Mycorrhizal inoculant alleviates salt stress in<Emphasis Type="Italic"> Sesbania aegyptiaca</Emphasis> and<Emphasis Type="Italic"> Sesbania grandiflora</Emphasis> under field conditions: evidence for reduced sodium and improved magnesium uptake

A field experiment was conducted to examine the effect of the arbuscular mycorrhizal fungus Glomus macrocarpum and salinity on growth of Sesbania aegyptiaca and S. grandiflora. In the salt-stressed soil, mycorrhizal root colonisation and sporulation was significantly higher in AM-inoculated than in uninoculated plants. Mycorrhizal seedlings had significantly higher root and shoot dry biomass production than non-mycorrhizal seedlings grown in saline soil. The content of chlorophyll was greater in the leaves of mycorrhiza-inoculated as compared to uninoculated seedlings. The number of nodules was significantly higher in mycorrhizal than non-mycorrhizal plants. Mycorrhizal seedling tissue had significantly increased concentrations of P, N and Mg but lower Na concentration than non-mycorrhizal seedlings. Under salinity stress conditions both Sesbania sp. showed a high degree of dependence on mycorrhizae, increasing with the age of the plants. The reduction in Na uptake together with a concomitant increase in P, N and Mg absorption and high chlorophyll content in mycorrhizal plants may be important salt-alleviating mechanisms for plants growing in saline soil.     

Growth and nutrition of mycorrhizal guayule plants*

Synthesis of mycorrhiza in guayule plants was achieved by inoculation of 8-day-old seedlings with hyphae and chlamydospores of an undescribed Glomus species. There was a five-fold increase in total dry weight of 30-day-old mycorrhizal- compared to nonmycorrhizal-guayule grown in sterile loamy-sand without additional fertiliser. Thirty-day-old, inoculated- and uninoculated-seedlings were transplanted to sterile or unsterile soil and grown an additional 60 days. The greatest total dry weight of guayule was attained by inoculated transplants grown in sterile soil. Inoculated transplants increased two- to three-fold in total dry weight compared to uninoculated transplants, both grown in unsterile soil. After 90 days, uninoculated plants grown in unsterile soil had formed mycorrhizae with resident vesicular-arbuscular mycorrhizal fungi to the same extent as inoculated-plants grown in unsterile soil. Total mineral uptake increased in inoculated guayule, irrespective of soil treatment or the presence of resident VA mycorrhizal fungi.     

The Role of Calcium Nutrition on Fusarium-Wilt Syndrome in Muskmelon

The influence of various calcium salts was evaluated on non-inoculated muskmelon plants and on plants inoculated with the Fusarium-wilt pathogen, and maintained in silica sand or vermiculite. Disease severity of inoculated seedlings maintained in vermiculite was markedly higher than that of seedlings grown in silica sand, and onset of wilt was recorded earlier in the former. These trends were more conspicuous in seedlings treated with Ca²⁺, especially when this cation was accompanied, by nitrate. In vermiculite–compared with silica sand, Mg and K contents in the shoot were higher while Ca values were lower. Irrespective of the form of calcium salt or the plant's growth medium, the Ca concentration was higher in Fusarium-inoculated shoots while K content was depleted, compared with non-inoculated plants.     

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.     

Effect of soil K, Ca and Mg saturation and endomycorrhization on growth and nutrient uptake of sugar maple seedlings

Nutrient imbalances of declining sugar maple (Acer saccharum Marsh.) stands in southeastern Quebec have been associated with high exchangeable Mg levels in soils relative to soil K and Ca. A greenhouse experiment was set up to test the hypothesis that the equilibrium between soil exchangeable K, Ca, and Mg ions influences the growth and nutrient status of sugar maple seedlings. Also tested was whether endomycorrhization can alter nutrient acquisition under various soil exchangeable basic cations ratios. Treatments consisted of seven ratios of soil exchangeable K, Ca, and Mg making up a total base saturation of 58%, and a soil inoculation treatment with the endomycorrhizal fungus Glomus versiforme (control and inoculated), in a complete factorial design. Sugar maple seedlings were grown for 3 months in the treated soils. Plant shoot elongation rate, dry biomass and nutrient concentrations in foliage were influenced by the various ratios of soil cations. The predicted plant biomass and foliar K concentration were highest at a soil Ca saturation of 38%, a soil K saturation of 12%, and a soil Mg saturation of 8%. Potassium concentration in foliage was dependent on the level of Ca and Mg saturation in the soil when soil K saturation was close to 12%. Foliar Ca and Mg levels were more dependent on their corresponding levels in soil than foliar K. Colonization by G. versiforme did not influence seedling growth and macronutrient uptake. The results confirm that growth and nutrition of sugar maple are negatively affected by imbalances in exchangeable basic cations in soils.     

