丛枝菌根真菌(AMF)对盐胁迫下芦笋幼苗生长及体内Na~+、K~+、Ca~(2+)、Mg~(2+)含量和分布的影响

以芦笋盐敏感品种‘NJ978’为材料,采用盆栽试验,研究了接种丛枝菌根真菌(AMF)对Na Cl胁迫下芦笋幼苗生长及体内Na+、K+、Ca2+、Mg2+吸收和分布的影响。结果表明:在Na Cl胁迫下,幼苗株高、鲜重、干重均显著降低,接种AMF可以有效缓解盐胁迫对芦笋幼苗生长的抑制;Na Cl处理的芦笋幼苗根系和地上部Na+含量显著高于对照,K+、Ca2+、Mg2+的含量则显著减少;AMF+Na Cl处理的芦笋幼苗根系K+、Ca2+、Mg2+含量与Na Cl处理相比,分别增加了76.9%、23.1%和22.5%,而Na+含量则减少了27.4%;AMF+Na Cl处理的芦笋幼苗地上部K+、Ca2+、Mg2+含量与Na Cl处理相比,分别增加了58.4%、50.4%和76.0%,而Na+含量则减少了42.3%。与Na Cl处理相比,接种AMF可以降低盐胁迫下芦笋幼苗根系和地上部Na+/K+、Na+/Ca2+、Na+/Mg2+,提高根系选择吸收性ASK,Na、ASCa,Na、ASMg,Na和根系向地上部的选择运输性TSK,Na、TSCa,Na、TSMg,Na。由此表明,盐胁迫下接种AMF可以通过调节芦笋体内的离子平衡,从而缓解盐胁迫对植株的伤害。     

亚硫酸钠处理对与采后竹笋木质化作用有关的细胞壁物质及酶活性的影响

研究了Na2SO3处理对与采后竹笋木质化作用相关的细胞壁物质及其酶活性的影响.结果表明1%Na2SO3处理能显著延缓竹笋组织中多聚半乳糖醛酸酶活性的降低和抑制苯丙氨酸解氨酶活性的上升,因此水溶性果胶含量显著高于对照,硬度、木质素和原果胶含量显著低于对照.但1%Na2SO3处理对纤维素酶、果胶甲酯酶活性和纤维素含量无显著影响.     

钾对能源植物杂交狼尾草耐盐性的影响

以盆栽的杂交狼尾草(Pennisetum americanum×P.purpureum)为实验材料,在不同浓度Na Cl(0%,0.5%)条件下,用含有不同钾浓度(0.1,3,6,9 mmol/L)的营养液处理4周后,测定植株高度、分蘖数、干重、叶片净光合速率、不同部位的离子含量、MDA(丙二醛)含量和细胞质膜透性等生理指标,以确定缓解盐害的适宜钾浓度。结果表明:0.5%Na Cl明显抑制了杂交狼尾草幼苗的生长和光合。在0.5%Na Cl处理下,随着钾素浓度增加,杂交狼尾草的生物量显著增加,其中6 mmol/L的钾显著降低杂交狼尾草所受盐害,即6 mmol/L的钾素处理缓解了Na Cl对杂交狼尾草株高、分蘖数、干重、光合速率的抑制;降低了杂交狼尾草叶片的MDA含量和质膜透性;降低了功能叶的Na+含量,增加了K+含量,从而增加了功能叶的K+/Na+。以上结果表明,适宜的钾浓度(6 mmol/L)能明显缓解Na Cl对能源植物杂交狼尾草生长和光合的抑制。这些结果为在盐碱地上大面积种植杂交狼尾草时合理施用钾肥提供了理论依据。     

