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Department of ^p^ Agriculture

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Agriculture Information Bulletin Number 444

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Alfalfa for Dryland Grazing

Abstract

Lorenz, Russell J., Ronald E. Ríes, Clee S. Cooper, Charles E. Townsend, and Melvin D. Rumbaugh. 1982. Alfalfa for Dryland Grazing. U.S. Department of Agriculture, Agriculture Information Bulletin Number 444, p. 24.

Arthur C. Wilton, chairman Committee on alfalfa for dryland grazing Central Alfalfa Improvement Conference

This publication is a compilation of literature review and concepts by alfalfa breeders, agronomists, and a range scientist on dryland grazing in the Northern Great Plains and other Western States. The authors report on such aspects of alfalfa production as persistence under dryland grazing, physiological characteristics contributing tov/ard longevity, diseases and insects of alfalfa, and availability of sources of germplasm.

KEYWORDS: alfalfa, dryland grazing, crested wheatgrass, Russian wildrye, legumes, drought

Issued June 1982

Preface

Legumes now are being used where, several years ago, their use would have been

impractical and uneconomical. Escalating energy demands and high oil and nitrogenous

fertilizer prices have caused farmers and ranchers to expand legume acreages. In the plains

of the West and in some intermountain areas, this means expanded alfalfa acreages. We

now believe that the alfalfa species-complex, without doubt, is the toughest and most

productive of the legumes for rangeland and dryland pasture use.

With increased interest in dryland legumes generally, and in alfalfa particularly, we cannot

help but realize the research challenges afforded by and the immense benefits to be gained

through dryland alfalfa research. For example, of the nearly 100 million acres of grassland

in the three northern States of the Great Plains—North Dakota, South Dakota, and

Montana—more than 90 percent is grazing land. Alfalfa can increase the productivity of

much of this area. With acreages of such immensity, huge yield increases are not necessary

to escalate our national livestock production. Yet, in specific instances, beef production on

dryland has been doubled by adding alfalfa.

The problem that ranchers and farmers face, however, is continued and reliable production.

All growth, productivity, and persistence factors necessary to ensure continuous production of

a range alfalfa are not yet known. The various types of alfalfa compatible with different

grazing systems or with various rangeland macroenvironments and microenvironments are

qlso unknown.

The problems in alfalfa breeding for rangeland and for dryland pasture may be more diverse

than those encountered in breeding for hay production, particularly where hay is produced

under conditions of adequate soil moisture. Because grazed alfalfa means livestock use,

livestock management must be considered as well as management of the grass-legume

mixture. Alfalfa in rangeland is exposed to varied environments, not only from year to year

but also from location to location. If alfalfa is to be used in these varied environments,

then the specific growth-governing environmental factors must be isolated and

their effect on alfalfa growth must be investigated. Finally, the available alfalfa germplasm

should be surveyed, and the most successful genotypes should be delineated if additional

cultivars of range alfalfa are to be produced and used.

A committee was assembled, therefore, (1) to review the literature concerning the persistence

of alfalfa under dryland grazing; (2) to develop and state, insofar as possible, concepts of

the salient physiological characteristics contributing toward stand longevity under range

conditions; and (3) to suggest germplasm sources that might contribute toward easy

establishment and stand longevity under range conditions.

The committee is a diverse group because the problems are diverse. It consists of three alfalfa

breeders, two research agronomists, and one range scientist. One research agronomist,

throughout his career, has specialized in the physiology of dryland legumes; the other has

specialized in grazing management in the Northern Great Plains. All the group are now in the

Northern Great Plains Region or were situated there previously. All are vitally interested in

dryland alfalfa. This publication is a report of the committee's work.

The approach in this publication has been that each researcher independently review the

literature on a particular phase of alfalfa in dryland agriculture. One section is devoted to

grazing management, one to range ecology, one to physiology related to persistence, one to

pests of alfalfa in rangeland, and one to availability of germplasm. Each section will stand

on its own, yet all contribute to the general knowledge that breeders, range management

specialists, and range scientists must know if alfalfa is to succeed as a dryland legume.

The authors wish to thank the National Alfalfa Improvement Association for sponsoring the

committee.

Contents

Alfalfa in western grazing management systems 1

Introduction 1

Literature review 1

Concluding remarks 3

References 3

Environmental factors and alfalfa persistence in dryland pastures and rangeland ^

Introduction 4

Environmental factors and dryland pasture and rangeland alfalfas 4

Promising alfalfas for dryland pastures and rangelands 6

Summary 6

Literature cited 7

Selection for drought resistance in alfalfa 8

Introduction 8

Influence of drought on plant growth 8

Resistance to drought and its measurement 8

Determining criteria for selecting drought-resistant alfalfas 10

References 11

Diseases, insects, and other pests of rangeland alfalfa 13

A review 13

Literature cited 14

Origins of alfalfa cultivars used for dryland grazing 15

Introduction 15

Root-proliferating alfalfas 15

Rhizomatous alfalfas 17

References 18

Trade names and the names of commercial companies are used in

this publication solely to provide specific information. Mention of a

trade name or manufacturer does not constitute a guarantee or war-

ranty of the product by the U.S. Department of Agriculture or an

endorsement by the Department over other products not mentioned.

Alfalfo In Western Grazing Managment Systems

Russtli J. Lorenz^

Introduction

References showing that legumes in a grass sward increase

herbage yield and crude protein content and improve forage

palatability and digestibility are found easily in both scientific

and popular literature. On a worldwide basis, alfalfa is

considered the most widely adapted and the most useful legume

known. Another fact almost as commonly known is that legumes,

particularly alfalfa, improve animal performance whenever they

are included in the ruminant diet.

Literally thousands of worker-years have been spent on alfalfa

breeding and management research. Volumes have been written

on the merits of alfalfa, and its history parallels that of all

major civilizations. Small wonder, therefore, that alfalfa has been

dubbed "queen of the forages" (7).^

But the Queen is not a simple creature. What is so easily

referred to as "alfalfa" is, in reality, a complex of species

capable of hybridization. Herein lies part of the secret to wide

adaptability and high productivity found in alfalfa. In the past,

scientists, seed producers, farmers, and all concerned with

alfalfa favored the more productive lines—those capable of

producing the most forage on productive soils adequately

supplied with water. Because of bloat potential, few would risk

grazing alfalfa, and certainly no one would try to raise alfalfa

in areas of low precipitation unless these areas could be

irrigated. Consequently, geneticists and agronomists devoted

their lives to selecting plant materials of the upright types

suitable for producing hay and to developing management

systems suited to the more favorable production situations, while

the prostrate and decumbent growth forms with fibrous and

creeping roots, suitable for dryland grazing, usually were

discarded.

The merits of alfalfa were heard by those of us in range

management in the arid and semiarid Great Plains and Western

States. Some tried raising and grazing alfalfa in these areas

with some degree of success but, more often, with poor or even

disastrous results. A few alfalfa breeders did select plant types

adapted to the arid and semiarid lands, notably those at

Swift Current, Saskatchewan, Canada, and at Brookings, S. Dak.

These breeders sacrificed yield in favor of persistence under

grazing and with limited soil water supply. Getting selections

from these lines released as cultivars was difficult, however,

because they did not look like improved lines when tested against

the conventional hay types.

Time and economic conditions do change, and with them demands

and standards also change. Farmers, ranchers, scientists, and

those in agribusiness now are engaged in a meager, but

gratifying, effort to find a legume suitable for grazing use in

semiarid and arid grasslands. At the present time, alfalfa is the

^ Research leader and research agronomist. Northern Great Plains

Research Center, Agricultural Research Service, U. S. Department of

Agriculture, Mandan, N. Dak. 58554.

^ Italic numbers in parentheses refer to References, p. 3.

legume that holds the greatest promise for success (6, 17).

In this report, I will briefly outline the relatively small amount of

information published in the last 20 years, related to grazing

use of alfalfas in the Great Plains and Western States. This

should not be considered an exhaustive review because

information on alfalfa often was included in a rather secluded

fashion in other grazing research reports.

Literature Review

Throughout the years, dryland alfalfa-grass mixtures have been

grazed on a limited basis in the Great Plains of United States

and Canada and in the Western United States. Most of the

research and most of the farmer-rancher usage, however, have

been with alfalfa seeded with crested wheatgrass, Russian

wildrye, or intermediate wheatgrass. Recent development of

interseeding technology opened new management doors by

providing a means of introducing alfalfa and other species to

native range and to established stands of seeded grasslands.

Ranchers or farmers who have successfully grazed alfalfa-grass

mixtures, or have interseeded legumes into native range, often

have their efforts documented in the popular press. In most cases,

these ranchers and farmers ore pleased with the results and are

in favor of developing technology and plant materials to improve

the practice. One Montana rancher expressed his enthusiasm for

alfalfa by publishing in a technical ¡ournal. He includes alfalfa in

a system that works for him (12).

Grazing Trials—Research at Dickinson, N. Dak., compared

crested wheatgrass pastures with crested wheatgrass-alfalfa

pastures (20). Throughout the 7-year trial, the crested wheatgrass-

alfalfa pasture was superior to the crested wheatgrass pasture

in forage and beef production. Yearling steers used as test

animals showed no difference in daily gain per head, although

daily forage consumption averaged 17.5 lb dry matter per head

per day on the crested wheatgrass and 17.0 lb on crested

wheatgrass-alfalfa. The average number of pounds of forage

required per pound of gain was 8.4 on the crested wheatgrass

and 8.1 on the crested wheatgrass-alfalfa.

Research at the Eastern Colorado Range Station north of

Akron (5), at the Archer Substation east of Cheyenne, Wyo. (15),

and at the Northern Great Plains Research Center, Mandan,

N. Dak. (16), all showed an advantage to alfalfa in the mixture

for animal performance as well as for forage production. In the

Colorado research, intermediate wheatgrass-alfalfa pasture

produced 51 percent more forage, had 67 percent greater

carrying capacity, and gave 21 lb greater seasonal gain per

head than did intermediate wheatgrass without alfalfa. Air-dry

forage required per pound of gain was 8.9 lb, and doily air-dry

forage consumption was 15.7 lb per head for the intermediate

wheatgrass-alfalfa; for intermediate wheatgrass alone, air-dry

forage per pound of gain was 8.5 lb and daily air-dry forage

consumption was 13.2 lb per head. The advantage for the

alfalfa-grass mixture in the Wyoming work increased as the

proportion of alfalfa increased, and the intermediate wheatgrass

decreased in the mixture.

1

In the 10-year study at Mandan, yearling steers had average

daily gains of 2.ÓÓ lb for crested wheatgrass alone, 2.Ó3 lb for

crested wheatgrass with 40-N applied annually, 2.53 lb for

crested wheatgrass with 80-N applied annually, and 2.82 lb

for crested wheatgrass with alfalfa. Carrying capacity was

significantly higher for the pastures with the legume than for

the crested wheatgrass alone but significantly less than for those

receiving 40-N or 80-N annually.

A grazing study at Miles City, Mont., compared crested

wheatgrass-alfalfa and Russian wild rye-alfalfa with native range,

but no direct comparison was made with the grass species without

alfalfa (9). For all parameters evaluated, the seeded pastures

exceeded the native range when grazed with Hereford breeding

cows and calves for 5 years. No management problems were

attributed to alfalfa in the mixture, but the authors did question

the effect of fall grazing of regrowth on date of beginning

grazing the following spring or on the amount of forage

produced the following year.

Crested wheatgrass and crested wheatgrass-alfalfa pastures were

compared as part of an 8-year study at the Archer Field Station

in Wyoming (2). The 8-year average sheep-days per acre was

121, and the lamb gain per acre was ó4 lb for the crested

wheatgrass alone. For crested wheatgrass with alfalfa, the 8-year

average sheep-days per acres was 164, and the lamb gain per

acre was 9ó tb. The actual daily gains were not reported, but

the authors made the following statement: "Analysis of the daily

gains made by the animals on these different pastures showed

little difference in gains for any given period and for animals of

similar age. Exceptions were found on the blue grama-

buffalograss pasture, where gains were quite low, and on the

grass-legume mixture, where gains were above average."

Mixtures of crested wheatgrass, intermediate wheatgrass, and

Russian wildrye, with and without alfalfa, were evaluated as

spring pasture using sheep [4] at Swift Current, Saskatchewan.

The mixture containing alfalfa exceeded the mixture without

alfalfa for all production parameters evaluated. Six-year averages

for each parameter with alfalfa were 1,020 lb dry matter per

acre; 13.4 lb gain per ewe; 35.3 lb gain per acre; and 333 ewe

days grazing per acre. Without alfalfa, ó-year averages for each

parameter were 750 lb dry matter per acre; 6.0 lb gain per

ewe; 11.0 lb gain per acre; and 257 ewe days grazing per acre.

Bloat is always of concern where alfalfa is included in a pasture;

however, finding reports of research designed to evaluate the

bloat problem or to document management systems designed to

reduce the bloat hazard satisfactorily is difficult. A study at

Swift Current (7) involved grazing pure stands of four alfalfa

varieties: 'Rambler', 'Siberian', 'Grimm', and 'Alfa'. Steers

grazed these pastures for 2 years with a very low incidence of

bloat. Although slight bloating sometimes occurred, no animal

reached the severe stages. Holstein cows grazed these pastures

for 1 year, and virtually no bloat was observed. In all 3 years,

'Rambler' was superior to 'Grimm' and 'Alfa' in yield and

carrying capacity. The authors concluded that alfalfa can be used

successfully for dryland pasture and that certain varieties are

better than others for this purpose.

