High and low molecular weight fractions of humic and fulvic acids

Summary The present investigation was initiated to study molecular weight fractionation of humic compounds isolated from surface samples of an Ultisol (Red Yellow Pc lzolic soil) and a Spodosol (Podzol), using fine (mol. wt. cutoff 3500) and coarse (mol. wt. cutoff 12000) dialysis membranes and sephadex gel filtration. Characterization of the humic fractions was conducted by elemental analysis and infrared spectroscopy. The results confirmed that fulvic acid (FA) was higher in ash and elemental content than humic acid (HA). With careful purification the amount of ash was found to be reduced to a minimum, but not to zero. Sephadex gel filtration revealed that fine HA (obtained with fine membranes) was composed of smaller amounts of HA-I (high mol. wt.) and large amounts of HA-II (low mol. wt. fraction). Coarse HA (obtained with coarse membranes) had almost equal amounts of HA-I and HA-II. Fine or coarse FA yielded only low molecular weight components after elution through sephadex. Infrared spectra of the humic fractions were indicative for the presence of phosphoglyceric acid as a possible constituent of the low molecular weight fraction of humic compounds.Contribution of the Univ. of Georgia, Agric. Expt. Sta., College Sta., Athens, Ga. Permission for the publication herein of Sadtler Standard spectrum has been granted, and all rights are reserved by Sadtler Res., Inc.Contribution of the Univ. of Georgia, Agric. Expt. Sta., College Sta., Athens, Ga. Permission for the publication herein of Sadtler Standard spectrum has been granted, and all rights are reserved by Sadtler Res., Inc.     

Effect of different levels of humic acids on nutrient content and growth of corn (Zea mays L.)

Summary The effect of humic acids on nutrient uptake and growth of corn plants (Zea mays L.) was investigated by growing corn in plastic growth pouches containing a Hoagland nutrient solution to which were added 0, 320, 640, 1,600 or 3,200 ppm HA, pH 7.0. The experiments were carried out in three replicates for a growing period of 16 days after germination. Humic acid was in general beneficial to shoot and root growth of corn plants. Dry matter yield in corn shoots was stimulated by HA, especially by treatments with 640 ppm HA. Nutrient uptake showed a number of differences as a result of treatments with HA. Moderate applications with HA resulted in a significant increase in N content of corn shoots, while large amounts of HA had a tendency to reduce the N concentration in corn shoots. As a result of the HA treatments, P concentrations in corn shoots were decreased, but differences in K contents were statistically nonsignificant and Mn contents in shoots were also nonsignificantly different among the treatments. However, Zn content showed a tendency to increase with increasing applications of HA.Contribution of the University of Georgia, College Agri. Exp. Stn., College Stn., Athens, GA 30602. Current address of junior author: c/o Soil and Fertilizer Section, Field Crop Division, Department of Agriculture, Bangkok, Thailand.     

Characterization of a toxin produced by a rhizobacterialPseudomonas sp. that inhibits wheat growth

A toxin produced by a deleterious rhizobacterial pseudomonad that inhibits both winter wheat (Triticum aestivum L.) root andEscherichia coli growth was characterized. The toxin was rapidly deactivated at pH 2 and 12 and by autoclaving (121°C, 15 minutes). Less toxin was destroyed as the temperature and time of exposure decreased, and at 40°C it was stable for at least 24 hours. The toxin was extremely polar and could not be extracted from culture filtrates with organic solvents. The compound eluted after the void volume from a Sephadex G-10 column indicating a molecular weight of less than 700. The toxin adsorbed to Dowex 50W strong cation exchange resin and eluted with 2M NH₄OH. Numerous thin layer chromatography solvent systems were unsuccessful at purifying the toxin. The partially purified toxin inhibited several different microorganisms while the producing strains were resistant. The toxin appears unique to toxins produced by recognized plant pathogenic bacteria.Contribution from the Agric. Res. Serv., U.S. Dept. of Agriculture in cooperation with the College of Agric. and Home Econ., Res. Ctr., Washington State University, Pullman, WA 99164, USA     

The effect of calcium bicarbonate on iron absorption and distribution byChrysanthemum morifolium, (Ram.)