野外模拟酸雨胁迫下接种外生菌根真菌对马尾松幼苗的缓解作用

外生菌根真菌能够提高宿主植物对外界环境胁迫的抵抗力。主要探讨野外条件下外生菌根真菌对酸雨胁迫下马尾松(Pinus massoniana)幼苗生长、养分元素以及表层土壤的影响,以期为酸雨严重区马尾松林恢复提供科学依据。以2年生马尾松幼苗为材料,采用原位试验,共设置6个处理:p H5.6(对照)处理未接种、对照处理接种、p H4.5酸雨处理未接种、p H4.5酸雨处理接种、p H3.5酸雨处理未接种、p H3.5酸雨处理接种。研究表明:(1)酸雨处理与对照处理相比显著降低了非菌根苗总生物量及各部位生物量(根、茎、叶),对株高无显著影响,接种外生菌根真菌可以缓解酸雨对马尾松幼苗生长的不利影响;(2)与对照处理相比,酸雨处理的非菌根苗的针叶中N、P、Ca含量升高,Mg含量降低,根系中N、P、Ca含量降低,Mg含量随p H的降低先升高后降低。接种外生菌根真菌显著提高了p H3.5酸雨处理的马尾松幼苗根系中N、P、Ca、Mg含量,而对针叶中N、P、Ca、Mg含量无显著影响。(3)在非菌根土壤中,p H3.5酸雨处理与对照处理相比显著降低了土壤中有机质、速效磷、速效钾、可溶性碳、可溶性氮、铵态氮、硝态氮含量,而接种外生菌根真菌显著提高了上述指标。酸雨对土壤阳离子交换量无显著影响。总而言之,接种外生菌根真菌促进了酸雨处理的马尾松幼苗生长、缓解了酸雨对马尾松幼苗养分元素和表层土壤的不利影响,由此可见接种外生菌根真菌是减轻酸雨对马尾松危害的一个重要途径。     

Influence of Mycorrhizal Fungus, Phosphorus,and Burrowing Nematode Interactions on Growth of Rough Lemon Citrus Seedlings

Rough lemon seedlings were grown in mycorrhizal-infested or phosphorus-amended soil (25 and 300 mg P/kg) in greenhouse experiments. Plants Were inoculated with the citrus burrowing nematode, Radopholus citrophilus (0, 50, 100, or 200 nematodes per pot). Six months later, mycorrhizal plants and nonmycorrhizal, high-P plants had larger shoot and root weights than did non-mycorrhizal, low-P plants. Burrowing nematode population densities were lower in roots of mycorrhizal or nonmycorrhizal, high-P plants than in roots of nonmycorrhizal, low-P plants; however, differences in plant growth between mycorrhizal and nonmycorrhizal plants were not significant with respect to initial nematode inoculum densities. Phosphorus content in leaf tissue was significantly greater in mycorrhizal and nonmycorrhizal, high-P plants compared with nonmycorrhizal, low-P plants. Nutrient concentrations of K, Mg, and Zn were unaffected by nematode parasitism, whereas P, Ca, Fe, and Mn were less in nematode-infected plants. Enhanced growth associated with root colonization by the mycorrhizal fungus appeared to result from improved P nutrition and not antagonism between the fungus and the nematode.     