盐胁迫对沙枣幼苗不同部位矿质元素含量的影响

沙枣(Elaeagnus angustifolia L.)是我国北方生态脆弱地区造林绿化的一个先锋树种,为进一步揭示其耐盐生理机制,本文采用温室水培方法,研究了0(CK)、100和200mmol·L-1NaCl胁迫下沙枣实生幼苗不同部位(根、茎、叶和地上部分)Na、Cl、K、Ca、Mg、Fe、Cu、Mn、NO_3~--N、SO_4~(2-)-S、P等11种主要矿质元素含量、含量比值以及转移系数的变化。结果表明:(1)与对照相比,盐胁迫沙枣幼苗根、茎、叶以及地上部分Na和Cl含量急剧增加,转移能力显著降低。200 mmol·L-1盐胁迫植株根、茎、叶和地上部分离子含量分别为对照的16.2、7.2、9.6和8.7倍(Na)以及4.8、2.7、3.7和3.4倍(Cl),Na和Cl转移系数分别为对照的53.6%和69.6%。根系成为Na和Cl含量最高的器官,200 mmol·L-1盐胁迫幼苗根Na含量分别是茎、叶Na含量的4.3和2.9倍,根Cl含量分别是茎、叶Cl含量的3.7和1.5倍;(2)盐胁迫沙枣幼苗根、茎、叶和地上部分K、Ca、Mg、Fe、Cu、NO_3~--N、SO_4~(2-)-S、P含量均低于或显著低于对照,K/Na、Ca/Na、Mg/Na比值均大幅低于对照,而Mg、Fe、Cu、SO_4~(2-)-S、P的转移系数则不同程度的高于对照;(3)Ca和Mn的转移系数随着盐胁迫浓度的升高而依次显著升高,K和Ca的转移系数始终维持在较高水平(分别为1.07~1.14和1.03~1.42),且植株体内的K、Ca和Mn优先向叶片分配。综合分析推测,沙枣耐盐主要是通过根系对Na和Cl的聚积与限制作用以及茎有效地限制Na向功能叶片运输来实现的,同时也与沙枣具有较强的K、Ca和Mn转移能力有关。     

北京地区14份柳枝稷生物量及分配差异研究

采用14份柳枝稷开展盆栽试验,研究了在北京地区条件下其生物量差异及分配规律。结果表明,低地型柳枝稷Kanlow生物量最高,其茎秆、地上部和整株生物量分别达到175.48 g/株、299.18 g/株和447.66 g/株,而高地型柳枝稷Nebraska生物量最低,其茎秆、地上部和整株生物量分别为29.86 g/株、58.08 g/株和140.51 g/株。就柳枝稷整株植株而言,Kanlow地上部生物量分配比例最高,达到63.13%,S2最低,为40.55%,Kanlow地上部营养器官生物量分配比例最高,达到48.67%,Nebraska最低,为31.88%。就柳枝稷地上部而言,Alamo、Kanlow和Trailblazer茎秆生物量分配比例及茎叶比均较高,分别为35.91%和2.75,37.09%和2.56,34.39%和2.48。起源纬度显著影响了柳枝稷的生物量及其分配,就柳枝稷整株植株而言,起源纬度与柳枝稷生物量显著负相关,与地下部生物量分配比例显著正相关,与地上部、种子和茎生物量分配比例显著负相关。就柳枝稷地上部而言,起源纬度与茎生物量分配比例及茎叶比显著负相关,与叶和鞘生物量分配比例显著正相关。生物量的差异及其分配规律反映出柳枝稷对生态环境长期适应的生殖与生长策略。本研究为柳枝稷遗传资源引种和品种选育提供了依据。     

3种禾草苗期生长和水分利用对土壤水分变化的反应

采用5种不同的水分处理,于室内生长箱内盆栽条件下对引种禾草柳枝稷(Panicum virgatum)、乡土禾草白羊草(Bothriochloa ischaemum)和栽培禾草谷子(Setaria italica)等苗期根冠生长和水分利用特征进行了比较分析.结果显示:(1)充分供水下3种禾草的苗期生物量和蒸腾效率均显著高于其它4种水分处理,而高水与低水处理下各自的根冠比无显著差异;(2)各水分处理下谷子苗期总生物量、蒸腾效率和耗水量均显著大于白羊草和柳枝稷;(3)在5种水分处理下,苗期根冠比谷子均最小,柳枝稷最大;(4)低降复水后,3种禾草生物量和蒸腾效率较低水处理分别显著提高16.7%-98.7%和28.2%-118.2%,显示出补偿效应,以白羊草增幅最大.结果表明,白羊草、谷子和柳枝稷在不同土壤水分处理下的苗期生物量、根冠分配比例以及水分利用效率差异反映了野生种、栽培种和引进种禾草苗期对半干旱环境条件水分生态适应性的异同.     