Summary Plants grown for two weeks in high-bicarbonate nutrient solution with iron became chlorotic, absorbed less iron, and translocated a lower percentage of absorbed iron than did green plants grown under low bicarbonate with iron. Chlorotic plants, pretreated in low-bicarbonate solutions lacking iron, absorbed more iron and translocated a higher percentage to leaves than the green plants. Plants induced to chlorosis by high bicarbonate absorbed less iron after transfer to low-bicarbonate solution containing iron than did chlorotic plants pretreated with low-carbonate solution lacking iron. Initial localization of iron occurred in the roots. A considerable amount of the iron initially found on the roots was translocated to developing shoots over a nine-week period unless the plants were grown in high bicarbonate solutions. More iron was translocated from roots of plants in minus-iron solutions following initial absorption than when iron was supplied in the nutrient solutions. Journal Series Paper736. University of Georgia, College of Agriculture Experiment Stations, College Station, Athens, Ga. 30601.     

Article Watch: April 2014

This column highlights recently published articles that are of interest to the readership of this publication. We encourage ABRF members to forward information on articles they feel are important and useful to Clive Slaughter, Georgia Regents University/University of Georgia Medical Partnership, 1425 Prince Ave., Athens, GA 30606, USA (Phone: 706-713-2216; Fax: 706-713-2221; E-mail; ude.agu@thgualsc), or to any member of the editorial board. Article summaries reflect the reviewer''s opinions and not necessarily those of the association.     

Response ofPinus resinosa ait. Plantations to potassium fertilization on a potassium-deficient site

Summary Using deviations of the cumulative height growth due to fertilization treatments from the linear finite difference curve of untreated red pine trees in plantations, it was noted that: 1) large-sized trees responded in height growth to fertilization in the year following treatment while the medium and small trees took two years to respond; 2) medium-size trees responded to fertilization similar to large trees, but to a lesser magnitude; and 3) small trees are further suppressed by fertilization due to growth responses in the large medium trees.Contribution of the Silviculture Department, State University College of Forestry at Syracuse University, Syracuse, New York 13210.The authors are, respectively, Professor of Silviculture, Tokyo University of Agriculture and Technology and Visiting Professor of Silviculture, State University College of Forestry at Syracuse University, 1966–67; Forester, Continental Can Co., Augusta Division, Georgia; Professor of Silviculture, State University College of Forestry at Syracuse University.     

Toxin production by a rhizobacterialPseudomonas sp. that inhibits wheat root growth

We studied the production of a toxin inhibitory to both winter wheat (Triticum aestivum L.) root growth andEscherichia coli that was produced by a rhizobacterial pseudomonad. Of several carbon sources tested, the most rapid growth and highest toxin concentrations were obtained with glucose, glycerol, or trehalose. Toxin production was repressed with L-cysteine as the nitrogen source. Toxin was produced during the late exponential and early stationary phase of growth by the bacterium and, contrary to studies with other toxins, was unaffected by Fe and P concentrations in the growth medium. Toxin production by the bacterium was the same at growth temperatures of 25 and 15°C while it produced less at 5°C. If the bacterium was able to grow, it produced toxin. No compound tested induced an increase in toxin production indicating toxin production is constitutive.Contribution from the Agric. Res. Serv., U.S. Dept. of Agriculture in cooperation with the College of Agric. and Home Econ., Res. Ctr., Washington State University, Pullman, Washington 99164.     

PHOTO-INHIBITION OF SPORULATION IN ALTERNARIA SOLANI

Lukens, R. J. (Connecticut Agric. Expt. Sta., New Haven.) Photo-inhibition of sporulation in Alternaria solani. Amer. Jour. Bot. 50(7): 720–724. Illus. 1963.—Day-old conidiophores from starved cultures of Alternaria solani require a 12-hr dark period to produce conidia. If the cultures are illuminated during the dark period, conidial production is inhibited. The action spectrum of light inhibiting conidial formation contains 2 maxima, a sharp one at 450 mμ and a broad one extending from 375 to 425 mμ. The entire action spectrum corresponds approximately to the absorption spectra of riboflavin-5-phosphate mononucleotide (FMN) and of 6-carotene. FMN nullifies the effect of light in inhibiting sporulation, but b-carotene does not. Flavins appear to be essential for conidial formation and are photo-inactivated. It is likely that flavins are photo-receptors through which light inhibits conidial formation in A. solani.     

Article Watch,December 2013

This column highlights recently published articles that are of interest to the readership of this publication. We encourage ABRF members to forward information on articles they feel are important and useful to Clive Slaughter, Georgia Regents University–University of Georgia Medical Partnership, 1425 Prince Ave., Athens, GA 30606, USA. Phone: 706-713-2216; Fax: 706-713-2221; E-mail: ude.agu@thgualsc; or to any member of the editorial board. Article summaries reflect the reviewer''s opinions and not necessarily those of the association.     