Effects of elevated nickel and cadmium concentrations on growth and nutrient uptake of mycorrhizal and non-mycorrhizal Pinus sylvestris seedlings

The effects of Ni and Cd on growth and nutrient uptake of mycorrhizal and non-mycorrhizal Pinus sylvestris L. seedlings were investigated in a pot experiment. Seedlings were either inoculated with Laccaria bicolor (Maire) Orton or left uninoculated before being planted in pots containing a mixture of sandy soil from the B-horizon of a coniferous forest, small stones and pure quartz sand. The pots were supplied with small amounts of a balanced nutrient solution every 24 h using peristaltic pumps. Nickel or Cd were added as chlorides to the nutrient solution at levels of 85 M Ni (Ni 1), 170 M Ni (Ni 2), or 8.9 M Cd. Mycorrhizal colonisation of the roots was nearly 100% in the mycorrhizal treatments. The mycorrhizal seedlings grew significantly better than the non-mycorrhizal ones. The weight of mycorrhizal seedlings in the Ni 2 treatment was 29% lower than that of the mycorrhizal controls, but still 34% greater than that of the non-mycorrhizal seedlings not exposed to metals. There was an overall, statistically significant, negative effect of metals on plant yield. Mycorrhizal plants had lower root:shoot (R:S) ratios than non-mycorrhizal plants and the R:S ratio was increased by metal exposure, particularly in the non-mycorrhizal seedlings. Plant concentrations of Cd or Ni were not affected by mycorrhizal colonisation, but total uptake of Cd and Ni was higher in bigger mycorrhizal seedlings. Nickel decreased P concentration in all seedlings and Cd decreased P concentration in the non-mycorrhizal seedlings. Generally, the mycorrhizal seedlings grew better than non-mycorrhizal ones and had better P, K, Mg and S status. Root growth was not significantly affected by the metal treatments. The reduction in mean shoot growth of non-mycorrhizal plants, relative to the metal-free control, appeared higher than in mycorrhizal plants but was not statistically significant due to high variation in the non-mycorrhizal plants not exposed to metals. The main mycorrhizal effect was thus increased nutrient uptake and growth of the seedlings.     

Growth promoting effect of Azospirillum brasilense on Casuarina cunninghamiana Miq. seedlings

The growth of Casuarina cunninghamiana seedlings was stimulated when inoculated with Azospirillum brasilense. This resulted in a higher biomass production than in uninoculated controls in the presence or absence of a non-nodulating strain of Frankia.Increase in whole plant dry weight was due to a significant increase in both shoot and root biomass, which corresponded with a higher total N content of the plants inoculated with Azospirillum. No such effects were observed under inoculation with a non-nodulating Frankia strain. These results suggest that the growth-promoting substances provided by A. brasilense may have enhanced the growth of Casuarina seedlings.     

The effect of Erwinia carotovora subsp. atroseptica (blackleg) on potato plants. II. Compensatory growth

In field experiments in 1981 and 1982, uninoculated seed tubers (cv. Désirée) and those inoculated with Erwinia carotovora subsp. atroseptica at the rose (apical) or heel (stolon attachment) ends were planted at normal (35 cm) or double spacing; in additional plots, inoculated and uninoculated tubers were planted alternately. Inoculation, especially at the rose end, decreased plant height and sometimes resulted in blackleg symptoms. Individual plant yields were recorded at the end of the season. In plots of uniform seed type at normal spacing, inoculation decreased total yield compared with uninoculated by 12–13% (heel-end inoculation) or 26–40% (rose-end inoculation). At double spacing, yields increased compared with normal spacing by 44–58% (uninoculated or heel-end inoculation) or 30–39% (rose-end inoculation). When rose-end-inoculated and uninoculated seed tubers were planted alternately, inoculated plants yielded less and uninoculated plants more than in plots planted throughout with the same seed treatment. The abilities of inoculated and uninoculated plants to compensate for weak or missing neighbours were combined using equations to predict the yields of crops with different proportions of diseased or missing plants.     

Effect of plant growth promoting <Emphasis Type="Italic">Pseudomonas</Emphasis> spp. on compatible solutes,antioxidant status and plant growth of maize under drought stress

