EVALUATION AND SELECTION OF SPRINGBARLEY (HORDEUM VULGARE L.) FOR THE

REVEGETATION AND STABILIZATION OFCOPPER MINE TAILING DISPOSAL BERMS

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Authors Ludeke, Kenneth Leroy, 1945-

Publisher The University of Arizona.

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LUDEKE, Kenneth Leroy, 1945-EVALUATION AND SELECTION OF SPRING BARLEY fHORDEUM VULGARE L.) FOR THE REVEGETATION AND STABILIZATION OF COPPER MINE TAILING DISPOSAL BERMS.

The University of Arizona, Ph.D., 1976 Agronomy

Xerox University Microfilms, Ann Arbor, Michigan 48106

EVALUATION AND

L.) FOR THE

SELECTION OF SPRING BARLEY (HORDEUM VULGARE

REVEGETATION AND STABILIZATION OF COPPER

MINE TAILING DISPOSAL BERMS

by

Kenneth Leroy Ludeke

A Dissertation Submitted to the Faculty of the

DEPARTMENT OF PLANT SCIENCES

• In Partial Fulfillment of the Requirements for the Degree of

DOCTOR OF PHILOSOPHY WITH A MAJOR IN AGRONOMY AND PLANT GENETICS

In the Graduate College

THE UNIVERSITY OF ARIZONA

19 7 6

THE UNIVERSITY OF ARIZONA

GRADUATE COLLEGE

I hereby recommend that this dissertation prepared under my

direction by Kenneth Leroy Ludeke

entitled EVALUATION AND SELECTION *C? SPRING BARLEY (HORDEUM

VULGARE L.) FOR THE REVEGETATION AND STABILIZATION OF COPPER MINE TAILING DISPOSAL BERMS

be accepted as fulfilling the dissertation requirement of the

degree of Doctor of Philosophy

Dissertation DirectorW Date

After inspection of the final copy of the dissertation, the

following members of the Final Examination Committee concur in

its approval and recommend its acceptance:*"'

P" 7 /

'41 An / ?76

"This approval and acceptance is contingent on the candidate's

adequate performance and defense of this dissertation at the

final oral examination. The inclusion of this sheet bound into the library copy of the dissertation is evidence of satisfactory performance at the final examination.

STATEMENT BY AUTHOR

This dissertation has been subtnitted in partial fulfillment of requirements for an advanced degree at The University of Arizona and is deposited in the University Library to be made available to borrowers under rules of the Library.

Brief quotations from this dissertation are allowable without special permission, provided that accurate acknowledgment of source is made. Requests for permission for extended quotation from or reproduction of this manuscript in whole or in part may be granted by the head of the major department or the Dean of the Graduate College when in his judgment the proposed use of the material is in the interests of scholarship. In all other instances, however, permission must be obtained from the author.

ACKNOWLEDGMENTS

The author expresses his sincere gratitude and

indebtedness to his major professor, Dr. A. D. Day, for

his advice, interest, encouragement, and guidance through­

out this study.

Deep appreciation is extended to Dr. L, S. Stith

for his helpful suggestions and review of the manuscript.

Sincere appreciation is extended to Dr. D. R.

Buxton for his constructive criticism and for reviewing

the manuscript.

The author thanks Dr. T. C, Tucker and Dr. J, L.

Stroehlein, Department of Soils, Water, and Engineering,

for their guidance throughout his graduate program.

The author expresses his appreciation in a special

way to Cyprus Pima Mining Company, Tucson, Arrzona for its

tremendous backing and financial assistance throughout this

study,

To my wife, Anne, I express my deepest appreciation

for her loyalty, understanding, and patience throughout

my entire graduate program.

