Abscisic Acid Response of Corn (<Emphasis Type="Italic">Zea mays</Emphasis> L.) Roots and Protoplasts to Lanthanum

Lanthanum ions antagonize calcium and are used as a Ca²⁺ channel blocker but their direct effects are unknown. We investigated lanthanum effects on endogenous abscisic acid (ABA) levels in protoplasts and intact primary roots of Zea mays L. Application of 1 mM La³⁺ reduced primary root elongation, caused swelling of root tips, and essentially doubled the ABA content in intact roots but decreased ABA in root protoplasts in a concentration-dependent manner. Osmotic stress increased ABA level in protoplasts more than in intact roots. Temporal ABA changes in response to La³⁺ treatment indicate that La³⁺ affects root growth at least partially via ABA pathway.     

The effects of La(III) on the peroxidation of membrane lipids in wheat seedling leaves under osmotic stress

The physiological effects of the rare earth ion La³⁺ on the peroxidation of membrane lipids in wheat (Triticum aestivum L.) seedling leaves under osmotic stress were determined. With the passage of time under osmotic stress, the inhibition ability of lanthanum ions to the relative membrane permeability and concentration of malondialdehyde, Superoxide radicals, and hydrogen peroxide caused by osmotic stress increased substantially, but no changes were noted in ferrous and relative water content. It indicated that lanthanum ions could not retain the water content because of osmotic stress. However, La³⁺ appears to decrease the production of OH by reducing the content of O₂ and H₂O₂ of Haber-Weiss and Fenton reactions, which efficiently alleviated peroxidation of membrane lipids under osmotic stress and, to some degree, protected the membrane from injury of free radicals. Thus, La³⁺ increased the tolerance ability of plant to osmotic stress, which could assure the function of membrane normal temporally after stressed.     

Growth-promoting bacteria and natural regulators mitigate salt toxicity and improve rapeseed plant performance

Salinity is a major environmental stress that limits plant production and portraits a critical challenge to food security in the world. In this research, the impacts of plant growth–promoting bacteria (Pseudomonas RS-198 and Azospirillum brasilense RS-SP7) and foliar application of plant hormones (salicylic acid 1 mM and jasmonic acid 0.5 mM) on alleviating the harmful effects of salt stress in rapeseed plants (Brassica napus cv. okapi) were examined under greenhouse condition. Salt stress diminished rapeseed biomass, leaf area, water content, nitrogen, phosphorus, potassium, calcium, magnesium, and chlorophyll content, while it increased sodium content, endogenous salicylic and jasmonic acids, osmolyte production, H₂O₂ and O₂^•− generations, TBARS content, and antioxidant enzyme activities. Plant growth, nutrient content, leaf expansion, osmolyte production, and antioxidant enzyme activities were increased, but oxidative and osmotic stress indicators were decreased by bacteria inoculation + salicylic acid under salt stress. Antioxidant enzyme activities were amplified by jasmonic acid treatments under salt stress, although rapeseed growth was not generally affected by jasmonic acid. Bacterial + hormonal treatments were superior to individual treatments in reducing detrimental effects of salt stress. The best treatment in rectifying rapeseed growth under salt stress was combination of Pseudomonas and salicylic acid. This combination attenuated destructive salinity properties and subsequently amended rapeseed growth via enhancing endogenous salicylic acid content and some essential nutrients such as potassium, phosphorus, and magnesium.

     

Effects of La<Superscript>3+</Superscript> on the Active Oxygen-Scavenging Enzyme Activities in Cucumber Seedling Leaves

The effects of La³⁺ on the antioxidant enzyme activities and the relative indices of cellular damage in cucumber seedling leaves were studied. When cucumber seedlings were treated with low concentrations of LaCl₃ (0.002 and 0.02 mM), peroxidase (PO) activity increased, and catalase (CAT) activity was similar to that of control leaves at 0.002 mM La³⁺ and increased at 0.02 mM La³⁺, whereas superoxide dismutase (SOD) activity did not change significantly. The increase in the contents of chlorophyll (including chlorophylls a and b), carotenoids in parallel with the decrease in the level of malondialdehyde (MDA) suggested that low concentration of La³⁺ promoted plant growth. However, except the increase in SOD activity at 2 mM La³⁺, CAT and PO activities and the contents of pigments decreased at high concentrations of La³⁺ (0.2 and 2 mM), leading to the increase of MDA content and the inhibition of plant growth. It is suggested that lanthanum ion is involved in the regulation of active oxygen-scavenging enzyme activities during plant growth.__________From Fiziologiya Rastenii, Vol. 52, No. 3, 2005, pp. 338–342.Original English Text Copyright © 2005 by Shi, Chen, Huang.This article was submitted by the authors in English.     

