Relationship between Soil Nitrate Content and Activities of NADH: and NAD(P)H:Nitrate Reductases in Indian Mustard

The pattern of NADH- and NAD(P)H-specific nitrate reductase (NRs) activities in Indian mustard (Brassica juncea L. Czern. and Coss.) was monitored throughout growth stages. NAD(P)H:NR (EC 1.6.6.2) activity was maximum at early stages of growth (30 days after sowing, DAS), then declined gradually reaching to almost zero at 90 DAS. Contrary to this, NADH:NR (EC 1.6.6.1) activity was low at 30 DAS, then gradually increased till 90 DAS and thereafter, it became constant. The decrease in NAD(P)H:NR activity and increase in the NADH:NR activity were associated with the seasonal decrease in nitrate content in the soil. This revised version was published online in July 2006 with corrections to the Cover Date.     

Growth and Protein Pattern in Cowpea Seedlings Subjected to Salinity

Cowpea (Vigna unguiculata) seeds were put to germinate on filter paper under control (distilled water) and salt stress (100 mM MaCl) conditions. Seeds and seedlings were classified in eight developmental stages (DS), according to their morphological traits. Under control conditions, 7 d after planting, 100 % of the seedlings reached DS VIII (seedlings with radicles measuring more than 5 cm, cotyledons leaving the filter paper, hypocotyls straight and cotyledonary leaves fully open) and under NaCl stress conditions, 11 d after planting only 68 % of the seedlings were at DS VIII. The length of the main root and of shoot has decreased 23 and 44 %, respectively. The two-dimensional electrophoretic patterns of the albumins isolated from stems and leaves were determined in seedlings at DS VIII. In stems 19 proteins (14.6 to 76.3 kDa) had their relative concentration increased by salinity, 8 (31.2 to 65.0 kDa) had their relative concentration decreased by salinity and 9 (16.3 to 39.8 kDa) were apparently synthesised de novo. In leaves, under salt conditions 9 proteins (18.2 to 33.2 kDa) increased in concentration, one (17.1 kDa) decreased in concentration and one (21.2 kDa) was apparently synthesised de novo. This revised version was published online in July 2006 with corrections to the Cover Date.     

Iron Mediated Nitrate Reductase Activity in Different Parts of Young Maize Seedlings

Incubation of 5-d-old maize seedlings in the half-strength Hoagland's nutrient solution containing 10 mM KNO₃ with FeCl₃ or FeSO₄ (0.5 or 2.0 mM) caused a significant increase in nitrate reductase (NR) activity and slightly increased total protein content in root, shoot and scutellum. In case of root, NADPH:NR activity was inhibited contrary to the NADH:NR activity. In spite of NR activity, nitrate uptake was inhibited from 13 to 37 % by the iron. The results presented demonstrate an isoform specific, organ specific, and to some extent salt specific responses of NR to iron.     

NaCl-Induced Changes in Putrescine Content and Diamine Oxidase Activity in Roots of Rice Seedlings

The effects of NaCl on putrescine (Put) content and diamine oxidase (DAO) activity in roots of rice seedlings were examined. NaCl treatment lowered the content of Put and increased the activity of DAO in roots. Our current results indicate that Cl^– is not required for NaCl-induced decline in Put content and increase in DAO activity in roots. Put content in roots of rice seedlings exposed to NaCl is possibly regulated by DAO activity.     

Effects of Energy Substrates on Nitrate Reduction and Nitrate Reductase Activity in a Ruminal Bacterium, Selenomonas ruminantium

The factors affecting the rate of nitrate reduction and the nitrate reductase content in Selenomonas ruminantium were examined. The rate of nitrate reduction per cell mass was higher when S. ruminantium was grown on lactate than when grown on glucose, and the rate was further enhanced when grown on succinate. The nitrate reduction rate was parallel to the nitrate reductase content in cells, suggesting that the amount of nitrate reductase limits the rate of nitrate reduction. The amount of nitrate reductase was inversely related to growth rate. The growth rate was related to the level of intracellular ATP, which was inversely related to the levels of ADP and AMP. The ratio of NADH to NAD⁺was related to the rate of nitrate reduction and to the amount of nitrate reductase. From these results, it is conceivable that the synthesis of nitrate reductase is regulated in response to the sufficiency of energy and electron supply. Intracellular concentrations of adenine nucleotides and pyridine nucleotides may be the regulating factors. The amount of nitrate reductase was increased by the presence of nitrate, suggesting that the synthesis of nitrate reductase is enhanced by nitrate. In addition, nitrate reduction altered the fermentation pattern as a result of electron consumption.     