Drought is one of the major abiotic stresses affecting yield of dryland crops. Rhizobacterial populations of stressed soils are adapted and tolerant to stress and can be screened for isolation of efficient stress adaptive/tolerant, plant growth promoting rhizobacterial (PGPR) strains that can be used as inoculants for crops grown in stressed ecosystems. The effect of inoculation of five drought tolerant plant growth promoting Pseudomonas spp. strains namely P. entomophila strain BV-P13, P. stutzeri strain GRFHAP-P14, P. putida strain GAP-P45, P. syringae strain GRFHYTP52, and P. monteilli strain WAPP53 on growth, osmoregulation and antioxidant status of maize seedlings under drought stress conditions was investigated. Drought stress induced by withholding irrigation had drastic effects on growth of maize seedlings. However seed bacterization of maize with Pseudomonas spp. strains improved plant biomass, relative water content, leaf water potential, root adhering soil/root tissue ratio, aggregate stability and mean weight diameter and decreased leaf water loss. The inoculated plants showed higher levels of proline, sugars, free amino acids under drought stress. However protein and starch content was reduced under drought stress conditions. Inoculation decreased electrolyte leakage compared to uninoculated seedlings under drought stress. As compared to uninoculated seedlings, inoculated seedlings showed significantly lower activities of antioxidant enzymes, ascorbate peroxidase (APX), catalase (CAT), glutathione peroxidase (GPX) under drought stress, indicating that inoculated seedlings felt less stress as compared to uninoculated seedlings. The strain GAP-P45 was found to be the best in terms of influencing growth and biochemical and physiological status of the seedlings under drought stress. The study reports the potential of rhizobacteria in alleviating drought stress effects in maize.     

丛枝菌根（AM）对无性繁殖茶苗生长及茶叶品质的影响

采用温室盆栽试验,分别接种丛枝菌根（AM）真菌Acaulospora lavis（光壁无梗球囊霉,菌号：34）、Glomus manihot（木薯球囊霉,菌号：38） 和Glomus caledonium（苏格兰球囊酶,菌号：90036）,观察AM对枝条繁殖茶苗生长和茶叶品质的影响。试验持续14个月。结果表明,接种AM真菌明显促进了无性繁殖茶苗的生长,无论是株高还是地上、地下干重都高于不接种者（CK）,且差异达极显著水平（P<0.01）。AM对茶树吸收无机元素有明显的促进作用,尤其是对P、Ca、Mg等的吸收。接种AM真菌的茶苗根际细菌、放线菌数量和酸性磷酸酶活性都明显高于CK。接种AM真菌还提高了茶叶水浸出物、氨基酸、咖啡碱 和茶多酚的浓度,改善了茶叶的品质。     

Response ofBromus inermis inoculated withGlomus fasciculatum to potassium fertilization and drought stress

Summary Bromus inermis Leyss. was grown in a 2×2×2 factorial design using different levels of mycorrhizal inoculation (inoculated and noninoculated), soil water stress (Ψ₁ or −0.8 MPa) and potassium (K) fertilization (0 or 150 ppm) as factors. Soil water stress and mycorrhizal inoculation significantly reduced plant top dry weight during the 18 week study. Chlamydospore production by the mycorrhizal symbiontGlomus fasciculatum (Thaxter sensu. Gerd.) Gerd. and Trappe was significantly reduced by soil water stress of −0.8 MPa. Potassium (K) fertilization did not significantly influence plant top growth or mycorrhizal colonization. However, foliar Ca and Mg were significantly lower in plants fertilized with K. Foliar Ca and Mg concentrations of P, K, N, Mn, Zn and Cu were significantly greater in drought stressed plants whereas Ca and Mg concentrations were significantly greater in well-watered plants.     

The Content of Elements in Infant Formulas and Drinks Against Mineral Requirements of Children

The present study aimed at analysing the content of fluorine (F), calcium (Ca), magnesium (Mg), iron (Fe) and zinc (Zn) in the drinks for children and infant formulas, a popular supplement or substitute for breast milk produced from cow milk on an industrial scale. Ca, Mg, Zn and Fe concentrations were determined using atomic absorption spectrophotometer, while F levels using a potentiometric method. F levels in the examined formula samples increased with the intended age range, until the intended age of 1 year, and then decreased. A lower content of Ca, Mg and Zn was observed in formulas intended for children <1 year of age and higher for older children. Fe content increased with the age range. A statistically significant higher content of Ca, Mg, Zn and Fe in samples intended for children with phenylketonuria in comparison to those intended for healthy children or children with food allergies was noted. The content of the analysed elements in juices and nectars showed the highest contents in products intended for infants (under 6 months of age). The lowest levels of elements tested were found in drinks for children over 6 months of age. In conclusion, the concentrations of the examined elements in infant formulas and juices for children were decidedly greater than the standards for the individual age groups. Although the absorption of these elements from artificial products is far lower than from breast milk, there is still the fear of consequences of excessive concentrations of these minerals.     