Effects of silicon on photosynthesis,water relations and nutrient uptake of <Emphasis Type="Italic">Phaseolus vulgaris</Emphasis> under NaCl stress

A greenhouse experiment was conducted to investigate the effects of silicon application on Phaseolus vulgaris L. under two levels of salt stress (30 and 60 mM NaCl in the irrigation water). Salinity significantly reduced growth, stomatal conductance and net photosynthetic rate, and increased Na⁺ and Cl⁻ content mainly in roots. Silicon application enhanced growth of salt stressed plants, significantly reduced Na⁺ content especially in leaves and counterbalanced the effects of NaCl on gas exchange; the effect was more evident at 30 mM NaCl. Cl⁻ content in shoots and roots was not significantly modified by silicon application; the drop in K⁺ content caused by salinity was partially counterbalanced by silicon, especially in roots.     

盐旱交叉胁迫对柽柳幼苗渗透调节物质含量的影响

以2年生柽柳幼苗为试验材料,采用盆栽模拟试验研究不同盐分和干旱胁迫对其叶片中渗透调节物质的影响,以探讨柽柳幼苗对盐旱交叉胁迫的适应性.结果表明:(1)随盐旱胁迫的不断加剧,幼苗叶片中可溶性糖含量呈先升高后降低的趋势,且中度和重度盐旱胁迫下均显著高于对照(CK).(2)幼苗叶片中脯氨酸含量在不同盐旱胁迫下均呈逐渐上升趋势,但在重度盐分和中度、重度干旱交叉胁迫下显著高于CK.(3)幼苗叶片中Na+、Cl含量在不同干旱胁迫下,随盐胁迫的加剧呈不同的变化规律,盐旱胁迫的各个处理水平下均显著高于CK,而K+、Ca2+、SO42-含量在轻度和重度干旱胁迫下随盐胁迫增强不断降低.(4)在中度盐旱胁迫下,K+、Ca2+含量与CK无明显差异.研究表明,柽柳幼苗中渗透调节物质在其抗旱耐盐性方面具有积极的调节作用;柽柳幼苗在盐旱胁迫下表现出一定的交叉适应性,适度的干旱胁迫能增强柽柳幼苗对盐分胁迫的耐受能力.     

Na2SO4和Na2CO3胁迫下苦楝幼苗的形态及光合生理特性

为探索苦楝应对盐胁迫的响应机制,该文以1年生苦楝(Melia azedarach)实生苗为材料,在盆栽条件下设置中性盐Na_2SO_4和碱性盐Na_2CO_33个盐浓度(200、400、600 mmol·L~(-1))处理40 d,研究苦楝的抗盐碱水平及在不同程度盐碱胁迫条件下的生长及光合生理变化。结果表明:随着盐浓度的提高,苦楝的苗高、地径和生物量的增长量均呈现下降趋势,且碱性盐胁迫条件下降程度更大,盐胁迫提高苦楝的根冠比。处理10 d时,苦楝幼苗的所有光合指标随中性盐和碱性盐浓度的提高呈相似的下降特征,碱性盐胁迫条件下的降低幅度显著大于中性盐胁迫,且随处理时间的增加,中性盐和碱性盐处理下苦楝幼苗的净光合速率和蒸腾速率显著降低。随着盐浓度的提高,苦楝的叶绿素含量呈现下降趋势,200 mmol·L~(-1)盐胁迫对叶绿素含量影响较小,400、600 mmol·L~(-1)盐胁迫均对叶绿素含量有显著影响。600 mmol·L~(-1)碱性盐胁迫条件下,苦楝叶片相对电导率和饱和水分亏缺最高,显著高于其余处理。同等浓度下,碱性盐胁迫的苦楝叶片相对电导率和饱和水分亏缺显著高于中性盐胁迫处理。综上结果认为,苦楝具有一定的耐盐碱能力,碱性盐比中性盐对苦楝幼苗的影响更大。     