Interseeding-—Interseeding has been studied at a number of

locations in the Great Plains and Western States (9, 14,18, 19).

Enough successful interseedings have been made to indicate that

technology can be developed for introducing alfalfa into existing

grasslands; however, research involving grazing of interseeded

grasslands is limited.

An interseeded pasture-grazing trial underway at Dickinson,

N. Dak. [13], has been grazed with cow-calf pairs for 2 years.

Below-normal precipitation has kept production from all

treatments low, but the native range interseeded with 'Travois'

alfalfa averaged 32 lb more beef per acre than the next highest

treatment and 67 lb more than the untreated native range. These

results are preliminary but of interest because very litle native

range interseeded with alfalfa has been experimentally grazed.

Persistence—Questions of persistence and longevity are often

raised in discussions of introducing alfalfa into grasslands. Many

very old stands of alfalfa can be found in the Northern Great

Plains of the United States and Canada, and I am sure there are

others in the Western States. Some have been documented {11,

17), and I am aware of several very old stands in the Dakotas

and Montana that have been grazed for many years. A germ-

plasm collection has been made from many of these old stands,

and plans are underway to collect from others.

Campbell (3) conducted a study near Swift Current in which six

grass-alfalfa mixtures were grazed with sheep for 4 years, with

season of use as a variable. Since no treatment without alfalfa

was included, the direct benefit of alfalfa cannot be identified

but its persistence is noteworthy. Campbell's study was

conducted in a low-precipitation area, during 4 years of below-

normal precipitation. The creeping-rooted strain of alfalfa used

was described as being similar to 'Rambler*. It maintained Its

stand in the spring-grazed pastures and persisted strongly in the

autumn-grazed pastures but decreased on the continuously grazed

and summer-grazed pastures. Campbell concluded that this

type of alfalfa would persist and provide excellent pasture when

grown with dryland grass species suited to the low-precipitation

areas of the Northern Great Plains of the United States.

To summarize alfalfa production in Canada, Heinrichs (8) made a

few comments related to use and management of dryland alfalfa

related to persistence. I include them here to remind us that

grazing management systems need to take into account the

increased complexity of adding a species to the system,

particularly if an alfalfa is developed for introduction in native

range or for use in permanent type seeded grasslands, and if it

is expected to become a permanent part of the species complex.

The following are quotations from Heinrichs (8):

-^"The main principle to follow in the utilization of alfalfa is to

avoid frequent cutting or overgrazing.

—"Alfalfa withstands continuous grazing quite well, but it thins

out rapidly when closely grazed. Varieties with wide crowns and

creeping roots survive better under grazing than tap-rooted

types with narrow crowns, provided they are adapted to a

region.

—"Do not cut or graze alfalfa during a ó-week period from September 1 to October 15. At this time, carbohydrate reserves are being stored in the roots in preparation for the long dormancy period, and if top growth is removed reserves will be insufficient and plants will suffer from winter killing."

Concluding Remarks

Introducing alfalfa to arid and semiarid grasslands is a viable means of increasing animal output from a shrinking grazing acreage with a minimum of fossil fuel energy input. We cannot expect alfalfa to miraculously improve all grasslands, but we can learn where to use it and when to use it so we can add it to the collection of alternatives available to the range and livestock managers.

To do this successfully, legume breeders need to know what situations alfalfa will be put into in grazing management systems. This will provide the guidelines for selecting materials capable of performing satisfactorily. In all probability, no one cultivar will be best for all situations. Managers need to know the limitations of available cultivars so they can manage for optimum animal product while maintaining the legume-grassland complex on a long-time basis. With these factors as a common ground, geneticists, physiologists, pathologists, entomologists, agronomists, range scientists, and range animal nutritionists need to apply a team effort to provide the materials and the technology needed to make the system work and to make it available to the livestock manager of the arid and semiarid regions of the Western United States and Canada.

References

(7) Ashford, R., and D. H. Heinrictis. 19Ó7. Grazing of alfalfa varieties and observations on bloat.

Journal of Range Management 20:152-153. (2) Barnes, O. K., and A. L. Nelson.

1950. Dryland pastures for the Great Plains. Wyoming Agricultural Experiment Station, Bulletin No. 302. 30 p.

(3) Campbell, J. B. 1961. Continuous versus repeated seasonal grazing of gross-

alfalfa mixtures at Swift Current, Saskatchewan. Journal of Range Management 14: 72-77.

{4) 1963. Grass-alfalfa versus grass-alone pastures grazed in a

repeated-season pattern. Journal of Range Management 16:78-81.

(5) Dahl, B. E., A. C. Everson, J. J. Norris, and A. H. Durham. 1967. Grass-alfalfa mixtures for grazing in eastern Colorado.

Colorado Agricultural Experiment Station, Bulletin No. 529-5. 25 p.

(Ó) Gomm, F. B.

1964. A comparison of two sweetclover strains and Ladak alfalfa alone and in mixtures with crested wheotgrass for range and dryland seeding. Journal of Range Management 17:19-23.

(7) Hanson, C. H., ed. 1972. Alfalfa science and technology. Agronomy Series No. 15,

American Society of Agronomy, Madison, Wis. (8) Heinrichs, D. H.

1969. Alfalfa in Canada. Canada Department of Agriculture, Publication No. 1377. 28 p.

(9) Houston, W. R., and R. E. Adams. 1971. Interseeding for range improvement in the Northern

Great Plains. Journal of Range Management 24:457-461. (10) and J. J. Urick

1972. Improved spring pastures, cow-calf production, and stocking rate carryover in the Northern Great Plains. U.S. Department of Agriculture, Technical Bulletin No. 1451.

{11) Kilcher, M. R., and D. H. Heinrichs. 1966. Persistence of alfalfas in mixtures with grasses in a

semiorid region. Canadian Journal of Plant Science 46:162-167.

{12) Miles, A. D. 1969. Alfalfa as a range legume. Journal of Range

Management 22:205-207. (Î3) Nyren, P. E.

1979. Interseeded pasture grazing trial. In 30th Annual Livestock Research Roundup, Dickinson Experiment Station, Dickinson, N. Dak., December 5, 1979, sec. IV, p. 7-12.

(14) H. Goetz, and D. Williams. 1978. interseeding of native mixed prairie in the Great Plains.

Proceedings of the First International Rangeland Congress, Denver, Colo., August 14-18, 1978, p. 636-638.

(15) Rouzi, F., R. Long, and O. K. Barnes. 1958. Dual purpose pastures for the Shortgrass Plains.

Wyoming Agricultural Experiment Station, Bulletin No. 359. 16 p.

{16) Rogler, G. A., and R. J. Lorenz. 1969. Pasture productivity of crested wheotgrass as influenced

by nitrogen fertilization and alfalfa. U.S. Department of Agriculture, Technical Bulletin No. 1402.

(17) Rumbough, M. D., and M. W. Pedersen. 1979. Survival of alfalfa in five semiorid range seedings.

Journal of Range Management 32:48-51. (Î8) and T. Thorn.

1965a. Initial stands of interseeded alfalfa. Journal of Range Management 18:258-261.

(19) and T. Thorn. 1965b. Interseeding legumes in South Dakota grasslands.

South Dakota Form and Home Research 16(2):7-9. {20) Whitman, W. C, L. Longford, R. J. Douglas, and T. J. Conlon.

1963. Crested wheotgrass and crested wheatgross-olfalfa pastures for eorly-seoson grazing. North Dakota Agricultural Experiment Station, Bulletin No. 442.

Environmental Factors And Alfalfa Persistence In Dryland Pastures And Rangeland

Ronald E. Rits^

Introduction

The use of legumes in dryland pasture and range is considered

beneficial because of increased total forage production,

improved animal performance from the presence of the legume,

increased use of all forage, and the possibility of increased

nitrogen for associated vegetation through the nitrogen-fixing

ability of legumes.

Opinions about these proposed benefits from legumes in pasture

and rangeland differ widely among scientists v/orking on them.

Existing evidence, hov/ever, indicates the need for further study to

better understand the legume-grass association in dryland

pasture and rangeland.

Heinrichs (73)^ proposes that alfalfa, because of its wide

climatic adaptability, is the most promising legume for rangeland

use in the temperate regions of the world. Hanson et al. [11]

briefly discuss the distribution and adaptation of alfalfa. They

reported that alfalfa is distributed worldwide and is well adapted

to widely divergent climatic and soil conditions. Yellow-flowered

alfalfa (Medicago falcata) has survived at temperatures as low

as -62° C (-80° F) and as high as 54° (130°). Because of

this wide distribution and diversity, improving alfalfa by

selection and breeding has been very successful.

Environmental Factors And Dryland Pasture

And Rangeland Alfalfas

Much research on alfalfa has been done since it was introduced

into the United States.

One report comprehensively reviewed and consolidated alfalfa

research results (70). Much of this research was concentrated on

the agronomic use of alfalfa for hay and pasture in humid,

semiarid, and arid climates, and on irrigated alfalfa in arid

climates. Rangeland alfalfa has been studied less. Under dryland

conditions, alfalfa has been used for hay production, in seeded

dryland pastures in association with grasses, and in a few

rangeland seedings. This section discusses the relationship of

environmental factors found under dryland pasture and rangeland

conditions to alfalfa survival and growth.

Wilsie (37) discusses crop adaptations and distribution and the

relationship between crop plants and their environment. He

groups environmental factors into three general categories;

climatic, edaphic, and biotic. Understanding the relationship of

these factors and alfalfas used in dryland pastures or rangeland

communities is essential for the success of such systems.

* Range scientist, Northern Great Plains Research Center, Agricultural Research Service, U.S. Department of Agriculture, Mandan, N. Dak. 58554. ^ Italic numbers in parentheses refer to Literature Cited, p. 7.

Dryland pastures differ somewhat from rangelands because they

usually are established on marginal cropland of reasonable

topography and under marginal climate for dryland farming.

Associated species may include one to three grass species, and

the pasture will receive moderate to high levels of management.

Rangeland, on the other hand, is usually poorer land than dryland

pastures and has more rough topography and drier climatic

conditions. Associated species usually are more diverse than

dryland pastures, and the range areas usually receive less

management than dryland pastures. The environmental conditions

confronted by alfalfa under these two uses are similar but

perhaps more severe in rangeland.

Climatic Factors—Temperature, water supply, and light are the

three most important climatic factors related to plant response.

All elements of climate are interrelated (74). Vegetative

response is affected by all environmental elements interacting to

determine plant establishment, survival, growth, and

productivity.

Alfalfa used for dryland pasture or rangeland would be exposed

to variable climatic conditions. In the areas where dryland alfalfa

can be used, seasonal temperatures range from as high as 49°C

(120°F) to as Iowas —46° ( — 50°). Diurnal temperature

fluctuations of 40° are common. Annual precipitation may

vary from 20 in (50 cm) to below 1 0 in (25 cm) with periods of

drought common at any time. Evapotranspiration rates are high.

Day length and, to a lesser extent, light intensities can also

vary. Aamodt (7) summarizes well the effect of climate on alfalfa.

The most important fact is that alfalfa strains and varieties

differ in their climatic requirements.

These climatic conditions often are tempered by associated

conditions. The effectiveness of precipitation in localized areas

can be influenced greatly by its intensity, type (rain or snow),

duration, and annual and seasonal distribution. Temperatures are

modified by topographic position and aspect (north, south, east,

west). The severity of winter temperatures can be lessened by

the insulating effect of snow cover. Light intensifies can be

modified by topographic position, aspect, and associated

vegetation.

Literature concerning environmental physiology of alfalfa was

reviewed (5). This review reflects the considerable amount of

work done on the germination and growth of current varieties of

alfalfa in relation to specific environmental conditions. In another

report the response of alfalfa to cold, drought, and heat was

reported (75). In both discussions, varieties responded significantly

differently to various environmental conditions. The difference

emphasizes the need to match varieties with environments where

they perform best. Genetic differences also allow for selecting

and breeding new varieties for specific environmental

conditions.

Edaphîc Factors—Edaphic conditions will be a very important

environmental consideration for dryland alfalfa. In the semiarid

and arid regions, soil properties that affect water infiltration and

storage will be of paramount importance to survival and growth

of alfalfa. Soil texture, sodium content, slope steepness, and

vegetative cover are very important in determining the amount

of water infiltration that can take place on a site. Soil texture,

soil depth, and salinity levels greatly infiuence the availability of

soil water for plant growth. Soil properties are more important

to alfalfa survival and growth under dryland conditions than

under higher rainfall or irrigation because the amount of

available water for growth is infiuenced primarily by soil

characteristics and is only slightly controllable by management.

Soils vary greatly across the area where alfalfa may be used in

dryland pastures or rongelands. The properties of these soils have

been documented through soil surveys for much of the area.

Some research has been done on soil water uptake and the

importance of subsoil moisture to alfalfa. Kohl and Kolar {19)

found that Medicago sativa roots preferentially take up water

from areas of high water potential over areas of lower water

potential, but water uptake continues in areas of low water

potential (even below 15 bars). The depth of the roots does not

appear to affect water uptake. Kiesselbach et al. (76) found that

alfalfa yield decreased as subsoil water was depleted by an

alfalfa stand in Nebraska. Irrigating part of the stand replenished

subsoil water and improved yield. Both these findings need to be

considered when alfalfa is used in either dryland pasture or

rangeland.