To all others who contributed in any way and are

not mentioned here, the author is deeply grateful.

iii

TABLE OF CONTENTS

Page

LIST OP ILLUSTRATIONS V

LIST OP TABLES vi

ABSTRACT viii

INTRODUCTION 1

REVIEW OP LITERATURE 3

Open-Pit Mine ,3 Crushing and Milling the Ore , 3 Tailihg Waste Material ....... 6 Tailing Pond Construction . . , 6 Physical and Chemical Stabilization of

Tailing Ponds ...... 10 Utilization of Vegetation in Disturbed Areas ... 11 Fertilization and Plant Nutrients ........ 12 Mulching 13 Soil Materials in Copper Mining Wastes 15 Barley Breeding 17

MATERIALS AND METHODS 22

Evaluation and Selection of Barley Genotypes ... 22 Physical and Chemical Characteristics of

Tailing Soil Material 23 Evaluating Barley Genotypes Growing in

Tailing Soil Material 24

RESULTS AND DISCUSSION 27

Chemical and Physical Characteristics of Tailing Soil Material 27

Barley Genotype Results 2 9 Correlation Coefficients for Barley Genotypes . , 37

SUMMARY 50

LITERATURE CITED 54

iv

LIST OF ILLUSTRATIONS

Figure Page

1. Power shovel loading a 17 0 metric ton haulage truck 4

2. Copper milling plant where minerals are extracted . 5

3. Copper tailing pond constructed of pure tailing soil material 7

4. A steep tailing pond slope 8

5. Tailing pond slopes illustrating erosion . . . , 9

6. Tailing pond stabilization with indigenous plants and cacti , 43

7. A tailing pond stabilized with barley . , , . . 45

8. A tailing pond stabilized with perennial plant species . . . , , 47

9. A landscaped service road 48

10. A vegetatively stabilized tailing pond , , , . , 49

v

LIST OF TABLES

Table Page

1, The average organic matter, bulk density, pH, total soluble salts, nitrate nitrogen, available phosphorus, extractable potassium, and extractable sodium in tailing soil material at Cyprus Pima Mining Company, Tucson, Arizona, in 1973, 1974, 1975, and 1976 28

2, The average shoot length, shoot weight, root length, root weight, heads per unit area, seeds per head, and grain yield for the Arizona barley genotypes evaluated at Cyprus Pima Mining Company, Tucson, Arizona, in 1973 30

3, The average shoot length, shoot weight, root length, root weight, heads per unit area, seeds per head, and grain yield for the Arizona barley genotypes evaluated at Cyprus Pima Mining Company, Tucson, Arizona, in 1974 31

4, The average shoot length, shoot weight, root length, root weight, heads per unit area, seeds per head, and grain yield for the Arizona barley genotypes evaluated at Cyprus Pima Mining Company, Tucson, Arizona, in 1975 32

5, The average shoot length, shoot weight, root length, root weight, heads per unit area, seeds per head, and grain yield for the Arizona barley genotypes evaluated at Cyprus Pima Mining Company, Tucson, Arizona, in 1973, 1974, and 1975 (3 year average) 33

vi

vii

LIST OF TABLES—Continued

Table Page

6. The average shoot length, heads per unit area, and ground cover for the Arizona barley genotypes evaluated at Cyprus Pima Mining Company, Tucson, Arizona in 1976 _ 38

7. Correlation coefficients for shoot length, shoot weight, root length, root weight, heads per unit area, seeds per head, and grain yield for the Arizona barley genotypes evaluated at Cyprus Pima Mining Company, Tucson, Arizona, in 1973, 1974, and 1975 39

8. Correlation coefficients obtained from average values for shoot length, shoot weight, root length, root weight, heads per unit area, seeds per head, grain yield, and ground cover for the Arizona barley genotypes evaluated at Cyprus Pima Mining Company, Tucson, Arizona, in 1973, 1974, 1975, and 1976 42

ABSTRACT

It has been estimated that in the United States

the mineral industries will be generating millions of

tons of solid wastes annually. These waste materials, when

stored around the mining operation, are susceptible to wind

and water erosion and require some form of immediate

stabilization. Tailing is the waste product from the

copper milling operation and contains high concentrations

of heavy metals and soluble salts. Tailing is also very

low in plant nutrients and organic matter, and is a very

poor form of soil material for plant growth. The purpose

of this research was to study the possibility of using plant

breeding techniques in the selection of adapted barley

genotypes for copper waste stabilization from barley

composite crosses,

Although indigenous plants and cacti were used to

stabilize tailing ponds, the sparse vegetation that they

provided was inadequate to effectively control wind and

water erosion. When barley (Hordeum vulgare L,) was

planted on tailing pond slopes it stabilized the waste

material and provided organic matter to be incorporated

into the surface 15 cm and this created a more suitable soil

medium for the establishment of perennial grass species.