Soil temperature effects on competitiveness and growth ofRhizobium japonicum and on Rhizobium-induced chlorosis of soybeans

Summary The effects of temperature on growth in broth and soil and on competition for nodule formation betweenRhizobium japonicum serotypes USDA 76 and 94 compared to 6 and 110 were studied. Increasing root temperatures of Lee soybean from 20 to 35°C increased the competitiveness of 76 and 94 relative to 6 and 110 for all inoculum ratios such that at 30 and 35°C symptoms ofRhizobium-induced chlorosis appeared. Tolerance to elevated temperatures was exhibited by 76 and 110, but not 94 and 6 in broth and soil which suggested that increased competitiveness of 76 and 94 at high soil temperatures was not dependent upon growth at elevated temperatures. Nodulation and vegetative growth of Lee soybeans were at a minimum at 20°C and optimum at 30°C. Differences in competitiveness of 6 to previous studies indicated the need to standardize temperatures of assays. Differences in growth responses of 76 and 94 to temperature from a previous study suggested a confounding effect on different carbon sources in growth media. Scientific Article No. A-3721 Contribution No. 6697 of the Maryland Agric Exp Sta, Dept of Agronomy, College Park, MD 20742 and the USDA, ARS, Beltsville, MD 20705. Part of a thesis submitted by the senior author in partial fulfillment of the requirements for the M.S. Degree.     

Influence of drought on competition between selected Rhizobium meliloti strains and naturalized soil rhizobia in alfalfa

Drought is an important environmental factor that can affect rhizobial competition and N₂ fixation. Three alfalfa (Medicago sativa L. and M. falcata L.) accessions were grown in pots containing soil from an irrigated (Soil 1) and a dryland (Soil 2) alfalfa field in northern Utah, USA. Mutants of three strains of Rhizobium meliloti Dang. from Pakistan (UL 136, UL 210, and UL 222) and a commercial rhizobial strain 102F51a were developed with various levels of resistance to streptomycin. Seeds inoculated with these individual streptomycin-resistant mutants were sown in the two soils containing naturalized rhizobial populations. Soils in the pots were maintained at −0.03, −0.5, and −1.0 MPa. After 10 weeks, plants were harvested and nodule isolates were cultured on agar medium with and without streptomycin to determine nodule occupancy (proportion of the nodules occupied by introduced rhizobial strains). Number of nodules, nodule occupancy, total plant dry weight, and shoot N were higher for Soil 1 than Soil 2. Number of nodules, plant dry weight, and shoot N decreased as drought increased from −0.03 to −1.0 MPa in the three alfalfa accessions. Rhizobial strains UL 136 and UL 222 were competitive with naturalized alfalfa rhizobia and were effective at symbiotic N₂ fixation under drought. These results suggest that nodulation, growth, and N₂ fixation in alfalfa can be improved by inoculation with competitive and drought-tolerant rhizobia and may be one economically feasible way to increase alfalfa production in water-limited environments. Joint contribution from USDA-ARS and the Utah Agric. Exp. Sta., Utah State Univ., Logan, UT 84322-4810, USA. Journal Paper No. 4931. Joint contribution from USDA-ARS and the Utah Agric. Exp. Sta., Utah State Univ., Logan, UT 84322-4810, USA. Journal Paper No. 4931.     

Lithium toxicity in seedlings of three cool season grasses

Summary Lithium toxicity in seedling of crested wheatgrass (Agropyron desertorum), Sherman bluegrass (Poa ampla), and Whitmar wheatgrass (Agropyron inerme) was investigated in 2 potted soil studies. Yields of roots and shoots were unaffected at 2.5 and 5 ppm but were significantly (P<0.05) depressed at 15 and 60 ppm. Li was much higher in the herbage than in the roots of grasses grown in Li treated soils. Species tolerancy to Li appeared to be: crested wheatgrass > Sherman bluegrass > Whitmar wheatgrass.The research is a cooperative investigation of the USDA, Science and Education Administration, Agricultural Research, and the Oregon State Agric. Exp. Sta., Squaw Butte Experiment Station, Burns, Technical Paper No. 4974 of the Oregon State Agric. Exp. Sta.     