盐胁迫对竹柳幼苗生理响应及结构解剖的研究

为了解盐胁迫对竹柳(Salix spp.)幼苗生长的影响,采用土培方法,对NaCl胁迫下半年生竹柳扦插苗的成活率、生理响应和根叶部结构进行研究。结果表明,在0.25%Na Cl胁迫(轻度盐胁迫)下竹柳能正常生长,而在0.5%NaCl(中度、重度盐胁迫)下生长受到抑制,推断竹柳的耐盐阈值是0.5%。随着NaCl浓度的增大,叶片相对含水量、叶绿素a含量、叶绿素总含量和叶绿素a/b均呈下降趋势;但叶绿素b含量、脯氨酸含量和MDA含量呈升高趋势。在轻度盐胁迫下,叶片SOD活性和可溶性蛋白含量均升高,在中、重度盐胁迫下显著下降。从根叶解剖结构来看,叶片、角质层、栅栏组织厚度和根部周皮和直径在轻度盐胁迫时最大,但在中度盐胁迫时叶片栅栏组织细胞长度减小且排列越来越疏松,根部输导组织细胞不正常。这表明竹柳在轻度胁迫时具有一定的耐盐性,但在中高度盐胁迫下生长不良。     

Phosphatidylinositol‐hydrolyzing phospholipase C4 modulates rice response to salt and drought

Phosphatidylinositol‐specific phospholipase C (PI‐PLC) is involved in stress signalling but its signalling function remains largely unknown in crop plants. Here, we report that the PI‐PLC4 from rice (Oryza sativa cv), OsPLC4, plays a positive role in osmotic stress response. Two independent knockout mutants, plc4‐1 and plc4‐2, exhibited decreased seedling growth and survival rate whereas overexpression of OsPLC4 improved survival rate under high salinity and water deficiency, compared with wild type (WT). OsPLC4 hydrolyses PI, phosphatidylinositol 4‐phosphate (PI4P), and phosphatidylinositol‐4,5‐bisphosphate (PIP₂) to generate diacylglycerol (DAG) in vitro. Knockout of OsPLC4 attenuated salt‐induced increase of phosphatidic acid (PA) whereas overexpression of OsPLC4 decreased the level of PI4P and PIP₂ under salt treatment. Applications of DAG or PA restored the growth defect of plc4‐1 to WT but DAG kinase inhibitor 1 blocked the complementary effect of DAG in plc4‐1 under salt stress. In addition, the loss of OsPLC4 compromised the increase of inositol triphosphate and free cytoplasmic Ca²⁺ ([Ca²⁺]_cyt) and inhibited the induction of genes involved in Ca²⁺ sensor and osmotic stress response to salt stress. The results indicate that OsPLC4 modulates the activity of two signalling pathways, PA and Ca²⁺, to affect rice seedling response to osmotic stress.     

Ce^3+和La^3+对人工老化沙葱种子活力及生理特性的影响

以未老化和人工老化后的沙葱(Allium mongolicum Regel.)种子为材料,采用氯化铈(Ce3+)和氯化镧(La3+)浸种,测定种子萌发和生理指标,探讨Ce3+和La3+浸种对种子萌发、老化种子活力和生理特性的影响。结果显示:(1)在老化0~5 h时,Ce3+和La3+处理可显著促进沙葱种子萌发,提高种子活力;在老化5 h后,Ce3+和La3+处理对种子萌发无明显促进作用。(2)在老化0~15 h时,Ce3+和La3+处理的沙葱种子中抗氧化酶活性和抗坏血酸(AsA)含量提高,其超氧阴离子自由基(O2-·)产生速率、过氧化氢(H2O2)含量和丙二醛(MDA)含量显著降低;在老化15 h后,Ce3+和La3+处理的种子抗氧化酶活性提高、AsA含量降低,O2-·产生速率和MDA含量提高。(3)在老化5 h时,沙葱种子呼吸速率发生跃变达到最大,Ce3+和La3+处理显著降低了种子呼吸速率。(4)Ce3+和La3+处理在老化0~5 h时提高了沙葱种子超弱发光(UWL)强度,但在老化5 h后沙葱种子的UWL强度降低。研究认为,在沙葱种子人工老化初期,Ce3+和La3+浸种处理可以诱导增强种子抗氧化酶活性和提高AsA含量,有效清除因老化产生积累的过量活性氧(ROS),减轻过氧化伤害,提高种子活力;种子老化中后期,其内部ROS产生与清除系统发生紊乱,加剧了ROS对种子结构的损伤,Ce3+和La3+浸种处理的缓解效应丧失。     