Assessment of AM biotechnology in improving agricultural productivity of nutrient-deficient soil in the tropics

Abstract

Growth, nutrient content and nodulation response of cowpea plants (Vigna unguiculata L. Walp) inoculated with a Arbuscular Mycorrhiza (AM) fungus (Glomus etunicatum) and Bradyrhizobium (BR) strain IRC 25B peat-based were assessed on an alfisol in a two-cropping cycle experiment conducted in the greenhouse. A total of 5 kg sieved unsterilized topsoil plastic pots was amended with compost consisting of 2.4% N, 1.7% P, 2.7% Ca, 0.4% Mg and 0.7% Fe. Analysis from this first cropping cycle showed that all cowpea plants were infected with mycorrhiza in both AM inoculated and uninoculated treatments. However, all the AM inoculated plants had higher infections than the uninoculated cowpea plants. Nevertheless, nodule number and nodule weight of cowpea plants generally increased in response to compost application when used alone, or when combined with BR or AM; except for nodule weight of BR + Compost treatment. At 13 weeks after planting, the plants were harvested for a second cropping cycle experimental analysis. Results showed higher mycorrhizal infections in all the treatments inoculated with AM. However, infection was highest in cowpea plants treated with AM + BR + Compost, followed by those treated with AM + BR. This shows an increase in the number of AM propagules during the period of cropping. All other parameters measured were found generally lower in their mean values compared to the first cropping cycle. It was observed in this study that compost applications with AM inoculation could substitute for inorganic fertilizer. Thus, tropical countries should direct their efforts towards making the best use of AM to improve conditions for the peasant farmers that account for over 70% agricultural productivity in the region.     

The effects of soil sterilization, mycorrhizal inoculation, and rates of phosphorus on growth and survival of Kalopanax septemlobus microplants during the acclimatization period

In order to establish some cultural practices that can improve growth and survival of somatic embryo (SE)-derived microplants during the acclimatization period, Kalopanax septemlobus was uninoculated or inoculated with mycorrhizal fungi coded as AMM6 (a mixture of unidentified species of Glomus and Acaulospora collected in a closed mine tailing site in Bonghwa, Korea) during ex vitro and grown in oven-sterilized peat vermiculite medium. After 2 months, treated microplants were transferred into pots filled with the same medium amended with phosphorus fertilizer {0, 2, 4, 8, 16 and 32 mg P [as Ca(H₂PO₄)₂·H₂O] kg medium^?1 coded as P0, P2, P4, P8, P16 and P32, respectively}. At this stage, inoculated plants were greener, with broader leaves and well-developed root systems and had higher survival than the uninoculated ones. After 6 months, inoculated plants were 54 % heavier than the uninoculated counterpart. In sterile medium, total dry weight of uninoculated plants was promoted at P8 and highest at P16. Total dry weight at P16 by uninoculated plants was attained at P4 by the mycorrhiza-inoculated counterpart. In non-sterile medium, total dry weight of inoculated plants was increased at P8. By contrast, uninoculated plants did not respond to the applied P rates. In conclusion, more SE-derived microplants survived and grew better in sterile medium. Maximum benefits from AMM6 was attained with applied 4 and 8 mg P kg medium^?1 (P4–P8) in sterile and non-sterile medium, respectively.     

Nitrogen source effects on rhizosphere pH and nutrient accumulation by Pacific Northwest conifers