Effectiveness of ph gene in inducing homoeologous chromosome pairing in agrotricum

Summary We observed pairing, when the ph gene was present, between wheat (Triticum aestivum L. em. Thell.) chromosome 4B, and an Agropyron intermedium (Host) Beauv. chromosome (Ai) carrying a gene resistant to wheat streak mosaic (WSM). In a monosomic addition polyhaploid [2n = 22 = 19' + 5B' (ph) + 4B' + Ai'], we recorded an average of 4.1 bivalents and 0.3 trivalents per cell. Induced homoeologous pairing was most effective when both 5B chromosomes carrying ph gene were present. Our data suggest that chromosome 4B of wheat and the Agropyron chromosome (Ai) carrying a gene for resistance to WSM are homoeologous and that it is possible to use either ph mutant or nullisomic 5B stock to induce genetic recombination between the two chromosomes.Contribution No. 1657-j, Kansas State Agric. Expt. Sta., Manhattan, KS. The research is partially supported by a grant from Kansas Wheat Commission     

Plant growth-inhibitory pseudomonads colonizing winter wheat (Triticum aestivum L.) roots

Summary Pseudomonads, which inhibit root extension, can be present in the winter wheat rhizosphere in large numbers, but they are not detectable until late winter or early spring. Their presence was not related to the presence of wheat straw residues or type of tillage, although they were present on the wheat residues when they appeared in the rhizosphere. Wheat seedlings were more sensitive to the bacteria at 15° C than at 20° C during bioassays. The type of agar used in the bioassay can affect the results obtained. The inhibitory factor expressed by the pseudomonads is quite variable and is radically affected by transfer of isolates.Contribution from Agric. Res. Serv. U.S. Dept. of Agric., in cooperation with the College of Agric. Res. Center. Washington State Univ., Pullman, WA 99164 (Scientific Paper No. 6743); and Agricultural Research Council, Letcombe Laboratory, Wantage, Oxon OX12 9JT, England.     

INFLUENCE OF N-(TRICHLOROMETHYLTHIO)-4-CYCLOHEXENE-1,2-DICARBOXIMIDE (CAPTAN) ON HIGHER PLANTS. II. EFFECT ON SPECIFIC ENZYME SYSTEMS

Dugger , W. M., Jr ., T. E. Humphreys , and Barbara Calhoun . (Florida Agric. Expt. Sta., Gainesville.) Influence of N-(trichloromethylthio) -4-cyclohexene-1,2-dicarboximide (captan) on higher plants. II. Effect on specific enzyme systems. Amer. Jour. Bot. 46(3) : 151-156. Illus. 1959.—The effect of N-(trichloromethylthio)-4-cyclohexene-1,2-dicarbomixide (captan) and 2 analogs on specific enzyme systems associated with plant metabolism has been studied. The fungicide inhibits yeast hexokinase, but not hexokinase from wheat germ or pea seedlings. Decarboxylation of pyruvate and α-ketoglutarate by lupine mitochondria was inhibited by captan and the phthalimide and hexahydrophthalimide analogs. This inhibition was reversible, at low levels of the fungicides, by adding cocarboxylase. The oxidation of ribose-5-phosphate by pea extract was also inhibited by captan and the hexadehydro analog, but cocarboxylase did not reduce the inhibition. TPN reduction was not affected.     

Nitrogen-tillage-residue management

Summary NCSWAP (nitrogen and carbon cycling in soil, water and plant) is a simulation model of the soil-crop-water system which integrates water flow dynamics, crop growth, N transformations, tillage and residue effects, soil temperature, and solute transport. A small plot field study was initiated in May of 1980 to determine the effects of N rate (2 or 20 g N/m²), tillage (rototill or no-till), and residue management system (residue return or noresidue) on soil parameters, and maize (Zea mays L.) production.Significant differences due to treatments (N rate, tillage, and residue) were not detected in 1981 for the measured soil-plant parameters including soil moisture, yield, and N uptake. Therefore, two representative treatment combinations (N rates of 2 or 20 g N/m²-tilled-no residue) characterized the field research data. Calculated and observed data sets were compared for several parameters including: (1) soluble NO₃–N, (2) N leaching losses (3) plant total-N and¹⁵N, (4) root growth, (5) soil moisture, and (6) fertilizer efficiency.The objectives of this study were to initiate the validation process of the model NCSWAP, and to illustrate how NCSWAP can be used as a research tool to infer operational characteristics of the N cycle.Contribution of the Soil and Water Management Research Unit, USDA-ARS, and the Department of Soil Science, University of Minnesota, St. Paul, MN 55108. Minn Agric. Exp. Sta., Sci. J., Ser. Paper 13907.Senior Laboratory Technician; Research Chemist, USDA-ARS and Professor; Professor of Soil Microbiology; and Soil Scientist, USDA-ARS and Assistant Professor; all Department of Soil Science, University of Minnesota, respectively. Inquiries about NCSWAP should be sent to J. A. E. Molina.     

