Life Sciences Commons^™

Size Distribution Of Soil Aggregates As Influenced By Microorganisms, H. E. Weakly, T. M. Mccalla, Francis A. Haskins

Department of Agronomy and Horticulture: Faculty Publications

Numerous reports have presented evidence that soil aggregates are formed and/or stabilized by microorganisms. In most instances, the aggregates were not studied in respect to size distribution. The present report is concerned with the size distribution of aggregates and particles in a soil material after inoculation with three different inocula and incubation for varying periods of time.

A Bioassay For Detecting Compounds Which Stimulate Or Deter Feeding By The Sweetclover Weevil, W. R. Akeson, G. R. Manglitz, H. J. Gorz, Francis A. Haskins

Department of Agronomy and Horticulture: Faculty Publications

A bioassay employing sweetclover root disks impregnated with various plant extracts has been developed. The bioassay has been used to demonstrate the distribution of substances influencing feeding in fractionated water-methanol-chloroforrn extracts of Melilotus infesta Guss. and M. oficinalis L. Lam. leaves. Indications are that substances responsible for the resistance of M. infesta or the susceptibility of M. officinalis to feeding by adult sweetclover weevils, Sitona cylindricollis Fåhraeus, reside in the water-methanol fraction.

Use Of Shoot-Root Grafts In Case Studies Of Site Of O-Hydroxycinnamic Acid Synthesis In Melilotus Alba, Herman J. Gorz, Francis A. Haskins

Department of Agronomy and Horticulture: Faculty Publications

The content of o-hydroxycinnamic acid was measured in shoot-root grafts involving four combinations of Melilotus alba plants of the CuCuBB and cucuBB genotypes. Six portions from each grafted plant were assayed. Results provide evidence that o-hydroxycinnamic acid synthesis occurs in the above-ground parts of sweetclover plants, with limited translocation to the roots. No support was obtained for the view that the root plays an important role in o-hydroxycinnamic acid synthesis.

Genetic And Biochemical Aspects Of O-Hydroxycinnamic Acid Synthesis In Melilotus Alba, Herman J. Gorz, Francis A. Haskins, A. Kleinhofs

Department of Agronomy and Horticulture: Faculty Publications

In sweetclover (Melilotus alba Desr.) the cis- and trans-isomers of o-hydroxycinnamic acid occur primarily as the respective, β-D-glucosides. Available evidence indicates that these glucosides are formed via the following pathway: phenylalanine (formed from shikimic acid) → trans-cinnamic acid → o-coumaric acid (trans-o-hydroxycinnamic acid) → o-coumaryl glucoside (trans-β-D-glucosyl-o-hydroxycinnamic acid) → coumarinyl glucoside (cis-β-D-glucosyl-o-hydroxycinnamic acid). In tissues that are disrupted, coumarinyl glucoside is rapidly hydrolyzed by the action of endogenous β-glucosidase to yield coumarinic acid, which lactonizes spontaneously to form coumarin. The cu …

Genetic Control Of The Metabolism Of O-Hydroxycinnamic Acid Precursors In Melilotus Alba, Francis A. Haskins, T. Kosuge

Department of Agronomy and Horticulture: Faculty Publications

In sweetclover (Melilotus aIba Desr.) the cis and trans isomers of o-hydroxycinnamic acid occur primarily as the respective β-D-glucosides (Rudorf and Schwarze 1958; Kosuge 1961; Haskins and Gorz 1961a; Stoker and Bellis 1962). The review of Brown (1963) summarizes evidence that these glucosides are formed via the following pathway: phenylalanine (formed from shikimic acid) → trans-cinnamic acid → trans-o-hydroxycinnamic acid (o-coumaric acid) trans-β-D-glucosyl-o-hydroxycinnamic acid (o-coumaric acid glucoside) → cis-β-D-glucosyl-o-hydroxycinnamic acid (coumarinic acid glucoside). Sweetclover plants of the Cu Cu genotype contain substantial amounts of both …

Ultraviolet-Induced Isomerization Of Β-D-Glucosyl O-Hydroxycinnamic Acid On Filter Paper, Andris Kleinhofs, Francis A. Haskins, Herman J. Gorz

Department of Agronomy and Horticulture: Faculty Publications

Coumarinic acid glucoside (β-D-glucosyl cis-o-hydroxycinnamic acid) and o-coumaric acid glucoside (β-D-glucosyl &am-o-hydroxycinnamic acid) are readily detected as absorbing areas on filter paper chromatograms exposed to ultraviolet light at wavelengths near 260 mp. Long wavelength ultraviolet radiation is frequently used to detect fluorescent compounds closely related to these two glucosides. The foregoing facts prompted this investigation concerning the influence of both long and short wavelength ultraviolet light on small amounts of coumarinic acid glucoside and o-coumaric acid glucoside, air-dried on filter paper strips. Ultraviolet-induced interconversion of these two isomers in aqueous solutions is well known.