Redmann [24] found alfalfa varieties were inhibited from

germinating by the osmotic and specific ion effects of various

salts. Again, certain varieties tolerated the osmotic and ionic

effects better. Such osmotic and ionic conditions can be

experienced under certain field conditions when establishing

alfalfa for dryland pasture or range.

The nutrient levels found in the soil where alfalfa can be used

also may be important. Nutritional requirements of alfalfa have

been discussed by Rhykerd and Overdahl [25]. A comprehensive

review of fertilizer experiments with alfalfa from 1915 to 19Ó0

at the University of Connecticut was made by Brown [4] and

provides an excellent review of nutrient requirements of alfalfa.

The articles provide basic nutritional requirements that must be

considered for alfalfa. Under dryland conditions in semiarid and

arid areas, however, nutrients may be less important because of

the limiting nature of water in most years.

Biotic Factors—To date, the relationship of alfalfa to biotic

conditions has been approached mainly from an agronomic

standpoint where considerable management was used. In dryland

pasture, and especially range situations, biotic factors will be

subject to considerably less management control. Dryland

alfalfas will have to withstand insects, rodents, grazing, and

occasional fire. App and Manglitz (2) discuss insects and related

pests in relationship to alfalfa survival and growth. Under

dryland conditions, diseases should be a lesser problem than

under more humid conditions. The primary insect pest is

grasshoppers. Rodents that feed on the roots of alfalfa in a

pasture and range area could pose a substantial problem to

alfalfa survival.

Competition from associated plants in pasture or rangeland will

be important and more severe than under agronomic monoculture

situations. Water available for plant growth is fixed, and

competition for its use will be intense. Alfalfa competes vigorously

for growth factors above and below ground (7). Kilcher and

Heinrichs (17) found alfalfa to be persistent in a mixture of

grasses in a semiarid region. Both these studies indicate that

alfalfa can be a valuable species in dryland pasture and

rangeland.

For alfalfa to become part of pasture or rangeland, and to

maintain itself, it must be established and continue to reestablish

itself because periodical reseeding is not practical. The ability

of an alfalfa to revegetate from roots or stems would be a

considerable advantage. The effect that competition from other

plants will have on seed production and establishment, as well

as on vegetative reproduction, is largely unknown but will be

crucial to the success of dryland pasture or range alfalfa.

Peters and Peters [23] discuss weeds and weed control for

alfalfa. Alfalfa, in general, was found to be susceptible to weed

competition in the seedling stage. Another study reviews

literature on competition between establishing forage species

with reference to alfalfa (3). Tesar and Jackobs [28) discuss

requirements and methods of alfalfa establishment. White [30)

presents information on establishing lucerne (M. sativa) in

uncultivated land in New Zealand. Establishing dryland alfalfa

under semiarid and arid conditions has been a problem, although

good success under favorable precipitation patterns and

amounts has been reported.

The ability of alfalfa to fix nitrogen is important in that it should

supply itself added nitrogen under dryland pasture and rangeland

conditions where nitrogen is often limited. Burton (Ó) discussed

the basics of nodulation and symbiotic nitrogen fixation by

alfalfa. The question of whether extra nitrogen will be available

for associated vegetation is of interest but quite controversial.

Simpson (26) reported lucerne released nitrogen gradually during

an experiment studying the transfer of nitrogen from pasture

legumes to an associated grass under several systems of man-

agement in pot cultures. Wilson and Wyss (32) discuss this

question comprehensively. They point out that under most

conditions where extra nitrogen was found, growth conditions

were excellent. Under dryland pasture and range conditions,

where soil water is often limited, the amount of excess nitrogen

for associated plants may be small. Yet the possibility of

available excess nitrogen exists and needs better understanding

and documentation.

Rangeland alfalfa has to survive and grow under the limited management it vf'iW receive. Conventional management and use of alfalfa are discussed by Graumann and Hanson (9) and Van Keuren and Marten (29). Because alfalfa is a desirable forage species, it is selectively grazed by livestock and v^ildlife. Even under proper stocking rates, the grazing pressure it receives could be quite heavy. A range alfalfa also must be able to survive chemicals and fires used for occasional weed and shrub control in rangelands. An important characteristic of an alfalfa that would best survive heavy grazing and fire would be one with vegetative primoidia close to or below the ground. Smith {27) discusses this characteristic for several alfalfa varieties. Because livestock are under less observation and control, rangeland alfalfa should have a low bloat tendency.

Promising Alfalfas For Dryland Pastures And Rangelands

Heinrichs (73) presents the most probable reasons for the noninclusion of legumes in current range improvement programs as poor survival of legumes under heavy grazing and the wariness of ranchers and farmers about bloat hazard. Lowe et al. (20) discuss in detail the current alfalfa varieties that are adapted to dryland production. Varieties considered as pasture type alfalfa include 'Nomad', 'Rambler', 'Rhizoma', 'Seveira*, 'Teton', and 'Travois'. They further point out that varieties used for pasture have low-set crowns, a procumbent growth habit, drought tolerance, marked fall dormancy, slow recovery from cutting, and a high degree of winterhardiness. These varieties usually produce less forage yield than varieties used for hay. Two papers by Graumann (8) and Heinrichs (12) discuss varieties of alfalfa in more detail concerning their suitability for dryland pasture and rangeland use.

Several varieties of alfalfa, therefore, are now available that could be a beneficial component of dryland pastures and rangelands. The benefits from alfalfa in pasture or rangeland areas need to be better documented and clarified, and better understanding and techniques are needed to establish these varieties. Research is needed on the beneficial minimum management of alfalfa in dryland and range communities along with better documentation of these varieties in relation to bloat incidence.

A review of older papers concerning alfalfa is of great interest from a range ecology standpoint (18, 21, 22), Many of the characteristics described for these early alfalfas are important for the persistence and success of many dominant range plants found today in dryland pastures and rangelands. The ability of selection and breeding programs using these early alfalfa plants to develop better dryland alfalfas, particularly for range use, appears to be excellent.

If the need and benefit of rangeland alfalfa warrants, an added collection of M. falcafa could be made from its original populations. This new collection could serve as a new breeding population to improve alfalfa for use in dryland forage communities.

Summary

From this discussion, the environmental factors limiting alfalfa survival and growth can be summarized as follows. Climate of the semiarid and arid areas where alfalfas would benefit pasture and rangeland involves limited precipitation amounts, often occuring irregularly. Periods of drought are common, and water is the most important single environmental factor. Temperature exhibits wide seasonal and diurnal fiuctuations, and évapo- transpiration rates are high. Winterhardiness is required over a large portion of the dryland pasture and rangeland area. Light intensity is fairly constant throughout the area, with daylength and its effect on fiowering and seed set being more variable.

Soils are most important in how they affect available soil water. Nutrient availability should be of secondary importance because soil water is inherently limiting. Pasture and rangeland alfalfa is subject to such pests as grasshoppers and rodents. Heavy grazing pressure from both livestock and wildlife can be expected. Alfalfa must survive the occasional management use of fire and chemicals for weed and shrub control. Because of limited control over range livestock, alfalfa used in rangeland should provide a low incidence of bloat.

Competition for nutrients and water for establishment, growth, and survival will be intense and largely outside the control of management. The ability of alfalfa to fix and supply itself with nitrogen may give it a competitive advantage in areas where nitrogen is limited. The ability of dryland pasture and rangeland alfalfa to go dormant during periods of unfavorable moisture and temperature, like other persistent dryland plants, would be beneficial.

An alfalfa that best meets these environmental requirements will be most successful in dryland pastures and rangelands. Production can be lower, but persistence and sustained yield under these conditions will determine its value as a component of dryland forage communities.

Uteroffure Cited

(?) Aaomdt O. S.

1941. Climate and forage crops. In Climate and man. U.S. Department of Agriculture, Yearbook of Agriculture 1941, p. 439-458.

(2) App, B. A., and G. R. Manglitz.

1972. Insects and related pests, p. 527-554. In C. H. Hanson,

ed.. Alfalfa science and tectinology. Agronomy Series No. 15, American Society of Agronomy, Madison, Wis.

(3) Blaser, R. E., T. Taylor, W. Griffeth, and W. Skrdla. 1956. Seedling competition in establishing forage plants.

Agronomy Journal 48(1): 1-6. (4) Brown, B. A.

1961. Fertilizer experiments with alfalfa 1915-1960. Connecticut Agricultural Experiment Station, Bulletin No. 363.

(5) Bula, R. J., and M. A. Mossengole.

1972. Environmental physiology, p. 167-184. In C. H. Hanson, ed.. Alfalfa science and technology. Agronomy Series No. 15, American Society of Agronomy, Madison, Wis.

(6) Burton, J. C.

1972. Nodulation and symbiotic nitrogen fixation, p. 229-246. In C. H. Hanson, ed.. Alfalfa science and technology. Agronomy Series No. 15, American Society of Agronomy, Madison, Wis.

(7) Chamblee, D. S.

1972. Relationship with other species in a mixture, p. 211-228. In C. H. Hanson, ed.. Alfalfa science and technology. Agronomy Series No. 15, American Society of Agronomy, Madison, Wis.

(8) Graumann, H. O.

1958. Progress report: Creeping alfalfa. What's New in Crops and Soils 10:18, 19, 37.

(9) and C. H. Hanson.

1954. Growing alfalfa. U.S. Department of Agriculture, Farmers' Bulletin No. 1722.

(10) Hanson, C. H., ed.

1972. Alfalfa science and technology. Agronomy Series No. 15, American Society of Agronomy, Madison, Wi«.

(IÎ) H. M. Tysdal, and R. L. Davis.

1966. Alfalfa, p. 127-138. In H. D. Hughes, M. E. Heath, and D. S. Metcalfe, eds.. Forages. Iowa State University Press, Ames.

(72) Heinrichs, D. H.

1963. Creeping alfalfas, p. 317-337. In A. G. Norman, ed.. Advances in agronomy. Academic Press, Inc., New York.

(J3)

1975. Potential of legumes for rangelands, p. 50-61. In R. S. Campbell and C. H. Herbei, eds.. Improved range plants. Range Symposium, Series 1. Society for Range Management, Denver, Colo.

(14) Hildreth, A. C, J. R. Magness, and J. W. Mitchell.

1941. Effects of climatic factors on growing plants. In Climate and man. U.S. Department of Agriculture, Yearbook of Agriculture 1941, p. 292-307.

(15) Jung, G. A., and K. L. Larson.

1972. Cold, drought, and heat tolerance, p. 185-209. In C. H. Hanson, ed.. Alfalfa science and technology. Agronomy Series No. 15, American Society of Agronomy, Madison, Wis.

(16) Kiesselbach, T. A., J. C. Russell, and A. Anderson. 1929. The significance of subsoil moisture in alfalfa

production. Journal of the American Society of Agronomy 21(3):241.268.

(77) Kilcher, M. R., and D. H. Heinrichs. 1966. Persistence of alfalfas in mixture with grass in a

semiorid region. Canadian Journal of Plant Science 46:163-167.

(78) Klinkowski, M.

1933. Lucerne: Its ecological position and distribution in the world. Imperial Bureau of Plant Genetics: Herbage Plants 12:1-62.

(79) Kohl, R. A., and J. J. Kolar.

1976. Soil water uptake by alfalfa. Agronomy Journal 68(3):536-538.

(20) Lowe, C. C, V. L. Marble, and M. D. Rumbaugh.

1972. Adaptation, varieties, and usage, p. 391-413. In C. H. Hanson, ed.. Alfalfa science and technology. Agronomy Series No. 15, American Society of Agronomy, Madison, Wis.

(27) Oakley, R. A., and S. Garver. 1913. Two types of proliferation in alfalfa. U.S. Department

of Agriculture, Circular 115. (22) and S. Garver.

1917. Medicago fo/cato, a yellow-flowered alfalfa. U.S. Department of Agriculture, Bulletin No. 428.

(23) Peters, E. J., and R. A. Peters.

1972. Weeds and weed control, p. 555-573. In C. H. Hanson, ed.. Alfalfa science and technology. Agronomy Series No. 15, American Society of Agronomy, Madison, Wis.

{24) Redmann, R. E.

1974. Osmotic and specific ion effects on germination of alfalfa. Canadian Journal of Botany 52(4):803-808.

{25) Rhykerd, C. L., and C. J. Overdohl. 1972. Nutrition and fertilizer use, p. 437-468. In C. H.

Hanson, ed.. Alfalfa science and technology. Agronomy Series No. 15, American Society of Agronomy, Madison, Wi$.

(26) Simpson, J. R.

1965. The transference of nitrogen from pasture legumes to an associated grass under several systems of management in pot culture. Australian Journal of Agricultural Research 16:915-926.

{27) Smith, D.

1955. Underground development of alfalfa crowns. Agronomy Journal 47:588-589.

{28) Tesar, M. B., and J. A. Jackobs.

1972. Establishing the stand, p. 415-435. In C. H. Hanson, ed.. Alfalfa science and technology. Agronomy Series No. 15, American Society of Agronomy, Madison, Wis.

(29) Von Keuren, R. W., and G. C. Marten.

