Life Sciences Commons^™

Comparison Of Vegetation Of Kansas-Nebraska Drift-Loess Hills And Loess Plains, J. E. Weaver

Department of Agronomy and Horticulture: Faculty Publications

The western edge of True Prairie gives way very gradually on the Loess Plains south of the Platte River to Mixed Prairie of the Great Plains. North of the Platte a similar transition occurs in the valleys and on the slopes of the Loess Hills. But in northern Kansas the True Prairie of the Kansas-Nebraska Drift-Loess Hills is definitely separated by the Flint Hills Region from its western edge on the Kansas-Nebraska Loess Plains. In this study the vegetation, soils, and other environmental factors of the two areas are described and compared.

Influence Of Spectral Composition Of Light On Cis-Trans Interconversion Of O- Hydroxycinnamic Acid, Francis A. Haskins, H. J. Gorz

Department of Agronomy and Horticulture: Faculty Publications

In a recent report (1) from this laboratory, an improved fluorometric assay for coumarin in sweetclover is described. Briefly, the method consists of opening the lactone ring of coumarin by treatment with alkali, after which the resulting non-fluorescent cis-o-hydroxycinnamic acid is partially converted, by means of ultraviolet irradiation, to the fluorescent trans isomer. Measurements of fluorescence are then made. In the interval between ultraviolet treatment and measurement of fluorescence, the solutions to be assayed must be protected from the usual light of the laboratory, since exposure to such light results in loss of fluorescence, indicating a reconversion of some of …

Influence Of Seed Irradiation With X-Rays And Thermal Neutrons Upon Cell Size And Mitotic Activity In Root Tips Of Maize, Francis A. Haskins, Merwyn Davidson, Russell Beers

Department of Agronomy and Horticulture: Faculty Publications

In recent years a number of reports (for example, Caldecott et al., 1952, 1954, 1955; Schmidt and Frolik, 1951; Schwartz, 1954; Schwartz and Bay, 1956; Spencer and Cabanillas, 1956; Yagyu and Morris, 1957) have appeared which deal with the effects of treating seeds with various high energy radiations. In all cases it is reported that seedlings grown from appropriately-irradiated seeds are reduced in stature. This reduction in stature must necessarily result from irradiation-induced decreases in number and/or size of the cells comprising the seedlings. Although some quantitative data relating to irradiation-induced changes in cell size and mitotic activity are available …

Native Grassland Of Southwestern Iowa, J. E. Weaver

Department of Agronomy and Horticulture: Faculty Publications

Studies of the prairie by the writer and Fitzpatrick during 1922-33 were both extensive and intensive. They were extensive in that they included an area of 60,000 sq. mi. in western Iowa, eastern Nebraska and portions of the four adjoining states. They were intensive in that a record of the kinds and distribution of grasses, the abundance and relative importance of forbs, and other pertinent data were ascertained and recorded separately for each of 135 selected areas. Since most of these prairies were examined two or more times each growing season, and many repeatedly during a five-year period, a clear, …

Classification Of Root Systems Of Forbs Of Grassland And A Consideration Of Their Significance, J. E. Weaver

Department of Agronomy and Horticulture: Faculty Publications

Plants other than grasses constitute an important part of the native grasslands of North America. Most of these are forbs, a few are shrubs and half-shrubs. Probably 85 to 90 percent of the forbs are perennial and most are as deeply rooted and many far more deeply rooted than the grasses. Their number varies considerably from place to place. In the prairie of the central part of the North American Lowland and on the hard lands and sandy soils of the Great Plains they compose, perhaps, between 5 and 15 percent of the vegetation. They are least abundant in the …

Comparison Of Effects Of X-Ray And Thermal Neutrons On Dormant Seeds Of Barley, Maize, Mustard, And Safflower, B. H. Beard, Francis A. Haskins, C. O. Gardner

Department of Agronomy and Horticulture: Faculty Publications

Comparisons of the biological effects of X-rays and thermal neutrons on dormant seeds of barley have been made by seedling height studies, root tip cytological analyses, and cytological studies of pollen mother cells in the first generation following irradiation and by seedling mutation studies the second generation after irradiation. The results of these studies have been reported by Caldecott, Frolik and Morris (1952) and Caldecott, Beard and Gardner (1954). The objective of the research reported in this paper was to extend the comparison of these two types of radiation by studying their effects on dormant seeds of four widely different …

Rapid Tests For Free And Bound Coumarin In Sweetclover, Herman J. Gorz, Francis A. Haskins

Department of Agronomy and Horticulture: Faculty Publications

Two qualitative fluorometric methods are described. The tube test, in which scoring is based upon visual comparison of the fluorescence of test solutions with the fluorescence of standards, was more reliable than the paper test. The paper test should be used primarily for rapid, initial screening of large populations.

