Life Sciences Commons^™

Transect Method Of Studying Woodland Vegetation Along Streams, J. E. Weaver, Herbert Hanson, John Aikman

Department of Agronomy and Horticulture: Faculty Publications

In pursuance of an investigation of competition among certain shrubs (Rhus glabra, Corylus americana, Symphoricarpos spp.), and between these shrubs and Quercus macrocarpa, it became imperative, for a proper understanding of their behavior, to ascertain just how near the edge of their range they were growing. The station, which is located at Weeping Water, Nebraska, is on the Weeping Water River, a branch of the Missouri, I5 miles west of its mouth. This stream arises I 5 miles farther west, and in general its course parallels that of the Platte River about I 5 miles north. As is …

Investigations On The Root Habits Of Plants, J. E. Weaver

Department of Agronomy and Horticulture: Faculty Publications

Ten years ago, while studying the vegetation of semi-arid eastern Washington, interest in root studies was aroused because of the extensive root systems of the native species. Balsamorrhiza sagittata, the first plant excavated, is representative. The strong tap root reaches a depth of six feet, and very numerous branches run laterally to distances of about two feet. Further investigations in several other states showed that extensive root systems are the rule among grassland species. Andropogon haliji, with exceedingly well branched fibrous roots seven feet deep, is representative of many of the dominants. About ninety percent of the more …

The Chromosome Number Of Maize, T. A. Kiesselbach, N. F. Petersen

Department of Agronomy and Horticulture: Faculty Publications

The wide-spread interest in the genetics of maize, coupled with the uncertainty as to the number of chromosomes occurring in this species prompted the investigation which is here reported. From a review of the literature it appears that Kuwada (1911, 1915, 1919) is the only worker who has reported extensive counts of maize chromosomes. His results are summarized in table 1. Variations were reported in the number of chromosomes both within and between varieties as well as between different cells of individual plants. He concluded that sweet varieties are usually characterized by having twelve chromosomes, and starchy varieties by having …

The Occurrence Of Starch And Erythrodextrin In Maize And Their Segregation In The Pollen Of Hybrids, T. A. Kiesselbach, N. F. Petersen

Department of Agronomy and Horticulture: Faculty Publications

A variety of maize (Zea mays) differing from other known sorts in the texture of its endosperm was described by Collins (1909). The type of endosperm of this variety was designated as “waxy” in contrast with the starchy and sweet types of other maize. It has since been shown by Weatherwax (1922) that the carbohydrate of this waxy endosperm is erythrodextrin which can be distinguished from other carbohydrates by its red color reaction with iodine. It has recently been reported by Demerec (1924) and Brink and MacGillivray (1924) that this carbohydrate is also present in the pollen of …

Plant Production As A Measure Of Environment: A Study In Crop Ecology, J. E. Weaver

Department of Agronomy and Horticulture: Faculty Publications

Table of Contents:
Introduction
Location and Description of Stations
Comparisons of Environments
Experimental Methods and Results, 1920
Experiments during 1921
Environmental Conditions
Plant Yield
Experiments during 1922
Environmental Conditions
Native Plant Yield
Growth Of Maize
Summary of Experiments on Native Vegetation
Summary

Western Yellow Pine Mistletoe, J. E. Weaver

Department of Agronomy and Horticulture: Faculty Publications

This bulletin gives the results of studies over a period of twelve years on the effect of mistletoe Razounzofskya cryptopoda (Engelm.) Cov. on the growth and seed production of western yellow pine. The intensive part of these studies was carried on near the San Francisco mountains in northern Arizona. " The parasite is the most widely distributed and one of the most serious enemies of the western yellow pine." On southern slopes and near the lower limit of the distribution of the pine, areas occur where 75 to 90 per cent of all trees above six inches in diameter are …