1972. Pasture production and utilization, p. 641-658. In C. H. Hanson, ed.. Alfalfa science and technology. Agronomy Series No. 15, American Society of Agronomy, Madison, Wis.

(30) White, J. G. H.

1970. Establishment of lucerne {Medicago sativa L.) in uncultivated country by sod-seeding and oversowing. Proceedings of the International XI Grassland Congress, Surface Paradise, Queensland, Australia, p. 134-138.

(37) Wilsie, C. P.

1962. Crop adaptation and distribution. Freeman and Company, San Francisco. 448 p.

(32) Wilson, P. W., and O. Wyss.

1937. Mixed cropping and the excretion of nitrogen by leguminous plants. In Proceedings of the Soil Science Society, p. 289-297.

Selection For Drought Resistance In Alfalfa

Clee S. Cooper, John R. Carlson, and Raymond L Ditterline^

Introduction

LitHe information is available on drought resistance in alfalfa

[Medicago sativa L.) (25).2 Drought reduces yield, quality, plant

height, and vigor (40). The development of adapted dryland

alfalfa varieties would enable limited water resources to be used

more efficiently.

Developing rapid screening and selection techniques would enable

plant scientists to measure many plants for traits linked to

drought resistance and to determine, eventually, which cultivars

are best suited for dryland environments. In searching for

criteria that may permit rapid selection for drought resistance,

the way drought affects plants and the morphological and

physiological characteristics associated with drought becomes

important.

Influence Of Drought On Plant Growth

Drought is a "sustained period of significantly subnormal water

or soil moisture supply" (57). Low rainfall is the basic cause of

drought, but other meteorological factors, such as wind, air

temperature, or radiation, also contribute to water deficit [50],

Nearly all physiological processes within a plant are affected by

water deficit. One study shows that water serves four

general functions in plants: (a) It is a major constituent of

physiologically active tissue; (b) it is a reagent in photosynthesis

and hydrolytic processes such as starch digestion; (c) it is the

solvent in which sugars, salts, and other solutes move in the

plant; and (d) it Is important in maintaining turgor for cell

enlargement and growth (20).

Wright (60) states, "there is little question that aridity seriously

limits germination and initial growth of plants." Moisture stress

may reduce the rate of germination and seedling growth (27) or

alter the metabolism of imbibing and germinating seeds to the

point where internal processes delay or even halt germination

(56).

Most plants show retarded or stunted growth with water stress

(32). Pulgar and Laude (42) observed a reduction in the number

and length of shoots in alfalfa regrowth after stress, that persisted

up to 6 weeks following stress, with no evidence of tissue

mortality. Perry and Larson (40) found a reduction in the

number of stems per plant, the internodes per stem, and the

internode length of the primary stem following water deficits in

alfalfa.

A series of metabolic changes and metabolic and mechanical

injuries occurs in dehydrated tissues. Dehydration of the

protoplasm (30) reduced photosynthetic capacity. Stomatal

^ Cooper (retired) was research agronomist, Agricultural Research

Service, U.S. Department of Agriculture; Carlson is graduate

assistant and Ditterline is associate professor. Plant and Soil Science

Department, Montana State University, Bozeman, Mont. 59717.

^ Italic numbers in parentheses refer to References, p. 11.

closure and related reduction in photosynthesis during

drought result in reduced leaf area and activity (32).

Respiration rates may exceed those of photosynthesis during water

stress (32). Structural changes in the protoplasm resulting from

cell water loss may cause mechanical injury (45). Drought retards

differentiation of cells and tissues and hastens their maturation,

which causes decreased development of stems, leaves, and

fruits (29). It also reduces rates of translocation and nutrient

uptake and inhibits synthesis of cytokinins and gibberellins in the

roots (32). Cell division may be infiuenced less by drought stress

than is cell elongation (20). Increased wall thickness and

decreased succulence also result from drought.

Maximum crop yields are dependent on the uninterrupted

maintenance of moisture supplies throughout the season (50),

Plant water balance is affected by a complex combination of

atmospheric, plant, and soil conditions (79/ 25),

Resistance To Drought And Its Measurement

General Forms of Drought Resistance-—Drought resistance

mechanisms in alfalfa are unclear as yet (25). A number of

factors affecting winterhardiness have been studied, however, and

many believe a close relationship exists between mechanisms

affecting cold and drought tolerance. One study states that

(a) plants hardened to cold also become hardened to drought;

(b) drought and cold tolerance both are associated with small

cell size; (c) species, and sometimes varieties within species, have

parallel rankings for drought and cold tolerance; (d) changes in

both drought and cold tolerance are associated with changes in

growth; and (e) many of the physiological changes that occur

during hardening to drought and cold are similar (34).

Another definition of drought resistance includes "the overall

suitability of plants for cultivation under dry conditions" (45),

There are two general categories of drought resistance in crop

plants (51). Drought avoidance refers to the ability of the plant

to evade drought injury. For example, sorghum (Sorghum bicolor

L.) (55) and 'Ladak 65' alfalfa remain quiescent during periods

of drought. Drought tolerance (51), or hardiness (45), refers to

the ability of a plant to survive varying degrees of tissue

desiccation. Both of these mechanisms may be present in a

plant (51).

Morphological and Anatomical Drought Resistance Factors-

Morphological characteristics that reduce water loss help plants

avoid dessication. Awareness of characteristics related to

drought resistance may aid in selecting drought-resistant alfalfas.

Pubescence slows air movement and reduces transpiration. In the

soybean (Glycine max Merr), pubescent leaves reduced

transpiration 1 0 to 20 percent under artificial conditions (59),

One report suggested that pubescence could be incorporated to

a greater extent in soybean cultivars to improve drought

resistance (27). Pubescence, however, is not a common

characteristic of alfalfa and is not likely to become a major

selection trait for drought resistance.

8

Plants with thick cuticles (39) and decreased leaf area [43, 54,

55] have been considered drought resistant. Succulent leaves

avoid desiccation by maintaining a high moisture content during

drought (33, 39).

Growth habit and root proliferation have been related to drought

resistance (36, 38, 49, 54). Koch et al. (28] suggest that slow

regrowth after first cuttings may be a factor conditioning drought

avoidance. They observed that sainfoin (Onobrychis viciifolia

Scop.) plants were dormant during long periods of drought

stress but that roots continued to absorb water to a depth of Ó4

in (180 cm). Similar results have been obtained with alfalfa (13).

In dry areas, large and highly developed root systems aid plant

survival (33, 38, 55).

Many studies reported the effect of stomata on plant drought

resistance (2, 9, 15, 33, 37, 55]. leave et al. (55) reported that

sorghum's ''ability to swiftly close its stomata" was a factor in

drought resistance. Dobrenz et al. (15) concluded that drought-

resistant clones of blue panicgrass (Panicum anf'idofale Retz.)

had fewer stomata per unit area than drought-susceptible clones.

Muenscher (37] found no constant relationship between

transpiration rate and stomate density or size. He concluded

that the differential water loss observed among species is

governed by a complex of factors and not ¡ust the size and

number of stomata.

Anatomical characteristics in plants also have been studied (6, 8,

45, 53) to determine their role in conditioning plant drought

tolerance. Bula (8) states that low alfalfa yields during hot, dry

summer periods may be explained by less leaf tissue, decreased

leaf area; and smaller, more densely packed, leaf cells. Large

cells in the vascular tissue allow for better translocation of

photosynthates and water, and large intercellular spaces enhance

carbon dioxide diffusion of alfalfa plants grown in growth

chambers. Blum (ó) reports that genotypic differences in sorghum

to dehydration might be caused by differences in cell wall

elasticity. Drought-hardy plants also have been purported (33, 45)

to have smaller cells. Smaller cells, when desiccated, undergo

a smaller proportionate reduction in volume (45).

Physiological Drought Resistance Factors and Selection

Techniques—The literature on the effect of water deficits on

plant physiological processes is extensive and will not be

discussed in detail here. For a list of references on this subject,

see Laude (32].

Selecting for drought resistance has met with limited success. A

number of techniques, most related to plant physiological

processes, have been tried, and these will be presented in this

section.

Germination Against Stress—Several workers have attempted to

relate germination in sodium chloride, mannitol, and similar

solutes to drought or cold hardiness. Rodger et al. (44) found a

significant negative relationship between the ability of seeds from

alfalfa cultivars to germinate against an osmotic stress and

winterhardiness of mature plants. Dotzenko and Dean (17)

reported similar results. Larsen and Smith ¡3 7) and Heinrichs

(24) concluded that germinating alfalfa in sugar or salt solutions

is not a reliable method for differentiating alfalfa varieties into

winter hardiness classes. Younis et al. (63) found no correlation

between seed germination at low potentials and drought tolerance

in mature alfalfa plants.

Cooper (12) evaluated winterhardiness of crested wheatgrass

(Agropyron deserforum] previously selected for differential ability

to germinate in mannitol. Crested wheatgrass clones differed in

winterhardiness, but differences were not related to germination

againsî osmotic stress. Sharma (46) found that five forage species

differed in ability to germinate in sodium chloride, mannitol, and

polyethylene glycol, but tolerance to germination in these solutions

was not necessarily an acceptable index of drought tolerance in

mature plants. From the studies cited above, we feel that

germination against stress holds little promise as a rapid technique

for selecting drought-resistant alfalfa lines.

Leaf Water Potential—Relative turgidity (RT) of leaves.

RT=: Fresh wt — dry wt

X 100, is a simple and inexpensive Turgid wt — dry wt

laboratory method that should be considered as a technique for

measuring drought resistance. Measuring leaf-water potential is

more complex, requires more expensive equipment, and is time

consuming. Sullivan (51) discusses a number of water potential

measurements as follows:

(1) Vapor equilibrium. This method is equivalent to diffusion

pressure deficit (DPD) and suction tension and requires

inexpensive and simple equipment. The basis of the method is to

allow several preweighed leaf discs or tissue sections to come

to vapor pressure equilibrium with a series of solutions with

known water potentials in laboratory ¡ars. This method has

limited application in plant breeding because only a small number

of samples can be handled.

(2) Liquid exchange. This method involves changes in volume or

length of tissue strips after immersion in solutions of known

osmotic pressure. It has not been particularly useful.

(3) Vapor pressure. This technique measures vapor pressure of

water in the air of a chamber in which a tissue sample is sealed

and which is in equilibrium with the sample. This is a popular

technique and usually is measured with a thermocouple

psychrometer. An advantage is that the osmotic potentials of

plant tissue, soils, and solutions can be measured. A disadvantage

is that it is relatively expensive and requires considerable time

and skill in setting up apparatus.

(4) Beta gage. This technique measures leaf density when a

Beta radiation source is placed on one side of a leaf and a Beta

detector is placed on the other side. Beta gage measurements

have been related closely to RT and DPD in some studies but not

in others. It is likely to be too time consuming and inaccurate

for determinations with large numbers of samples.

(5) Osmotic potential of cell sap. Freezing point depression of

expressed sap is the most popular method of determining

osmotic potential. The method is limited for selection in breeding

because of the time required in making determinations.

Stomatal Measurements—Leaf porometers, which measure

internai resistance to gas flow, are used to measure stomatal

closure and leaf diffusion resistance. Leaf porometer

measurements are reasonably rapid and may be used to monitor

diurnal changes in stomatal behavior that may be related to

drought resistance. Stomata impressions are taken with silicone

rubber or acrylic resins sprayed on leaves.

Stomata length and density have been evaluated in five alfalfa

cultivars and in two experimental lines differing widely in

winterhardiness (10). Although winterhardy types had higher

stomate densities than the nonhardy types, additional work is

needed along these lines to study the relation of stomata density

to drought resistance of alfalfa.

Measuring Desiccation Tolerance—Desiccation injury from heat,

cold, or drought is measured most often by vital staining of tissue

[52] or by measuring electrical conductivity of electrolytes

exosmosed from leaf disc (?4). For screening purposes,

desiccation tolerance is difficult to control and tests are time

consuming (53). Because desiccation tolerance often is correlated

with cold or heat tolerance (34), it is often easier to impose the

latter stresses. Sullivan et al. (52) reported that heat tests with

leaf discs were good indicators of both heat and drought

tolerance. Cooper (//) stressed orchardgrass (Dacfylis glomerafa

L.) seedlings by emersing tops of plants in water at 50°C (122°F)

for 60 s. Photosynthetic rate was reduced 70 percent for 1 to 5 h

following treatment but recovered to nearly normal 1 week

later. Heat tolerance of plants increased with age to 31 days of

age and then plateaued. Laude (32) heat stressed two red brome

(Bromus rubens L.) ecotypes in air at 54° (1 29°) for 41/2 h, and

then grew them to maturity. Height, number of leaves, and tillers

of both ecotypes were depressed significantly, but one was more

depressed than the other. Wright et al. (61, 62) used a

programed artificial heat environment to evaluate large numbers

of seedlings and precisely select superior genotypes within a

species for drought tolerance.

Ethylene Determination—increased ethylene content in drought-

stressed plants appears to affect leaf abcission. Ethylene

production in petioles of intact cotton plants increased within

hours when water deficits developed (35). Water stress also

resulted in increased ethylene production in orange (Cifrus

simens'is Osbeck) leaves (4) and broad bean (Vicia faba L.) (5).