Soil Aggregation By Microorganisms Following Soil Fumigation, T. M. Mccalla, Francis A. Haskins, R. D. Curley

Department of Agronomy and Horticulture: Faculty Publications

The influence of autoclaving and of fumigation with eight chemical formulations upon microbial numbers in straw-amended Peorian loess and the extent to which these treatments affect the degree of aggregation brought about by subsequently introduced inocula were determined. A mixed soil flora, Stachybotrys atra and a blank inoculum consisting of sterile salt solution, were compared. Only in the autoclaved soil was a mixed soil flora inoculum consistently superior to the blank inoculum in promoting aggregation of the Peorian loess. It was found that inoculation with S. atra could greatly increase the aggregation of fumigated Peorian loess in treatments where the …

Summary And Interpretation Of Underground Development In Grassland Communities, J. E. Weaver

Department of Agronomy and Horticulture: Faculty Publications

Table of Contents:
Introduction
Grassland Soils
Underground Parts of Grasses of Lowland
True Prairie
Big Bluestem
Other Grasses
Discussion and Interpretation
Underground Pats of Grasses of Upland True Prairie
Little Bluestem
Needlegrass
Prairie Dropseed
Big Bluestem
Other Grasses
Experiments with Underground Parts
Discussion and Interpretation
Underground Parts of Grasses of Mixed Prairie of Hard Lands
Buffalo Grass
Blue Grama
Purple Three-Awn
Western Wheatgrass
Side-Oats Grama
Needle-and-Thread
Other Grasses
Other Studies in Hard Lands
Discussion and Interpretation
Underground Parts of Grasses of Mixed Prairie of Loess Hills
Underground Parts of Grasses of Sand Hills
Sand Bluestem
Sand Reed
Blowout Grass
Sandhills …

Influence Of Various Factors On Aggregation Of Peorian Loess By Microorganisms, T. M. Mccalla, Francis A. Haskins, E. F. Frolik

Department of Agronomy and Horticulture: Faculty Publications

Soil structure is important in the attainment of adequate aeration for the aerobic microorganisms whose activities maintain such higher plant nutrients as sulfur, phosphorus, and nitrogen in a highly oxidized and thus readily available state. Good soil structure is also necessary for soil and water conservation, Under Nebraska conditions microorganisms and their decomposition products constitute a major source of soil-aggregating agents. The decomposition of crop residues and plant roots is important in the nutrition of these aggregating microorganisms. Other microorganisms, however, also utilize crop residues and plant roots, and they may decompose the aggregating agents as well, so that the …

Fluorometric Assay Of Free And Bound Coumarin Rn Sweetclover, Francis A. Haskins, Herman J. Gorz

Department of Agronomy and Horticulture: Faculty Publications

Free and bound coumarin are extracted by autoclaving leaf tissue in water. Free coumarin is determined directly from an aliquot of the water extract diluted in alkali. Additional autoclaving of the extract in concentrated alkali is required for release of the coumarin from the bound form, permitting an assay for total coumarin. Bound coumarin values are then obtained by difference. Results of the assay as applied to four different phenotypes of sweetclover are given.

Effects Of Irradiation, Maleic Hydrazide, Temperature, And Age On Enzyme Activity In Seedlings Of Corn (Zea Mays L.), Francis A. Haskins, Harold Chapman

Department of Agronomy and Horticulture: Faculty Publications

The work of Schmidt and Frolik (1951) and of Beard (1955) has shown that plants of corn (Zea mays L.) grown from seeds treated with appropriate doses of X-rays or thermal neutrons are greatly reduced in stature and survival in comparison with control plants, and that pronounced increases in chromosomal abnormalities and pollen sterility also result from seed irradiation. It is reasonable to suspect that these morphological and cytological effects might be associated with changes in the metabolism of the plant. Accordingly, a series of experiments has been conducted in which preparations of normal corn seedlings and preparations of …

