Soil salt and nutrient concentration in the rhizosphere of desert halophytes

North-West China is an arid region where halophyte plants are rich. Very little is known on the rhizospheric soil of the halophytes in this arid desert region. We conducted a rhizobag experiment on the desert Solonchak soil to investigate the salt and nutrient content in the rhizospheric soil of the desert halophytes. The total salt and the concentrations of 8 major kinds of salt ions increased in the rhizosphere of both succulent halophytes and salt secreting halophytes, but this increase was insignificant for salt-resisting halophytes. Accumulation of Cl^– and Na⁺ is the most significant among the 8 major kinds of salt ions. Accumulation of Cl^– was more significant than that of SO₄^2– in succulent halophytes and salt secreting halophytes. The Na⁺/K⁺, Na⁺/Ca²⁺ and Na⁺/Mg²⁺ ratios in the rhizosphere of all 7 kinds of halophytes were higher than those in the bulk soil. Total N increased significantly in the rhizosphere, but total P and total K decreased. However, the available N, P and K in the rhizosphere of the 7 kinds of halophytes except Phragmites communis Trin. behaved in such an opposite way that available N decreased but available P and available K increased. The ionic contents in the aboveground parts were higher than those in the underground parts of the 7 kinds of halophytes, in particular of both the succulent halophytes and the salt secreting halophytes. Accumulation of Cl^– and Na⁺ in the aboveground parts of the plants was the most significant among that of the 8 major kinds of salt ions.     

EFFECTS OF THE HALOPHYTES TECTICORNIA INDICA AND SUAEDA FRUTICOSA ON SOIL ENZYME ACTIVITIES IN A MEDITERRANEAN SABKHA

In the present work, we studied the effectiveness of the predominant halophytes of Soliman sabkha (Tecticornia indica and Suaeda fruticosa) to promote soil biological activities and ecosystem productivity. Soil Arylsulphatese ARY, β-glucosidase β-GLU, phosphatase PHO, invertase INV, urease URE, and dehydogenase DES activities in Extra- and Intra-tuft halophytes and plant productivity were assessed. Results revealed a high increase of microbial community and ARY, β-GLU, PHO, INV, URE and DES activities (+298%, +400%, +800%, +350%, +320%, +25% and +759%, respectively) in Intra-tuft rhizosphere as compared to Extra-tuft one, which is likely due to the significant decrease of salinity in the rhizosphere of Tecticornia indica and Suaeda fruticosa. Both perennial plants exhibited high productivities (7.4 t dry weight ha^?1 and 2.2 t dry weight ha^?1, respectively) and Na⁺-hyperaccumulating capacities (0.75 t Na⁺ ha^?1 and 0.22 t Na⁺ ha^?1, respectively), reducing salt constraint and favouring soil fertility. This constitutes a promising alternative to enhance productivity in such a salt-affected biotope by offering suitable microhabitat for annual glycophytes.     

Effect of sodium chloride on the response of the halophyte species <Emphasis Type="Italic">Sesuvium portulacastrum</Emphasis> grown in mannitol-induced water stress

Sesuvium portulacastrum is a halophytic species well adapted to salinity and drought. In order to evaluate the physiological impact of salt on water deficit-induced stress response, we cultivated seedlings for 12 days, in the presence or absence of 100 mmol l⁻¹ NaCl, on a nutrient solution containing either 0 mmol l⁻¹ or 25 mmol l⁻¹ mannitol. Mannitol-induced water stress reduced growth, increased the root/shoot ratio, and led to a significant decrease in water potential and leaf relative water content, whereas leaf Na⁺ and K⁺ concentrations remained unchanged. The addition of 100 mmol l⁻¹ NaCl to 25 mmol l⁻¹ mannitol-containing medium mitigated the deleterious impact of water stress on growth of S. portulacastrum, improved the relative water content, induced a significant decrease in leaf water potential and, concomitantly, resulted in enhancement of overall plant photosynthetic activity (i.e. CO₂ net assimilation rate, stomatal conductance). Presence of NaCl in the culture medium, together with mannitol, significantly increased the level of Na⁺ and proline in the leaves, but it had no effect on leaf soluble sugar content. These findings suggest that the ability of NaCl to improve plant performance under mannitol-induced water stress may be due to its effect on osmotic adjustment through Na⁺ and proline accumulation, which is coupled with an improvement in photosynthetic activity. A striking recovery in relative water content and growth of the seedlings was also recorded in the presence of NaCl on release of the water stress induced by mannitol.     