Twelve hundred barley genotypes possessing some adaptation

viii

ix

to soil and irrigation water containing high soluble salts

and the environment in southern Arizona were compared when

planted in tailing soil material at Cyprus Pima Mining

Company. A number of barley genotypes were more adapted

to growing in tailing soil material than was "Arivat,"

which is the most superior barley cultivar for the revege-

tation of tailing soil material that is commercially

available at the present time.

Twelve barley genotypes, which were selected from

Arizona Composite Cross I produced longer shoots, heavier

shoots, longer roots, heavier roots, more heads per unit

ground area, more seeds per head, and higher grain yields,

when grown in tailing soil material than did Arivat barley.

Correlation coefficients indicated that it is possible to

evaluate barley genotypes in planter boxes and select elite

genotypes for tailing berm evaluation, with confidence that

the selected genotypes will respond on tailing berms the

same as they responded in planter boxes.

Plant breeding techniques were utilized success­

fully in selecting barley genotypes from barley composite

crosses adapted to growing in tailing soil material. The

foregoing procedures have the potential for significantly

reducing the costs involved in the revegetation and

stabilization of mining wastes.

INTRODUCTION

The United States Bureau of Solid Waste Management

estimated that by 1980 the United States mineral industries

will be generating between 2,000,000,000 and 4,000,000,000

metric tons of solid wastes annually (2 4), Mineral wastes

consist of barren overburden, submarginal grade ore, milling

wastes, and strip-mine spoils, The copper mining industry

is responsible for a large percentage of the mineral

wastes in'the Southwest. Tailing, which is the waste

product from copper milling, is basically finely ground

silica sand that contains high concentrations of heavy

metals and soluble salts. Since tailing soil material is

very low in plant nutrients and organic matter, it is a

very poor form of soil material for plant growth. The

development of vegetation on newly graded tailing slopes

is the most economical method of controlling erosion and

providing for tailing pond stabilization. The establish­

ment of vegetation on tailing, especially the grass

components, is extremely difficult. The purpose of this

dissertation was to study the possibility of utilizing

plant breeding techniques in the development and selection

of barley (Hordeum vulgare L.) genotypes better adapted to

the revegetation and stabilization of tailing soil material

than commercial barley cultivars presently available. The

1

initial requirement in revegetating tailing in southern

Arizona is to grow a winter annual grass that will produce

high concentrations of organic matter than can be

incorporated into the surface 15 cm to provide a suitable

soil medium for the germination and establishment of

perennial grass species. Based on prior information,

spring barley was the annual species chosen for the fore­

going purpose.

REVIEW OF LITERATURE

Open-Pit Mine

Thousands of square miles of valuable land adjacent

to copper mines throughout the world are used to store

copper mining wastes. Most of the copper ore mined in the

southwestern United States is extracted from open-pit

mines. At Cyprus Pima Mining Company, Tucson, Arizona

copper ore from the open^pit mine is loaded into 170 metric

3 ton trucks, utilizing 18 m shovels, and hauled to the

milling processing plant (Figure 1).

Crushing and Milling the Ore

In the milling processing plant (Figure 2), the

copper ore is crushed into 1 cm rock in a series of primary,

secondary, and tertiary crushers (4). The crushed ore is

transported to the grinding circuits where it is ground

into approximately 80% minus 65-mesh material. The ground

ore is pumped into large, open containers, called flota­

tion cells, where chemical agents and agitation cause the

copper reagent to float to the surface. The copper reagent

is then removed, concentrated, and transported to the

smelter for final processing (4).

3

Figure 1. Power shovel loading a 170 metric ton haulage truck — Copper ore is loaded into 170 metric ton trucks, utilizing 18 m3 shovels, and hauled from the open—pit mine to the tailing processing plant.