氮素营养对苗期菘蓝叶中硝酸还原酶活性与矿质元素吸收的影响

采用正交试验设计,研究铵态氮、硝态氮和酰胺态氮3种氮素形态及其不同浓度配比对苗期菘蓝的单株干重、叶内的硝酸还原酶活性及矿质元素吸收的影响。结果显示:(1)影响苗期菘蓝单株干重的氮素形态依次为酰胺态氮>铵态氮>硝态氮。(2)不同氮素形态对叶片硝酸还原酶活性影响有差异,铵态氮影响最大,其次是硝态氮和酰胺态氮。(3)不同形态氮素配合施用后均能促进P、K、Ca、Mg、Cd、Mn、Cr、Sr 8种元素的吸收,但不利于Ni和Fe的吸收;元素吸收受铵态氮影响最大的矿质元素有K、Ba、Se、Ni、B、Si、Fe 7种元素,受硝态氮影响最大的元素有P、Cd、Ti、Al、Cu 5种元素,受酰胺态氮影响最大的元素有Na、Ca、Mg、Zn、Mo、Mn、Cr、Sr 8种元素。研究表明,不同形态氮素对苗期菘蓝吸收矿质元素的影响存在很大的差异,应注重酰胺态氮与无机的铵态氮、硝态氮的配合施用;适宜氮素形态及其配比能提高叶中硝酸还原酶的活性并促进矿质元素的吸收,从而有效地促进菘蓝的生长。     

Effect of Increasing Concentrations of Heavy Metals on the Growth of Barley and Wheat Seedlings

The tolerance to increasing doses of lead and cadmium salts on the growth and survival of barley (Hordeum vulgare L.) and wheat (Triticum aestivum L.) seedlings were studied. Seedlings grown under controlled conditions were treated with dilute (0.001–0.005 mM) solutions of either lead nitrate or cadmium bromide for 1, 4, or 7 days. Subsequently, they were incubated for 7 days in solutions of the same compounds, but at sublethal or lethal concentrations (0.05–10 mM). Plant pretreatment with low concentrations of heavy metals induced an increase in their tolerance to the metals, because pretreated plants could tolerate heavy metals at high concentrations. It is concluded that plant tolerance to increasing concentrations of heavy metals is related to the activation of protective and adaptive processes in their tissues.     

铯对印度芥菜幼苗生长的影响及其亚细胞分布和化学形态

以印度芥菜为材料,用含铯(Cs+)[8.24(CK),25,50,100,200mg·L~(-1)]的Hoagland营养液培养印度芥菜种子和幼苗,采用IMAGE-J软件测定根、茎长度,通过差速离心法、化学试剂提取法分别提取幼苗根、茎、叶各亚细胞组分及不同化学形态的Cs+,并用火焰原子分光光度计测定Cs+含量,分析Cs+对幼苗生长的影响及其亚细胞分布和化学形态,进而探讨Cs+对植物的伤害机理。结果显示:(1)Cs+对印度芥菜幼苗生长具有明显的抑制作用,根、茎的EC50(相对抑制率达到50%的Cs+浓度)分别为112.09和118.42mg·L~(-1);(2)各器官中Cs+的积累量总体表现为叶根茎;Cs+在印度芥菜中的亚细胞分布呈现为可溶性组分细胞壁组分细胞器组分,三者所占比例分别为52.86%~79.19%、20.81%~45.05%和1.43%~9.00%;(3)Cs+在印度芥菜各器官中主要以无机盐和水溶态赋存,两种形态根、茎、叶占比分别达到88.02%~92.20%、97.33%~100%和95.06%~100%。研究表明:印度芥菜积累过量的Cs+可抑制其根、茎生长,导致叶片枯萎,主要是因为Cs+在印度芥菜体内大部分以无机盐态和水溶态形式存在,使Cs+在植物体内具有较强迁移能力和毒理生物有效性,更易分布到重金属的毒性敏感区(如细胞器),导致细胞器受到功能性损伤,从而使植物表现出明显中毒症状。     

Photosynthetic Rate, Growth, and Yield of Mustard Plants Sprayed with 28-Homobrassinolide