Phytoextraction of heavy metals by Sesuvium portulacastrum l. a salt marsh halophyte from tannery effluent

The present study investigated the sources for remediation of heavy metals and salts from tannery effluent using salt marsh halophyte Sesuvium portulacastrum. From the results observed, in tannery effluent treated soil from 1 kg dry weight of plant sample, Sesuvium portulacastrum accumulated 49.82 mg Cr, 22.10 mg Cd, 35.10 mg Cu and 70.10 mg Zn and from 1 g dry weight of the plant sample, 246.21 mg Na Cl. Cultivation of Sesuvium portulacastrum significantly reduced the EC, pH and SAR levels in tannery effluent and salt treated soil and correspondingly increased in plant sample after 125 days of cultivation. In conclusion, Sesuvium portulacastrum was an efficient in accumulating heavy metals such as Chromium, Cadmium, Copper and Zinc, sodium and chloride maximum through its leaves when compared to stem and root. The finding of these bioacccumulation studies indicates that Sesuvium portulacastrum could be used for phytoremediation of tannery effluent contaminated field.     

不同耐盐植物根际土壤盐分的动态变化

以甘肃秦王川引大灌区盐渍化土壤为研究背景,用盆栽根袋法对4种耐盐植物根际和非根际土壤pH和盐分离子的动态变化进行了分析比较。结果表明:4种待测植物随着培养时间的延长土壤pH和EC值呈降低趋势。新疆大叶(Medicago Sativa L.cv.Xinjiangdaye)、向日葵(Helianthus annuus)和霸王(Zygophyllum xanthoxylum)生长90 d后根际土壤pH明显低于非根际,而裸麦(Hordeum vulgare var. vulgare)根际较非根际pH差异不大。霸王和新疆大叶根际土壤EC值较非根际高,而裸麦和向日葵的根际与非根际差异不大。4种供试植物根际K⁺均出现亏缺,Ca²⁺、Na⁺、Mg²⁺、SO^2-₄和Cl^-在新疆大叶、霸王和向日葵3种植物根际均出现富集,对于裸麦:Ca²⁺、Mg²⁺和SO^2-₄ 3种离子在植物根际富集,而Cl^-和Na⁺在根际亏缺。随着待测植物培养时间的增加Na⁺/K⁺、Na⁺/Ca²⁺和Na⁺/Mg²⁺ 这3个比值呈降低趋势,说明Na⁺相对于K⁺、Ca²⁺和Mg²⁺的含量降低,生物措施对Na⁺的移除效果较显著。     

Relationship between cation accumulation and water content of salt-tolerant grasses and a sedge