Stachybotrys Atra, An Effective Aggregator Of Peorian Loess, S. C. Downs, T. M. Mccalla, Francis A. Haskins

Department of Agronomy and Horticulture: Faculty Publications

Twelve cellulose-decomposing fungi were tested for aggregating ability with Peorian loess containing ground straw at a concentration of 1%. Of the 12 fungi, Stachybotrys atra was the most effective soil aggregator. Under laboratory conditions used, it produced from 2 to 30 times more aggregation than any of the other fungi tested. Studies were made of the influence of various environmental factors on the degree of aggregation effected by S. atra. An incubation time of 1 week was sufficient for a relatively high degree of aggregation. In comparison, longer periods resulted in only slightly improved aggregation. Varying the temperature between …

Nature And Place Of Transition From True Prairie To Mixed Prairie, J. E. Weaver, W. E. Bruner

Department of Agronomy and Horticulture: Faculty Publications

As a memorial to Dr. Frederic E. Clements, it is a pleasure to present this paper on the midcontinental grasslands of North America. Born and reared at Lincoln, Nebraska, he developed a remarkable interest in and love for the prairie. He has often stated to the first author that of all the vegetation of North America, he liked the grassland best. Clements was the first to recognize the Mixed Prairie as a distinct plant association and to describe its nature and range and the grouping of the dominants ( 1920).

When one examines the prairies of western Iowa and then …

A Seventeen-Year Study Of Plant Succession In Prairie, J. E. Weaver

Department of Agronomy and Horticulture: Faculty Publications

The nature and rate of regeneration of a 23- yr.-old bluestem pasture under complete protection from grazing were studied near Lincoln, Nebraska. The pasture adjoined a large tract of True Prairie, 0.5 mi. long and 0.25 mi. wide, of which it was originally a part. The prairie, of the upland mid- grass type, had not been grazed for at least 40 yr., and probably only moderately since the disappearance of the bison. It is used for the production of hay and is mowed annually in late summer or autumn. A portion of the pasture adjoining the prairie was separately fenced …

Quantitative Study Of Degeneration Of Mixed Prairie, Farrell Branson, J. E. Weaver

Department of Agronomy and Horticulture: Faculty Publications

The vegetation of great areas of Mixed Prairie has been destroyed by plowing. But even larger ones, still intact, have degenerated far from a climax condition. The almost universal cause for such deterioration, aside from drought, is grazing. The objective of this study has been to ascertain the changes in vegetation that have resulted from 60-70 years of different intensities of grazing by cattle and to express them quantitatively. Since the early work of SAMPSON (7) it has been generally recognized that the forage value and carrying capacity are highest where the vegetation represents a stage close to the herbaceous …

Cytochromes And The Succinic Acid Oxidase System Of Poky Strains Of Neurospora, Francis A. Haskins, Alfred Tissieres, Herschell K. Mitchell, Mary B. Mitchell

Department of Agronomy and Horticulture: Faculty Publications

Recent investigations in this laboratory (1) have demonstrated that in Neurospora crassa growth characteristics representing at least two stable states are possible with the same constitution of nuclear genes. If a slow growing strain, designated poky, functions in a cross to wild type as the "maternal" or protoperithecial parent, then all progeny from the cross exhibit the poky character. If the cross is made in the reverse, or reciprocal manner, that is, with the wild type strain functioning as a protoperithecial parent, then all progeny are normal in growth rate.
During the course of the work on inheritance it was …

Studies On The Respiratory System Of The Poky Strain Of Neurospora, Alfred Tissieres, Herschel Mitchell, Francis A. Haskins

Department of Agronomy and Horticulture: Faculty Publications

It was shown recently that the poky strain of Neurospora accumulates large amounts of cytochrome c, but is deficient in cytochromes a and b and thus in cytochrome oxidase and succinic acid oxidase activities (1). These findings, which suggest that respiration in poky does not utilize the cytochrome system, led to a study of the respiratory system of poky compared with that of wild type. The experiments reported here are concerned with the effects of the inhibitors cyanide and azide on the respiration of intact mycelium of poky and wild type, the oxygen uptake of cell-free extracts in the …

Effects Of Excessive Natural Mulch On Development, Yield, And Structure Of Native Grassland, J. E. Weaver, N. W. Rowland

Department of Agronomy and Horticulture: Faculty Publications

Prairie vegetation is so universally mowed, grazed, or burned that little information has been recorded on its behavior under complete protection. Climax grassland, when grazed lightly or even moderately, may retain essentially its natural composition over extremely long periods (16, 18). But aside from observation there is little information upon the unusual and rare phenomenon of complete protection of grassland from disturbance over a considerable period of time.

