铜尾矿白羊草各生长阶段根际土壤丛枝菌根真菌群落特征

以北方铜业铜矿峪矿十八河尾矿坝主要恢复植被白羊草为研究对象，分析重金属污染环境下，白羊草不同生长阶段根际土壤中丛枝菌根真菌（Arbuscular mycorrhizal fungi，AMF）群落结构与多样性的变化特征，研究各生长阶段白羊草AMF群落结构与环境因子的相互关系。结果发现，白羊草不同生长阶段根际土壤的理化性质和酶活性均存在显著差异。白羊草各生长阶段根际土壤中具有相同的优势科球囊霉科，但AMF群落组成在各个生长阶段的结构存在明显不同。白羊草各生长阶段主要AMF物种对生态因子的响应表现为：幼苗期根际土壤中球囊霉科主要受土壤养分和碳氮比的影响，分蘖期根际土壤中多样孢囊霉科的主要影响因子为土壤pH，成熟期根际土壤中，双型囊霉科双型囊霉科与土壤过氧化氢酶显著相关，类球囊霉科与土壤脲酶显著正相关。总体看来，白羊草各生长阶段根际土壤AMF群落特征受到的生态因子影响具有明显差异。这有助于进一步认识污染环境下AMF的群落特征及其关键影响因子，为铜尾矿生态恢复过程中发掘和利用菌种资源提供科学依据，从而提高矿区生态修复效率。     

Competitive abilities of native grasses and non-native (Bothriochloa spp.) grasses

Old World Bluestems (OWB), introduced from Europe and Asia in the 1920s, recently have begun to raise concerns in the Great Plains. Despite suggestion in the late 1950s that OWB were weedy and negatively impacted biological diversity, they were widely introduced throughout the Great Plains for agricultural purposes. Anecdotal evidence suggests that OWB exhibit invasive characteristics that promote competitive exclusion of native species. The objective of our study was to quantify the competitive abilities of two OWB species (Caucasian bluestem; Bothriochloa bladhii (Retz.) S.T. Blake (= Bothriochloa caucasica (Trin.) C.E. Hubb.) and yellow bluestem; Bothriochloa ischaemum (L.) Keng) with three native grass species (big bluestem (Andropogon gerardii Vitman), little bluestem (Schizachyrium scoparium (Michx.) Nash), and sideoats grama (Bouteloua curtipendula (Michx.) Torr.)). A greenhouse target-neighbor study was conducted to assess both interspecific and intraspecific competition. A total of 480 pots (4.4 l) filled with native soil was used with all pair-wise combinations of species and four density treatments (six replications). Vegetative tiller height, above- and belowground biomass were measured at the end of 16 weeks. Both of the OWB significantly inhibited at least one growth parameter of the three native grass species, while most of the native species did not inhibit growth of either OWB species. Growth of B. ischaemum was enhanced when grown in association with S. scoparium. Based upon the results of our study of OWB competitive superiority and previous research, many of the characteristics possessed by OWB are found to be in common with known invasive species. Hence, we propose that two OWB are competitively superior to three common native prairie species providing them with the ability to invade and threaten the native grasslands of the Central and Southern Great Plains.     

Biomass allocation, relative competitive ability and water use efficiency of two dominant species in semiarid Loess Plateau under water stress

A better understanding of the growth and interspecific competition of native dominant species under water stress should aid in prediction of succession in plant communities. In addition, such research would guide the selection of appropriate conservation and agricultural utilization of plants in semiarid environments that have not been very well characterized. Biomass production and allocation, relative competitive ability and water use efficiency of one C₄ herbaceous grass (Bothriochloa ischaemum) and one C₃ leguminous subshrub (Lespedeza davurica), both important species from the semiarid Loess Plateau of China, were investigated in a pot-cultivation experiment. The experiment was conducted using a replacement series design in which B. ischaemum and L. davurica were grown with twelve plants per pot, in seven combinations of the two species (12:0, 10:2, 8:4, 6:6, 4:8, 2:10, and 0:12). Three levels of water treatments included sufficient water supply (HW), moderate water stress (MW) and severe water stress (LW). These treatments were applied after seedling establishment and remained until the end of the experiment. Biomass production and its partitioning, and transpiration water use efficiency (TWUE) were determined at the end of the experiment. Interspecific competitive indices (competitive ratio (CR), aggressiveness (A) and relative yield total (RYT)) were calculated from the dry weight for shoots, roots and total biomass. Water stress decreased biomass production of both species in monoculture and mixture. The growth of L. davurica was restrained in their mixtures for each water treatment. L. davurica had significantly (P < 0.05) greater root:shoot allocation than B. ischaemum for each water treatment and proportion within the replacement series. Aggressiveness (A) values for B. ischaemum with respect to L. davurica were negative only at the proportions of B. ischaemum to L. davurica being 8:4 and 10:2 in LW treatment. B. ischaemum had a significantly (P < 0.05) higher CR value under each water treatment, and water stress considerably reduced its relative CR while increased that of L. davurica. RYT values of the two species indicated some degree of resource complimentarity under both water sufficient and deficit conditions. The results suggest that it is advantageous for growing the two species together to maximize biomass production, and the suggested ratio was 10:2 of B. ischaemum to L. davurica because of significantly higher (P < 0.05) RYT and TWUE under low water availability condition.     