Because ethylene content increases with drought stress, drought-

resistant lines of a species may be delineated by measuring

ethylene following stress. Ethylene is measured readily by gas

chromatography, and techniques for its extraction from plants can

be simplified. The physiological roles of ethylene in plants and

measurement techniques are discussed in an excellent review by

Pratt and GoeschI (4 7). The most common techniques are some

variation of placing stressed material in sealed glass containers

and withdrawing samples after a period of time (23, 35) or by

extracting ethylene from plant tissue under vacuum (5).

Proline Accumulation—Free proline accumulates in leaves of

many plants following water stress. This proline accumulation

represents a major pathway of N metabolism. Hanson et al. (23)

cite many papers that show the main source of free proline

accumulated during drought $fress is synthesis of proline from

carbohydrate via a-ketoglutarate and glutamate. Several research

groups have studied genetically controlled accumulation of proline

in field crops. In rice (Oryza safiva L.) (3) and sorghum (7), field

drought ratings and proline accumulation were not positively

correlated. Singh et al. (47) found that proline accumulating

ability of 10 lines of barley was positively correlated with their

grain yield stability. More recently Hanson et al. (23) in a

detailed study with a drought-resistant and a drought-susceptible

barley cultivar concluded that proline accumulation followed

water stress and that differences in proline accumulation could

be accounted for by differences in internal water status. In their

studies, the drought-susceptible cultivar accumulated proline faster

than the resistant cultivar. They further conclude that selection

for high-proline accumulation would likely result in genetic

advance toward susceptibility to water sUess rather than drought

resistance. Using proline as a selection tool appears to be

questionable and its determination is probably too time consuming

to be of practical value in a breeding program.

Chlorophyll Stability Index—In 1958, Kaloyereas (26)

proposed the chlorophyll stability index as a technique for

evaluating drought resistance. This index is the difference in

chlorophyll light absorption readings from heated and unheated

leaves. He found that the critical temperature was 55° to 56° C

(131° to 133° F) for loblolly pine (Pinus iaeda L.) seedlings.

Above this temperature, chlorophyll degradation proceeded

rapidly. Significant correlation was found between chlorophyll

stability and drought resistance of pine. The method, however,

has found use, possibly because of the time required extracting

chlorophyll and determining the light absorption. With the advent

of such equipment as the portable refiectance meter for

estimating chlorophyll concentrations of leaves (58), the

chlorophyll stability index technique may warrant further

consideration as a screening tool.

Determining Criteria For Selecting Drought Resistant Alfalfas

A major problem in breeding for dryland alfalfa is defining the

objective. Do we want drought tolerance, avoidance, or both?

Do we want plants that can persist on range under stress but are

low yielding, or do we select for higher yield and possibly a

shorter lifespan?

Survival and drought tolerance are important during the seedling

stage. During establishment, any factor that increases rate of

germination, root elongation, and seedling vigor also increases

chances of seedling survival under dryland or rangeland

conditions. In areas where surface soils dry quickly following a

rain, seeds must germinate and roots must grow quickly into

moist soil layers. Thus, speed of germination and rate of root

elongation are drought-avoidance mechanisms. Factors have been

reported by workers as components of vigor for a number of

species (61), One researcher discusses those relevant to the

growth of the legume seedling. Speed of germination and root

elongation have been shown to be related to first season growth

of birdsfoot trefoil (Lotus corniculatus L.) (11),

10

The value of rates of seed germination and root elongation in

alfalfa need further clarification. Rate of root elongation is

more rapid for A4, faicafa than for M. satîva in the seedling stage

(48). This may explain the greater hardiness of the wild alfalfas.

Selection for branched or fibrous root-type alfalfa seedlings

appears to be heritable (Carlson, John R., Ph.D. thesis,

Montana State University, 1981).

On rangeland, alfalfa seedlings may become subjected to drought

stress for short or long periods. Selection for drought tolerance

(growth during stress) and the ability to withstand tissue

dehydration would be important to survival. Screening tests are

needed to differentiate drought-tolerant from nontolerant

seedlings. One of the easiest and quickest ways may be the

ability of the seedlings to form new leaf tissue under applied

artificial drought or to resume growth following stress.

Once alfalfa becomes established, both tolerance and avoidance

mechanisms become important. While selection of early maturing

cereals has increased water use efficiency and yield in the Great

Plains, this may not be true for alfalfa. Alfalfa grows best at

warm temperatures. A later maturing variety may be more

productive than an earlier one in that optimum leaf area index

is more likely to coincide with the period of maximum incident

solar radiation in June when soil water is still available.

In most of the West, little regrowth is made after alfalfa matures

in late June and early July because soils are often at or near

wilting point in both July and August. Thus, selecting alfalfa with

'Ladak' type growth (rapid early season growth; slow late-season

growth) should help avoid drought. In contrast, regrowth types

that grow 6 to 8 in (15 to 20 cm) before water becomes

unavailable are likely to have low levels of carbohydrates going

into the winter. Drought at this time would be analogous to a

hard frost in the fall that occurs before growth is adequate for

stored reserves. In Montana, we recently selected both regrowth

and nonregrowth types from a 50-year-old dryland alfalfa field

with average precipitation of 13 in (32 cm). It may be possible

to select plants that will reg row rapidly in years with extra

water after first bloom but go dormant in other years.

One approach to determining which characteristics are most

important for a dryland or rangeland alfalfa may be to develop

divergent populations of alfalfa for many traits—for example,

regrowth versus nonregrowth, heat tolerant versus nonheat

tolerant, and tap versus fibrous root—from a common germplasm

pool and to test these populations over a broad range of

droughty conditions. Characterizing the populations that perform

the best may allow us to determine which trait or traits are most

closely related to drought resistance and should be selected for

in a breeding program.

We are initiating this approach in Montana, even though we know

the research will be time consuming, expensive, and there are

no guarantees for success. We believe a truly superior drought-

resistant alfalfa cannot be developed without a better

understanding of the traits involved and their interactions.

References (7) Adato, I., and S. Gazit.

1974. Water-deficit stress, ethylene production and ripening in

avocado fruits. Plant Ptiysiology 53:45-46.

(2) Aivin, Paulo, de T.

1959. Stomatal opening as a practical indicator of water stress

in plants. Proceedings of the 9th International Botany

Congress 4:5.

(3) Anonymous.

1975. Annual report for 1974. International Rice Research

Institute, Bonos, Philippines, p. 173-175.

(4) Ben-Yehoshuo, S., and B. Alohi.

1974. Effect of water stress on ethylene production of detached

leaves of Valencia orange {Citrus simensis Osbeck). Plant

Physiology 53:863-865.

(5) Beyer, E. M., Jr., and P. W. Morgan.

1976. A method for determining the concentration of ethylene

gas phase of vegetative plant tissues. Plant Physiology

(Lancaster) 46:354.

(Ó) Blum, A.

1974. Genotypic responses in sorghum to drought stress.

II. Leaf tissue water relations. Crop Science 14:691-692.

(7) and A. Ebercon.

1976. Genotypic responses in sorghum to drought stress.

III. Free proline accumulation and drought resistance.

Crop Science 16:428-431.

(8) Bula, R. J.

1972. Morphological characteristics of alfalfa plants grown at

several temperatures. Crop Science 12:683-686.

(9) Cain, S. A., and J. E. Potzger.

1940. A comparison of leaf tissues of Gay/ussocJa boccoto

grown under different conditions. American Midland

Naturalist 24:444-462.

(70) Cole, D. P., and A. K. Dobrenz.

1970. Stomate density of alfalfa {Medicago sativa L.). Crop

Science 10:61-63.

(7 7) Cooper, C. S.

1966. Winterhordiness of orchordgross and crested wheotgross

clones in relation to the ability of their seeds to germinate

against an osmotic stress. Agronomy Journal 58:494-495.

(72)

1977. Growth of the legume seedling. Advances in Agronomy

29:119-137.

(73) Doigger, L. A., L. S. Axthelm, and C. L. Ashburn.

1970. Consumptive use of water by alfalfa in western Nebraska.

Agronomy Journal 62:507-508.

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1932. Investigations of the hardiness of plants by measurement

of electrical conductivity. Plant Physiology 7:63-78.

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1969. Stomate density and its relationship to water-use efficiency

of blue panicgross {Panicum antidotale Retz.). Crop Science

9:354-357.

(76) Dotzenko, A. D., C. S. Cooper, A. K. Dobrenz, and others.

1967. Temperature stress on growth and seed characteristics of

grasses and legumes. Colorado Agricultural Experiment

Station, Technical Bulletin No. 97.

(77) and J. G. Dean.

1959. Germination of six alfalfa varieties at three levels of

osmotic pressure. Agronomy Journal 51:308-309.

(78) El-Beltagy, A. S., and M. A. Hall.

1974. Effect of water stress upon endogenous ethylene levels in

Vicia faba. New Phytologist 73:47-60.

(79) Erie, L. J., O. F. French, and K. Harris.

1965. Consumptive use of water by crops in Arizona.

Technical Bulletin 169:5-7.

11

(20) Gates, C. T.

1964. The effect of water stress on plant growth. Journal of

the Australian Institute of Agricultural Science 30:3-22.

(2Ï) Ghorashy, S. R., J. W. Pendleton, D. B. Peters, and others.

1971. Internal water stress and apparent photosynthesis with

soybeans differing in pubescence. Agronomy Journal 63:

674-676.

(22) Guinn, G.

1976. Water deficit and ethylene evolution by young cotton

bolls. Plant Physiology 57:403-405.

(23) Hanson, A. D., C. E. Nelson, and E. H. Everson.

1977. Evaluation of free proline accumulation as an index of

drought resistance using two contrasting barley cultivars.

Crop Science 17.720-726.

{24) Heinrichs, D. H.

1959. Germination of alfalfa varieties in solutions of varying

osmotic pressure and relationship to winterhardiness.

Canadian Journal of Plant Science 39:384-394.

{25) Jung, G. A., and K. L. Larson.

1972. Cold, drought, and heat tolerance, p. 185-209. In C. H.

Hanson, ed., Alfalfa science and technology. Agronomy

Series No. 15, American Society of Agronomy, Madison, Wis.

(26) Kaloyereos, S. A.

1958. A new method of determining drought resistance. Plant

Physiology 33:223-233.

(27) Knipe, D., and C. H. Herbei.

1960. The effects of limited moisture on germination and

initiol growth of six grass species. Journal of Range

Management 13:297-302.

(28) Koch, D. W., A. D. Dotzenko, and G. O. Hinze.

1972. Influence of three cutting systems on the yield, water use

eflPiciency, and forage quality of sainfoin. Agronomy Journal

64:463-467.

(29) Kramer, P. J.

1959. The role of water in the physiology of plants. Advances

in Agronomy 11:51-70.

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1963. Water stress and plont growth. Agronomy Journal

55:31-35.

(3?) Larson, K. L., and D. Smith.

1963. Association of various morphological characters and seed

germination with the winterhardiness of alfalfa. Crop Science

3:234-237.

(32) Laude, H. M. .

1971. Drought influence on physiological processes and

subsequent growth, p. 45-56. In K. L. Larson and J. D. Eastin,

eds.. Drought injury and resistance in crops, CSSA Special

Publication No. 2, Crop Science Society of America, Madison,

Wis.

(33) Levitt, J.

1951. Frost, drought and heat resistance. Annual Review of

Plant Physiology 2:145-168.

(34)

1956. The hardiness of plants. Academic Press: New York

and London.

(35) McMichael, B. L., W. R. Jordan, and R. D. Powell.

1972. An effect of water stress on ethylene production by

intact petioles. Plant physiology 49:658-660.

(36) Morley, F. H. W., and D. H. Heinrichs.

1960. Breeding for creeping root in alfalfa, Medicago media

Pers. Canadian Journal of Plant Science 40:424-433.

(37) Muenscher, W. L. C.

1915. A study of the relationship of transpiration to the size

and number of stomates. American Journal of Botany 2:

487-504.

(38) Ogata, C, L. A. Richards, and W. R. Gardner.

1960. Transpiration of alfalfa determined from soil water

content changes. Soil Science 89:179-182.

(39) Penfound, W. T.

1931. Plant anatomy as conditioned by light intensity and

soil moisture, American Journal of Botany 18:558-572.

(40) Perry, L. J., Jr., and K. L. Larson.

1974. Influence of drought on tillering and internode number

and length in alfalfa. Crop Science 14:693-696.

(47) Pratt, H. K., and J. D. Goeschl.

1969. Physiological roles of ethylene in plants. Annual Review

of Plant Physiology 20:541-584.

(42) Pulgar, C. E., and H. M. Laude.

1974. Regrowth of alfalfa after heat stress. Crop Science

14:28-30.

(43) Robinson, G. D., and M. A. Mossengale.

1967. Use of area-weight relationship to estimate leaf area in

alfalfa [Medicago sativa L. cultivar 'Moapa'). Crop Science

7:394-395.

(44) Rodger, J. B. A., G. G. Williams, and R. L. Davis.

1957. A rapid method for determining winterhardiness in

alfalfa. Agronomy Journal 49:88-92.

(45) Russell, M. B.

1959. Drought tolerance of plants. Advances in Agronomy

11:70-73.

(46) Sharma, M. L.

1973. Simulation of drought and its effect on germination of

five pasture species. Agronomy Journal 65:982-987.

(47) Singh, T. N., D. Aspinall, and L. G. Poleg.