水培条件下pH值对柳枝稷幼苗生长发育的影响

土壤的p H值是限制植物生长发育的一个关键因素。柳枝稷是一种可作为牧草,水土保持的多年生C4能源植物。试验在水培条件下,利用裂区试验设计,以柳枝稷品种(系)为主区,水培液p H值为副区,对反映柳枝稷幼苗生长发育状况的指标进行统计分析。结果显示,随水培液p H值的酸碱强度增大,柳枝稷不同品种(系)幼苗的分蘖数、株高、苗鲜重、根冠比、根系活力以及净光合速率都极显著降低(P0.01),而幼苗保护酶活性以及丙二醛(MDA)含量则极显著升高(P0.01)。尤其是当PH值低于5.0时,幼苗的受到的胁迫更为明显,幼苗超氧化物歧化酶(SOD)和过氧化物酶(POD)活性反而急剧下降。与酸胁迫(p H值7.0)相比,柳枝稷对碱胁迫(p H值7.0)的适应能力更强,其中以西稷2号的抗逆性表现最好。因此应用柳枝稷在边际土壤地区推广种植时,要尽量避免强酸性土壤(p H值5.0),且选用西稷2号品系较为适宜。     

NaCl胁迫对滨梅扦插苗生物量和水分积累的影响

以1年生滨梅(Prunus maritima Marshall)扦插苗为实验材料,在盆栽条件下用质量浓度为0.15%、0.29%、0.58%、0.88%、1.17%、1.46%的NaCl溶液进行盐胁迫处理,测定胁迫后根、茎、叶Na+、K+含量以及全叶、一年生茎、二年生茎和根系生物量、含水率、根系活力变化,探讨滨梅的抗盐胁迫机制。结果显示:(1)盐胁迫80d后,随着盐胁迫强度提高,滨梅植株根、茎、叶Na+含量显著提高,而其根、茎K+含量显著降低,根、茎、叶K+/Na+值显著降低;根Na+含量在低于0.58%NaCl胁迫下显著高于茎、叶,而在高于0.58%NaCl胁迫下却表现为叶Na+含量显著高于根、茎。(2)滨梅根、茎、叶生物量均随盐胁迫强度的提高呈先增加后减少的趋势;随着盐胁迫时间的延长,茎、叶生物量在低于0.58%NaCl胁迫下均呈积累趋势,且茎生物量在0.58%NaCl胁迫下显著提高,而根、一年生茎、叶生物量在高于0.58%NaCl胁迫下均显著下降。(3)滨梅茎、叶含水率均随盐胁迫强度的增加呈先增加后减少的趋势,而随着胁迫时间的延长呈逐渐减少趋势;根系活力及根含水率均随盐胁迫强度的提高而增加,但根含水率随着胁迫时间的延长变化不明显。由此可见,滨梅能通过根系稀释并蓄积Na+,保护地上部分正常生长,当进入根系的Na+量超过吸收阈值时,Na+迅速在叶中积累储存,且叶中较高含量的K+对Na+形成了有效的缓冲。     

海滨锦葵萌发期和苗期盐胁迫反应及耐盐性鉴定指标筛选

选用海滨锦葵自然群体为研究材料,以Na Cl溶液为盐胁迫,研究海滨锦葵在不同浓度盐胁迫下萌发期和幼苗期生长状况的变化,并筛选萌发期和幼苗期耐盐鉴定指标。结果表明,Na Cl胁迫下海滨锦葵种子发芽率、发芽势、发芽指数、下胚轴长、胚根长、鲜重、活力指数及幼苗株高均降低,并且各指标的盐害系数随着盐胁迫浓度的升高而升高。较低Na Cl浓度(0.5%~1.5%)胁迫下的幼苗地上干重和地上鲜重高于未用Na Cl胁迫的幼苗,2.0%和2.5%浓度的Na Cl胁迫抑制了地上干重和地上鲜重。1.0%和2.0%的Na Cl浓度分别是萌发期和幼苗期鉴定海滨锦葵耐盐性的适宜浓度,发芽率、发芽势、发芽指数、下胚轴长、根长、鲜重以及活力指数可以作为萌发期耐盐性的鉴定指标,株高、地上鲜重和地上干重可以作为幼苗期耐盐性的鉴定指标。     