Thirty-day-old plants of mustard (Brassica juncea L.) were sprayed with 10⁻¹⁰, 10⁻⁸, or 10⁻⁶ M aqueous solution of 28-homobrassinolide (HBR). The HBR-treated plants were healthier than those treated with water and yielded more. Maximum increase over control was found in 60-d-old, 10⁻⁸ M-HBR-treated plants in fresh and dry mass per plant, carbonic anhydrase (CA, E.C. 4.2.1.1) activity, and net photosynthetic rate (P _N), at harvest in number of pods per plant and seed yield per plant (the respective values were 25, 30, 34, 69, 24, and 29 %). A further increase in the concentration of HBR (10⁻⁶ M) did not make any additional impact on the growth and yield. Increased CA activity and P _N were correlated with growth and seed yield. This revised version was published online in August 2006 with corrections to the Cover Date.     

温度对旋链角毛藻(Chaetoceros curvisetus)和米氏凯伦藻(Karenia mikimotoi)生长及硝酸还原酶活力的影响

选用东海常见的两种赤潮肇事藻种:旋链角毛藻和米氏凯伦藻,采用一次性培养实验,研究了不同温度对两种赤潮藻生长及硝酸还原酶活力(NRA)的影响.研究结果表明,在10℃~30℃条件下旋链角毛藻均能正常生长,且生长曲线均符合S-logistic2种群增长模型;而米氏凯伦藻在10℃和30℃条件下不能正常生长,在其他温度条件下生长情况与旋链角毛藻相似.温度适宜时,两种藻的硝酸还原酶活力最大值(NRAmax)、最大生长速率(μmax)和终止生物量(Bf)随温度的变化趋势基本一致,说明温度的高低可通过影响细胞硝酸还原酶活力大小间接影响藻类的生长.旋链角毛藻单位体积的NRAmax和最大生长速率均大于米氏凯伦藻,说明旋链角毛藻能够更好地吸收利用硝酸盐.     

NaCl处理对西伯利亚白刺幼苗生长及离子平衡的影响

以1年生西伯利亚白刺水培幼苗为材料,研究了不同浓度NaCl(0、200、400mmol·L~(-1))处理对幼苗生长及不同器官(根、茎、叶)中Na~+、K~+、Ca~(2+)、Mg~(2+)的吸收、运输与分配的影响,探讨西伯利亚白刺的盐适应机制。结果表明:(1)200mmol·L~(-1) NaCl处理促进了西伯利亚白刺幼苗的生长及叶片肉质化程度,400mmol·L-1 NaCl处理显著抑制其生长。(2)随着NaCl处理浓度的升高,西伯利亚白刺幼苗根、茎、叶中Na~+含量显著增加,且叶中Na~+含量显著高于茎和根中;根系中K~+含量显著增加;根、茎、叶中Ca~(2+)、Mg~(2+)含量在200mmol·L~(-1) NaCl处理下保持平稳或上升,而在400mmol·L-1 NaCl处理下显著下降。(3)各器官中K~+/Na~+、Ca~(2+)/Na~+和Mg~(2+)/Na~+比值总体随NaCl处理浓度的升高呈下降趋势,且根部离子比值始终高于叶片和茎。(4)随着NaCl处理浓度的升高,西伯利亚白刺幼苗根-茎SK,Na显著下降,而根-茎SCa,Na、SMg,Na及茎-叶SK,Na、SCa,Na、SMg,Na逐渐提高。研究发现,西伯利亚白刺的盐适应机制主要是通过植株的补偿生长效应及叶片对Na~+的聚积作用实现的,同时也与根系对K~+的扣留及茎叶对K~+、Ca~(2+)、Mg~(2+)选择性运输能力增强有关。     

Relationships between Nitrate Reductase Activity, Plant Weight and Nitrogen Content in Seedlings of Triticum, Aegilops and Triticale