1972. Proline accumulation and varietal adaptability to drought

in barley: A potential measure of drought resistance. Nature

(London), New Biology 236:188-190.

(48) Sins Kayo, E. H.

1961. Flora of cultivated plants of USSR. Israel Program for

Scientific Translations, Ltd., Jerusalem. 661 p.

(49) Slatyer, R. O.

1964. Efficiency of water utilization by arid zone vegetation.

Annals of Arid Zone 3:1-12.

(50) Staple, W. J.

1964. Dryland agriculture and water conservation, p. 15-30.

In Research on water, ASA Special Publication, Serial No. 4,

Soil Science Society of America, Madison, Wis.

(57) Sullivan, C. Y.

1971. Techniques for measuring plant drought stress, p. 1-18.

In K. L. Larson and J. D. Eastin, eds.. Drought injury and

resistance in crops, CSSA Special Publication No. 2, Crop

Science Society of America, Madison, Wis.

(52) J. D. Eastin, and E. J. Kinbacher.

1968. Finding the key to heat and drought stress in groin

sorghum. Quarterly, University of Nebraska, Summer Issue.

(53) and J. Levitt.

1959. Drought tolerance and avoidance in two species of oak.

Physiology of Plants 12:299-304.

(54) Tanner, C. B., and E. R. Lemon.

1962. Radiant energy utilized in évapotranspiration. Agronomy

Journal 54:207-212.

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1973. Water-use efficiency and its relation to crop canopy area,

stomatal regulation and root distribution. Agronomy Journal

65:207-210.

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1966. Plant hormones and regulators. Science 152:721-731.

Continued at bottom of next page.

12

Diseases, Insects, And Other Pests Of Rangeland Alfalfa^

Charles E. Townsend

A Review

Information on the importance of diseases, insects, and other

pests on rangeland alfalfa is sparse. Frequently, the information

is observational and must be documented by properly designed

investigations.

The distribution and importance of the various diseases, insects,

and nematodes that attack alfalfa in the United States have been

discussed (2).^ Some report that common leaf spot (Pseudopeziza

medicaginis [Lib.] Saac), yellow leaf blotch (Lepfofrochiia

medicaginis [Fckl.], syn. Pseudopeziza jonesii [Nannf.]), spring

blackstem (Pfïoma medicaginis Malbr. & Roum. var. medicaginis],

summer blackstem and leaf spot [Cercospora medicaginis Ell. &

Ev.), and rust (Uromyces striatus Schroet.) are the most destructive

foliar pathogens in dryland areas (9). Bacterial wilt [Corynebac-

terium insidiosum [McCull.] H. L. Jens.) may be important in low

areas where moisture accumulates. Root and crown diseases are

more prevalent in older stands, and viruses may be important

under some conditions.

Of the various species of insects that attack alfalfa, the spotted

alfalfa aphid (Therioaphis maculata Buckton), pea aphid

(Acyrfhos/pon pisum Harris), alfalfa weevil {Hypera posfica

Gyllenhal), potato leafhopper (Empoosca fabae Harris), and

several species of grasshoppers are considered important in

dryland areas (9). Of these, grasshoppers are potentially the

most important on rangeland. Outbreaks are most common in

the Northern Great Plains, but the migratory characteristics of

some species make grasshoppers a particularly destructive pest

[16). There are many species of grasshoppers, but five species—

the lesser migratory grasshopper (Melanoplus sanguinipes P.),

the differential grasshopper (M. differenfiaiis Thomas), the red-

legged grasshopper (M. femur-rubrum DeGeer), the two-striped

grasshopper (M. biviffatus Say), and the clear-winged grasshopper

[Camnula pellucida Scudder)—cause 90 percent or more of the

damage to crops on cultivated lands (15). The relative importance

of species changes as one species is replaced by another [18).

An excellent review has been presented on forage losses caused

by rangeland grasshoppers (ó).

^ Joint contribution of the Agricultural Research Service, U.S. Department

of Agriculture, and the Colorado State University Experiment Station,

Fort Collins, Colo. 80523.

^ Research geneticist, Crops Research Laboratory, Colorado State

University, Fort Collins, Colo. 80523.

^ Italic numbers in parentheses refer to Literature Cifed, p. 14.

Continued

{57) Viets, F. G., Jr.

1971. Effective drought control for successful dryland agriculture,

p. 57-76. In K. L. Larson and J. D. Eastin, eds.. Drought

injury and resistance in crops, CSSA Special Publication No. 2,

Crop Science Society of America, Madison, Wis.

{58) Wallihan, E. F.

1973. Portable reflectance meter for estimating chlorophyll

concentrations of leaves. Agronomy Journal 65:659-662.

(59) Wolley, J. T.

1964. Water relations of soybean leaf hairs. Agronomy Journal

56:569-571.

(60) Wright, N. L.

1970b. Water use in relation to management of blue panicgross

{Panicum antidotale Retz.). Journal of Range Management

23:193-196.

{61)

1971. Drought influence on germination and seedling emergence,

p. 19-44. In K. L. Larson and J. D. Eastin, eds.. Drought injury

and resistance in crops, CSSA Special Publication No. 2,

Crop Science Society of America, Madison, Wis.

{62) and A. K. Dobrenz.

1970a. Efficiency of water use and seedling drought tolerance of

Boer lovegrass {Eragrostic curvula Nees). Crop Science 10:1-2.

{63) Younis, N. A., F. E. Stickler, and E. L. Sorenson.

1963. Reaction of alfalfa varieties to moisture stress in the

seedling stage. Agronomy Journal 55:177-181.

Some researchers have discussed the food habits and preferences

of grasshoppers in the grasslands of the north-central Great

Plains (70, 11). Some species of grasshoppers feed on many

different plant species while others are very selective and feed on

only a few. Some grasshoppers might even be considered

beneficial because they feed primarily on undesirable forbs.

Species that are destructive to cultivated crops may or may not

be of importance in grasslands. For example, A^. biviffafus and

M. differenfiaiis are not considered to be of economic importance

in grasslands and M. femur-rubrum is only of limited importance.

On the other hand, M. sanguinipes is polyphagous in its feeding

habit and is one of the most destructive species on both

grasslands and cultivated lands. M. packardii (Scudder) prefers

legumes but is of limited importance. Schisfocerco ¡ineata

(Scudder) has a definite preference for native legumes, and

species that prefer native legumes also might be expected to

attack alfalfa and other introduced legumes.

Grasshoppers have been controlled primarily by spraying with

insecticides because little is known about resistance mechanisms

or whether such mechanisms even exist in crop plants. To be

effective, the control program must be initiated at the proper

time and on all of the infested rangeland in an area. Which

grasshopper species will be the most serious in rangeland can

be determined by making an egg survey in the fall or spring

and by observing the nymphs and adults of the different species

during the spring and summer (13). With this method, proper

control measures may be initiated later during the same year or

in the following year.

13

Biological methods show considerable promise for grasshopper control. Of the parasites used, the protozoan Nosema locusfae Canning has potential value (4, 5). One of the problems with this method, however, is the time required for the protozoan to reach population densities that will control the grasshoppers. N. locusfae also was found compatible with a chemical insecticide, indicating that if insecticides could be used to reduce the existing grasshopper population, then N. locusfae would keep the grasshopper population under control (12), Other recent studies have shown that species of rangeland grasshoppers were variable in their acceptance of the wheat bran bait that is used to distribute the insecticide and N. tocusfae {14], This finding suggests that various bait formulations of N. locusfae and chemical insecticides might be used to control the many species of rangeland grasshoppers.

The general topics of breeding for disease, insect, and nematode resistance in alfalfa have been discussed (7, 8, 17). The importance of having multiple-pest resistance in rangeland alfalfa is not known, but the thin stands found in range seedings and the semiarid environment reduce the severity of most insect and disease pests. Introducing a legume into the rangelands, however, may cause certain species of insects, primarily grasshoppers, to increase. The effects that nematodes might have on the culture of rangeland alfalfa are not known.

Pocket gophers, which occur only in the Western hemisphere, probably present a greater hazard to alfalfa culture on rangelands than any other pest. Four species are found in Colorado: the mountain pocket gopher (Thomomys falpoides), the valley pocket gopher (T. boffae), the plains pocket gopher (Geomys bursarius), and the Mexican pocket gopher [Crafogeomys casfanops), {!] Pocket gophers feed on both above-ground and below-ground plant parts, but the root system is damaged most. They prefer plants with large, fleshy roots (3j. Alfalfa plants with creeping roots are damaged less than plants with taproots. The value of creeping-rooted alfalfa in rangeland infested with pocket gophers has not been established.

In range seedings in eastern Colorado, alfalfa seldom lasts longer than 10 years because of pocket gophers. Most control methods are not economical in rangelands, but the burrow-builder method, which consists of an artificially constructed burrow containing poisoned bait, may be the most promising. Assessing the true damage to alfalfa by gophers, rabbits, and other pests in small rangeland nurseries is difficult because such plantings attract pests from large areas.

Literature Cited (1) Anonymous.

19Ó0. Pocket gophers in Colorado. Colorado Agricultural

Experiment Station, Bulletin No. 508-S, 26 p.

(2) Barnes, D. K., F. I. Frosheiser, E. L. Sorensen, and others.

1974. Standard tests to characterize pest resistance in alfalfa

varieties. U.S. Department of Agriculture, Agricultural

Research Service, ARS-NC-19. 23 p.

(3) Hansen, R. M., and A. L Ward.

1966. Some relations of pocket gophers to rangelands on Grand

Mesa, Colorado. Colorado Agricultural Experiment Station,

Technical Bulletin No. 88, 22 p.

(4) Henry, J. E. 1971. Experimental application of Nosema locusfae for control

of grasshoppers. Journal of Invertebrate Pathology 18:389-394.

(5) K. Tiahrt, and E. A. Oma.

1973. Importance of timing, spore concentrations, and levels

of spore carrier in applications of Nosemo locusfae

(Microsporida:No$ematidae) for control of grasshoppers.

Journal of Invertebrate Pathology 21:263-272.

(6) Hewitt, G. B.

1977. Review of forage losses caused by rangeland grasshoppers.

U.S. Department of Agriculture, Miscellaneous Publication

No. 1348, 22 p.

(7) Hunt, O. J., L. R. Faulkner, and R. N. Peoden.

1972. Breeding for nematode resistance, p. 355-370. In

C. H. Hanson, ed., Alfalfa science and technology, American

Society of Agronomy, Madison, Wis.

(8) Kehr, W. R., F. I. Frosheiser, R. D. Wilcoxson, and D. K. Barnes.

1972. Breeding for disease resistance, p. 335-354. In

C. H. Hanson, ed.. Alfalfa science and technology, American

Society of Agronomy, Madison, Wis.

(9) Lowe, C. C, V. L. Marble, and M. D. Rumbaugh.

1972. Adaptation, varieties, and usage, p. 391-413. In

C. H. Hanson, ed.. Alfalfa science and technology, American

Society of Agronomy, Madison, Wis.

(TO) Mulkern, G. B., K. P. Pruess, H. Knutson, and others.

1969. Food habits and preferences of grassland grasshoppers

of the north central Great Plains. North Dakota Agricultural

Experiment Station, Bulletin No. 481, p. 32.

(17) D. R. Toczek, and M. A. Brusven.

1964. Biology and ecology of North Dakota grasshoppers. II.

Food habits and preference of grasshoppers associated with

the Sand Hills Prairie. North Dakota Agricultural Experiment

Station, Report No. 11, 59 p.

(12) Mussgnug, G. L, and J. E. Henry.

1979. Compatibility of malathion and Nosema locusfae Canning

in Me/anop/u$ sanguinipes (F.). Acrida 8:77-81.

(T3) Newton, R. C, C. O. Esselbaugh, G. T. York, and H. W. Prescott.

1954. Seasonal development of range grasshoppers as related

to control. Mimeograph Report No. E-873, p. 18.

(14) Onsager, Jerome A., J. E. Henry, R. Nelson Foster, and R. T. Stoten.

1980. Acceptance of wheat bran bait by species of rangeland

grasshoppers. Journal of Economic Entomology 73:548-551.

(Ï5) Parker, J. R.

1952. Grasshoppers. In Insects. U.S. Department of

Agriculture, Yearbook of Agriculture 1952, p. 595-605.

(J6) R. C. Newton, and R. I. Shotwell.

1955. Observations on mass flights and other activities of the

migratory grasshopper. U.S. Department of Agriculture,

Technical Bulletin No. 1109, 46. p.

(77) Sorensen, E. L, M. C. Wilson, and G. R. Manglitx.

1972. Breeding for insect resistance, p. 371-390. In C. H.

Hanson, ed.. Alfalfa science and technology, American Society

of Agronomy, Madison, Wis.

(78) Wakeland, Claude.

1961. The replacement of one grasshopper species by another.

U.S. Department of Agriculture, Product Research Report No. 42,

9 p.

14

Origins Of Alfalfa Cultivars Used For Dryland Grazing

M«lvin D. Rumbaugh^

Introduction

The alfalfa cultivars and strains considered here were selected

because of their intended use and areas of adaptation. 1 included

only those specifically suggested by researchers or consumers as

being well suited for range or pasture in semiarid and nonhumid

temperate climates. The order of presentation is based in

part on the type of roots and crowns and in part according to

the chronology of introduction, licensing, registration, or release,

with some adjustments for ease of discussion.