干旱胁迫下柳枝稷在露天矿区土壤中的种子萌发和生长特性

将能源植物用作矿区生态修复物种,对矿区的经济发展和生态环境具有重要意义。以能源植物柳枝稷为研究对象,通过盆栽试验,分析其在对照、轻度、中度以及重度干旱胁迫下柳枝稷幼苗在矿区土壤基质和非矿区土壤基质下的生长特性,并结合不同干旱胁迫下矿区土壤基质中种子萌发特征,揭示柳枝稷对干旱胁迫的响应机制和对矿区土壤的生态适应性。试验结果表明：（1）柳枝稷种子发芽总数、发芽率、发芽势以及发芽指数在轻度胁迫下达到最大值,活力指数在对照组最高,而在重度胁迫下,各项指标均达到最小值;种苗各生长指标在轻度胁迫下最小,幼苗根长和鲜重在重度胁迫下最高,芽长和芽重在其余三组胁迫下相差不大。（2）干旱胁迫使两种土壤基质下的柳枝稷株高降低,枯叶率增加,在对照、轻度胁迫和重度胁迫下能够保持叶片水分含量和分蘖数稳定;矿区土壤基质中,柳枝稷根体积在轻度胁迫下最大,中度胁迫下根长最长,重度胁迫下根数最多;根冠比随着干旱胁迫的加剧表现出先减后增的趋势,在轻度胁迫下最小,在重度胁迫下最大。（3）与非矿区土壤基质相比,柳枝稷在矿区土壤基质下根冠比更大,其余生长指标均更小;随着干旱胁迫的加剧,柳枝稷在矿区土壤基质下的株高、枯叶率、叶片相对含水量以及分蘖数与非矿区土壤基质下变化趋势一致。综上,柳枝稷在矿区土壤下的生长特性比在非矿区土壤下表现更差;在轻度干旱胁迫下各项生理指标表现更好,在中度和重度干旱胁迫下虽然其生长发育受到限制,但能通过调整生物量配比确保自身存活。因此,柳枝稷在矿区土壤环境下具有一定的抗旱性和抗贫瘠性,将其作为矿区生态修复品种具有可行性。     

盐胁迫对藜麦种子萌发的影响研究

再生水资源可浇灌农田,但水中含有的阴离子可使土壤产生盐胁迫。为研究盐胁迫对藜麦(Chenopodium quinoa)种子萌发特性及胚根、胚芽生长的影响,该研究以6个藜麦品种(红藜麦、国红藜麦、台红藜麦、台紫红藜麦、黄藜麦、台黄红藜麦)为材料,分别以NaCl、Na₂SO₄、NaHCO₃和对照(CK)处理6个藜麦品种种子,测定其发芽率、胚根、胚芽抑制率等指标,运用均方差决策法对不同藜麦品种耐盐性进行综合评价,初步筛选出不同盐胁迫下耐盐性较强的品种。结果表明:(1)三种盐胁迫中,Na₂SO₄对种子萌发指标抑制作用最明显,6个藜麦品种的发芽率均相对较低,一直保持在5%以下,除黄藜麦、台黄红藜麦,其余4个品种的活力指数和生长速率均为0,除黄藜麦外,Na₂SO₄ 对其余5个藜麦品种的胚根、胚芽抑制率均达到100%; NaCl对种子萌发和生长的抑制作用较小,甚至可促进胚根和胚芽生长,国红藜麦和台黄红藜麦的生长速率在NaCl处理下始终高于对照,在9 h和21 h时国红藜麦胚根抑制率为-28.32%和-37.57%。(2)运用均方差决策法对6个藜麦品种的萌发指标和生长指标进行综合评价结果显示,国红藜麦对NaCl、NaHCO₃抗性较高,黄藜麦对Na₂SO₄抗性较高。综合以上结果表明,盐胁迫不利于藜麦种子萌发及生长,但在不同盐分地区种植适宜生长的品种可提高藜麦成活率,提高其生长质量,以达到藜麦园林绿化及再生水资源灌溉的要求。     