Range And Pasture Management, J. E. Weaver

Department of Agronomy and Horticulture: Faculty Publications

Sampson's range and pasture management is an excellent example of the application of the principles of ecology to the solution of economic problems. In grazing experiments it is of equal importance to know what is happening to the stock and to the vegetation. This emphasizes the fact, which ecologists are coming more and more to recognize, that animals, both wild and domesticated, have a proper place in the environment and that they play an important role in modifying the vegetational development. This volume consists largely of first-hand information obtained by the author during fifteen years of intensive pasture investigations for …

Direct Measurement Of Water Loss From Vegetation Without Disturbing The Normal Structure Of The Soil, J. E. Weaver, John Crist

Department of Agronomy and Horticulture: Faculty Publications

One of the most serious objections to the usual method of determining the water losses from plants is the almost universal use of containers which are quite too small to accommodate the normal development of the root system. But even where containers of sufficient size to overcome this obstacle are employed, the plants are grown in a mass of soil which has been at least fairly recently screened, mixed, aerated and watered and thus its structure is wholly unlike that which occurs in nature. This difference has been noticed for a number of years in connection with investigations of root …

Absorption Of Nutrients From Subsoil In Relation To Crop Yield, John W. Crist, J. E. Weaver

Department of Agronomy and Horticulture: Faculty Publications

Investigations of the development of root systems of native and crop plants have been pursued for a number of years at the University of Nebraska. The gradual intensification of this work has led to a type of experimentation designed to discover the nature of the activities of roots at great depths in relation to absorption of water and nutrients. In the present investigation the effects of absorption of nutrients from deep levels upon quantity and quality of yield were determined. Studies on the amounts of water and nitrates removed by crops from various soil levels were begun in i919, but …

Development Of Root And Shoot Of Winter Wheat Under Field Environment, J. E. Weaver, Joseph Kramer, Maud Reed

Department of Agronomy and Horticulture: Faculty Publications

Numerous studies have been made on the winter killing of cereals, but few data are available on their actual growth rates during fall, winter, and early spring. No attempt has been made to correlate growth with environmental conditions, at least in the great wheat belt of the Mississippi Valley and Great Plains. During the fall of 1921 a study of the development of winter wheat both above and below ground was begun. A strain of Turkey Red winter wheat recently developed at the Kansas Agricultural College and known as Kanred was grown.

A plat of one tenth acre of fertile …

Control Of Flowering In Teosinte: Short-Day Treatment Brings Early Flowers, R. A. Emerson

Department of Agronomy and Horticulture: Faculty Publications

Attempts to force teosinte into flower in mid-summer, in order to facilitate hybridizing it with maize, have afforded considerable information concerning the flowering time of teosinte under diverse conditions. The possibility that some of this information may be of use to others suggests its publication. The paper is, therefore, to be considered as a help in the technique of teosinte and maize hybridization rather than a contribution ~to the solution of the physiological problems involved.

A Genetic View Of Sex Expression In The Flowering Plants, R. A. Emerson

Department of Agronomy and Horticulture: Faculty Publications

It seems a conservative statement to say that studies

of the past twenty years among animal forms have

tended increasingly to link the phenomena of sex inheritance

with the behavior of chromosomes. To this

result, cytology and genetics have contributed perhaps

almost equally. The number of forms in which

one sex is known to have a morphologically different

chromosome complex from the other sex are many.

That, with respect to the chromosomes, the female of

certain forms produces gametes of a single kind,

whereas the male produces two kinds, and that in

turn an egg fertilized by one kind of …

Pericarp Studies In Maize. I. The Inheritance Of Pericarp Colors, E. G. Anderson, R. A. Emerson

Department of Agronomy and Horticulture: Faculty Publications

Introduction ... 466

Nomenclature ... 467

Pigments present in colored pericarp ... 467

Factor relations of pericarp colors ... 468

Factor relations of red pericarp, P ... 468

Factor relations of cherry pericarp ... 471

Discussion and Summary ... 474

Literature Cited ... 475

Development And Activities Of Roots Of Crop Plants: A Study In Crop Ecology, J. E. Weaver, Frank C. Jean, John W. Crist