Abstract Salt-tolerant grasses and a sedge were grown at three salinities in a controlled-environment greenhouse. They were measured for growth rate, ash content, water content and cations. Fourteen species from the genera Sporobolus, Aeluropus, Leptochloa, Paspalum, Puccinellia, Hordeum, Elymus, Distichlis and Spartina survived up to the highest salt treatment (540 mol m^?3 NaCl). These were designated halophytes. Eleven species from the genera Triticum, Phragmites, Dactylotenium, Cynodon, Polypogon, Panicum, Jovea and Heleocharis only survived up to 180 mol m^?3 NaCl and were designated salt-tolerant glycophytes. All species except Distichlis palmeri grew fastest on the non-saline control treatment. All species tended to have higher Na⁺ contents and lower K⁺ and water contents on saline treatments compared to control plants. Halophytes differed from glycophytes in having statistically significant lower water contents on the non-saline treatment, and lower ash contents and Na:K ratios on 180 mol m^?3. However, the range of values among species was greater than the differences between halophytes and glycophytes. All species appeared to use Na⁺ accumulation and loss of water as the main means of osmotic adjustment. Three halophytic species were grown for a longer period of time to check the above results. The osmolality of the cell sap was measured directly by the vapour pressure method and compared to calculated values based on Na⁺, K⁺ and water contents (and assuming a balancing anion such as Cl^?). Na⁺ and K⁺ alone could account for greater than 75% of the osmotic potential at all salinities. Hence, the accumulation of organic solutes did not appear to be an important factor in the osmotic adjustment of these species. The results support the conclusion that grasses coordinate Na⁺ uptake and water loss to maintain a constant osmotic potential gradient between the shoot tissues and the external solution. The results were compared to a previous study with dicotyledonous halophytes at the same location.     

Influence of rhizosphere on the nutrient status of dwarf French beans

French bean seedlings grown on choline, ammoniacal and nitrate forms of nitrogen together with equivalent basal application of P as KH₂PO₄ were tested for nutrient uptake from the rhizosphere. Statistical tests on soil (rhizosphere and non-rhizosphere) and plant (root and shoot) revealed that with the exception of P, levels of all other estimated macro-(Na⁺, K⁺, Ca²⁺, Mg²⁺) and micro-nutrients (Fe²⁺, Mn²⁺, Zn²⁺) were significantly changed after 42 days growth as compared to 21 days growth period. The higher uptake into shoots of Na⁺, K⁺, Fe²⁺, Mn²⁺, Zn²⁺ and H₂PO₄ ⁻ and higher biomass accumulation in the rhizosphere were associated with lower rhizosphere pH. The uptake of Ca²⁺ and Mg²⁺ increased with higher rhizosphere pH. While ammoniacal and choline forms decreased rhizosphere pH and increased the P uptake, nitrate form reversed the trend showing significant inverse relationship between shoot phosphate and rhizosphere pH. Calcium and iron were associated with an inhibition of the translocation of P from root to shoot. However, no causal relationships could be established. Both shoot weight and shoot P content were closely associated with a number of rhizosphere soil parameters. The paper forms a part of the Ph. D thesis submitted by the first author to the University of Wales, 1977.     

Cd-induced growth reduction in the halophyte <Emphasis Type="Italic">Sesuvium portulacastrum</Emphasis> is significantly improved by NaCl

The effects of Cd²⁺ and NaCl, applied together or separately, on growth and uptake of Cd²⁺ were determined for the halophyte Sesuvium portulacastrum L. Seedlings were cultivated in the presence of 50 or 100 μmol L⁻¹ Cd²⁺ alone or combined with 100 or 400 mmol L⁻¹ NaCl. Data showed that alone, Cd²⁺ induced chlorosis, necrosis, and inhibited growth. Addition of NaCl to Cd²⁺-containing medium restored growth and alleviated the toxicity, however. NaCl also enhanced the amounts of Cd²⁺ accumulated in the shoots. All Cd²⁺ treatment reduced K⁺ and Ca²⁺ uptake and transport to the shoots. Accumulation of Na⁺ in the shoots was not affected by Cd²⁺, however. Thus S. portulacastrum maintained its halophytic characteristics in the presence of Cd²⁺. We suggest this halophyte could be used for phytoextraction of Cd²⁺ from salt-contaminated sites.     