Plant Communities: Native Vegetation Of Nebraska, J. E. Weaver

Department of Agronomy and Horticulture: Faculty Publications

Thanks to our rapid increase in population ,and the largely indiscriminate spread of urban, industrial, and transport facilities, the time is not far distant when land-use capabilities must receive much more attention than they have enjoyed. Natural, that is pre-settlement, vegetation, integrating as it did the manifold factors of environment, is un-excelled as a guide to potential land use.

Absence Of Dominance Of The B Gene In Influencing Β-Glucosidase Activity In Melilotus Alba, Francis A. Haskins, Herman J. Gorz

Department of Agronomy and Horticulture: Faculty Publications

In sweetclover (Melilotus alba Desr.) the allelic pair designated B/b was originally thought to be concerned with coumarin biosynthesis. Extracts of BB plants were reported to contain substantial amounts of both free and bound coumarin, while extracts of bb plants contained only bound coumarin (Goplen, Greenshields and Baenzinger 1957; Haskins and Gorz 1957), more recently identified as coumarinic acid glucoside (β-D-glucosyl-cis-o-hydroxycinnamic acid) (Kosuge 1961; Stoker and Bellis 1962). The bound-coumarin character behaved as a simple recessive in crosses between bb and BB plants (Goplen, Greenshields and Baenzinger 1957).

Native Vegetation Of Nebraska, J. E. Weaver

Department of Agronomy and Horticulture: Faculty Publications

Nebraska is in the central part of the prairie plains. Yet grassland is only one kind of its varied vegetation. A westward extension of the great deciduous forest occurs along the Missouri River. It is bordered by shrubs, patches of which occur in favorable places to the western border. The foothills of the northwest have a forest of pine not unlike that of the Black Hills. On the level lands and among the wind-blown hills of sand there are hundreds of lakes, swamps, and marshes. The Missouri, Platte, and Niobrara Rivers extend across the state. They and their numerous tributaries …

Peroxidase And Polyphenoloxidase Activities And Free Ninhydrin-Positive Substances In Underground Buds Of Ironweed And Leafy Spurge, W. G. Monson, Francis A. Haskins

Department of Agronomy and Horticulture: Faculty Publications

Peroxidase activity in extracts of underground buds of ironweed and leafy spurge was at the lowest level during the period of dormancy in both species, and increased when dormancy was broken. Polyphenoloxidase activity of bud extracts was high for ironweed and very low for leafy spurge, and showed no relationship with dormancy in either species. Ninhydrin-positive substances generally and sulfur-containing amino acids in particular increased during the dormant period.

Culture And O-Hydroxycinnamic Acid Content Of Excised Melilotus Roots, Larry G. Williams, Francis A. Haskins, Herman J. Gorz

Department of Agronomy and Horticulture: Faculty Publications

Excised roots of biennial sweetclover were successfully cultured through repeated transfers on a modified White's medium solidified with agar. Roots also grew well in shaker-agitated liquid cultures over the pH range 4.5 to 7.0. Exposure of the cultures to bright illumination resulted in submaximal growth. No net synthesis of o-hydroxycinnamic acid was observed in the cultured roots.

Using Fertilizer Nitrogen Effectively On Grain Crops, Robert A. Olson, A. F. Dreier, C. Thompson, K. Frank, Phillip H. Grabouski

Department of Agronomy and Horticulture: Faculty Publications

Fertilizer nitrogen is necessary for the efficient production of grain crops throughout the midwest. Farmers have recognized this need by tremendous increases in nitrogen consumption duhng the past decade.