An Example Of The Influence Of Modifying Genes In Neurospora, Francis A. Haskins, Herschel K. Mitchell

Department of Agronomy and Horticulture: Faculty Publications

The influence of genetic modifiers, those genes which affect the expression of other genes, has been demonstrated in a wide variety of organisms. In Neurospora crassa the influence of modifiers is suggested by quantitative differences in growth substance utilization among different reisolates of a mutant strain (Good, Heilbronner, and Mitchell, 1950), and genetic suppression (Houlahan and Mitchell, 1947) may be regarded as an extreme type of modification. In addition, Houlahan and Mitchell (1948) and Mitchell and Mitchell (1952) have demonstrated extensive interactions among genes causing pyrimidine, lysine, and arginine requirements, and Srb (private communication) has found a case in which …

Ecological Studies In A Midwestern Range: The Vegetation And Effects Of Cattle On Its Composition And Distribution, J. E. Weaver, G. W. Tomanek

Department of Agronomy and Horticulture: Faculty Publications

There is continued need for a better understanding of range vegetation and its use by range animals. Range preservation and improvement in the midwest are largely matters of wise use and proper management of our natural grasslands. A more comprehensive understanding of the range itself is needed--its forage, soil, and water supply, and factors influencing a proper distribution of livestock. The degree of utilization of forage that will result in the maintenance of excellent or good range condition and the improvement of a range in fair condition should be ascertained. Soil conservation on range lands is accomplished primarily by improvement …

Range Condition Classes Of Native Midwestern Pasture: An Ecological Analysis, John Voigt, J. E. Weaver

Department of Agronomy and Horticulture: Faculty Publications

Table of Contents:
Introduction
Classes Of Prairie Plants
Process Of Degeneration Of Prairie
Stages Of Degeneration
The Areas Studied
Location And Size
Topography, Water, And Soil
Vegetation
Excellent Pastures
Good Pastures
Fair Pastures
Poor Pastures
Methods
Comparison Of Range Condition Classes
Excellent Range Condition
Good Range Condition
Page Fair Range Condition
Poor Range Condition
Resume
Occurrence Of Forbs
Basal Area, Mulch, And Bare Soil
Height Of Grazing
Unconsumed Forage Furnished By Grasses And By Forbs
Forage From Grasses
Forage From Forbs
Resume
Amount And Composition Of Unconsumed Forage
Discussion
Summary
Literature Cited

The Growth-Promoting Properties Of Quinic Acid, Malcom Gordon, Francis A. Haskins, Herschel Mitchell

Department of Agronomy and Horticulture: Faculty Publications

Evidence is accumulating that there is a common metabolic precursor to many of the benzene ring derivatives found in living organisms. Recent work by Davis and Tatum indicates that one such precursor is the naturally occurring shikimic acid (Fig. 1) since this compound serves as a growth factor for certain mutants of Escherichia coli and Neurospora which otherwise require a combination of tyrosine, phenylalanine, tryptophan and p-aminobenzoic acid for growth. These mutants cannot utilize the closely related, naturally occurring quinic acid (Fig. 1) as a substitute for any of their requirements.

Stabilization Of Midwestern Grassland, J. E. Weaver

Department of Agronomy and Horticulture: Faculty Publications

Table of Contents:
Introduction
Introduction
Upland Communities Preceding And Following The Drought
Persistence And Effect Of Western Wheat Grass
Development Of Understory
Chief Invaders
Competition In Drought
Relative Penetration Of Water
Rate Of Infiltration
Relative Amounts Of Soil Moisture
7 Effects On Vegetation
Severity Of Competition In Drought
Persistence Of Effects After Drought
Effects On Forbs And Seedlings
Competition With Big Bluestem
Needle Grass Consociation
Prairie Dropseed Consociation
Indicators Of Delay In Recovery
Role Of Big Bluestem
Little Bluestem And The Return Of Its Type
Spreading Of Kentucky Bluegrass
Establishment Of Seedlings
New Soil Mulch And Return Of Understory
Return …