The response of mycorrhizal colonization to elevated CO2 and climate change in Pascopyrum smithii and Bouteloua gracilis

Large intact soil cores of nearly pure stands of Pascopyrum smithii (western wheatgrass, C₃) and Bouteloua gracilis (blue grama, C₄) were extracted from the Central Plains Experimental Range in northeastern Colorado, USA and transferred to controlled environment chambers. Cores were exposed to a variety of water, temperature and CO₂ regimes for a total of four annual growth cycles. Root subsamples were harvested after the completion of the second and fourth growth cycles at a time corresponding to late winter, and were examined microscopically for the presence of mycorrhizae. After two growth cycles in the growth chambers, 54% of the root length was colonized in P. smithii, compared to 35% in blue grama. Field control plants had significantly lower colonization. Elevation of CO₂ increased mycorrhizal colonization in B. gracilis by 46% but had no effect in P. smithii. Temperatures 4° C higher than normal decreased colonization in P. smithii by 15%. Increased annual precipitation decreased colonization in both species. Simulated climate change conditions of elevated CO₂, elevated temperature and lowered precipitation decreased colonization in P. smithii but had less effect on B. gracilis. After four growth cycles in P. smithii, trends of treatments remained similar, but overall colonization rate decreased.     

Connection of Gnomonia intermedia to Discula betulina and its relationship to other taxa in Gnomoniaceae

Discula betulina is a foliar pathogen on birch (Betula) and Gnomonia intermedia is found on overwintered birch leaves. Perithecia of G. intermedia developed in vitro on colonies of D. betulina isolated from birch tissues in late summer, and single ascospores of G. intermedia consistently developed into colonies similar to D. betulina, producing typical D. betulina conidia. Isolates of D. betulina could be grouped into two mating types, which produced fertile perithecia of G. intermedia when mated with each other. Mycelia from single-ascospore and single-conidial isolates were inoculated onto shoots of downy birch, causing lesions and die-back from which D. betulina was consistently isolated. ITS region ribosomal DNA sequence analysis confirmed the results of the morphological and mating studies, and found that the closest known relatives of G. intermedia/D. betulina are Gnomoniella nana and Sirococcus clavigignenti-juglandacearum. The conclusion from these studies is that D. betulina is the anamorph of G. intermedia.     

Effects of auxin concentration on induction and growth of embryogenic callus from young inflorescence explants of Old World bluestem (Bothriochloa spp.) and bermuda (Cynodon spp.) grasses

Objectives of this research were to test the effects of plant genotypes and auxin 2,4-D (2,4-dichlorophenoxyacetic acid) medium concentrations on embryogenic (E) callus production of two grass species. Two Old World bluestem,Bothriochloa ischaemum, accessions (A-8793 and A-8911c) and three bermudagrass,Cynodon dactylon (L.) Pers., accessions (A-10978b, A12164, and Brazos) supplied the explant material. Immature inflorescences 9 mm in length were placed on modified Murashige-Skoog (MS) agar medium containing 0, 1, 3, or 5 mg L^-1 of 2,4-D. Explants of all genotypes produced callus by the end of a 4-week dark incubation period at 25°C. When subcultured onto fresh media and maintained at 25°C with a 16 hr photoperiod, calli became embryogenic within 8 weeks of inoculation. Three mg L^-1 of 2,4-D in the media maximized E callus production in both bluestem genotypes and in A-10978b and A-12164 bermudagrass genotypes. Maximum E callus production from Brazos bermudagrass resulted from the 1 mg L^-1 treatment. Somatic embryos developed after subculture under light. Embryos showed scutellum-like structures and coleoptile-coleorhiza bipolar organization. Plantlets were regenerated from all genotypes except Brazos, whose embryoids failed to germinate. All callus from Brazos eventually senesced. Light and scanning electron microscopy confirmed regeneration through somatic embryogenesis.     