Growth responses ofCasuarina cunninghamiana to inoculation withFrankia are described in unsterilized field soils at three sites. At Mt Crawford, South Australia, seedlings of three provenances ofC. cunninghamiana were inoculated with a singleFrankia source just prior to planting out. Forty-four months after planting, inoculation had more than doubled wood production by twoC. cunninghamiana provenances, whilst a third provenance grew poorly and did not respond to inoculation. In Zimbabwe, seedlings of one provenance ofC. cunninghamiana were inoculated in the nursery with one of four differentFrankia strains. In an N deficient soil at Kadoma, three of theseFrankia increased tree height 14 months after planting by between 50% and 70% in comparison to the uninoculated seedlings. The fourthFrankia strain resulted in increased tree height to three times that of the uninoculated controls and up to double that of the other threeFrankia strains. At Gympie, Queensland, Australia, seedlings ofC. cunninghamiana raised open-rooted in a nursery bed were inoculated withFrankia seventeen weeks before planting out. During the 22 months following planting in the field, tree growth was limited by soil P status and there was no response in tree height or stem diameter to inoculation withFrankia or to N fertilizer unless P was applied. In the presence of added P there was a significant response both toFrankia inoculation and to N fertilizer. This positive interaction between P application and N treatment was reflected in wood volumes-inoculated trees and those trees supplied N fertilizer produced 34% and 95% more wood volume than did the uninoculated trees. These results demonstrate the potential to increase the productivity of Casuarina plantings by inoculation withFrankia and by alleviation of P deficiency.     

Differences in the effects of three arbuscular mycorrhizal fungal strains on P and Pb accumulation by maize plants

The effect of arbuscular mycorrhizal (AM) fungi on the accumulation and transport of lead was studied in a pot experiment on maize plants grown in anthropogenically-polluted substrate. The plants remained uninoculated or were inoculated with different Glomus intraradices isolates, either indigenous to the polluted substrate used or reference from non-polluted soil. A considerably lower tolerance to the conditions of polluted substrate was observed for the reference isolate that showed significantly lower frequency of root colonisation as well as arbuscule and vesicule abundance. Plants inoculated with the reference isolate also had significantly lower shoot P concentrations than plants inoculated with the isolate from polluted substrate. Nevertheless, inoculation with either indigenous or reference G. intraradices isolate resulted in higher shoot and root biomass and inoculated plants showed lower Pb concentrations in their shoots than uninoculated plants, regardless of differences in root colonisation. Root biomass of maize plants was divided according to AM-induced colouration into brightly yellow segments intensively colonised by AM fungus and non-colonised or only slightly colonised whitish ones. Intensively colonised segments of the isolate from polluted substrate contained significantly higher concentrations of phosphorus and lead than non-colonised ones, which suggest significant participation of fungal structures in element accumulation. Responsible Editor: Peter Christie.     

Responses to Mg/Ca balance in an Iranian serpentine endemic plant, Cleome heratensis (Capparaceae) and a related non-serpentine species, C. foliolosa

A soil Ca/Mg quotient greater than unity is generally considered necessary for normal plant growth but some serpentine plants are adapted to much lower Ca/Mg quotients, resulting from a major cation imbalance in their substrata. In order to investigate the growth and tolerance responses of serpentine and non-serpentine species to varied Ca/Mg quotients, controlled nutrient solution experiments were performed using an a newly reported Iranian endemic serpentine plant, Cleome heratensis Bunge et Bien. Ex Boiss. and a related non-serpentine species Cleome foliolosa DC. and a Eurasian Ni-hyperaccumulating species Alyssum murale Waldst. and Kit. Seedlings were grown in modified Hoagland’s solutions with varying Ca and Mg concentrations (0.2–2.5 and 0.5–10 mM, respectively) in a fully factorial randomised block design. The yields of the two serpentine plants increased significantly as Mg concentrations in the nutrient solution were increased from 0.5 to 4 mM but decreased in the 10 mM Mg treatment. For C. foliolosa yields decreased significantly from 0.5 to 10 mM Mg, indicating the sensitivity of this non-serpentine plant, and the relative tolerance of the serpentine plants to extremely high levels of Mg. Shoot and root Mg and Ca concentrations in C. heratensis and A. murale were higher than those in C. foliolosa in the low and moderate Mg treatments, supporting the view that many serpentine plants have a relatively high requirement for Mg. Maximum Mg concentrations were found in the roots of C. heratensis. Yields of C. heratensis and A. murale did not change significantly as Ca levels in nutrient solution increased from 0.2 to 2.5 mM Ca, However the yield of C. foliolosa increased significantly from 0.2 to 1.5 mM Ca, indicating sensitivity in this non-serpentine plant and tolerance of the two serpentine plants to low levels of Ca correlated with tissue Ca concentrations, probably because of a greater ability for Ca uptake at low-Ca availability. Calcium deficiency in the low-Ca treatments could be a reason for reduced yield in the non-serpentine plants.