮素供应对根系的影响可能表现为促进,也可能表现为抑制的作…     

根区限制及氮营养对杂交小麦生长的影响

To study the physiological effects of small root zone, plants of a hybrid wheat variety (Triticum aestivum L. cv. Meiyou 4) were grown in small pots (1 litre) or large pots (8 litre) with low nitrogen (50 mg kg^-1 soil) and high nitrogen (200 mg kg^-1 soil). Restricting root zone decreased dry weight of plants at the stages of stem elongation and flowering, compared to those of control plants grown in the large pots (P<0.01). Spraying of 6-benzylaminopurine (50 μmol L^-1) increased dry weight of plants and chlorophyll concentration in leaves. Restriction of root zone decreased the concentrations of total nitrogen, chlorophyll and soluble protein in the flag leaf and accelerated senescence of the leaves. Supply of high nitrogen delayed senescence of the flag leaf. The results suggested that the shortage of nutrients, especially nitrogen deficiency, was the primary reason for the decreased growth of plant in the treatment of root zone restriction.     

Influence of ammonium uptake on bean nutrition

A glasshouse experiment was carried out in order to study the effect of ammonium supply [0 and 1.5 mmol L^‐1 in the nutrient solution, whereas total nitrogen (N) concentration was 9.5 mmol L^‐1] on nutrient uptake, leaves, and xylem sap composition and growth of bean plants in sand culture. Ammonium supply caused higher nitrogen, phosphorus (P), potassium (K), and calcium (Ca) uptake. However, K, Ca, and magnesium (Mg) concentrations in the plants (in xylem sap and leaves) were lower when ammonium was supplied. Plants vegetative growth was higher with ammonium supply than without it, specially after four weeks of cultivation.     

不同镁浓度对水稻根系生长及生理特性的影响

在温室条件下, 采用溶液培养法研究了不同Mg2+ 浓度对水稻(Oryza sativa L.)根系生长及生理特性的影响。结果表明,水稻根系干重、根冠比、总根长、Mg吸收、根系活力、伤流速度、伤流液中游离氨基酸总量和Mg含量、Mg流入速率以及Mg2+ 吸收速率与Mg2+ 供应水平密切相关。在低Mg2+ 浓度(0.05 mmol/L)条件下,水稻植株叶片在缺Mg症状出现之前分配较大比例的干物质到根系,使总根长和根冠比增加, 这可能是水稻早期对低Mg胁迫的适应机制之一。适中的Mg2+ 浓度(1.0 mmol/L)有利于水稻生长发育,促进养分吸收,提高根系活力和伤流速度以及伤流液中游离氨基酸总量。低Mg2+ 和高Mg2+ 浓度(5.0 mmol/L)在一定程度上抑制根系活力和氨基酸合成能力。植物Mg的吸收、伤流液Mg2+ 浓度、根系平均Mg流入速率和Mg2+ 吸收速率随营养液Mg2+ 浓度的增加而相应增加。     

根区饲养蚯蚓对椪柑树体营养和根系生长的影响

以4年生桠柑为试验材料,研究根区饲养蚯蚓对椪柑树体营养和根系生长的影响。试验设4个处理,分别是穴施牛粪、穴施牛粪并接种蚯蚓、根系输液和对照。研究结果表明：穴施牛粪并接种蚯蚓很好地诱导了椪柑根系的生长,其诱导的根量比穴施牛粪和对照的分别高出100．62％和126．27％;穴施牛粪并接种蚯蚓处理的椪柑根系吸收和累积的氮、磷、钾元素分别比对照的高出21．13％、35．44％和76．31％;穴施牛粪并接种蚯蚓明显提高植株叶片的氮、磷、钾营养水平和叶绿素含量,在改善植株矿质营养状况方面优于穴施牛粪处理和根系输液处理。根系输液处理能在短时间内明显增加植株叶片营养含量。     

