Saline Soil Samples Research Articles

Modelling the concentration or dilution of saline soil‐water systems

SummaryFor the survey of saline and alkali soils sampling soil solution in situ is difficult. An alternative is to take soil samples, analyse their extracts and then calculate the chemical composition of the soil solution. A model (EXPRESO) has been designed to calculate both the chemical speciation of electrolyte solution and the exchange equilibrium with an adsorbed phase during simulated dilution and concentration. EXPRESO was validated using reclaimed saline soil samples. Results demonstrated that EXPRESO is a thermodynamically coherent and mass conservative model that allows the calculation of the chemical composition of both the soil solution and the exchange complex over a large range of soil water content (0.250–5 kg water kg–1 soil). EXPRESO enables the estimation of the chemical composition of the in situ soil solution, giving a comprehensive picture of the soil status under different field conditions. Modélisation de la concentration ou de la dilution des systèmes eau‐sols salés Résumé

Actinopolyspora iraqiensis sp. nov., a New Halophilic Actinomycete Isolated from Soil

Halophilic actinomycete strains, IQ-H1T (T = type strain) and IQ-H2, were isolated from extremely saline soil samples in Iraq. Besides morphological properties, strains IQ-H1T and IQ-H2 have a type IV cell wall, type PIII phospholipid, and menaquinone MK-9 (H4, H6), which are characteristic of Actinopolyspora spp. In addition, both strains required high concentrations of sodium chloride (10 to 15% [wt/vol] and 15 to 25% [wt/vol] NaCl, respectively), for optimal growth. However, strains IQ-H1T and IQ-H2 differed from other previously described species of the genus Actinopolyspora in cultural, morphological, and physiological characteristics. In addition, the size of the internal transcribed spacer in the rDNA (gene encoding rRNA) of IQ-H1T was different from those of known published species, while the size of the internal transcribed spacer of IQ-H2 was similar to that of Actinopolyspora halophila JCM 3278T. Thus, we propose strain IQ-H1T as a new species and name it Actinopolyspora iraqiensis sp. nov. Strain IQ-H1T has been deposited in the culture collection of the Institute of Microbiology, Academia Sinica, Beijing, the People's Republic of China (strain A.S. 4.1193).

Nocardiopsis halophila sp. nov., a New Halophilic Actinomycete Isolated from Soil

A new species, Nocardiopsis halophila, is proposed. This species is represented by a single isolate obtained from a saline soil sample in Iraq. This organism grows in both synthetic and organic media containing concentrations of NaCl up to 20% (wt/vol) and is resistant to lysozyme. Whole-cell hydrolysates contain meso-diaminopimelic acid (cell wall type III) and no diagnostic sugars (sugar pattern C). The phospholipid type is type PHI. The predominant menaquinone is MK-10(H6,H8), and mycotic acids are absent. This organism forms abundant white aerial mycelia and long irregularly branched spore chains that have a zigzag appearance and fragment into spores of various lengths. The substrate mycelia are extensively branched and are rarely fragmented. These properties suggest that this bacterium should be placed in the genus Nocardiopsis. However, this organism differs from all previously described species of the genus Nocardiopsis in its ability to grow in the presence of 20% (wt/vol) NaCl and also in many other physiological and biochemical characteristics. Thus, we propose that this organism is a new species, Nocardiopsis halophila. Type strain IQ-H3 has been deposited in the Culture Collection of the Institute of Microbiology, Academia Sinica, Beijing, People’s Republic of China, as strain A.S.4.1195.

Improved Growth of Tomato in Salinized Soil by Vesicular-Arbuscular Mycorrhizal Fungi Collected from Saline Soils

Vesicular-arbuscular (VA) mycorrhizal fungi were collected and identified from saline locations throughout southern and central California and Nevada. From this collection, 38 soil samples containing VA mycorrhizal fungi from 22 plant species were used to inoculate tomato seedlings and evaluate their growth under artificial salinization. Six samples significantly improved growth of tomato in salinized soil when compared to a salinized, nonmycorrhizal control. Growth with 14 samples in salinized soil was as good as growth of a nonmycorrhizal control in nonsalinized soil. Glomusfasciculatum consistently provided the largest growth response. Negative correlations were found between the amount of mycorrhizal colonization on tomato roots in the greenhouse and electrical conductivity, Na concentration, and osmotic potential of the saline soil samples from the field. The amount of mycorrhizal colonization on hosts in the field from which the soil samples were collected was not correlated to growth response or mycorrhizal colonization of tomato in the greenhouse.