Fertilizer nitrogen where needed for optimum yield usually increases slightly the total water used by the crop. The water required in making this optimum yield, however, is used a good deal more efficiently than where nitrogen is omitted. Nebraska studies on fertilizer economy have demonstrated nitrate leaching losses in some cases, especially serious on sandy soils of low water holding capacity and with irrigation. Strong circumstantial evidence also suggests denitrification of …

Occurrence Of O-Hydroxycinnamic Acid In Species Of Melilotus And Trigonella, Herman J. Gorz, Francis A. Haskins

Department of Agronomy and Horticulture: Faculty Publications

Leaf samples from available species of Melitotus and the closely related genus, Trigonella, were assayed for free as well as glucosidically bound cis- and trans-o-hydroxycinnamic acids. A qualitative evaluation of β-glucosidase activity also was made. In none of the species were appreciable quantities of the free acids detected. Of the 19 species of Melilotus sampled, 14 contained high levels of the o-hydroxycinnamic acid glucosides, one (M. infesta) was intermediate, and four were essentially free of these glucosides. The intermediate level in M. infesta is unlike that in any other species of Melilotus, …

Effect Of Genotype And Growth Stage On Distribution Of Melilotic Acid, O-Coumaric Acid, And Coumarinic Acid In Melilotus Alba Desr., Walter R. Akeson, Herman J. Gorz, Francis A. Haskins

Department of Agronomy and Horticulture: Faculty Publications

Percentages of melilotic acid, o-coumaric acid, and coumarinic acid were highest in leaves, intermediate in stems. and lowest in roots of greenhouse-grown sweetclovcr plants of the CuCuBB genotype. In leaves, percentages of each of the three compounds decreased as the leaves grew older. but amounts per leaflet increased with age except for content of o-coumaric acid, in which a brief increase was followed by a sharp decrease. Seed from plants of the Cu phenotype was higher in content of each of the three compounds than seed from cu plants. Levels of o-coumaric and coumarinic acids were much …

Glucosides Of Coumarinic And O-Coumaric Acids In The Tonka Bean, Francis A. Haskins, H. J. Gorz

Department of Agronomy and Horticulture: Faculty Publications

The β-glucosides of coumarinic and o-coumaric acids were detected in extracts of cotyledons, exocarps, and seedling leaves of the tonka bean. The existence of these compounds and the presence of a β-glucosidase having specificity for coumarinyl glucoside suggest that, the tonka bean synthesizes coumarin by a pathway similar to the one found in sweetclover.

The Wonderful Prairie Sod, J. E. Weaver

Department of Agronomy and Horticulture: Faculty Publications

A magnificent expanse of grassland occupied the central part of North America before the coming of the white man. This paper is the result of a continuous investigation which began in 1916 of a large portion of this prairie. The area of most intensive study included approximately the western third of Iowa and the eastern third of Nebraska. The advent of the great drought of 1933 to 1940 offered an exceptional opportunity to ascertain the responses of native plants to extremely adverse conditions. The role played by rhizomes of grasses in endurance of drought and frequently their recovery from it …

A Modified Procedure For Assay Of Melilotic Acid In Sweetclover1, Walter R. Akeson, Francis A. Haskins, Herman J. Gorz

Department of Agronomy and Horticulture: Faculty Publications

A modified procedure for the assay of melilotic acid in sweetclover leaves is described. The procedure provides for (a) extraction of melilotic acid and melilotyl glucoside by autoclaving the plant tissue in water, (b) hydrolysis of melilotyl glucoside by autoclaving in 1 N HCl, (c) separation of melilotic acid from interfering compounds by paper chromatography, and (d) colorimetric assay of the chromatographically-separated melilotic acid. Application of the procedure to plants representing various genotypes of sweetclover yielded results indicating that the melilotic acid content of leaves from plants high in content of o-hydroxycinnamic acid is about three times as high …

Translocation Of Coumarin Across A Graft Union M Sweetclover, Herman J. Gorz, Francis A. Haskins

Department of Agronomy and Horticulture: Faculty Publications

Despite several recent investigations of the biosynthesis of coumarin and related compounds in sweetclover, little is known of the site or sites within the plant at which coumarin is formed. Weygand and Wendt reported coumarin formation in root cultures of Melilotus officinalis (L.) Lam. when suitable precursors were supplied. Mothes and Kala concluded that scopoletin and umbelliferone, compounds closely related to coumarin, can be synthesized by root cultures of Atropa belladonna L. The experiments cited gave no indication that the roots are the preferred site of synthesis or that synthesis takes place at all in the roots of intact plants. …