Salt Tolerance and Crop Potential of Halophytes

Although they represent only 2% of terrestrial plant species, halophytes are present in about half the higher plant families and represent a wide diversity of plant forms. Despite their polyphyletic origins, halophytes appear to have evolved the same basic method of osmotic adjustment: accumulation of inorganic salts, mainly NaCl, in the vacuole and accumulation of organic solutes in the cytoplasm. Differences between halophyte and gly-cophyte ion transport systems are becoming apparent. The pathways by which Na⁺ and Cl^? enters halophyte cells are not well understood but may involve ion channels and pinocytosis, in addition to Na⁺ and Cl^? transporters. Na⁺ uptake into vacuoles requires Na⁺/H⁺ antiporters in the tonoplast and H⁺ ATPases and perhaps PP_i ases to provide the proton motive force. Tonoplast antiporters are constitutive in halophytes, whereas they must be activated by NaCl in salt-tolerant glycophytes, and they may be absent from salt-sensitive glycophytes. Halophyte vacuoles may have a modified lipid composition to prevent leakage of Na⁺ back to the cytoplasm. Becuase of their diversity, halophytes have been regarded as a rich source of potential new crops. Halophytes have been tested as vegetable, forage, and oilseed crops in agronomic field trials. The most productive species yield 10 to 20 ton/ha of biomass on seawater irrigation, equivalent to conventional crops. The oilseed halophyte, Sali-cornia bigelovii, yields 2?t/ha of seed containing 28% oil and 31% protein, similar to soybean yield and seed quality. Halophytes grown on seawater require a leaching fraction to control soil salts, but at lower salinities they outperform conventional crops in yield and water use efficiency. Halophyte forage and seed products can replace conventional ingredients in animal feeding systems, with some restrictions on their use due to high salt content and antinutritional compounds present in some species. Halophytes have applications in recycling saline agricultural wastewater and reclaiming salt-affected soil in arid-zone irrigation districts.     

Impact of defoliation intensities on plant biomass,nutrient uptake and arbuscular mycorrhizal symbiosis in Lotus tenuis growing in a saline‐sodic soil

The impact of different defoliation intensities on the ability of Lotus tenuis plants to regrowth, mobilise nutrients and to associate with native AM fungi and Rhizobium in a saline‐sodic soil was investigated. After 70 days, plants were subjected to 0, 25, 50, 75 and 100% defoliation and shoot regrowth was assessed at the end of subsequent 35 days. Compared to non‐defoliated plants, low or moderate defoliation up to 75% did not affect shoot regrowth. However, 100% treatment affected shoot regrowth and the clipped plants were not able to compensate the growth attained by non‐defoliated plants. Root growth was more affected by defoliation than shoot growth. P and N concentrations in shoots and roots increased with increasing defoliation while Na⁺ concentration in shoots of non‐defoliated and moderately defoliated plants was similar. Non‐defoliated and moderately defoliated plants prevented increases of Na⁺ concentration in shoots through both reducing Na⁺ uptake and Na⁺ transport to shoots by accumulating Na⁺ in roots. At high defoliation, the salinity tolerance mechanism is altered and Na⁺ concentration in shoots was higher than in roots. Reduction in the photosynthetic capacity induced by defoliation neither changed the root length colonised by AM fungi nor arbuscular colonisation but decreased the vesicular colonisation. Spore density did not change, but hyphal density and Rhizobium nodules increased with defoliation. The strategy of the AM symbiont consists in investing most of the C resources to preferentially retain arbuscular colonisation as well as inoculum density in the soil.     

长苞香蒲对人工盐碱湿地Na+和K+的吸收与转运特征

为揭示长苞香蒲(Typha domingensis)对盐生湿地生态系统中Na⁺和K⁺的吸收与转运特征,探讨长苞香蒲对盐生湿地的生态修复效果,该研究采用人工模拟盐生湿地的方法,设置CK(对照)、T1(浇灌100 mmol·L^-1盐水)、T2(浇灌200 mmol·L^-1盐水)及T3(浇灌300 mmol·L^-1盐水)4种不同盐浓度的人工湿地生态系统,并分别于5月5日(开始盐胁迫处理,S0)、5月30日(S1)、6月30日(S2)和7月30日(S3)测量其株高和干重、植株地上与地下部分Na⁺和K⁺的含量以及底泥和水体中Na⁺和K⁺的含量以分析长苞香蒲对盐碱湿地的脱盐作用。结果表明：(1)各处理的长苞香蒲的株高和干重随着处理时间的延长呈增加趋势,但与CK相比,各处理生长量随盐浓度升高出现下降趋势。(2)高浓度盐处理(T3)使长苞香蒲的地上部分和地下部分的Na⁺分别增加了2.5...     