Response of Lotus rhizobia to acidity and aluminium in liquid culture and in soil

Measurements of multiplication in liquid culture indicated that fast-growing Lotus rhizobia (Rhizobium loti) were tolerant of acidity and aluminium (at least 50 μM A1 at pH 4.5). Slow-growing Lotus rhizobia (Bradyrhizobium sp. (Lotus)) were less tolerant of acidity but equally tolerant of A1. Both genera were able to nodulateLotus pedunculatus in an acid soil (pH 4.1 in 0.01M CaCl₂) and the slow-growing strains were more effective than the fast-growing strains in this soil over 30 days.     

Genetic variability of Bouteloua gracilis populations differing in forage production at the southernmost part of the North American Graminetum

Bouteloua gracilis (blue grama grass) native populations have been shown to be highly variable, however the genetic basis of this variability has not been well established. Determining the extent of genetic variability within and among plant populations have important repercussions for the management and conservation of species, and in particular for those subjected to intensive use such as forage plants. Using RAPD, this study was undertaken to investigate the genetic variability of four B. gracilis native populations developed in three grasslands and one shrubland at the southernmost part of the North American Graminetum in México. Significant differences in grass aboveground production were found among the study sites, while considerable genetic variation within each of the four blue grama populations evaluated was detected. The molecular analysis, based on 55 individuals, revealed a total of 108 scorable repeatable bands, with 99 of them being polymorphic (overall polymorphism= 91.7%). Within every population each individual was genetically distinct and no population-specific bands (fixed marker differences) were identified. Pair-wise Φ _ST comparisons indicated that the four blue grama populations examined were significantly different in their genetic constitution (P<0.001). AMOVA revealed that most of the genetic variation detected in Bouteloua gracilis was explained by intra- (88.53%), rather than by inter-population (11.47%) differences. UPGMA based on the Φ _ST values indicated that the blue grama population collected from the shrubland displayed the RAPD profiles that most differed among the study sites. Possible causes of these results could reside on intensive grazing reducing, and proper management conserving, the forage production and genetic diversity of blue grama native populations. Our results are consistent with previous studies analyzing population genetic variation in outcrossing grasses and, in particular, with ecological and cytological evidence for a high genetic variability in native populations of B. gracilis. The implications of our findings and prospective studies to be undertaken using molecular tools in the study of blue grama biology and ecology are discussed. This revised version was published online in August 2006 with corrections to the Cover Date.     

Production of acetic acid by Dekkera/Brettanomyces yeasts under conditions of constant pH

Sixty yeast strains were previously screened for their ability to produce acetic acid, in shaken flask batch culture, from either glucose or ethanol. Seven of the strains belonging to the Brettanomyces and Dekkera genera, from the ARS Culture Collection, Peoria, IL, were further evaluated for acetic acid production in bioreactor batch culture at 28 °C, constant aeration (0.75 v/v/m) and pH (6.5). The medium contained either 100 g glucose/l or 35 g ethanol/l as the carbon/energy source. Dekkera intermedia NRRL YB-4553 produced 42.8 and 14.9 g acetic acid/l from the two carbon sources, respectively, after 64.5 h. The optimal pH was determined to be 5.5. When the initial glucose concentration was 150 or 200 g/l, the yeast produced 57.5 and 65.1 g acetic acid/l, respectively.     

MORPHOLOGY OF THE COMPILOSPECIES BOTHRIOCHLOA INTERMEDIA

The widely distributed and morphologically variable grass species Bothriochloa intermedia (R. Br.) A. Camus was studied in detail. Morphological and cytogenetical observations indicated that variation is due to interspecific and intergeneric hybridization. The species B. grahamii (Haines) Bor and B. glabra (Roxb.) A. Camus represent intergeneric hybrid derivatives between B. intermedia and Dichanthium annulatum (Forssk.) Stapf, and between B. intermedia and Capillipedium parviflorum (R. Br.) Stapf, respectively. These intergeneric hybrids, and also the apomictic hybrid derivatives of both B. grahamii and B. intermedia with the related B. ischaemum (L.) Keng, are included in the compilospecies. Morphological and cytogenetical studies suggested that the apomictic B. odorata (Lisboa) A. Camus and B. haenkei (Presl) Ohwi are biotypes of B. glabra. The genera involved, Bothriochloa O. Kuntze, Capillipedium Stapf and Dichanthium Willemet, behave phylogenetically like sections of a single genus, with the last-mentioned generic name taking priority.     