外源5-氨基乙酰丙酸对盐胁迫下菘蓝种子萌发及幼苗抗氧化酶活性的影响

采用砂培方式,研究了外源5-氨基乙酰丙酸(ALA)对盐胁迫下菘蓝种子的萌发、幼苗叶片的可溶性糖含量、丙二醛(MDA)含量及其抗氧化酶活性的影响,探讨ALA缓解菘蓝受盐胁迫伤害的响应机制。结果显示:(1)菘蓝种子萌发及幼苗生长在100 mmol·L^-1 NaCl胁迫下受到明显的抑制,种子发芽率、发芽势、发芽指数、活力指数与自然含水量均显著降低,丙二醛含量、可溶性糖含量以及超氧化物歧化酶(SOD)、过氧化物酶(POD)活性显著升高。(2)盐胁迫下适宜浓度的ALA处理显著提高了种子萌发率、自然含水量及SOD、POD和CAT活性,降低了可溶性糖和丙二醛的含量,并以16.7 mg·L^-1 ALA处理盐胁迫下菘蓝种子的发芽率、发芽势最大,其幼苗的SOD、POD、CAT活性最强。研究表明,盐胁迫显著抑制菘蓝种子的萌发及幼苗生长,适宜浓度的ALA能够有效缓解盐胁迫对菘蓝种子萌发及幼苗生长的伤害,提高植株的抗盐性,并以16.7 mg·L^-1 ALA处理效果最佳。     

The <Emphasis Type="Italic">Arabidopsis</Emphasis><Emphasis Type="Italic"> cax3</Emphasis> mutants display altered salt tolerance,pH sensitivity and reduced plasma membrane H<Superscript>+</Superscript>-ATPase activity

Perturbing CAX1, an Arabidopsis vacuolar H⁺/Ca²⁺ antiporter, and the related vacuolar transporter CAX3, has been previously shown to cause severe growth defects; however, the specific function of CAX3 has remained elusive. Here, we describe plant phenotypes that are shared among cax1 and cax3 including an increased sensitivity to both abscisic acid (ABA) and sugar during germination, and an increased tolerance to ethylene during early seedling development. We have also identified phenotypes unique to cax3, namely salt, lithium and low pH sensitivity. We used biochemical measurements to ascribe these cax3 sensitivities to a reduction in vacuolar H⁺/Ca²⁺ transport during salt stress and decreased plasma membrane H⁺-ATPase activity. These findings catalog an array of CAX phenotypes and assign a specific role for CAX3 in response to salt tolerance.     

Amelioration of salt-induced oxidative stress in eggplant by application of 24-epibrassinolide

The effects of exogenous 24-epibrassinolide (EBR) on the growth, oxidative damage, antioxidant system and ion contents in eggplant (Solanum melongena L.) seedlings under salt stress were investigated. Eggplant seedlings were exposed to 90 mM NaCl with 0, 0.025, 0.05, 0.10 and 0.20 mg dm⁻³ EBR for 10 d. EBR, especially at concentration 0.05 mg dm⁻³, alleviated growth suppression caused by NaCl stress, decreased electrolyte leakage, superoxide production and content of malondialdehyde and H₂O₂ in NaCl-treated plants. EBR also increased activities of superoxide dismutase, guaiacol peroxidase, catalase and ascorbate peroxidase and the contents of ascorbic acid and reduced glutathione. Furthermore, we also found that Na⁺, Cl⁻ contents were decreased, K⁺, Ca²⁺ contents and K⁺/Na⁺, Ca²⁺/Na⁺ ratios were increased in the presence of EBR under salt stress.     