Biochemical,physiological and growth changes in response to salinity in callus cultures of <Emphasis Type="Italic">Sesuvium portulacastrum</Emphasis> L.

In vitro-grown cells of Sesuvium portulacastrum L., an important ‘salt accumulator’ mangrove associate, were incubated on a medium containing different levels of salt, including 0, 100, 200, or 400 mM NaCl, in order to evaluate biochemical, physiological, and growth responses. A significant decrease in callus growth, water status, and cell membrane damage was observed under salt stress. Osmotic adjustment was revealed by the accumulation of inorganic ions, such as sodium (Na⁺), and organic osmolytes (proline, glycine betaine, and total soluble sugars) in NaCl-treated calli compared to control. However, accretion of osmolytes and inorganic ions did not support growth of calli under NaCl stress conditions. The observed reduced growth rate in calli subjected to stress, up to 200 mM NaCl, was coupled with lower catalase and ascorbate peroxidase activities and with a significantly higher superoxide dismutase activity. These findings suggested that S. portulacastrum cell cultures exhibited higher osmotic adjustment to salt stress.     

Regulated alterations in redox and energetic status are the key mediators of salinity tolerance in the halophyte <Emphasis Type="Italic">Sesuvium portulacastrum</Emphasis> (L.) L

The present work addresses the importance of antioxidant, redox and energetic parameters in regulating salt-tolerance in Sesuvium portulacastrum. Experiments were conducted on 45 days old plants subjected to 250 and 1,000 mM NaCl stress for 2–8 days. Plants showed no significant change in growth parameters (shoot length, dry weight, and water content) at 250 mM NaCl as compared to control. However, growth of plants was significantly affected at 1,000 mM NaCl. The differential growth behaviour could be attributed to a greater decline in the energetic parameters (in terms of ratios of NADP/NADPH and ATP/ADP) at 1,000 mM NaCl than at 250 mM NaCl. The osmotic stress imposed to plants at 250 mM NaCl was presumably balanced by the accumulation of sodium ions (Na⁺), an energetically favorable process, and did not require an increased synthesis of proline. In contrast, to counter osmotic stress at 1,000 mM NaCl, plants accumulated Na⁺ as well as proline and were, therefore, energetically stressed. Further, the response of enzymatic and molecular antioxidants at 1,000 mM was either close to or even lower than that at 250 mM, which resulted in oxidative damage at 1,000 mM, particularly on longer durations. In conclusion, it is suggested that altered redox and energetic status of the plants could play a key role in mediating the tolerance of Sesuvium under salinity stress.     

Foliar and root absorption of Na+ and Cl− in maize and barley: Implications for salt tolerance screening and the use of saline sprinkler irrigation