Department of Agronomy and Horticulture: Faculty Publications

Introduction
I. INVESTIGATIONS AT PERU, NEBRASKA, IN 1919.
University No. 21 oats, Avena sativa
Swedish Select oats, Avena sativa
Durum wheat, Triticum durum
Marquis wheat, Triticum aestivum
Manchuria barley, Hordeum vulgare
Corn, Zea mays indentata
Earlier investigations of corn
Potato, Solanum tuberosum
Earlier investigations of potatoes
Comparison of root systems
Environmental conditions of growth
Summary of root development
II. INVESTIGATIONS AT LINCOLN, NEBRASKA, IN 1919 AND 1920.
Oats, Avena sativa
Barley, Hordeum vulgare
Wheat, Triticum aestivum
Alfalfa, Medicago sativa
Sweet clover, Melilotus alba
Comparison of root systems
III. INVESTIGATIONS AT PHILLIPSBURG, KANSAS, IN 1920.
Oats, Avena sativa
Barley, Hordeum vulgare …

Relation Of Hardpan To Root Penetration In The Great Plains, J. E. Weaver, John Crist

Department of Agronomy and Horticulture: Faculty Publications

During the excavation of root systems of native and crop plants through- out the Great Plains region during the past five years (Weaver, 1919,1920, 1922) contact has been made in more than thirty fields with the so-called hardpan. Such a layer of soil underlies much of this area of low rainfall, at depths varying from 15 inches to 3 feet. It varies from 8 inches to over 1.5 feet in thickness. In connection with studies on the physical and chemical composition of the soils and their seasonal water-content under natural and cropped conditions, a more detailed study has been made …

Genetic Interrelations Of Two Andromonoecious Types Of Maize, Dwarf And Anther Ear, R. A. Emerson, Sterling H. Emerson

Department of Agronomy and Horticulture: Faculty Publications

Attention was called by Montgomery (1906)to the occasional appearance

of perfect flowers in the staminate inflorescence of maize and similar

cases were reported by Kempton (1913). Montgomery (1911) described

with illustrations a true-breeding type of semi-dwarf dent maize, the ears

of which were perfect-flowered. Perfect-flowered maize was described

and illustrated also by Blaringhem (1908, pp. 180-183). East and

Hayes (1911, pp. 13, 14) noted and illustrated a perfect-flowered sweet

corn. Weatherwax (1916, 1917) showed that typically pistillate

flowers of maize exhibit in microscopic sections the rudiments of stamens

and that staminate flowers show rudiments of pistils.

The Relative Frequency Of Crossing Over In Microspore And In Megaspore Development In Maize, R. A. Emerson, C. B. Hutchison

Department of Agronomy and Horticulture: Faculty Publications

One of the early developments in the study of linkage in Drosophila was the discovery that the phenomenon of crossing over is confined to the female sex (Morgan 1912). The fact that no crossing over occurs in the male Drosophila holds true not only for sex-linked genes but for factors in the autosomes as well and is so well established that it affords a most convenient method of determining to which of the different linkage groups a new factor belongs.

The same phenomenon, but with the sexes reversed, obtains in the silkworm moth. Tanaka (1914, 1915) has found from back-cross …

Heritable Characters Of Maize: Ix. Crinkly Leaf, R. A. Emerson

Department of Agronomy and Horticulture: Faculty Publications

In 1910 a strain of dent corn obtained at the National Corn Exposition held at Omaha was crossed with a strain of flint corn obtained from the Department of Agronomy of the University of Nebraska. The F₁ plants of this cross were normal and no abnormalities had been observed in the parent strains. But since the latter had not been subjected to self-pollination, there is no assurance that one or other of them did not have in it the character to be described here. In the F₂ generation of this cross there occurred a tpe of plant that …

Heritable Characters Of Maize Ii.-Pistillate Flowered Maize Plants, R. A. Emerson