Effect of conservation tillage systems on corn root growth

The effects of conservation tillage on crop production have been widely investigated, but less information is available on root growth with different tillage systems over a range of soils. In this study, we compared corn (Zea mays L.) root length density and distribution with conventional moldboard plowing (MP) and 3 conservation-tillage treatments: chisel plowing (CH); ridge-tillage (RT); no-tillage (NT); for Griswold and Kewaunee silt loam and Plainfield loamy-sand soils. Root length densities were determined for the row (R), non-wheel track (NWT) and wheel track (WT) positions for two growing seasons (1982 and 1983). Conservation-tillage systems had equal or higher root densities than MP for all positions and depths at all 3 sites. Maximum root densities occurred between 10 and 40 cm for all tillage systems at all locations. In most cases, reduced root growth was associated with wheel traffic positions. Wheel traffic reduced root densities in the surface 10 cm by as much as 52% in MP at the Plainfield site.     

不同钾水平下外源铵对烟草幼苗根系生长及钾吸收的影响

为探明铵参与低钾胁迫下烟株根系的生长及吸钾机制,采用室内水培法,以“豫烟6 号”为试验材料,研究了不同供钾水平下外源NH4+ 对烟株根系的生长生理和钾吸收速率的影响。结果表明,未添加外源NH4+ 时,低钾胁迫下烟株根系可溶性蛋白、根系活力、烟株各部位干重和钾含量均显著低于常钾水平。两种供钾水平下,随着外源NH4+ 浓度增加,烟株根系干重、根系扫描参数、钾积累量和钾最大吸收速率均呈下降趋势,但根系可溶性蛋白含量和根系活力则先上升后下降并在外源NH4+ 浓度为1 mmol/L 时最大。外源NH4+ 可抑制植物根系高亲和及低亲和K+ 吸收系统,且NH4+浓度越大,钾吸收速率越低,其中溶液K+ 浓度为0.2 和10 mmol/L 时,N5.00 较N0处理分别显著降低55.78% 和37.68%。可见,低钾胁迫显著抑制烟株根系生长和钾吸收,而外源NH4+ 可抑制高亲和或低亲和的K+ 吸收系统,从而影响烟株的钾吸收速率和吸收量。     

Effect of calcium/potassium ratio ammonium supply on nutrition and yields of cucumber plants

A greenhouse experiment was conducted in order to study the influence of two calcium/potassium (Ca/K) ratios (0.75 and 0.33) and ammonium supply (0 and 1 mmol/L) in the nutrient solution on nutrient uptake, mineral composition, and productivity of cucumber plants grown in sand culture. There were not significant differences in nitrate consumption between the four treatments. Calcium and potassium consumptions were directly related with the Ca/K ratio in the nutrient solution. The treatment with Ca/K = 0.75 and ammonium supply, that showed the lowest potassium and nitrogen plant levels and the highest calcium uptake and concentration in plant, offered the highest yields.     

种间相互作用对作物生长及养分吸收的影响

田间试验采用裂区设计,研究了蚕豆、大豆和小麦在两个施氮水平下与玉米间作对作物生长和养分吸收的影响。结果表明,与单作相比,间作对蚕豆生长和养分吸收无明显影响;间作促进大豆前期生长,但在玉米旺盛生长期其生长和养分吸收受到抑制;间作对小麦生长和养分吸收有明显的促进作用。与蚕豆间作,玉米能够获得更高的产量和养分吸收量;与大豆间作,对玉米前期生长有抑制作用,但玉米旺盛生长后其生长和养分吸收有明显增加;与小麦间作,在共处期玉米生长受到强烈抑制,小麦收获后玉米生长开始逐渐恢复。蚕豆/玉米间作具有产量优势,大豆/玉米间作为产量劣势;小麦/玉米间作在低氮条件下为产量劣势,提高氮肥用量会恢复以至达到单作水平。分析认为,蚕豆和大豆生物固氮和根系分泌物活化土壤磷的特点促进了玉米的生长,小麦强的根系竞争能力抑制了玉米生长;在共处期玉米的遮荫作用会抑制大豆的生长,而小麦收获后受抑制的玉米产量有向单作水平恢复的能力。表明选择合理的作物配置能够充分利用各种资源,促进种间有益作用,提高作物产量。     

Effect of root residues on the growth of upland rice

The effect of root residues of upland rice, which had been left in a field for ca. 7 months from autumn to the next spring, on the growth of succeeding upland rice was examined. The root residues incorporated into field soil inhibited the upland rice growth. This effect was considered to be caused not by toxic substances accumulating in root residues, but by aerobic detrimental organisms inhabiting root residues.     