牛叠肚幼苗对盐碱胁迫的生理响应及其耐盐阈值

以盆栽牛叠肚组培苗为试材,比较研究了不同浓度中性盐(NaCl、Na2SO4)和碱性盐(NaHCO3、Na2CO3)胁迫对其生长和生理指标的影响。结果显示:(1)牛叠肚幼苗生长在碱性盐(NaHCO3、Na2CO3)处理下表现出"低促高抑"现象,而在中性盐(NaCl、Na2SO4)处理下均受到不同程度的抑制。(2)随着盐碱胁迫浓度的升高,牛叠肚叶片的相对电导率呈增加趋势,丙二醛(MDA)积累波动变化;Na2SO4和NaHCO3处理下二者之间的变化趋势相似,而NaCl和Na2CO3处理下二者之间变化趋势则不同。(3)牛叠肚叶片中超氧化物歧化酶(SOD)活性随胁迫浓度增加先升高后下降,而过氧化物酶(POD)活性呈先下降后升高趋势,说明牛叠肚主要通过SOD和POD的互补作用来降低氧化伤害。(4)以相对株高生长量下降50%为标准,求得牛叠肚幼苗对NaCl、Na2SO4、NaHCO3、Na2CO34种单盐的耐受阈值分别为85.18(0.50%,W/V)、40.77(0.58%,W/V)、171.00(1.44%,W/V)、114.20(1.21%,W/V)mmol·L-1。研究表明,各盐碱胁迫使牛叠肚幼苗的生长受到不同程度的抑制,但其在一定浓度范围内通过提高抗氧化酶(SOD、POD)活性来减轻盐碱伤害,维持植株的正常生理代谢;牛叠肚幼苗对碱性盐(NaHCO3、Na2CO3)的耐受能力强于中性盐(NaCl、Na2SO4)。     

Expression of a carbonic anhydrase gene is induced by environmental stresses in Rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.)

Expression of the gene (OsCA1) coding for carbonic anhydrase (CA) in leaves and roots of rice was induced by environmental stresses from salts (NaCl, NaHCO₃ and Na₂CO₃), and osmotic stress (10%, w/v, PEG 6000). CA activity of rice seedlings more than doubled under some of these stresses. Transgenic Arabidopsis over-expressing OsCA1 had a greater salt tolerance at the seedling stage than wild-type plants in 1/2 MS medium with 5 mM NaHCO₃, 50 mM NaCl, on 100 mM NaCl. Thus CA expression responds to environmental stresses and is related to stress tolerance in rice.     

四翅滨藜生理生化特征对盐胁迫的响应

采用温室盆栽试验研究四翅滨藜(Atriplex canescens)幼苗株高、地径、生物量、净光合速率、蒸腾速率、气孔导度、叶绿素含量、抗氧化酶活性及丙二醛含量对不同浓度NaCl和Na_2SO_4(0、100、200、300和400mmol·L~(-1))胁迫的响应,以探讨四翅滨藜对不同种类及不同浓度盐渍环境的适应机制及其耐盐机理。结果显示:(1)随着盐分浓度的升高,四翅滨藜幼苗的株高、地径及生物量增量呈现出先升高后降低的趋势,低盐浓度下2种盐均促进幼苗生长,盐浓度超过400mmol·L~(-1)时,NaCl对幼苗生长具有明显抑制作用。(2)2种盐处理下,四翅滨藜幼苗净光合速率(Pn)和叶绿素含量(Chl)随盐浓度增大而升高,即2种盐均对幼苗Pn和Chl含量具有促进作用,且Na_2SO_4的促进效果大于NaCl;而幼苗蒸腾速率(Tr)和气孔导度(Gs)随盐浓度升高呈先增大后减小的趋势,且Na_2SO_4的促进作用强于NaCl。(3)与对照相比,四翅滨藜幼苗的丙二醛、SOD、POD酶活性在NaCl和Na_2SO_42种盐处理下,随着盐浓度的升高均呈现出不同程度的增大,且增大幅度总体表现为NaClNa_2SO_4。研究表明,四翅滨藜在NaCl和Na_2SO_4胁迫下,叶绿素的分解速率以及发挥作用的渗透调节物质均有差异,使得幼苗叶片健康程度不同,导致叶片光合能力大小的差异,最终表现为植株的生长差异;四翅滨藜具有较强的耐盐能力,而且对Na_2SO_4的适应能力强于NaCl。     