Breakdown of phosphatidylinositol in soybean callus

We have investigated the breakdown of membrane-bound phosphatidylinositol (PI) in homogenates of soybean (Glycine max) callus. The breakdown of PI was stimulated by the detergent deoxycholate. At pH 7.0 and 1·gl^-1 of deoxycholate the loss of PI was rapid and extensive: more than 80% was broken down within 10 min. The breakdown of PI was also stimulated by millimolar concentrations of Ca²⁺. The products of breakdown of added PI (purified from soybean callus) in this system were identified from their chromatographic mobilities as 1,2-diacylglycerol, myo-inositol 1-phosphate and myo-inositol 1:2-cyclic monophosphate.Abbreviations DOC deoxycholate - EDTA ethylenedi-aminetetraacetic acid,-acetate - Pi Inorganic phosphate - PI phosphatidylinositol - PS phosphatidylserine - TLC thinlayer chromatography     

Effect of the cyclopoid copepod Mesocyclops thermocyclopoides on the interactions between the predatory rotifer Asplanchna intermedia and its prey Brachionus calyciflorus and B. angularis

In many shallow, eutrophic subtropical ponds, brachionid rotifers are common prey of the predatory copepod Mesocyclops thermocyclopoides. The predatory rotifer Asplanchna intermedia, which is itself a potential prey of the copepod, also feeds preferentially on brachionids. We studied in the laboratory the population dynamics of two mutually competing prey species, Brachionus angularis and B. calyciflorus, in the presence of the two predators A. intermedia and M. thermocyclopoides. The experimental design included separate population dynamics studies with one prey–one predator, two prey–one predator, one prey–two predator, and two prey–two predator systems. These combinations were compared with controls, in which both the prey species (B. angularis and B. calyciflorus) were grown separately and in combination with each other. In the absence of any predator, B. angularis generally eliminated the larger B. calyciflorus. Selective predation by the copepod allowed B. calyciflorus to persist longer in competition with B. angularis. Feeding by M. thermocyclopoides on A. intermedia reduced the predation pressure on B. calyciflorus. However, given enough time, the cyclopoid copepod was able to eliminate both the brachionids as well as the predatory Asplanchna.     

Epizoic mode of life in Brachionus rubens Ehrenberg as a deterrent against predation by Asplanchna intermedia Hudson

The planktonic rotifer Brachionus rubens has a propensity for an epizoic mode of life, and in nature is often found attached to cladocerans. In this way the rotifer avoids to a certain extent the adverse effects of interference competition with cladocerans. We test the hypothesis that the epizoic habit of B. rubens acts also as a deterrent against invertebrate predation. Using Asplanchna intermedia as predator, we followed the population growth patterns of B. rubens alone and in the presence of the host species Daphnia carinata and Ceriodaphnia rigaudi. In the absence of cladocerans, the prey was eliminated within three days, followed by extinction of the predator due to starvation. With D. carinata in the medium, the prey-predator system persisted much longer, with B. rubens reaching high population densities. With the smaller-sized C. rigaudi, allowing a significantly smaller fraction of B. rubens population to be epizoic, the system persisted longer than in the controls, but both the prey and predator eventually became extinct. We conclude that the epizoic habit of B. rubens, by acting as a prey refugium, helps a portion of the population to escape from predation, and facilitates its coexistence with Asplanchna intermedia.     