施肥对切花玫瑰生长及养分吸收特性的影响

为了给切花玫瑰栽培提供科学的施肥依据,采用田间试验研究了云南玫瑰主要种植及热销品种"黑魔术"在营养生长期和切花期对营养元素N、P、K的养分吸收特点。研究结果表明,切花玫瑰株高的影响因子的主次顺序为钾>钙>磷>氮,施肥以N1P2K2Ca2时收率最大;切花玫瑰冠宽的影响因子的主次顺序为钙>钾>磷>氮,施肥以N2P3K2Ca3时收率最大;在苗期玫瑰施肥的最佳配比为N2P1K2Ca2[氮肥(尿素)450 kg/hm2,磷肥(普钙)131.4 kg/hm2,钾肥(硫酸钾)400.05 kg/hm2,钙肥(石灰粉)1 300.5 kg/hm2],在之后的整个切花延续期以N2P1K3Ca2(氮肥450 kg/hm2,磷肥131.4 kg/hm2,钾肥600 kg/hm2,钙肥1 300.5 kg/hm2)为最佳施肥配比。     

局部水分胁迫对玉米根系生长的影响

采用分根法进行玉米水培试验, 研究局部水分胁迫对玉米根系生长的影响。设4个水分胁迫水平: CK, 0.2 MPa, 0.4 MPa, 0.6 MPa, 在整个根系经受一定的水分胁迫之后对部分根系复水处理, 测定局部供应后 0 h、6 h、12 h、1 d、3 d、5 d、7 d、9 d等不同时期各部分根系的面积、长度及干重。结果表明, 各胁迫程度均表现为, 与对照相比, 复水侧根区的根系面积、根长与根干重出现了明显增长, 且始终显著大于持续胁迫侧根区, 且随处理时间延长更加明显。不同胁迫程度下复水侧玉米根系的增长幅度不同。水分胁迫预处理后, 0.2 MPa水平下, 复水侧根区根系的面积、长度与干重以及整个根区总根长、总面积均可以达到甚至高于对照水平, 其他处理均显著低于对照。轻度胁迫后复水的根区根系产生明显的补偿效应。适度胁迫后复水有利于作物根系总面积增长, 但对总根长、根干重无显著影响。根系补偿效应与胁迫强度及复水的时间有关。     

Effect of planting date and tillage system on soybean root growth

Soil erosion and moisture retention are major concerns of soybean growers. Conservation tillage provides residue cover to reduce soil loss and water evaporation. This study was conducted on a Tiptonville silt loam near Portageville, MO, USA. to determine the effect of tillage system and planting date on soybean [Glycine max (L.) Merrill] root growth and distribution. Tillage systems were conventional (clean) tillage, ridge tillage, and no‐tillage. ‘Essex’ soybean was planted on 14 May, 15 June, and 7 July in 1992 and 12 May, 2 June, and 21 June in 1993. Roots were observed 30 and 60 days after emergence (DAE) using a minirhizotron system. Stand density was not affected by tillage in either year or by planting date in 1992. Tillage did not effect rooting depth in either year. In 1992, rooting depth 30 DAE was greater for the 14 May planting date than for either of the other two planting dates. No other planting date effects on rooting depth were found. Among soil depths, root length density (RLD) was greatest for the 14 to 26 cm depth in 1992 and for the 0 to 13 cm depth in 1993. Neither tillage system nor planting date affected RLD in either year and there was no interaction between these main effects and soil depths. The largest changes in RLD (CRLD) were observed in the 14 to 26 cm and 27 to 39 cm depths in 1992 and the 0 to 13 cm depth in 1993. Tillage did not planting date in 1992 and the 12 May and 2 June planting dates in 1993 produced the highest yields. Tillage did not affect yield and there was no interaction between tillage and planting date.     

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

Abstract

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

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