Effects of various mixed salt-alkaline stresses on growth,photosynthesis, and photosynthetic pigment concentrations of <Emphasis Type="Italic">Medicago ruthenica</Emphasis> seedlings

Soil salinization and alkalinization frequently co-occur in naturally saline and alkaline soils. To understand the characteristics of mixed salt-alkali stress and adaptive response of Medicago ruthenica seedlings to salt-alkali stress, water content of shoots, growth and photosynthetic characteristics of seedlings under 30 salt-alkaline combinations (salinity 24–120 mM and pH 7.03–10.32) with mixed salts (NaCl, Na₂SO₄, NaHCO₃, and Na₂CO₃) were examined. The indices were significantly affected by both salinity and pH. The interactive effects between salt and alkali stresses were significant, except for photosynthetic pigments. Water content of shoots, relative growth rates of shoots and roots and pigment concentrations showed decreasing trends with increasing salinity and alkalinity. The root activity under high alkalinity and salinity treatments gradually decreased, but was stimulated by the combined effects of low alkalinity and salinity. The survival rate decreased with increased salinity, except at pH 7.03–7.26 when all plants survived. Net photosynthetic rate, stomatal conductance and intercellular CO₂ concentration decreased with increased salinity and pH. M. ruthenica tolerated the stress of high salt concentration when alkali concentration was low, and the synergistic effects of high alkali and high salt concentrations lead to the death of some or all seedlings. M. ruthenica appeared to be saltalkali tolerant. Reducing the salt concentration or pH based on the salt components in the soil may be helpful to abate damage from mixed salt-alkaline stress.     

披针叶黄华试管苗适应盐胁迫的渗透调节机制

以披针叶黄华(Thermopsis lanceolata)试管苗为材料,通过组培方法研究其在0、0.2%、0.4%、0.6%、0.8%和1.0%NaCl和Na2SO4胁迫30d后的生长、有机渗透调节物质和无机渗透调节物质(Na+、K+和Ca2+)含量的变化,以探讨其耐盐性机制。结果显示:(1)随NaCl和Na2SO4胁迫浓度的增加,披针叶黄华试管苗叶片脯氨酸和可溶性糖含量均显著持续增加,且NaCl胁迫下脯氨酸上升的幅度均大于相同浓度Na2SO4胁迫下的增幅,而可溶性糖上升的幅度却小于相同浓度Na2SO4胁迫下的幅度;可溶性蛋白含量随NaCl浓度的增大呈先升高后降低的趋势,但随Na2SO4浓度的增加呈持续上升的趋势。(2)随NaCl和Na2SO4浓度的增加,披针叶黄华试管苗Na+含量呈增加趋势且各处理均显著高于对照,Ca2+含量和叶片K+含量却呈逐渐减少趋势且各处理均显著低于对照,而根系K+含量呈先降后升的趋势;Na2SO4胁迫下披针叶黄华试管苗叶片Na+含量上升幅度以及K+和Ca2+含量下降幅度均明显低于相同浓度NaCl胁迫组;而Na+/K+和Na+/Ca2+比值随NaCl和Na2SO4浓度增加而升高;NaCl胁迫下,叶片Na+/K+和Na+/Ca2+高于相同浓度Na2SO4胁迫下的比值,而根系Na+/K+和Na+/Ca2+却低于相同浓度Na2SO4胁迫下的比值。研究表明,盐胁迫下,披针叶黄华试管苗通过抑制叶片中Na+积累并增加可溶性糖和可溶性蛋白含量,在根系中维持较高K+和Ca2+含量以及较低水平Na+/K+和Na+/Ca2+比,以降低披针叶黄华细胞渗透势来适应盐渍环境;披针叶黄华对NaCl胁迫的调节能力弱于Na2SO4。     

Salt tolerance of two differently drought-tolerant wheat genotypes during germination and early seedling growth