Root-Proliferating Alfalfas

Medicago falcafa. The name 'Siberian' has been used to identify

seed stocks and populations of M. falcafa L. seeded on a limited

acreage in the Northern Great Plains and included in

experimental plantings in Western States and provinces. I believe

that many of these, if not most, descended from introductions

distributed by N. E. Hansen of the South Dakota agricultural

experiment station between 1898 and 1937.

The following M. falcafa accessions were collected during a 1906

expediation (Î9):2

P.I. 20717 Kharkof Province, southeastern Russia 20718 Omsk, Siberia 20719 Omsk, Siberia 20720 Irkutsk, eastern Siberia 20721 Samara Province, Volga River region 20722 Saratov Province, central Volga River region 20724 Tomsk, Siberia 20725 Don Province, lov/er Volga River region, southeastern

Russia 20726 Samara Province

This listing was repeated in a later publication [20). Hansen's

collections in a 1908 trip included the following:

P.I. 24452 V/estern Siberia (Hansen called this his 'Obb Siberian") 24453 Western Siberia (named 'Omsk 1908 Siberian' to differentiate

it from P.I. 20718 and 20719, although Hansen considered them to be agronomicaily similar)

24454 Eastern Siberia (collected north of Irkutsk near the western shore of Lake Baikal)

24455 Siberia (collected along the Irtysh River, 10 miles north of Semipolatinsk)

2445Ó 'Siberian alfalfa' (collected in the Gobi Desert in Manchuria)

Three accessions were obtained from previous introductions:

P.I. 27268 Selection from Hansen's plot of P.I. 24452 from Siberia 27375 Karkof (propagated from cuttings of P.I. 20717) 27394 Samara, Russia (a seed increase from P.I. 20721)

Two other accessions of considerable importance were from seeds

collected by a contact in Russia and mailed to Hansen. These

were:

P.i. 28070 Semipolatinsk, southwest Siberia 28071 Orenburg Province. This A4, falcata cannot be considered as

originating in Siberia but is similar to the 'Siberian' strains in adaptation. Hansen described it as having a small proportion of blue-flowered plants {20).

Seed and plants of these stocks were distributed widely for many

years. In 1912, for example, seeds of nine accessions were

advertised for sale by the South Dakota Agricultural Experiment

Station. Three of these were 'Siberian' alfalfas; one was called

'Semipolatinsk', which might also be 'Siberian', and an additional

offering was A4, falcafa from Samara. Seeds of 'Semipolatinsk'

were distributed as recently as 1922. Hansen described the

strain as having the strongest growth of the M. falcafa

collections (22).

Rooted plants were also disseminated in large quantities. More

than 50,000 were shipped to one recipient, and this practice

continued at least as late as March 20, 1920. On that date, on

order was filled for plants of both 'Cossack' and 'Orenburg*. An

old price list shows that 'Semipolatinsk' seed was sold at $5.00

per pound and l-yeor old plants of 'Cossack' were sold by mail,

postpaid, for $1.00 per hundred (15). The distribution of

Hansen's introductions and their use in cultivar development have

been described (40).

Publications of the period indicate that any ^1. falcafa might

hove been described as 'Siberion' alfalfa by some authors. In one

classification of alfalfas, the authors (37) attempted to correct

this by explaining, "In a fifth group are included the various

forms of the yellow-flowered species, sometimes referred to as

'Siberian' alfalfas. This term, however, is misleading since not

all of the yellow-flowered alfalfas come from Siberia."

All known root-proliferating cultivars now used ore related to

one or more of Hansen's introductions. This trait was first

described in a publication after the discovery was mode in a

nursery at Highmore, S. Dak., in 1912 (36). The annual report

for that season states, "Many plants of S.D. 55 at Highmore

show peculiar root systems. Laterals from the main roots of

plants often extend for a distance of from 30 to 36 inches, then

send stems to the surface. These laterals, parallel to the surface,

are from 6 to 10 inches below the surface" [(13) p. 64]. S.D. 55

is known to be on increase of P.I. 28071, the accession of

M. falcafa collected from Orenburg. One year later, the some

trait was found in P.I. 24455 from Semipolatinsk (14), A third

strain exhibiting the trait was referred to in a 1914 annual report,

which states, "This root characteristic has now been found in

P.I. 28071, 24455, and 28070" (?5). One other accession

from Orenburg, P.I. 23625, was similar to P.I. 28071 (36). I

believe all modern root-proliferating cultivars ore derived in port

from af least one of these four strains. The contributions of the

germplosm collected by Hansen to recently developed cultivars

hove been described in great detail (40).

^ Research geneticist. Agricultural Research Service, U.S. Department of Agriculture, Utah State University, logon, Utah. 84332. ^ Italic numbers in parentheses refer to References, p. 18.

16

'Siberian' alfalfa is grown for forage on a limited scale in the

western Dakotas. Fields designated as 'Orenburg' remain in

hay production in Wyoming and Montana. Seeds of these strains

have been used for range and pasture experiments. The 'Siberian'

strain tested on a mountain range in Utah was found to be

inferior in persistence and forage yield to 'A-1Ó9', 'Ladak', and

'Rhizoma' (7). Others determined that a strain of 'Siberian'

obtained from near Coal Springs, S. Dak., persisted and was

productive 23 years after planting at a lower elevation than

the Utah experiment {41, 43). Numerous dryland seedings of

M. falcofa in Montana have been summarized (Ió). In some

trials, the M. faicafa was identified as 'Orenburg' and in others

as 'Ladak'. 'Semipalatinsk' was the most productive alfalfa

tested in a dryland experiment conducted between 1953 and

19Ó3 in eastern Oregon {45).

*Rambler'. The first root-proliferating cultivar of alfalfa was bred

{32) and released in 1955 {26). The early breeding program

leading to its development has been described {25).

'Rambler' is a seven-clone synthetic with parentage tracing to

the cultivar 'Ladak' and 'Rhizoma' and to a Siberian strain of

M. faicafa L., introduced to North America by Hansen. The 'Ladak*

and 'Siberian' seed stocks were planted at the research station,

Swift Current, Saskatchewan, in 1934, and were subjected to

intensive natural selection through several years of severe drought

and winterkill. Surviving 'Siberian' plants were selected on the

basis of root proliferation and upright growth habit; 'Ladak'

plants were selected for high seed yield. The clones retained

were further evaluated by agronomic trials of their selfed,

backcross, and controlled-cross progenies.

•Rhizoma' and 2,300 related plants were established in 1940, but

only 45 survived the unusually harsh winter of 1940-41. Several

of these were crossed with chosen plants of the 'Siberian'

populations, and their progenies were used for further selection.

After examining 10,000 plants for root proliferation in 1947,

the selections subsequently were tested for combining ability.

Between 1949 and 1951, a number of experimental synthetics

were formed and tested. The best among these was named

'Rambler'. The seven parental clones have the following origins:

3 clones: 'Ladak' X ('Ladak' X 'Siberian')

2 clones: {'Ladak' X 'Siberian') X ('Ladak' X 'Siberian') 'Ladck'

1 clone: ('Rhizoma' X 'Ladak') X 'Siberian' ('Ladak' X 'Siberian')

1 clone: 'Siberian' ('Ladak' X 'Siberian') X 'Siberian' ('Ladak' X

'Siberian')

None of the parental plants were related; hence, the genetic base

of the cultivar is quite broad.

*Travois'. This root-proliferating cultivar was derived from

germplasm introduced by Hansen and subjected to natural

selection for many years in two environments. An undetermined

number of the 10 parental clones were selected from among

progenies tracing to seed stocks obtained in 1948 from Canadian

scientists. These seed stocks were from the 'Ladak'-'Siberian'

population, which ultimately gave rise to the cultivar, 'Rambler'

(42, 44).

A search of old alfalfa fields resulted in the discovery of eight

root-proliferating hybrid plants in Perkins County, S.Dak. (1).

Adjoining fields of 'Cossack' and 'Semipalatinsk' (P.I. 24455)

were sown in 1912 with seed from Hansen. Introgression

occurred, and the root-proliferating plants found in the 'Cossack'

stand in 1950 were distinct, morphologically, from the

noncreeping forms (2). Each was 3 to 4 ft (90 to 120 cm) in

diameter, markedly delayed in recovery height, yellow or

variegated flowered, and sickle podded. These plants were

included in the breeding effort, which ultimately resulted in the

release of 'Travois'.

The selection process emphasized lateral spread by root

proliferation, growth habit, rapid recovery following cutting, and

resistance to bacterial wilt and to foliage and stem diseases.

'Roomer'. This seven-clone, cree ping-rooted, synthetic cultivar

was also developed in Saskatchewan {27, 28). Parental

background included strains of M. faicafa and the cultivars

'Cossack', 'Hardistan', 'Ladak', 'Rambler', 'Ranger', and

'Rhizoma'. The breeding method was based on selecting desirable

plants grown in spaced plantings, intercrossing them, growing

progeny lines, selecting within the best of these polycross-progeny,

testing the selections, and then using the best parent plants to

form the synthetic {31). Flowers are strongly variegated, and the

seed pods have one and one-half to three loose coils. 'Roomer',

winterhardy and drought resistant, was licensed for sale in

Canada in 1966.

*Drylander'. Tested under the experimental designation of Sc.

Syn. 3651, this yellow-flowered alfalfa, M. media Pers., was

developed at the research station at Swif^ Current and licensed

in 1971 for use in Canada (29). It is a synthetic from 15 yellow-

flowered clones selected from a large number in old breeding

nurseries that had been overseeded with bromegrass. Traits

considered included longevity, creeping rootedness, competitive

ability, seed set, and resistance to pod shattering. Additional

clonal trials for seed yield and disease resistance were followed

by progeny tests for creeping rootedness and winterhardiness.

Approximately 70 percent of the plants of 'Drylander' are

creeping rooted. This is 10 percent more than 'Rambler' or

'Roomer'. 'Drylander' is more winterhardy than 'Rambler' or

'Roomer' and as tall as 'Rambler'. Sixty-eight percent of the

plants of this cultivar were not diseased in a bacterial wilt trial.

Seed production averaged 78 percent of 'Vernal' in Canadian

tests with leaf-cutter bees as pollinators. This was less than the

seed yield of 'Rambler' or 'Roomer'.

'Drylander' is well adapted for hay and pasture use on dryland

in the Canadian Prairie region {30); competes well with crested

wheatgrass, Agropyron crisfafum (L.) Goertn, and with Russian

wild rye, Elymus junceus Fisch.; and is recommended in Canada as

a mixture component with these grasses.

16

'Kane*. Creeping-rooted plants from the research station at Swift

Current were crossed with wilt-resistant plants from the station at

Saskatoon in 1952. Spaced plant nurseries of F^, F2, from

intercrossed F^ plants, and backcross progenies, were established

at Lethbridge in 1952, 1955, and 195Ó. Selection for the

creeping-rooted habit of growth, recovery after cutting, vigor,

and resistance to bacterial wilt was followed by polycross progeny

tests in 1959 to 19Ó3. Six F^ clones with high combining ability

were the parents of experiment strain Syn. LC-B tested from 1965

to 1970 and licensed as 'Kane' in 1971 (17, 18).

'Kane' yielded 4 percent more forage than 'Roomer' over 42

station years at 10 locations in western Canada. Winterhardiness

and wilt resistance were equal to or better than those of

'Roomer'. Seed yield with leaf-cutter bees averaged less than

'Beaver', 'Ladak', 'Rambler', or 'Roomer'. Sixty percent of the

plants of 'Kane' showed some expression of the creeping-rooted

character in spaced plantings or thin stands. Flower color is

predominantly blue and purple but includes various shades of

yellow and variegated types.

'Roverde'. This is a cultivar merchandized by the L. Teweles Seed

Company. Breeding and parentage are unrecorded, but

descriptions of the cultivar are similar to that for 'Travois', and it

is believed to be a variety cross of 'Travois' X 'Teton'.

'Spredor'. This is a proprietary cultivar bred by the research staff

of Northrup, King and Company, and approved for

certification in 1974. It was developed by intercrossing and

selecting for persistence, wilt resistance, and vigor, with emphasis

on developing root proliferation in a high percent of the

population. Original parentage traces to four clones from the

cultivar 'Travois', one from 'Rambler', one from 'Vernal', and one

M. sativa from Arabia, P.I. 183262.

'Spredor' was intended primarily for overseeding rangeland and

for use in permanent or semipermanent pastures. Area of

adaptation is reported to be the Central and Northern United

States and Southern Canada (4). Plants of this cuüivar have

highly variegated flowers, low set crowns, a prostrate or

semiprostrate growth habit, and early fall dormancy. 'Spredor'

is resistant to bacterial wilt. An improved cultivar, 'Spredor 2',

with superior seed-yield potential, will be marketed by Northrup,

King and Company in 1981.

Xancreep*. The breeding program, which resulted in the cultivar

'Concreep', was initiated in 1954 by H. V. A. Daday of the

Commonwealth Scientific and Industrial Research Organization

(CSIRO) Division of Plant Industry in Australia. The goal was to

combine the creeping habit and underground stem crown of

'Rambler' with the summer and winter vigor of 'Hunter River',

'Hairy Peruvian', and 'African' (5). Twenty-five creeping-rooted

plants selected from 400 plants of 'Rambler' and 5 clones

obtained from Swift Current were crossed with 20 plants selected

from a population of 3,000 plants of 'African', 'Hairy Peruvian',

and 'Hunter River'. The F^ plants were intercrossed and

backcrossed to 'Rambler' (8). These progenies formed the basic

germplasm pool subjected to the combination of family and

individual selection that resulted in the cultivar 'Concreep' (9).