Plant regeneration through somatic embryogenesis in the forage grass Caucasian bluestem (Bothriochloa caucasica)

Plantlets were regenerated from cultured seed explants of the forage grass Caucasian bluestem [Bothriochloa caucasica (Trin.) C.E. Hubbard] via somatic embryogenesis. Embryogenic callus was produced in four weeks when surface sterilized seeds were cultured on a medium containing MS-salts, B-5 vitamins, 12 mM L-proline, 2% sucrose, 0.8% agar and 5M 2,4-D. Plantlets were regenerated in 6–8 weeks after culture initiation. Healthy root and shoot systems were produced within three weeks after the plantlets were transferred to a medium lacking 2,4-D. Approximately 95% of the plantlets survived greenhouse acclimation and produced healthy plants and viable seeds. Caucasian bluestem callus cultures exhibit natural resistance to kanamycin. High levels of kanamycin (up to 800 mg/l) did not completely inhibit callus growth. However, the regeneration of healthy-plantlets was completely inhibited by kanamycin even at low levels (50 mg/l).     

不同平茬年限人工柠条林光合特性及土壤水分的响应变化

平茬是荒漠草原老化人工柠条林营林抚育的重要措施,为系统认识柠条平茬后连续的生理与生态响应过程及其变化规律,该研究设置对比观测样地,以未平茬柠条(WPC)为对照,以平茬后连续生长1～5年(PC1～PC5)的柠条为处理,对各样地柠条净光合速率、蒸腾速率、气孔导度、胞间CO2浓度、水分利用效率等光合生理特征及其土壤含水量分布的影响进行测定分析。结果表明:(1)平茬处理对柠条生理特性的影响因平茬年限的增加而异,其中PC1和PC2柠条的净光合速率和蒸腾速率较WPC略有提高,PC1柠条处于补偿生长的活跃期,水分利用效率明显高于其他平茬处理,PC2柠条的水分利用效率开始下降;PC3和PC4的柠条蒸腾速率、净光合速率和气孔导度显著上升,且PC4处理下达到最大值,相应水分利用效率也逐步回升;PC5的柠条几乎不存在补偿性生长,净光合速率、蒸腾速率和水分利用效率开始回落,逐渐接近WPC;平茬措施对PC1与PC5柠条胞间CO2浓度大小的影响较大。(2)PC1的土壤水分含量在0～100cm土层因受冠层截留大幅减小的影响而低于其他年限平茬处理;PC2的土壤水分略有改善,PC3、PC4的土壤含水量显著提高,PC5的土壤水分状况则逐渐接近于WPC。(3)随平茬年限的增加,柠条光合特性与土壤含水量间存在一定的动态互馈关系,其中PC1的土壤水分略有下降,柠条生长减缓;PC2土壤含水量逐步恢复;PC3土壤含水量增长幅度开始下降,柠条的各项生理指标上升;PC4柠条的光合生理指标、土壤含水量都达到了最高值;PC5柠条的各项指标开始下降。研究发现,PC4处理是柠条光合生理和土壤水分响应变化的拐点,可参考作为平茬柠条优化管理的一个时间节点。     

Regulation of gene expression by pH of the growth medium in Aspergillus nidulans

Summary In the fungus Aspergillus nidulans the levels of a number of enzymes whose location is at least in part extracellular (e.g. acid phosphatase, alkaline phosphatase, phosphodiesterase) and of certain permeases (e.g. that for -amino-n-butyrate) are controlled by the pH of the growth medium. For example, at acidic pH, levels of acid phosphatase are high and those of alkaline phosphatase are low whereas at alkaline pH the reverse is true. Mutations in five genes, palA, B, C, E and F, mimic the effects of growth at acid pH whereas mutations in pacC mimic the effects of growth at alkaline pH. palA, B, C, E and F mutations result in an intracellular pH (pH_in) which is more alkaline than that of the wild type whereas pacC mutations result in a pH_in more acidic than that of the wild type. This indicates that these mutations exert their primary effects on the regulation of gene expression by pH rather than on the pH homeostatic mechanism but that the expression of at least some component(s) of the pH homeostatic mechanism is subject to the pH regulatory system. It is suggested that pacC might be a wide domain regulatory gene whose product acts positively in some cases (e.g. acid phosphatase) and negatively in others (e.g. alkaline phosphatase). The products of palA, B, C, E and F are proposed to be involved in a metabolic pathway leading to synthesis of an effector molecule able to prevent the (positive and negative) action of the pacC product.These genes are, to our knowledge, the first examples of genes involved in the regulation of extracellular enzyme and permease synthesis by the pH of the growth medium to be described in any organism.     