Figure 1. Power shovel loading a 170 metric ton haulage truck.

Figure 2. Copper milling plant where minerals are extracted — In the copper milling plant, copper concentrate is extracted from the ore and tailing soil material is fed into 1 meter diameter transit lines and transported to the -tailing pond.

' •}- ' y^'.^i-'^V'-r'-V^VWV-S^I

)5S?S&

Figure 2. Copper milling plant where minerals are extracted.

6

Tailing Waste Material

The waste material from the milling of copper ore,

which is, primarily, finely ground silica sand, is called

tailing, and for the purposes of this dissertation wiil be

referred to as tailing soil material. In areas throughout

the world where copper mines are located adjacent to large

bodies of water tailing waste material has been effectively

released in water (61), In semi-arid areas, such as

southern Arizona, tailing is transported from the copper

mill, as a liquid slurry in 1 m diameter transit lines,

to tailing disposal ponds (Figure 3). Tailing ponds have

steep slopes (1.5 vertical:1 horizontal) that require some

form of immediate stabilization (Figure 4). Unstabilized

tailing pond slopes are subjected to severe wind and water

erosion (Figure 5),

Tailing Pond Construction

According to Yutes (62) many copper mines produce

copper mill tailing in amounts that range from 100,000,000

3 to 1,000,000,000 m which require large retention dams

several hundred meters in height. If these massive

structures are improperly constructed, they may fail to

retain their contents. For example, in 1965 the El Cobre

tailing dam broke in Chile and in 1966 the Aberfan dam

failed in Great Britain (17). CasaGrande (10) reported

that tailing dams must be designed to remain stable during

Figure 3. Copper tailing pond constructed of pure tailing soil material — Tailing, which is the waste material from the milling of copper ore, is transported to tailing disposal ponds in one-meter diameter transit lines. New tailing lifts are constructed of pure tailing soil material.

Figure 3. Copper tailing pond constructed of pure tailing soil material.

Figure 4. A steep tailing pond slope — Tailing ponds have steep slopes that require some form of immediate stabilization to protect them against wind and water erosion.

Figure 4. A steep tailing pond slope. 00

Figure 5.—Tailing pond slopes illustrating erosion — Unstabilized tailing pond slopes are subjected to severe wind and water erosion that can reduce the success of vegetative stabilization.

t!P±*+i w* _r '/afr;^

Figure 5. Tailing pond slopes illustrating erosion.

10

construction, use, and for many years after mining is

completed. According to Bassarear (4), tailing disposal

does not generate profit for a copper mine; therefore, the

cost of tailing pond stabilization must be conservative.

To be successful, stabilization must effectively contain

the waste materials and it must be consistent with safety

and ecological requirements.

Physical and Chemical Stabilization of Tailing Ponds

Janbu (33) illustrated that tailing ponds may be

stabilized using both physical and chemical techniques, In

some instances, a layer of overburden, which is the material

that was removed from the top of the copper ore deposit, has

been used to stabilize the surface of tailing ponds (52).

Since the surface of overburden soil material is extremely

rough and rocky, it is virtually impossible for native

plant species to encroach upon the physically stabilized

tailing "pond. Ludeke (42) found that it was possible to

cap tailing ponds with a layer of desert soil material to

control wind erosion of tailing. This physical means of

stabilization, however, did not control water erosion.

Capping tailing ponds with desert soil material did permit

indigenous plant species to, partially, reestablish them­

selves on the area over a period of years. Struthers (55)

observed that petroleum biproducts (bitumer emulsions)

have been used to partially stabilize fine tailing sand;

11

however, chemical stabilization provided only temporary

control and it was a very expensive form of stabdlization.