外源Ca2+和IBA对NaCl胁迫下能源植物杂交狼尾草幼苗生长的影响

以能源植物杂交狼尾草(Pennisetum americanum×P.purpureum)为实验材料,在NaCl胁迫条件下用外源IBA(100 mg/L),CaCl_2(浓度分别为0、1、2、5 mmol/L)处理杂交狼尾草幼苗,处理3周后测定植物的存活率、鲜重、干重、株高、生根数和地上部分、地下部分的离子含量。结果表明,经过IBA溶液预处理的杂交狼尾草幼苗的存活率、鲜重、干重、株高、生根数明显高于未处理的幼苗;在NaCl胁迫下,随着外源Ca~(2+)浓度的升高,杂交狼尾草幼苗的存活率、鲜重、干重、株高、生根数以及Ca~(2+)含量都明显升高并在CaCl_2浓度为2 mmol/L时达到最大值;随着外源Ca~(2+)浓度的升高,Na~+含量、Na~+/K~+降低,当CaCl_2的浓度为2mmol/L时,Na~+含量、Na~+/K~+最低。以上结果表明外源Ca~(2+)和IBA对NaCl胁迫下杂交狼尾草幼苗生长有促进作用,可以缓解NaCl胁迫对杂交狼尾草幼苗生长的抑制作用,提高杂交狼尾草幼苗在NaCl胁迫下的成活率;缓解盐害的最适的Ca~(2+)浓度为2mmol/L。     

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.     

Salt tolerance of prickly pear cactus (Opuntia ficus-indica)

In view of the need to exploit saline water resources in agriculture in arid zones, we investigated the salt tolerance of Opuntia ficus-indica in plants growing in solution culture. Salt (NaCl) was added in concentrations ranging from 5 (control) to 200 mol m^-3. Cladode growth was sensitive to salinity, being 60% of the control at 50 mol m^-3 NaCl. The root-to-stem ratio decreased significantly only at 200 mol m^-3. Various other parameters were studied, such as water content, Na, K and Cl content, osmotic pressure, and CO₂ uptake. Of these parameters the decreases in cladode water content and CO₂ uptake were related to the decrease in cladode growth. Raised salinity increased cladode osmotic pressure, which was associated with tissue dehydration. We concluded that osmotic adjustment does not occur in prickly pear under salt stress.     

盐分胁迫对啤酒大麦幼苗生长、离子平衡和根际pH变化的影响

盐分胁迫不仅影响植物的生长,而且会影响植物根际微域环境。根际pH的改变对土壤养分的有效性和微生物群落组成的变化有重要影响。为了探究啤酒大麦幼苗对不同类型盐分胁迫的生理生态响应机制和根际pH变化影响的生理机制,采用水培法,通过不同类型盐分(对照、混合Na盐、混合Cl盐和NaCl)胁迫处理啤酒大麦幼苗,对其生长、离子平衡和根际pH变化进行了研究。结果表明,1)在3种不同类型盐分胁迫下,啤酒大麦幼苗地上部干重、含水量均有所降低,而根冠比增加,尤其在NaCl胁迫下啤酒大麦幼苗地上部干重较对照显著降低了17.88%,而根干重和根冠比则分别增加了19.12%和43.86%。不同类型盐分胁迫抑制了啤酒大麦幼苗根长的生长,尤其在混合Na盐胁迫下根长降低明显(P0.05),但促进了根表面积和根体积的增加,尤其在混合Cl盐胁迫下,根表面积和根体积分别增加了41.76%和84.38%。2)不同类型盐分胁迫下啤酒大麦幼苗地上部离子平衡发生改变,在混合Na盐和NaCl胁迫下啤酒大麦幼苗主要吸收Na~+,地上部K~+/Na~+、Ca~(2+)/Na~+和Mg~(2+)/Na~+显著降低;混合Cl盐和NaCl胁迫下则过量吸收Cl~-,抑制了H_2PO_4~-、NO_3~-和SO_4~(2-)的吸收。3)在混合Na盐、混合Cl盐和NaCl盐分胁迫下,啤酒大麦幼苗对阴离子的吸收总量高于对阳离子的吸收总量,离子平衡计算结果表明根际呈碱化现象,与原位显色结果一致,且在混合Cl盐胁迫下根际碱化程度最大。     

Salt stress effects on growth,pigments, proteins and lipid peroxidation in <Emphasis Type="Italic">Salicornia persica</Emphasis> and <Emphasis Type="Italic">S. europaea</Emphasis>