Department of Agronomy and Horticulture: Faculty Publications

In the "freak"

class at the Annual

Corn Show held at Lincoln, Nebraska,

in the winter of 1913-14,

there was exhibited a corn tassel

with a heavy setting of seeds. A few

seeds are not infrequently found in the

staminate inflorescence of maize, particularly

in pod com, and tillers of various

corn varieties often end in ears instead

of in tassels or have tassels, the central

spikes of which are ear like. The freak

exhibited at the com show, however,

was a large. much branched affair.

wholly tassel-like in form except for the

fact that it bore a heavy crop …

Relative Transpiration Of Coniferous And Broad-Leaved Trees In Autumn And Winter, J. E. Weaver, A. Mogensen

Department of Agronomy and Horticulture: Faculty Publications

Transpiration has been of special interest to many investigators for a long time. At first it was considered without reference to environmental factors, but later, as more observations were made and these factors were noted to have a marked effect upon the water loss, they were taken into consideration. Many of the data assembled have been limited to plants during the growing season, so that it has seemed profitable to obtain not only quantitative data on winter losses, but also a comparison of the relative transpiration of conifers and broad-leaved trees in summer and winter.

The Quadrat Method In Teaching Ecology, J. E. Weaver

Department of Agronomy and Horticulture: Faculty Publications

The quadrat method of studying vegetation has become an integral part of many of the more important ecological investigations. Although occasionally used throughout the past century for determining the amount of plant material produced or for purposes of enumeration, it was organized into a definite system for the study of the structure and development of vegetation by Pound and Clements (15, 16) and Clements (2, 3, 5) only about eighteen years ago. Since that time it has been used, sometimes in a modified form (12, 21), by numerous investigators both American and European. Indeed, with the rapid increase in the …

Further Studies In The Ecotone Between Prairie And Woodland, R. J. Pool, J. E. Weaver, F. C. Jean

Department of Agronomy and Horticulture: Faculty Publications

A series of intensive investigations of the ecological features of the tension zone between prairie and woodland in the Mississippi valley was begun by Weaver and Thiel in 1915. These studies were continued for two seasons in Minnesota and were also extended to the prairies of eastern Nebraska in 1916. These investigations represent the first attempt to attack the prairie-forest problem on a comprehensive scale by means of the quantitative methods of modern ecology. Some of the results secured from these studies have been published as the first paper of a series planned to deal with critical investigations in the …

Ecological Studies In The Tension Zone Between Prairie And Woodland, J. E. Weaver, Albert F. Thiel

Department of Agronomy and Horticulture: Faculty Publications

Upon the completion of a series of investigations in southeastern Washington and adjacent Idaho, in which there was found to be a direct relation between the available water content of the soil and the evaporating power of the air as succession progressed from grassland through scrub to forest, the senior writer moved to Minneapolis, Minnesota. Here such excellent conditions of prairie invaded by scrub and followed by forest offered themselves for study that the services of the junior author were enlisted and an analysis of the situation attempted. Later this study was supplemented by similar work carried on at Lincoln, …

A Study Of The Vegetation Of Southeastern Washington And Adjacent Idaho, J. E. Weaver

Department of Agronomy and Horticulture: Faculty Publications

Introduction
Extent and position of area
Physiographic regions and geology
Soils
Topography and drainage
General plant-life conditions
General vegetational distribution
Outline of developmental series
Evaporatidn and soil moisture in relation to succession
Soil temperature in relation to succession
The prairie-plains formation
Agropyron-Festuca association
Festuca consociation
Agropyron consociation
Rhizocarpon-Lecidea associes
Gyrophora-Parmelia associes
Grimmia-Tortula associes
Poa-Polygonum associes
The desert scrub formation
Artemisia-Atriplex association
Artemisia consociation
The Pacific Coast forest formation
Thuja-Tsuga association
Symphoricarpos-Opulaster associes
Pinus-Pseudotsuga associes
Larix-Abies associes
Thuja consociation
Adsere Alnus-Salix associes
Subsere Natural reforestation in cut-over areas and in burns
Hydrosere
Chara-Potamogeton associes
Nymphaea-Potamogeton associes
Scirpus-Typha associes
Eleocharis-Carex associes
Wet …