Seedlings of 12 genotypes were grown in pots and watered withnutrient solutions providing 0, 1, 6 and 20 mg equivalents ofnitrate per I. Increasing the external nitrate supply broughtabout increases in plant weight, nitrate, reduced nitrogen concentrationsand in vivo nitrate reductase activity. When given solutioncontaining 6 mg equivalents of nitrate per litre, the plantscontained approximately 0.1 per cent nitrate, a concentrationsimilarto that found in field-grown plantsat thesamestage of growth.At the 6 mg equivalent level nitrate supply, nitrate reductaseactivity was strongly positively correlated with the concentrationsof nitrate and reduced nitrogen and negatively correlated withplant weight. Similar, though weaker, correlations were foundat the lower and higher levels of nitrate supply. The two Triticalegenotypes however, had higher than average plant weights andnitrate reductase activities, while plants of the two Aegilopsspecies weighed much less, especially at the higher levels ofnitrate supply, than the average of all 12 genotypes and generallyhad correspondingly greater nitrate and reduced nitrogen concentrationsand nitrate reductase activities. For individual genotypes,plant weight at a given level of nitrate supply was stronglycorrelated with weight at all other levels. In a second experiment seedlings of 150 genotypes were grownin compost watered with 10 mM Ca(NO₃)₂ Nitrate and reduced nitrogenconcentrations were negatively correlated with plant weightbut there was no significant correlation between nitrate reductaseactivityand either plant weight, nitrate or reduced nitrogen concentration. The results are taken to indicate that genetic factors, otherthan those determining the supply of reduced nitrogen, werelimiting growth and that as a consequence small plants accumulatednitrate and reduced nitrogen compounds in greater concentrationsthan large ones. The greater nitrate concentrations in smallplants may have induced the increased nitrate reductase activityfound in these, as compared with larger plants. Because plantweight varied more than did reduced nitrogen concentration,variation in reduced nitrogen per plant was more highly correlatedwith plant weight than with per cent reduced nitrogen.     

Effect of Kinetin on Starch and Sucrose Metabolising Enzymes in Salt Stressed Chickpea Seedlings

Higher amylase activity in cotyledons of kinetin treated salt stressed (75 mM NaCl) chickpea (Cicer arietinum L. cv. PBG-1) seedlings, as compared to salt stressed seedlings was observed during a growth period of 7 d. The activities of acid and alkaline invertases were maximum in shoots and minimum in cotyledons under all conditions. The reduced shoot invertase activities under salt stress were enhanced by kinetin with a simultaneous increase in reducing sugar content. Kinetin increased the activities of sucrose synthase (SS) and sucrose phosphate synthase (SPS) in both the cotyledons and shoots of stressed seedlings. Kinetin appears to increase the turnover of sucrose in the shoots of stressed seedlings.     

硝酸盐水平对芹菜幼苗生理及生长特性的影响

以西芹‘文图拉’幼苗为试材,通过水培方式研究了不同浓度NO3-(0、1、5、10、15、50、100、150mmol·L-1)对芹菜植株生物量、养分含量、叶绿素、丙二醛(MDA)及两种渗透调节剂含量的影响。结果显示:(1)随着NO3-浓度的增加(1～50mmol·L-1),芹菜株高、生物产量、根冠比以及叶面积显著增加,植株对N、P、K养分的吸收和叶绿素明显提高,同时植株的MDA含量上升,POD和CAT的活性增强,可溶性糖和可溶性蛋白含量显著增加。(2)当NO3-浓度等于或大于100mmol·L-1时,芹菜的生物产量和叶绿素含量下降,植株对K、P养分的吸收降低,膜脂过氧化物MDA、可溶性糖和可溶性蛋白含量及SOD活性达到最高峰值,POD和CAT活性有所下降。研究表明,NO3-浓度为15mmol·L-1时最有利于芹菜植株的生长;NO3-浓度为100mmol·L-1时对植株生长产生了硝酸盐胁迫,导致膜脂过氧化伤害,但芹菜植株能通过调节抗氧化物酶活性及渗透调节剂的合成代谢抵御环境胁迫,从而表现出一定的硝酸盐耐受性。     

Effect of Growth Regulators on Photosynthesis, Transpiration and Related Parameters in Water Stressed Cotton

Gas exchange in Gossypium hirsutum L. cv. H-777 as affected by water deficit and growth regulators (IAA, GA₃, BAP, ABA, ethrel) was examined. Sixty days after sowing, growth regulators in concentration 50 µM were applied as foliar spray and irrigation was withheld to get desired (moderate and severe) water deficit. All the parameters were measured on the third leaf from the top between 10:00 and 11:00. Net photosynthetic rate (P_N), transpiration rate (E), stomatal conductance (g_s), carboxylation efficiency (CE), and water potential (_w) decreased significantly with the increasing water stress, however, water use efficiency (WUE) was unaffected. Foliar spray with IAA, GA₃ and BAP partially counteracted the effect of water deficit on the above parameters except _w, which became more negative. ABA and up to some extent ethrel increased WUE and maintained higher _w, however, caused further decrease in P_N, E, and g_s.     