Above-canopy sprinkler irrigation with saline water favours the absorption of salts by wetted leaves and this can cause a yield reduction additional to that which occurs in salt-affected soils. Outdoor pot experiments with both sprinkler and drip irrigation systems were conducted to determine foliar ion accumulation and performance of maize and barley plants exposed to four treatments: nonsaline control (C), salt applied only to the soil (S), salt applied only to the foliage (F) and salt applied to both the soil and to the foliage (F+S). The EC of the saline solution employed for maize in 1993 was 4.2 dS m^–1 (30 mM NaCl and 2.8 mM CaCl₂) and for barley in 1994, 9.6 dS m^–1 (47 mM NaCl and 23.5 mM CaCl₂). The soil surface of all pots was covered so that in the F treatment the soil was not salinized by the saline sprinkling and drip irrigation supplied nutrients in either fresh (treatments C and F) or saline water (treatments S and F+S).Saline sprinkling increased leaf sap Na⁺ concentrations much more than did soil salinity, especially in maize, even though the saline sprinkling was given only two or three times per week for 30 min, whereas the roots of plants grown in saline soil were continuously exposed to salinity. By contrast, leaf sap Cl^– concentrations were increased similarly by saline sprinkling and soil salinity in maize, and more by saline sprinkling than saline soil in barley. It is concluded that barley leaves, and to a greater extent maize leaves, lack the ability to selectively exclude Na⁺ when sprinkler irrigated with saline water. Moreover, maize leaves selectively absorbed Na⁺ over Cl^– whereas barley leaves showed no selectivity. When foliar and root absorption processes were operating together (F+S treatment) maize and barley leaves accumulated 11–14% less Na⁺ and Cl^– than the sum of individual absorption processes (treatment F plus treatment S) indicating a slight interaction between the absorption processes. Vegetative biomass at maturity and cumulative plant water use were significantly reduced by saline sprinkling. In maize, reductions in biomass and plant water use relative to the control were of similar magnitude for plants exposed only to saline sprinkling, or only to soil salinity; whereas in barley, saline sprinkling was more detrimental than was soil salinity. We suggest that crops that are salt tolerant because they possess root systems which efficiently restrict Na⁺ and Cl^– transport to the shoot, may not exhibit the same tolerance in sprinkler systems which wet the foliage with saline water. ei]T J Flowers     

淋洗与植物作用耦合对盐渍化土壤的改良效应

以甘肃秦王川引大灌区盐渍化土壤为背景,以当地5种耐盐植物为材料,采用根袋法盆栽试验动态研究了淋洗结合植物种植对盐渍化土壤改良的效应。结果表明:与种前相比,单纯的淋洗作用对土壤pH值影响不大,而淋洗结合植物种植明显降低了土壤pH值,且根际土壤pH值小于非根际土壤的,5种耐盐植物中霸王根际土壤pH值降低幅度最大,达0.6个单位。K+、Ca2+、Na+、Mg2+、Cl-和SO2-4在5种植物根际土壤中均有不同程度的富集,富集程度因物种的不同而不同,随培养时间的延长而呈波动状态。5种供试植物和对照组土壤中的6种主要的可溶性盐分离子随淋洗次数和培养时间的延长呈下降趋势。在培养120d后,单纯淋洗的土壤中K+、Ca2+、Na+、Mg2+、Cl-和SO2-4的含量相比种前平均分别降低了33.3%、26.1%、35.6%、32.5%、35.5%和36.3%,植物吸收带走的上述各离子的含量平均分别占种前的46.2%、8.1%、30.2%、7.2%和21.6%,其中霸王吸收带走的盐分离子最多,而淋洗结合种植植物的土壤中上述各离子的含量与种前相比平均分别降低了67.25%、63.73%、83.8%、67.5%、81.55%和78.46%,由此可见,淋洗结合植物种植的脱盐效果优于单纯淋洗,且土壤中主要的盐分离子Na+、Cl-和SO2-4的含量降低幅度最大,通过计算得出,在Cl-、SO2-4和Na+减少的总量中还有37.73%的Na+、38.22%的Cl-和35.14%的SO2-4的减少量是由植物根系的物理化学作用机制引起的。     