Genetical Studies Of Variegated Pericarp In Maize, R. A. Emerson

Department of Agronomy and Horticulture: Faculty Publications

Two years ago there were presented some results of a study of the inheritance of self pattern in the pericarp of maize seeds, occurring as a sporophytic2 variation in variegated ears (EMERSON1 914). Further results, in entire accord with those previously reported, have now been obtained. In addition, data bearing upon new phases of the problem are also available.

The chief results reported in the earlier paper were the following: ( I ) The more nearly self-colored the pericarp of any seed of a variegated ear, the more likely is the progeny of that seed to produce a self-colored ear …

The Inheritance Of A Recurring Somatic Variation In Variegated Ears Of Maize, R. A. Emerson

Department of Agronomy and Horticulture: Faculty Publications

The inheritance of variegation has special interest and importance in genetics. It is with forms of variegation that the only two certainly known cases of non-Mendelian inheritance have had to do. I refer to Baur's experiments with Pelargonium, in which crosses of green-leaved and white-leaved forms exhibited somatic segregations in F₁ that bred true in later generations, and to Correns 's work with Mirabilis, which showed green and white leaf color, to be inherited through the mother only. De Vries's con- ception of "ever-sporting" varieties was apparently founded largely upon the behavior of variegated flowers in pedigree …

Multiple Factors Vs. "Golden Mean" In Size Inheritance, R. A. Emerson

Department of Agronomy and Horticulture: Faculty Publications

Groth's preliminary note on the "golden mean" in the inheritance of sizes in SCIENCE of April 17, 1914, pp. 581-584, deserves the attention of geneticists. Its publication is of such recent date that I need only call attention to one or two points that seem to me of particular moment.

In brief, Groth's hypothesis is that the mode

of inheritance in F_l not only of surfaces and

volumes, but also of linear dimensions is to be

expressed by √ab rather than by a + b /2

where a and b are parent sizes. The hypothesis

is based upon …

Shorter Articles And Discussion Simplified Mendelian Formulae, R. A. Emerson

Department of Agronomy and Horticulture: Faculty Publications

I was somewhat surprised by 'Morgan's and Castle's suggestions for a simplification of Mendelian formulae. My surprise was not occasioned so much by the forms these suggestions took as by the fact that any pronounced changes were deemed necessary. I had not only employed the usual formula in my own work but had found no difficulty worth mentioning in understanding the formula used by most other workers in Mendelian fields. My experience with students in elementary courses in genetics had not prepared me for the idea that such formula were particularly difficult. Nevertheless I believe in simplifying the formulae if …

The Possible Origin Of Mutations In Somatic Cells, R. A. Emerson

Department of Agronomy and Horticulture: Faculty Publications

That mutations are accompanied by some change in the germ-plasm is, I take it, indisputable. Have we, however, any reason to suppose that the change takes place within the germ cells? I am not sure, as a matter of fact, that genetists in general regard the gametes as the place of origin of mutations. It is true, however, that experiments in the artificial production of mutations in plants have been limited largely to treatments of the ovaries from about the time of the reduction division to about the time of fertilization. This suggests a belief on the part of investigators …

Shorter Articles And Reports: The Simultaneous Modification Of Distinct Mendelian Factors, R. A. Emerson

Department of Agronomy and Horticulture: Faculty Publications

In another paper on the inheritance of a recurring somatic variation in variegated ears of maize, it was shown that the amount of red color developed in the pericarp of variegated seeds bears a definite relation to the development of color in the progeny of such seeds. The relation is such that the more color there is in the pericarp of the seeds planted the more likely are they to produce plants with wholly self-red ears and correspondingly the less likely to produce plants with variegated ears. Self-red ears thus produced behave just as if they were hybrids between self-red …