NaCl胁迫对圆柏幼苗生长和离子吸收及分配的影响

以当年生圆柏幼苗为实验材料,采用温室调控盆栽土培法研究了不同浓度NaCl(0、100、200、300mmol·L-1)胁迫21d对其生长情况及不同器官(根、茎、叶)中K~+、Na~+、Ca~(2+)和Mg~(2+)的吸收和分配的影响,以探讨圆柏幼苗对盐环境的生长适应性及耐盐机制。结果表明:(1)随着NaCl胁迫浓度的增加,圆柏幼苗生长,包括株高、地径、相对生长量以及生物量的积累均呈下降趋势,而其根冠比却增加。(2)在各浓度NaCl胁迫处理下,圆柏幼苗根、茎、叶中Na~+含量较对照均显著增加,而且叶中Na~+含量显著高于茎和根,叶中Na~+含量是根中的5倍。(3)随着NaCl胁迫浓度的升高,圆柏幼苗各器官中K~+、Ca~(2+)和Mg~(2+)含量以及K~+/Na~+、Ca~(2+)/Na~+及Mg~(2+)/Na~+比值均呈下降趋势。(4)在NaCl胁迫条件下,圆柏幼苗根系离子吸收选择性系数SK,Na、SCa,Na、SMg,Na显著提高,茎、叶离子转运选择性系数SCa,Na、SMg,Na则逐渐降低,叶中离子转运选择性系数SK,Na则随着NaCl胁迫浓度的升高显著降低,大量Na~+进入地上部,减缓了盐胁迫对根系的伤害。研究认为,圆柏幼苗的盐适应机制主要是通过根系的补偿生长效应及茎、叶对Na~+的聚积作用来实现的,同时也与根对K~+、Ca~(2+)、Mg~(2+)的选择性运输能力增强和茎、叶稳定的K~+、Ca~(2+)、Mg~(2+)的选择性运输能力有关。     

硝酸盐对球形棕囊藻生长和硝酸还原酶活性的影响

以我国南海海域分离的赤潮原因种——球形棕囊藻(Phaeocystis globosa)为材料, 研究了不同硝酸盐浓度下藻细胞生长及硝酸还原酶活性的变化。当培养基中不含硝酸盐时, 藻细胞内硝酸还原酶的活性保持在非常低的水平, 藻细胞的生长受到限制, 不能形成正常的生长曲线: 当培养基中硝酸盐浓度为3.62 mmol.L-1时, 藻细胞的硝酸还原酶活性和比生长速率达到最大。在含有硝酸盐的培养基中, 接种培养后第9天藻细胞硝酸还原酶活性达到最大值, 并且在4种不同硝酸盐浓度下, 藻细胞硝酸还原酶活性的差异性达到极显著水平(P<0.01)。在接种培养第16天藻细胞密度达到最大值, 并且4种不同硝酸盐浓度培养的藻细胞密度之间的差异性也达到极显著水平(P<0.01)。实验结果表明, 在培养基中添加不同浓度的硝酸盐, 对球形棕囊藻细胞硝酸还原酶的活性和藻细胞的生长有极显著的影响, 含有较高硝酸盐的富营养化海域有利于球形棕囊藻细胞的持续生长。     

硝酸盐对球形棕囊藻生长和硝酸还原酶活性的影响

以我国南海海域分离的赤潮原因种——球形棕囊藻(Phaeocystisglobosa)为材料,研究了不同硝酸盐浓度下藻细胞生长及硝酸还原酶活性的变化。当培养基中不含硝酸盐时,藻细胞内硝酸还原酶的活性保持在非常低的水平,藻细胞的生长受到限制,不能形成正常的生长曲线:当培养基中硝酸盐浓度为3.62μmol.L-1时,藻细胞的硝酸还原酶活性和比生长速率达到最大。在含有硝酸盐的培养基中,接种培养后第9天藻细胞硝酸还原酶活性达到最大值,并且在4种不同硝酸盐浓度下,藻细胞硝酸还原酶活性的差异性达到极显著水平(P<0.01)。在接种培养第16天藻细胞密度达到最大值,并且4种不同硝酸盐浓度培养的藻细胞密度之间的差异性也达到极显著水平(P<0.01)。实验结果表明,在培养基中添加不同浓度的硝酸盐,对球形棕囊藻细胞硝酸还原酶的活性和藻细胞的生长有极显著的影响,含有较高硝酸盐的富营养化海域有利于球形棕囊藻细胞的持续生长。     