Effects Of Different Intensities Of Grazing On Depth And Quantity Of Roots Of Grasses, J. E. Weaver

Department of Agronomy and Horticulture: Faculty Publications

The writer has been interested in prairies, pastures, and root depth and distribution over a period of many years. He had the privilege of examining these relationships in the Palouse prairie of Washington long ago while numerous representative areas still remained in a virgin condition (5, 6). Extensive studies have been made in the hardlands of Colorado, Kansas, and Nebraska many years before, during, and following the great drought of 1933-40 (7, 8, 1, 11). Vegetation and root habits have been studied in sand hills (7, 8, 4), in bluffs of wind-blown loess (12), and wet soils of lowland. The …

Monolith Method Of Root-Sampling In Studies On Succession And Degeneration, J. E. Weaver, John Voigt

Department of Agronomy and Horticulture: Faculty Publications

A new method has been devised by which a complete sample of an entire root system may be taken from soil surface to maximum depth of penetration. The roots are separated from the soil without injury to them or displacement of individual roots from their natural position. They are examined in the laboratory in relation to the various horizons of the soil profile. Monoliths 12 inches wide, 3 inches thick, and 3-5 feet in depth are taken from the walls of trenches made in selected pure stands of each species. Roots are obtained from the monolith by a system of …

Microorganisms And Soil Structure, T. M. Mccalla

Department of Agronomy and Horticulture: Faculty Publications

SUMMARY

Laboratory tests were made to determine the effectiveness of different compounds and microbial groups in increasing the stability of Peorian loess lumps against the action of falling water drops. The influence of these on percolation tests in the laboratory was also determined.

Many organic substances-dextrose, sucrose, starch, peptone, cullulose, and gum arabic-did not themselves contribute directly to soil-structure stability, though these substances do furnish energy material for soil microorganisms, which can convert them readily into either microbial tissue or decomposition products that increase soil-structure stability. Lignin, proteins, oils, fats, waxes, resin, and paraffin increased the stability of lumps of …

Soil-Root Relationships Of Certain Native Grasses In Various Soil Types, J. E. Weaver, R. W. Darland

Department of Agronomy and Horticulture: Faculty Publications

Table of Contents:
Introduction
Methods
Selecting The Site
Preparing The Trench
Marking Out The Monolith
Examination Of Soil
Preparing And Washing Away Of The Soil
Preparing The Roots For Photographing And Quantitative Study
Photographing And Sectioning The Root System
Examples Of Root Distribution In Different Types Op Sol
Kentucky Bluegrass
Blue Grama
Big Bluestem
Root Distribution In Soils With Claypans
Western Wheat Grass In Crete Silty Clay Loam
Western Wheat Grass In Butler Silt Loam
Root Development In Adjacent Soil
Western Wheat Grass In Scott Silty Clay Loam
Western Wheat Grass In Rendzina Soil
Root Distribution In Mellow Loess Soils …

A Filter Paper "Chromatopile", Herschel Mitchell, Francis A. Haskins

Department of Agronomy and Horticulture: Faculty Publications

The application of one- and two-dimensional paper chromatography to the separation of small amounts of many kinds of compounds has become a well-established and useful technique (1, 2, 3, 5, 6). In general these methods do not handle sufficiently large quantities of materials for isolation and chemical identification. Large columns of starch and other materials have been used satisfactorily for handling larger quantities of mixtures (4). Starch columns proved to be unsatisfactory, how- ever, for isolation of certain substances under investigation in this laboratory. As a consequence, a new and simple apparatus and technique have been developed, using …

Quantitative Study Of Root Systems In Different Soil Types, J. E. Weaver, R. W. Darland

Department of Agronomy and Horticulture: Faculty Publications

Study of soil-root relations of various crop plants and range grasses has lagged far behind the pressing need for an understanding of these relationships. Little progress in devising new methods for such study, at least methods that have been widely used in the field, has been made since the extensive researches by the direct method, using trench and hand pick, employed by Weaver (1, 2) during the period 1919 to 1926. This lack of a quantitative approach to comparative root studies in various soil types has undoubtedly been a chief reason for the dearth of more definite information on this …