Summary Osmotic and specific ion effect are the most frequently mentioned mechanisms by which saline substrates reduce plant growth. However, the relative importance of osmotic and specific ion effect on plant growth seems to vary depending on the drought and/or salt tolerance of the plant under study. We studied the effects of several single salts of Na⁺ and Ca²⁺−NaCl, NaNO₃, Na₂SO₄, NaHCO₃, Na₂CO₃, and Ca(NO₃)₂—on the germination and root and coleoptile growth of two wheat (Triticum aestivum L.) cultivars, TAM W-101 and Sturdy, the former being more drought tolerant than the latter. The concentrations used were: 0, 0.02, 0.04, 0.08, 0.16, and 0.32 mol L⁻¹. Significant two- and three-way interactions were observed between cultivar, kind of salt, and salt concentration for germination, growth of coleoptile and root, and root/coleoptile ratio. Salts differed significantly (P<0.001) in their effect on seed germination, coleoptile and root growth of both cultivars. Germination of TAM W-101 seeds was consistently more tolerant than that of Sturdy to NaCl, CaCl₂, Ca(NO₃)₂, and NaHCO₃ salts at concentrations of 0.02, 0.04, 0.08, 0.16 mol L⁻¹. The osmotic potential, at which the germination of wheat seeds was reduced to 50% of that of the control, was different depending on the kind of salt used in the germination medium. NaCl at low concentrations (0.02 and 0.04 mol L⁻¹) stimulated the germination of both wheat cultivars. At concentrations of 0.02 to 0.16 mol L⁻¹, Ca²⁺ salts (CaCl₂ and Ca(NO₃)₂) were consistently more inhibitory than the respective Na⁺ salts (NaCl and NaNO₃) for germination of Sturdy. This did not consistently hold true for TAM W-101. Among the Na⁺ salts, NaCl was the least toxic and NaHCO₃ and Na₂CO₃ were the most toxic for seed germination. Root and coleoptile (in both wheat cultivars) differed in their response to salts. This differential response of coleoptile and root to each salt resulted in seedlings with a wide range of root/coleoptile ratios. For example, the root/coleoptile ratio of cultivar TAM W-101 changed from 2.09 (in the control) to 3.77, 3.19, 2.8, 2.44, 1.31, 0.32, and 0.0 when subjected to 0.08 mol L⁻¹ of Na₂SO₄, NaCl, CaCl₂, NaNO₃, Ca(NO₃)₂, NaHCO₃, and Na₂CO₃, respectively. Na₂CO₃ at 0.08 mol L⁻¹ inhibited root growth to such an extent that germinated wheat seeds contained coleoptile but no roots. The data indicate that, apart from the clear and more toxic effects of NaHCO₃ and Na₂CO₃ and lesser toxic effect of NaCl on germination and seedling growth, any toxicity-ranking of other salts done at a given concentration and for a given tissue growth may not hold true for other salt concentrations, other tissues and/or other cultivars. The more drought-tolerant TAM W-101, when compared to the less drought tolerant Sturdy, showed higher tolerance (at most concentrations) to NaCl, CaCl₂, Ca(NO₃)₂ and NaHCO₃ during its seed germination and to Na₂SO₄ and CaCl₂ for its root growth. This supports other reports that some drought-tolerant wheat cultivars are more tolerant to NaCl. In contrast, the coleoptile growth of drought-sensitive Sturdy was noticeably more tolerant to NaNO₃, Ca(NO₃)₂ and NaHCO₃ than that of drought-tolerant TAM W-101. Based on the above and the different root/coleoptile ratios observed in the presence of various salts, it is concluded that in these wheat cultivars: a) coleoptile and root tissues are differently sensitive to various salts, and b) at the germination stage, tolerance to certain salts is higher in the more drought-tolerant cultivar.     