The impact of nutrition on spore yields for various fungal entomopathogens in liquid culture

Spore yields were measured for various fungal entomopathogens grown in six nutritionally different liquid media with low and high carbon concentrations (8 and 36 g l^–1, respectively) at carbon-to-nitrogen (C:N) ratios of 10:1, 30:1 and 50:1. Six fungi were tested: two Beauveria bassiana strains, three Paecilomyces fumosoroseus strains and one Metarhizium anisopliae strain. Spore yields were examined after 2, 4 or 7 days growth. In general, highest spore yields were obtained in media containing 36 g/l and a C:N ratio of 10:1. After 4 days growth, highest spore yields were measured in the three Paecilomyces isolates (6.9–9.7 × 10⁸ spores ml^–1). Spore production by the B. bassiana isolates was variable with one isolate producing high spore yields (12.2 × 10⁸ spores ml^–1) after 7 days growth. The M. anisopliae isolate produced low spore concentrations under all conditions tested. Using a commercial production protocol, a comparison of spore yields for the coffee berry borer P. fumosoroseus and a commercial B. bassiana isolate showed that highest spore concentrations (7.2 × 10⁸ spores ml^–1) were obtained with the P. fumosoroseus isolate 2-days post-inoculation. The ability of the P. fumosoroseus strain isolated from the coffee berry borer to rapidly produce high concentrations of spores prompted further testing to determine the desiccation tolerance of these spores. Desiccation studies showed that ca. 80% of the liquid culture produced P. fumosoroseus spores survived the air-drying process. The virulence of freshly produced, air-dried and freeze-dried coffee berry borer P. fumosoroseus blastospores preparations were tested against silverleaf whiteflies (Bemisia argentifolii). While all preparations infected and killed B. argentifolii, fresh and air-dried preparations were significantly more effective. These results suggest that screening potential fungal biopesticides for amenability to liquid culture spore production can aid in the identification of commercially viable isolates. In this study, P. fumosoroseus was shown to possess the production and stabilization attributes required for commercial development.     

Genetic mapping with dispersed repeated sequences in the rice blast fungus: mapping the SMO locus

Summary The SMO genetic locus in strains of the fungus Magnaporthe grisea that infect weeping lovegrass, directs the formation of correct cell shapes in asexual spores, infection structures, and asci. We have identified and characterized a Smo^– strain of M. grisea that infects rice. The smo mutation in this strain segregates as a single gene mutation and is allelic to previously identified smo alleles. A marked reduction in pathogenicity co-segregates with the Smo^– phenotype, suggesting that the SMO locus plays a role in rice pathogenicity. A family of dispersed repeated DNA sequences, called MGR, have been discovered in the nuclear DNA of M. grisea rice pathogens. Genetic crosses between Smo^– rice pathogens and Smo⁺ non-rice pathogens were used to follow the segregation of the SMO locus and individual MGR sequences. Using DNA blot analysis with cloned MGR hybridization probes, we mapped the SMO locus to a chromosomal region flanked by two closely linked MGR sequences. We demonstrated that the copy number of MGR sequences could be reduced in subsequent crosses to non-rice pathogens of M. grisea, and that new MGR sequences did not occur following meiosis indicating that these sequences are stable in the genome. We conclude that restriction fragment polymorphism mapping with cloned MGR sequences as hybridization probes is an effective way to map genes in the rice blast fungus.     

Alleviation of salt-induced stress on seed emergence using soil additives in a greenhouse

Use of sodium chloride (NaCl) as a deicing salt results in high concentrations of ions in roadside soils, which decreases seedling emergence in these areas. Greenhouse experiments performed in soil culture tested the efficacy of three soil fertilizers, gypsum (CaSO₄), potash (potassium chloride, KCl) and potassium nitrate (KNO₃), in alleviating NaCl stress on seedling emergence of three grass species exhibiting a range of salt tolerance, Poa pratensis (Kentucky bluegrass), Bouteloua gracilis (blue grama), and Puccinellia distans (alkali grass). Two-factor factorial designs were utilized for each species-fertilizer combination. Treatments of 5000 mg/L (0.086 M) NaCl with or without fertilizer, in concentrations that were equal to 0.5, 1, and 2 times the molar equivalent of 5000 mg/L NaCl were applied biweekly. Salt stress on Poa pratensis emergence was alleviated by all fertilizers with CaSO₄ having the greatest effect in alleviating NaCl stress and potash and potassium nitrate alleviating stress at lower treatment levels. Emergence of Bouteloua gracilis and Puccinellia distans was in most cases negatively effected by soil amendments.