In Australia, 70 percent of the plants of 'Concreep' show the

creeping trait. It has yielded more forage in temperate ciimrtes

than 'Hunter River' and is on equally prolific seed produce .

Survival is superior to any of the parents. 'Concreep' perorms

poorly in regions with hot, dry summers or with a subtr pical

climate (TO).

'Victoria'. 'Victoria' has been described as producing "wide, low

crowns, a much-branched taproot with an inherent capacity to

spread by means of creeping roots or rhizomes, a large number

of relatively small stems per crown, and a semi-decumbent growth

habit" (38). It is a nine-clone synthetic, tracing to the following

source materials:

two clones: Canada Ma 5110

two clones: Canada Sc 3513 one clone: Canada ScMa 531 one clone: Nebraska A224

two clones: 'Rhizomo' one clone: unknown

These parents were selected on the basis of polycross and Si

progeny performance from among 50 clones chosen from source

nurseries of 500 creeping-rooted or rhizomotous plants.

The suggested oreo of probable adaptation includes all or port of

the States of Arkansas, Oklahoma, Kansas, Missouri, Illinois,

Indiana, Kentucky, and Tennessee.

Rhîzomatous Alfalfas

'Sevelra'. Limited information about this strain was published by

Hanson et al. [24]. it is a selection from an old stand in the

dryland area of southern Idaho, and detailed history of its

origin was written (6). Hansen sent seed samples of numerous

alfalfas to A. E. Yoder, who homesteoded on the Sunnyside

Desert in 1908. The seeds were planted on a site that received

less than 10 in (25 cm) of annual precipitation. Three populations,

'Grimm', 'Orenburg', and 'Semipolotinsk', appeared to be

outstanding. These three were allowed to cross-pollinate and oil

other alfalfa plants were rogued. Further natural and moss

selection resulted in 'Sevelro*. The name was derived from that

of the Seven-L Ranch, where the cultivar hod been grown since

1918.

The growth habit of 'Sevelro' plants is quite variable. They range

from upright to procumbent, and flower color is extremely

variegated. Some plants do show considerable rhizome

development under dryland conditions. 'Seveira' is believed to

be less winterhardy than 'Ranger* but is quite drought resistant.

It is best adapted to dryland range and pasture in the western

States. In 1958, the estimated acreage of 'Sevelro' comprised

less than 0.01 percent of the total U.S. alfalfa plantings, and its

use has declined since that time.

'Nomad'. The origins of this cultivar ore somewhat obscure. It

was developed from persistent alfalfa plants growing on a

Klomath County, Oreg., dryland form at 4,500 ft (1,350 m)

elevation, where precipitation averaged 11 in (27.5 cm) per year {24).

17

The field where the 'Nomad' source material was found was

seeded to alfalfa in 1918 (33). By 1925, the stand was believed

gone, and the field was plowed and cropped for 17 years.

W. F. Cyrus selected surviving plants for creeping habit, leafmess,

seed set, and hardiness after the E. F. Burlingham Seed

Company took over the farm in 1943.

Plants of 'Nomad' are hardy but susceptible to bacterial wilt.

Some have well developed rhizomes that enable the plants to

spread in certain environments. Forage and seed yields are

relatively low under good growing conditions. This cultivar often

is recommended for use in range revegetation programs. No seed

of 'Nomad' was available from the originating company in

August 1977(39).

'Rhizoma'. 'Rhizoma' is a broad-crowned, wilt-susceptible,

variegated cultivar developed at the University of British

Columbia, Vancouver, by mass selection from a cross between

'Grimm' and a yellow-flowered alfalfa identified as 'Don' [35].

'Rhizoma' was released in 1947 (24) under the Canadian license

number 483.

'A-169'. This is an Alfalfa Improvement Conference designation

for Nebraska experimental population 03-Ó03. The population

was based on hybrids involving M. falcafa, M. glutinosa, a

Turkistan selection, and a spreading alfalfa from Turkey,

P.I. 107298. •A-169' yielded more forage than 'Ladak', 'Rhizoma',

or 'Siberian' in a 15-year-old high-altitude test in Utah (7).

'A-224'. This cultivar is a synthetic of four clones with a

spreading or rhizomatous growth form. The clones were selected

by the Alfalfa Improvement Conference from the breeding

programs in Pennsylvania (C87), Iowa (C63), and Nebraska (C53,

C130) ¡46). Origins of the clones as recorded (47) were as

follows:

C53 A wilt-resistant survivor from the polycross progeny of another

clone, C8, which itself was a wilt-resistant survivor from seed

from a natural crossing block involving hybrids between a

spreading introduction from Turkey (P.I. 107298), a 'Ladak'

selection, M. fakaia (P.I. 69137), and M. glutinosa.

C63 A rhizomatous selection from Woodside Golf Course, Des Moines,

Iowa.

C87 A selection from the Nebraska single cross 1124 X 1128.

C130 A wilt-resistant survivor from the polycross progeny of clone

Cl 1. Cl 1 was the Fi of a cross between a selected 'Ladak'

plant with cream-colored flowers X (selection from an old

Turkestan field X Cossack).

'A-224' yielded more hay than 'Nomad' or 'Seveira' but less than

'Rhizoma' when tested under dryland conditions in northeastern

Wyoming (34). It was the highest yielding of the four cultivars

at the Archer station in southeastern Wyoming.

'Teton\ In 1914, Hansen made an interspecific cross of two of

his alfalfa collections. The M. sativa I. parent was described as

Hansen's 'Select Turkestan' (P.I. 20711) from Tashkent in Russian

Turkestan. The M. falcata L. parent was Hansen's yellow-flowered

'Siberian' alfalfa (P.I. 24455), which he collected as seed from

wild plants near Semipalatinsk in Siberia (2, 23). A spaced-plant

nursery was established in which some plants survived until 1949.

At that time, certain survivors were selected for a breeding

program.

Clonal and progeny testing for resistance to bacterial wilt and

to common leafspot, low wide crowns, vegetative vigor, and seed

yield led to a four-clone synthetic released in 1958. 'Teton' was

intended to be used for either hay or grazing. In South Dakota,

it appeared to persist under grazing better than 'Nomad' or

'Rhizoma' and to develop more and longer rhizomes than

'Rhizoma*.

'College Glutinosa*. This cultivar was cited as being similar in

rhizome development to 'Rhizoma', 'Nomad', 'Seveira' and

'Teton' (M). The name implies at least partial origin from

M. glutinosa.

References

(7) Adams, M. W.

1956. Creeping alfalfa. South Dakota Farm and Home

Research VI 1:74-77, 95.

(2)

1958. Events associated with introgression of root proliferation

into domestic alfalfa. Agronomy Journal 50:761.

(3) and George Semeniuk.

1958. Teton alfalfa. South Dakota Agricultural Experiment

Station, Bulletin No. 469.

(4) Alfalfa Variety Review Board.

1974. Report of meeting of the National Certified Alfalfa Variety

Review Board. Mimeographed.

(5) Australian Country Magazine.

1968. New grazing lucerne is here and the name is 'Cancreep'.

Australian Country Magazine 24:10-11, 53, 96.

(6) Beck, J. O. [No date.] Seveira alfalfa. Albert Dickinson Company,

Nampa, Idaho.

(7) Bleak, A. T.

1968. Growth and yield of legumes in mixtures with grasses on

a mountain range. Journal of Range Management 21:259-261.

(8) Daday, H.

1962. Breeding for creeping root in lucerne (Medicogo sativa L.).

I. The initial response to selection. Australian Journal of

Agricultural Research 13:813-820.

(9)

1968. Registration of Cancreep lucerne. Commonwealth

Scientific and Industrial Research Organization. Plant

Introduction Review 5:12-14.

— J. W. Peak, T. Launders, and others. (10) 1968. Seasonal growth of an Australian cultivar of creeping-

rooted lucerne {Medicago sativa). Australian Journal of

Agricultural Research and Animal Husbandry 8:548-554.

(11) Dunbier, M. W.

1971. Associations between characters in populations of

creeping-rooted lucerne (Medicogo sativo L.). I. Correlations

between noncreeping characters. New Zealand Journal of

Agricultural Research 14:772-780.

18

(12) Falrchild, D.

1909. Seeds and plants imported during the period from

January 1 to March 31, 1909: Inventory No. 18; Nos. 24430

to 25191. U.S. Department of Agriculture, Bulletin No. 162.

{13) Gary er, S.

1912. A report of alfalfa and clover investigations conducted

by the South Dakota Agricultural Experiment Station and the

Bureau of Plant Industry. Unpublished. On file with the

South Dakota Agricultural Experiment Station, Plant Science

Department.

(U)

1913. A report of alfalfa and clover investigations conducted

by the South Dakota Agricultural Experiment Station and the

Bureau of Plant Industry. Unpublished. On file with the

Plant Science Department, South Dakota Agricultural

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(10)

(Ï7)

(78)

(Ï9)

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(21)

{22)

(23)

{24)

{25)

{26)

{27)

1914. A report of alfalfa and clover investigations conducted

by the South Dakota Agricultural Experiment Station and the

Bureau of Plant Industry. Unpublished. On file with the

Plant Science Department, South Dakota Agricultural

Experiment Station.

Gomm, F. B.

1974. Forage species for the Northern Intermountain Region.

A summary of seeding trials. U.S. Department of Agriculture,

Technical Bulletin No. 1479.

Hanno, M. R.

1972. Kane alfalfa. Canadian Journal of Plant Science

52:116-118.

1973. Registration of Kane alfalfa. Crop Science 13:130.

Hansen, N. E.

1909. The wild alfalfas and clovers of Siberia, with a

perspective view of the alfalfas of the world. U.S. Department

of Agriculture, Bulletin No. 150.

1913. Cooperative tests of alfalfa from Siberia and European

Russia. South Dakota Agricultural Experiment Station,

Bulletin No. 141.

1914. 1. Plants for dry western uplands. 2. Some new hybrid

plums. South Dakota Agricultural Experiment Station,

unnumbered publication.

1927. Plant introductions. South Dakota Agricultural Experiment

Station, Bulletin No. 224.

Hanson, C. H.

1961. Registration of varieties and strains of alfalfa. Agronomy

Journal 53:400.

C. S. Garrison, and H. O. Groumonn.

1960. Alfalfa varieties in the United States. U.S. Department

of Agriculture, Agriculture Handbook No. 177.

Heinrichs, D. H.

1954. Developing creeping-rooted alfalfa for pasture.

Canadian Journal of Agricultural Science 34:269-280.

1965. Registration of Rambler alfalfa. Crop Science 5:483.

1967. Roomer alfalfa. Canadian Journal of Plant Science

47:220-221.

{28)

(29)

{30)

(31)

1968. Alfalfa in Canada. Canada Department of Agriculture,

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1971. Drylonder alfalfa. Canadian Journal of Plant Science

51:430-432.

1977b. Registration of Drylonder alfalfa. Crop Science

17:977-978.

1977a. Registration of Roomer alfalfa. Crop Science 17:977.

{32) and J. L Bolton.

1958. Rambler alfalfa. Canada Department of Agriculture,

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{33) Jackmann, E. R., and R. G. Fowler, Jr.

1951. New alfalfa you con pasture and keep too. Farm

Journal 75:55-56.

{34) Long, R. L.

1961. Alfalfa varieties for Wyoming. Wyoming Agricultural

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{35) Nilon, R. A.

1951. Rhizomo alfalfa: Chromosome studies of the parent

stocks. Scientific Agriculture 31:123-126.

{36) Oakley, R. A., and S. Gorver.

1913. Two types of proliferation in alfalfa. U.S. Department

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(37) and H. L. Westover.

1927. Commercial varieties of alfalfa. U.S. Department of

Agriculture, Farmers' Bulletin No. 1468.

{38) Offutt, M. S.

1971. Registration of Victoria alfalfa. Crop Science 11:600.

{39) Rumbaugh, M. D.

1977. Personal communication from Robert J. Peterson, E. R.

Burlingham and Sons.

{40)

1978a. N. E. Honsen's contributions to alfalfa breeding in North

America. South Dakota Agricultural Experiment Station

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(47)

1978b. Characteristics of on old stand of dryland alfalfa.

Utah Science 39:6-9.

(42) J. D. Colburn, and G. Semeniuk.

1964. Registration of Travois alfalfa. Crop Science 4:117.

{43) and M. W. Pedersen.

1979. Survival of alfalfa in five semiorid range seedings.

Journal of Range Management 32:48-51.

{44) G. Semeniuk, R. Moore, and J. D. Colburn.

1965. Travois—on alfalfa for grazing. South Dakota

Agricultural Experiment Station, Bulletin No. 525.

{45) Sneva, F. A., G. B. Rumburg, and D. N. Hyder.

1964. A summary of alfalfa investigations conducted on the

Squaw Butte Experiment Station. Oregon Agricultural

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{46) Tysdol, H. M.

1947. Report of the uniform alfalfa nurseries. U.S. Department

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{47)

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JÎ-U.S. Government Printing Office : 1982 -522-011/3797 19