Utilization of Vegetation in Disturbed Areas

LeRoy and Keller (4 0) noted that various plant

species have been used to stabilize a Variety of disturbed

land areas throughout the world for many years. Astrup (1)

stated that the following characteristics should be con­

sidered in choosing plants for erosion control and uniform

ground cover on disturbed soils: (a) plants must have the

ability to thrive under the existing conditions of soil,

moisture, and exposure; (b) rapid growing species should be

chosen since they provide earlier protection; (c) plants

producing the most mulch are most effective in controlling

erosion; (d) plants should be resistant to insects and

diseases; and (e) plants that are poisonous to man or

animals should not be used. Augustine (2) noted that

stabilizing critical areas where fine sand is the primary

soil material is best accomplished with grasses and

mulches. Knabe (37) observed that when shrubs and trees

were transplanted in critical areas without grasses that

small rodents invaded the areas and destroyed the newly

transplanted species. Hafenrichter (2 9) stated that

grasses, which have fibrous root systems, were more

effective in improving soil aggregation than were legumes,

Coupland (11) reported that great variation occurs between

12

the water requirement of different plant species in relation

to the amount of dry matter produced. Generally, in areas

where erosion has exposed subsoils, which have a low level

of plant nutrients, a high rate of fertilization is

required for successful plant establishment, A thick,

vigorous vegetative cover is better able to prevent water

erosion, resist the ravages of diseases, and stand abuse

from wildlife traffic than is a shallow-rooted sod of non-

vigorous plants (26). vigorous grass covers are more

attractive and offer more competition to weed growth than

do sparse stands of grass (50). Plants require many

essential elements for growth and elements are absorbed

from the soil by the root system and then transported into

the upper parts of plants (38). Nitrogen was found to be

the most frequent limiting fertilizer element for the

establishment of vegetative cover on disturbed soil

sites (1?),

Fertilization and Plant Nutrients

The use of nitrogen fertilizers applied to grass-

legume mixtures stimulated the grasses more than the

legumes (60). Nitrogen was found to be a very mobile plant

nutrient that was rapidly depleted by the plants during the

growing season and was subjected to leaching as water moved

through sandy soils (23), Soil analysis generally give

accurate information on the level of phosphorus in the

soil; however, in areas of high pH, phosphorus is likely

to be in a form that is unavailable for plant growth (7).

Due to the residual properties of phosphorus in the soil

and the lower sensitivity of established plants to

phosphorus, maintenance applications of phosphorus for

grasses may not be as necessary as maintenance applications

of nitrogen (41). Potassium is not as limiting for plant

growth in most soils as nitrogen and phosphorus; however,

potassium deficiencies may be encountered in sandy soils

(20), Experiments by Blaser and Brady (5) showed that,

when grown in mixtures, grasses contained higher levels

of potassium than did legumes. The differences in potassium

content between grasses and legumes was explained on the

basis of the differences in the cation exchange capacity

of the roots, Drake, Vengris, and Colley (20) maintained

that roots with a high cation exchange capacity absorbed

more divalent cations, such as calcium and magnesium than

did roots with a low cation exchange capacity. They also

found that roots with a low exchange capacity absorbed more

monovalent ions, such as potassium, than did roots with a

high cation exchange capacity.

Mulching

In sandy soils, with an open structure, Moore (48)

observed that the emergence of surface plantings of small

seeded legumes and grasses was greater than the emergence

14

of surface planting of the same plant species in heavier

soils. Cannon (9) reported that soil mulching improved

the germination and seedling establishment of many plant

species because mulching improved the soil moisture condi­

tions around the germinating seeds, insulated the soil

surface against excessive heat and cold, and bound the

soil together around the growing seedlings. Ayers (3)

stated that soil salinity may affect the germination and

establishment of seedlings in two ways: (a) by lowering

the rate of water uptake and (b) by increasing the uptake

of certain ions in sufficient amounts to be toxic to the

germinating seeds or growing seedlings.

Edgerton, Sopper, and Kardos (22) reported that

municipal sewage effluent and sewage sludge were used to

provide plant nutrients in the revegetation of coal mine

spoils in Pennsylvania, Jones, Armiger, and Bennett (35)

used a two-step seeding system successfully to revegetate

surface coal mine spoils in West Virginia, Small grain

species were seeded the first year to give a quick ground

cover and to produce a straw mulch into which perennial

legume and grass species were interseeded the second year,

Gould, Howard, and Valentine (27) inventoried the soil

characteristics and vegetation production of areas leased

by Western Coal Company for strip mining in New Mexico,

They observed that Indian ricegrass (Sorghastrum nutans Lf),

15

fourwing saltbush (Atriplex canescens L.), and winterfat

CEurotia lanata L.) grew best on coal spoils in New Mexico.