A Reappraisal Of The Relationship Between Free And Bound Coumarin In Melilotus, Francis A. Haskins, Herman J. Gorz

Department of Agronomy and Horticulture: Faculty Publications

In early work on coumarin in sweetclover, the assumption was made that the free form of the compound predominated in the intact plant. Subsequent investigations demonstrated the presence of bound coumarin in addition to free, and it was then thought that both forms were normally present. Recent work indicates that when suitable extraction procedures are used, virtually all the coumarin is obtained in the bound form. Such extraction procedures must provide for the rapid inactivation of β-glucosidase, thus preventing the hydrolysis of bound coumarin (apparently the glucoside of cis-o-hydroxycinnamic acid) during the extraction process. In the present study, inactivation …

The Living Network In Prairie Soils, J. E. Weaver

Department of Agronomy and Horticulture: Faculty Publications

This study treats of our midcontinental soils and of the wonderful network of roots within them of a vegetation which has clothed them for untold centuries. This vegetation has almost vanished so great has been the toll of the tractor-drawn plow, over- grazing and trampling, injudicious use of poisonous sprays, building of highways, and other causes. Virgin prairie and undisturbed soil occur in quantity only in areas where limestone underlies a shallow soil and prevents plowing or in sand so unstable that destroying the vegetation with its binding roots is almost synonymous with losing the soil. The many thousands of …

Chromatographic Study Of Ninhydrin-Positive Substances In Etiolated Shoots From Control And Irradiated Maize Seeds, Francis A. Haskins

Department of Agronomy and Horticulture: Faculty Publications

Treatment of dormant seeds of a wide variety of plants with X-rays or thermal neutrons results in pronounced effects on stature, survival, and various other attributes in seedlings grown from the treated seeds. It seems highly probable that some of these effects involve alterations in the protein metabolism of the seedling, and these alterations might be expected to lead to changes in levels of such ninhydrin-positive substances as amino acids and peptides. This paper is concerned with a preliminary study in which filter paper chromatography was used to investigate possible differences in ninhydrin-positive substances in etiolated maize shoots grown from …

Genetic, Developmental, And Within-Plant Variation In Free And Bound Coumarin Content Of Sweetclover, G. W. Schaeffer, Herman J. Gorz, Francis A. Haskins

Department of Agronomy and Horticulture: Faculty Publications

Seeds of sweetclover contained a low level of both free and bound coumarin. An increase in both forms of coumarin occurred when seedlings were grown in the light, but no increase was found when they were kept in the dark. First- and second-year plants of Evergreen (CuB phenotype), W-7 (Cub), and W-31 (cu-) were sampled in the field at intervals throughout the 1959 growing season. Leaves, stems, and roots were assayed for free and total coumarin content. The level of free coumarin was highest in the leaves of plants of the CuB phenotype, with a …

Activities Of Acid Phosphatase, Peroxidase, And Polyphenolase In Etiolated Shoots From Control And Irradiated Maize Seeds, Francis A. Haskins, S. C. Downs

Department of Agronomy and Horticulture: Faculty Publications

Evidence is presented that enzymatic differences exist between etiolated shoots from appropriately irradiated maize seeds and shoots from control seeds. Differences in specific activities of acid phosphatase and peroxidase became apparent only when individual portions (first internode, coleoptile, and unexpanded foliage leaves) of the shoot were considered. Contributions of the three shoot portions to total activities of acid phosphatase, peroxidase, and polyphenolase also were studied, and irradiation-induced differences in the patterns of contribution were noted.

Assay Of Cis And Trans-O-Hydroxycinnamic Acids In Sweetclover Extracts, Francis A. Haskins, H. J. Gorz

Department of Agronomy and Horticulture: Faculty Publications

Various investigations related to the biosynthesis of o-hydroxycinnamic acid in sweetclover require that simple, rapid methods of assay be available for both the cis isomer (coumarinic acid) and the trans isomer (o-coumaric acid). This report deals with two such methods, both of which represent refinements of a technique for the fluorometric assay of coumarin described in an earlier publication from t h i s laboratory a ask ins and Gorz, 1957). In one procedure, designatled method I, o-coumaric acid and total o-hydroxycinnamic acid are determined, and coumarinic acid is estimated by difference; while in the other procedure, method 11, coumarinic …

Microorganisms And Soil Structure, T. M. Mccalla, F. A. Haskins

Department of Agronomy and Horticulture: Faculty Publications

SUMMARY

Good stable soil structure is valuable for promoting the growth of plants and micro-organisms by permitting enhanced aeration and water penetration and by decreasing erosion under some conditions.