The effects of NaCl stress on growth, water status, contents of protein, proline, malondialdehyde (MDA), various sugars and photosynthetic pigments were investigated in seedlings of Salicornia persica and S. europaea grown in vitro. Seeds were germinated under NaCl (0, 100, 200, 300, 400, 500 and 600 mM) on Murashige and Skoog medium for 45 d. The shoot growth of both species increased under low NaCl concentration (100 mM) and then decreased with increasing NaCl concentrations. In contrast to S. persica, root length in S. europaea reduced steadily with an increase in salinity. Proline content in S. persica was higher than in S. europaea at most NaCl concentrations. Proline, reducing saccharide, oligosaccharide and soluble saccharide contents increased under salinity in both species. In contrast, contents of proteins and polysaccharides reduced in both species under salt stress. MDA content remained close to control at moderate NaCl concentrations (100 and 200 mM) and increased at higher salinities. MDA content in S. europaea was significantly higher than S. persica at higher salinities. Salt treatments decreased K⁺ and P contents in seedlings of both species. Significant reduction in contents of chlorophylls and carotenoids due to NaCl stress was also observed in seedlings of both species. Some differences appeared between S. persica and S. europaea concerning proteins profile. On the basis of the data obtained, S. persica is more salt-tolerant than S. europaea.     

Improved Salinity Tolerance of <Emphasis Type="Italic">Arachis</Emphasis><Emphasis Type="Italic">hypogaea</Emphasis> (L.) by the Interaction of Halotolerant Plant-Growth-Promoting Rhizobacteria

Salinity adversely affects plant growth and development. Halotolerant plant-growth-promoting rhizobacteria (PGPR) alleviate salt stress and help plants to maintain better growth. In the present study, six PGPR strains were analyzed for their involvement in salt-stress tolerance in Arachis hypogaea. Different growth parameters, electrolyte leakage, water content, biochemical properties, and ion content were analyzed in the PGPR-inoculated plants under 100 mM NaCl. Three bacterial strains, namely, Brachybacterium saurashtrense (JG-06), Brevibacterium casei (JG-08), and Haererohalobacter (JG-11), showed the best growth of A. hypogaea seedlings under salt stress. Plant length, shoot length, root length, shoot dry weight, root dry weight, and total biomass were significantly higher in inoculated plants compared to uninoculated plants. The PGPR-inoculated plants were quite healthy and hydrated, whereas the uninoculated plant leaves were desiccated in the presence of 100 mM NaCl. The percentage water content (PWC) in the shoots and roots was also significantly higher in inoculated plants compared to uninoculated plants. Proline content and soluble sugars were significantly low, whereas amino acids were higher than in uninoculated plants. The MDA content was higher in uninoculated plants than in inoculated plants at 100 mM NaCl. The inoculated plants also had a higher K⁺/Na⁺ ratio and higher Ca²⁺, phosphorus, and nitrogen content. The auxin concentration was higher in both shoot and root explants in the inoculated plants. Therefore, it could be predicted that all these parameters cumulatively improve plant growth under saline conditions in the presence of PGPR. This study shows that PGPR play an important role in inducing salinity tolerance in plants and can be used to grow salt-sensitive crops in saline areas.     

The effects of NaCl on growth,water relations,osmolytes and ion content in <Emphasis Type="Italic">Kochia prostrata</Emphasis>

The effects of NaCl (0, 50, 100, 150 and 200 mM) on growth, water relations, glycinebetaine, free proline, ion contents, stomata number and size of Kochia prostrata (L.) Schard were determined. Shoot and root fresh and dry matter, root and shoot length, relative growth rate, net assimilation rate, relative water content, water use efficiency, soluble sugars and glycinebetaine contents were not changed at low NaCl concentrations, but they were significantly decreased at 200 mM NaCl. The K⁺, Mg²⁺ and Ca²⁺ contents, water potential, chlorophyll a+b and carotenoides contents, and stomata number and size were reduced already at low concentrations of NaCl. In contrast, the Na⁺, Cl^– and proline contents increased several times with increasing NaCl concentration. Kochia prostrata is a salt tolerant species, the optimal growth of this plant occurred up to 150 mM NaCl. The mechanisms of salt tolerance in the plant may be balance among ion accumulation and production of glycinebetaine, proline, soluble sugars for maintenance of pressure potential.