Effects of inclusion level and source of dietary sodium on performance and meat characteristics of broiler chickens

The effect of different concentrations of dietary Na from three Na salts (NaCl, NaHCO₃ and Na₂SO₄) was assessed in two experiments carried out on broiler chickens aged from 1 to 35 days. In Exp. 1, diets were supplemented with 0.15, 0.20 and 0.25% Na, which increased the average Na content of the diets to 0.19, 0.24 and 0.30% respectively. In Exp. 2, the amounts of selected Na salts (NaCl and Na₂SO₄) were reduced and the estimated Na contents of experimental diets amounted to 0.10, 0.13, 0.15 and 0.19%. In view of the risk factors for the development of foot pad dermatitis, our aim was to find an optimum source of Na and to keep dietary Na intake at the minimum level sufficient to support normal growth and acceptable slaughter quality. The present results suggest that the amount of Na required for the undisturbed growth of broilers and adequate feed conversion is not less than 0.15% of additional Na in the starter period (1–14 d), and not less than 0.11% in the grower period (until day 35). Higher dietary Na levels did not lead to further production advantages, and were found to increase the moisture content of droppings. Dry matter concentration of excreta was also affected by Na source. In comparison with NaHCO₃, Na₂SO₄ seemed to be a better alternative for NaCl. Na₂SO₄ also tended to surpass NaHCO₃ as a dietary alternative for NaCl in terms of feed utilisation during the starter period. The applied additional Na levels (0.25 and 0.15%) and Na sources had no effect on the sensory profile and composition of breast meat.     

Effects of four types of sodium salt stress on plant growth and photosynthetic apparatus in sorghum leaves

Sorghum variety Longza 17 was used as the experimental organism in a study of the effects of different types of sodium salt (two neutral salts, NaCl and Na₂SO₄; and two alkaline salts, NaHCO₃ and Na₂CO₃), at an equivalent Na⁺ concentration (100?mmol·L^?1) on leaf growth parameters and PSII and PSI function by using the Fast Chlorophyll Fluorescence Induction Dynamics technique and 820?nm light reflectance curves. The results showed that at Na⁺ concentration of 100?mmol·L^?1, different types of sodium salt stress significantly inhibited the growth of sorghum plants. Different types of sodium salt stress showed significant inhibition on the activities of PSII and PSI in sorghum leaves, the impact of different types of sodium salt on the activities of PSII and PSI in sorghum leaves was consistent, listed from greatest to least impact as Na₂CO₃ > NaHCO₃ > Na₂SO₄ > NaCl. The effects of alkaline salt stress on the growth and photosynthetic properties of sorghum were greater than those under the neutral salt stress, therefore, in addition to considering the impact of Na⁺ concentration in the sorghum planting area, emphasis should also be given to the influence of the degree of alkalization, especially the higher alkalinity of Na₂CO₃.     

Photosynthesis,chlorophyll fluorescence,inorganic ion and organic acid accumulations of sunflower in responses to salt and salt-alkaline mixed stress

Sunflowers were treated with mixing proportions of NaCl, Na₂SO₄, NaHCO₃, and Na₂CO₃. Effects of salt and saltalkaline mixed stress on growth, photosynthesis, chlorophyll fluorescence, and contents of inorganic ions and organic acids of sunflower were compared. The growth of sunflower decreased with increasing salinity. The contents of photosynthetic pigments did not decrease under salt stress, but their contents decreased sharply under salt-alkaline mixed stress. Net photosynthetic rates, stomatal conductance and intercellular CO₂ concentration decreased obviously, with greater reductions under salt-alkaline mixed stress than under salt one. Fluorescence parameters showed no significant differences under salt stress. However, maximal efficiency of PSII photochemistry, photochemical quenching coefficient, electron transport rate, and actual PSII efficiency significantly decreased but non-photochemical quenching increased substantially under salt-alkaline mixed stress. Under salt-alkaline mixed stress, sunflower leaves maintained a low Na⁺- and high K⁺ status; this may be an important feature of sunflower tolerance to salinity. Analysis of the mechanism of ion balance showed that K⁺ but not Na⁺ was the main inorganic cation in sunflower leaves. Our results indicated that the change in organic acid content was opposite to the change of Cl⁻, and the contribution of organic acid to total charge in sunflower leaves under both stresses decreased with increasing salinity. This may be a special adaptive response to stresses for sunflower. Sunflower under stress conditions mainly accumulated inorganic ions instead of synthesizing organic compounds to decrease cell water potential in order to save energy consumption.