Micro-organisms influence water percolation through the soil. They may plug up soil pores with byproducts of growth and reduce water percolation. On the other hand, if a soil containing a large amount of microbial products is stirred and allowed to dry, then the percolation may be high.

Micro-organisms are involved in stabilizing soil structure by their products of decomposition and their cellular binding material, such as mycelia. Microorganisms differ greatly in …

Pensternon In Your Garden, Glenn Viehmeyer

Department of Agronomy and Horticulture: Faculty Publications

A new race of hardy perennials is beginning to appear in American gardens. These are the penstemons, a genus of plants closely related to the familiar snapdragon, which may become important ornamentals as they become better known to gardeners. The purpose of this bulletin is to show the possibility of the genus as an ornamental and to suggest species and species hybrids of possible value to Great Plains gardeners; to provide information about propagation and culture; and to encourage gardeners to engage in penstemon breeding as an avocation.

Genetic Control Of Coumarin Biosynthesis And Β-Glucosidase Activity In Melilotus Alba, G. W. Schaeffer, Francis A. Haskins, H. J. Gorz

Department of Agronomy and Horticulture: Faculty Publications

Two pairs of alleles, Cu/cu and g/5, are known to influence coumarin biosynthesis in Melilotus alba Desr. (Goplen e t al., 1957 ; Haskins and Gorz, 1957). Young leaves from CuCuBB plants characteristically contain substant i a l akounta of both free and bound co-in, CuCubb leaves are high in "coumarin" but virtually a l l the substance is in the bound form, and cucuBB and cucubb leaves are low in both forms. Lt has been suggested that the gene is involved in the formation of bound coumarin from coumarin precursors and that the gene is concerned with the conversion …

Extent Of Communities And Abundance Of The Most Common Grasses In Prairie, J. E. Weaver

Department of Agronomy and Horticulture: Faculty Publications

The area in which True Prairie has been most intensively studied lies wholly within the central Missouri Valley. True Prairie is the characteristic vegetation of the western third of Iowa, the eastern third of Nebraska, and adjacent areas in Kansas, Missouri, South Dakota, and Minnesota. The chief communities (consociations) or types have been ascertained and fully described (13). TheAndropogon scoparius type (names of grasses from HITCHCOCK [5]) was the most extensive of those of uplands and probably exceeded in area all the other grassland types combined. The Sporobolus heterolepis community was of small extent. Stipa spartea was dominant in …

Genetic Blocks In The Synthesis Of Coumarin In Melilotus Alba, Herman J. Gorz, Francis A. Haskins

Department of Agronomy and Horticulture: Faculty Publications

The influence of the two genes, cu and b upon the level and form of coumarin in sweetclover leaf tissue was determined by assaying 25 sweetclover plants of each of the four homozygous genotypes, CuCuBB, CuCubb, cucuBB, and cucubb. An assay of alfalfa leaves provided an indication of the magnitude of fluorescence not ascribable to coumarin. Approximately 0.2 percent total coumarin (dry weight basis) was found in plants homozygous for cu, which is 11.5 times the amount found in alfalfa, but only about 1/20 of the level found in CuCu plants. Thus, the cu-effected …

Flood Plain Vegetation Of The Central Missouri Valley And Contacts Of Woodland With Prairie, J. E. Weaver

Department of Agronomy and Horticulture: Faculty Publications

Table of Contents:
Introduction
Origin And Development Of Streams And Their Woody Vegetation
Contacts Of Woodland With Prairie
The Larger Bottom Lands And Their Vegetation
Development Of Flood Plains
Flood Plain Soils
Flood Plain Forest
Page Extent Of Flood Plain Forest
Swamps
Marshes
Coarse Grasses Of Wet Lands
Transition To Big Bluestem Prairie
Community Life in Big Bluestem Prairie
Summary
Literature Cited