Separation and Determination of Heavy Metals Associated with Low Molecular Weight Chelators in Xylem Saps of Indian Mustard (<Emphasis Type="Italic">Brassica juncea</Emphasis>) by Size Exclusion Chromatography and Atomic Absorption Spectrometry

To elucidate the role of low molecular weight chelators in long-distance root-to-shoot transport of heavy metals in Indian mustard, an “off-line” size exclusion high-performance liquid chromatography–graphite furnace atomic absorption spectrometry was developed to investigate heavy metals associated with low molecular weight chelators in xylem saps of Indian mustard (Brassica juncea). The size exclusion chromatogram presented only the peaks with molecular weight for all xylem saps and directly indicated the long-distance transport of phytochelatins (PCs) of Indian mustard under Cd stress. In the absence of Cd stress, only organic acids and inorganic anions participated in the long-distance transport of Cd, but organic acids, inorganic anions, glutathione (GSH), and cysteine might relate to the long-distance transport of Cu or Zn. In the presence of Cd stress, PCs were induced, and Cd ions in xylem saps were associated with the induced PCs. As the Cd levels in nutrient solution increased, more Cd in xylem saps adopted the form of PC–Cd. Although PCs might participate in the long-distance transport of Cd under Cd stress, the majority of Cd was still transported by organic acids and inorganic anions in xylem vessels. Moreover, results indicated the existence of complexation competition for GSH and cysteine between Cd and Cu (or Zn) and complexation competition for Cd between PCs and GSH (or cysteine) in xylem vessels. Our work might be very useful for understanding the mechanism of long-distance transport of heavy metals in hyperaccumulator.     

外源CaCl2对NaCl胁迫下酸枣幼苗氮代谢的影响

为了研究CaCl₂对NaCl胁迫下酸枣幼苗根、茎、叶的氮代谢影响,探索钙缓解幼苗NaCl胁迫的作用途径。该研究以酸枣幼苗为试验材料,检测不同浓度CaCl₂(0、5、10、20 mmol/L)对NaCl(150 mmol/L)胁迫下幼苗叶片H₂O₂、O^-·₂含量,根、茎、叶中硝酸还原酶(NR)、谷氨酰胺合成酶(GS)、谷氨酸合酶(GOGAT)活性及游离氨基酸、可溶性蛋白、硝态氮含量的影响,并采用主成分分析法筛选出评价CaCl₂缓解NaCl胁迫效应的生理指标。结果表明：与NaCl胁迫相比,盐胁迫幼苗叶片的H2O₂、O^-·₂积累量在5、10 mmol/L CaCl₂处理下显著减少;GOGAT活性在5、10 mmol/L CaCl₂处理下的植株根和茎内以及各浓度 CaCl₂处理的叶内均显著升高, GS、NR活性在10、20 mmol/L CaCl₂处理的根内和10 mmol/L CaCl₂处理的茎内以及5、10、20 mmol/L CaCl₂处理的叶内均显著升高;可溶性蛋白含量在5、10、20 mmol/L CaCl₂处理的根、茎、叶内均显著升高,游离氨基酸含量在10、20 mmol/L CaCl₂处理的根和茎内以及10 mmol/L CaCl₂处理的叶内均显著升高,硝态氮含量在10 mmol/L CaCl₂处理的根和茎内以及5、10、20 mmol/L CaCl₂处理的叶内均显著升高。研究发现,150 mmol/L NaCl胁迫对酸枣幼苗造成明显过氧化伤害,抑制了体内氮代谢;外源CaCl₂可通过促进幼苗根和茎内GS/GOGAT循环对NH₄⁺的同化作用,提高叶片NR活性,加快硝态氮的转化速率,从而增强幼苗对NaCl胁迫的适应性,并以10 mmol/L CaCl₂处理缓解效果最佳;游离氨基酸、GOGAT、NR可以作为CaCl₂缓解幼苗NaCl胁迫伤害的评价指标。