Growth rate in Neurospora crassa: Linkage of polygenes

Part of the polygenic system controlling the response to selection for fast linear growth rate in Neurospora crassa is linked to the aurescent locus on chromosome I. This genotypic material accounts for approximately 18 percent of the total response to selection. There was no evidence of linkage to the yellow locus on chromosome VI.Journal Series Paper No. 890. University of Georgia College of Agriculture Experiment Stations, College Station, Athens.     

The allotetraploidization of maize

Summary Allotetraploidization is the creation of artificial allotetraploids. Allotetraploidization of maize can be achieved by restructuring a maize genome so that its chromosomes will not pair with those of the normal maize genome. The restructuring can be done by concentrating induced or naturally occurring visible and cryptic chromosome aberrations and qualitatively different genetic material into a single line by a recurrent selection type of breeding program. The basis of allotetraploidization is the presence of differential pairing affinity between normal and restructured chromosomes. Experiments demonstrate that differential pairing affinity factors occur naturally in exotic races and in standard corn belt inbred lines and that they may be readily induced by X-irradiation and chemical mutagens.Contribution from the Science and Education Administration, U.S. Department of Agriculture, and the Agronomy Department, University of Missouri, Columbia, Missouri, Missouri Agric. Exp. Sta. Journal Series No. 8092     

Purification and characterization of isoforms of cinnamyl alcohol dehydrogenase fromEucalyptus xylem

Two distinct isoforms of cinnamyl alcohol dehydrogenase, CAD 1 and CAD 2, have been purified to homogeneity from xylem-enriched fractions ofEucalyptus gunii Hook and partially characterized. They differ greatly in terms of both physical and biochemical properties, and can be separated by hydrophobic interaction chromatography on Phenyl Sepharose CL-4B. The native molecular weight of of CAD 1 is 38 kDa as determined by gel-filtration chromatography on Superose 6, and this isoform is likely to be a monomer since it yields a polypeptide of 35 kDa upon sodium dodecyl sulfatepolyacrylamide gel electrophoresis. It has a low substrate affinity for coniferyl andp-coumaryl alcohols and their corresponding aldehydes. No activity with sinapyl aldehyde and alcohol was detected. The more abundant isoform is CAD 2, which has a native molecular weight of 83 kDa and is a dinier composed of two subunits of slightly different molecular weights (42–43 kDa). These subunits show identical peptide patterns after digestion with N-chlorosuccinimide. The isoform, CAD 2, has a high substrate affinity for all the substrates tested. The two isoforms are immunologically distinct as polyclonal antibodies raised against CAD 2 do not cross-react with CAD 1. The characterization of two forms of CAD exhibiting such marked differences indicates their involvement in specific pathways of monolignol utilisation.Abbreviations CAD cinnamyl alcohol dehydrogenase - DTT dithiothreitol - NCS N chlorosuccinimide - SDS-PAGE sodium dodecyl sulfate-polyacrylamide gel electrophoresis This work was supported by the European Economic Community project AGRE 0021 (OPLIGE) in the scope of the ECLAIR PROGRAMME. The authors whis to thank Drs. L. Davin and N. Lewis (Washington State University) for kindly providing synthesized substrates, Dr. Annie Boudet for excellent technical assistance, and Dr. M. Campbell for fruitful discussions (Université Paul Sabatier, Toulouse, France). We would also like to thank Dr. M. M. Cordonnier-Pratt and Dr. L. Pratt (University of Georgia, Athens, USA) for helpful advice and antibody production.     

Edaphic mobility of complete humic acid and fractions of high and medium molecular weight

Soil mobility of a complete humic acid and high and medium molecular weight fractions was determined by a soil TLC method. High and medium molecular weight fractions were obtained by ultrafiltration and then labeled with radioiodine. Infrared, visible- and UV spectra, as well as isotachophoretic studies, showed marked differences among the three humic fractions. The results obtained made evident the presence of soil mobile humic fractions of medium molecular weight. Alkalinization increased the soil mobility of humic acid.