新疆北部主要盐生植物根部内生细菌群落结构的高通量分析

【目的】揭示同一盐渍环境中不同种盐生植物根部内生细菌群落多样性特征和分布规律,结合根际土壤理化因子探讨其对内生细菌群落结构的影响。【方法】通过罗氏454高通量测序获得内生细菌16S r RNA片段,然后进行生物信息分析。【结果】研究的16种盐生植物其内生细菌群落主要由Proteobacteria、Tenericutes、Actinobacteria和Firmicutes 4个门的细菌组成。从植物"种"的水平来看,不同种盐生植物内生细菌群落存在差异;从植物"属"的水平来看,同一属的盐生植物内生细菌相似;从植物"科"的水平来看,藜科盐生植物内生细菌以Actinobacteria和Proteobacteria门为主;蒺藜科盐生植物内生细菌以Proteobacteria门为主;柽柳科盐生植物内生细菌以Tenericutes门为主;白花丹科盐生植物内生细菌以Proteobacteria、Fimicutes和Actinobacteria门为主。根际土壤中Cl~–含量对盐生植物内生细菌群落变化具有显著影响;而Cl~–、Mg~(2+)和总氮组成的集合与内生细菌群落结构相关性最高。【结论】盐生植物内生细菌多样性丰富。在同一盐渍生境中,盐生植物内生细菌群落分布呈现宿主的种属特异性,根际土壤中Cl~–是影响其内生细菌群落变化的主要驱动因素之一。     

Enzymatic degradation of the antibiotic sulfamethazine by using crude extracts of different halophytic plants

Abstract

The biodegradation of the antibiotic sulfamethazine (SMT) by using different crude extracts of halophytes was investigated. For this purpose, crude water extracts of the halophytes Chenopodium quinoa, Sesuvium portulacastrum, and Tripolium pannonicum were prepared. Different amounts of SMT were added to the different extracts (final concentration of 1, 2, and 5?mg L^?1) and incubated at 37?°C. Crude extracts of T. pannonicum were further used to evaluate the degradation rate over time. In order to evaluate the influence of endophytic or naturally plant-associated microorganisms on the biodegradation of SMT, extracts from plants grown in sterile and non-sterile conditions were compared. SMT was analyzed by liquid chromatography coupled to positive ion electrospray mass spectrometry (ESI LC-MS). Based on the findings, crude extracts of T. pannonicum have a high potential to biodegrade SMT with a decrease up to 85.4% (4.27?±?0.10?mg L^?1) from an initial concentration of 5?mg L^?1. The lowest activity was obtained using extracts of C. quinoa with degradation of 4.5%. Extracts of plants cultivated under sterile and non-sterile conditions do not have any significant difference in SMT degradation. Therefore, microorganisms and their enzymatic activities do not seem to play a significant role during this process.     

The effect of competition and edaphic conditions on the establishment of halophytes on brine effected soils

In order to test the feasibility of using native halophytes to reclaim brinecontaminated soil, seedlings of five inland halophytes, Atriplexprostrata, Hordeum jubatum, Salicornia europaea, Spergularia marina, and Suaeda calceoliformis, were planted at threedensities on a site near Athens, Ohio which had been contaminated by oilwell brine water. Ten replicates of each density treatment weretransplanted on two distinct areas of high and low salinity in May of 1993. Seedling survivorship, soil moisture, and soil salinity were monitored weeklythroughout the growing season. Biomass production and ion uptake weredetermined for each plant surviving until harvest. Soil analyses wereperformed prior to planting and after harvest to determine overall changesin soil chemistry and to determine the amount of Na⁺ reductionfrom the soil due to leaching by precipitation during the course of theexperiment. Survival was determined to be density independent for all ofthe species with the exception of S. marina where survival wasfacilitated at high density. Increased salinity negatively affected the survivaland yield of A. prostrata. The remaining species had greater survivalunder high salinity conditions, and density appeared to be the key factorinfluencing yield. Sodium and chloride ions were accumulated in planttissues in much greater amounts than K⁺, Ca⁺²or Mg⁺². Salicornia europaea plants grown in high densityon the high salinity site accumulated the highest amount of Na⁺ andH. jubatum grown in low density on the high salinity site accumulatedthe lowest amount of Na⁺. Soil salinities measured directly from theroot zone were significantly reduced (p<0.05) at the end of thegrowing season when compared to their controls. Atriplex prostrata(high density/low salinity) plots produced the greatest reduction in soilsalinity (15.8%) and S. marina (high density/high salinity) plots hadthe least reduction (1.2%).