Soil Materials in Copper Mining Wastes

Four different soil materials (tailing, tailing-

overburden, overburden, and desert) were identified in

copper mining wastes (45), The physical and chemical

properties of tailing, tailing-overburden, overburden, and

desert soil materials in copper mining wastes were studied

and described by Ludeke et al. (47). Ludeke and Day (43)

proposed the use of vegetative stabilization of copper

mining wastes. Ludeke and Day (46) noted that straw from

cereal grains planted on copper tailing soil material with

a "Hydroseeder11 and incorporated in the top 15 cm of tail­

ing with a "Sheepfoot Roller" resulted in the most desirable

soil material for plant growth (13). Copper tailing

soil material was successfully rehabilitated in Arizona by

growing a variety of plant species on their surfaces (45).

Day, Tucker, and Ludeke (15) reported that perennial grasses

were more easily established and maintained than most other

plants in tailing soil material from copper mines^ due to

their drought tolerance and low water requirements, Day

et al. (14) suggested that forage for livestock feed can be

produced by growing barley on copper mining wastes if the

crop is heavily fertilized with commercial, inorganic

16

fertilizers and supplied with irrigation water throughout

the growing season.

Ludeke and Day (46) demonstrated that barley

produced the most desirable straw for mulching the surface

of copper mining wastes in preparing the soil material for

the establishment of perennial grasses, shrubs, and trees.

Traditionally, the straw has been transported to the site

and applied to the tailing surface, manually, prior to

incorporation. This method of application has been

unsatisfactory because much of the straw blows away or

slides down to the base of the tailing slope during

application. Growing barley directly on the tailing slope

made it possible to obtain uniform distribution and the

plant roots held the straw in place until it could be

incorporated into the surface area with a "Sheepfoot

Roller." Arivat is the most desirable barley cultivar,

presently available, to provide vegetative growth directly

on tailing soil material (42), Since numerous cultural

practices are needed, heavy applications of commercial

inorganic fertilizers are required, and supplemental

irrigation water must be provided throughout the barley

growing season, this method of obtaining a straw mulch is

very costly, If a new barley genotype could be developed

that was more adapted to growing on tailing soil material

than Arivat, it would save the mining industry millions of

dollars annually in mine waste revegetation costs.

17

Barley Breeding

Barley is normally self-pollinated, and the dis­

covery of a genetic male-sterile mutant in barley has

simplified the procedure for making hybrids and/or crosses

in barley (56). The genetic male-sterile barley plants

lack functional anthers, a feature that is governed by a

simple recessive gene pair (ms ms), Introduction of the

recessive male-sterile genes into genotypes that are to be

used as female parents in crosses eliminates the need for

emasculation when making the crosses. New genotypes of

barley can be developed when using a breeding technique such

as composite crossing. This is a complex system in which a

number of varieties are systematically crossed by crossing

pairs of parents, and then crossing pairs of F^'s until all

parents enter into a common progeny (32). This system of

crossing has the advantage of bringing together quickly

combinations of genes from several parents, When barley

species are grown over a period of years in the same

general area, the genotypes best adapted to the local

conditions tend to survive while the unadapted genotypes

tend to be lost from the population (36-) .

Hybridization breeding techniques used in breeding

self-pollinated crops, such as barley are based on the

assumption that individual plants within a normal self-

fertilized population will be homozygous and that relatively

true breeding lines can be developed from superior plants

18

selected from mixed populations or hybrid progenies (53).

New hybrid barley genotypes may produce more forage and/or

grain in a particular area, than the existing cultivars.

Barley, through the slow adaptive processes of

nature, has developed a diversity of head and seed types,

disease resistance, and quality characteristics (31). More

is known about the inheritance of barley than any other

cereal crop except corn (51). The genus Hordeum comprises

about twenty-five species (57). Both diploid and tetra-

ploid species are found. Unlike wheat (Triticum aestivum

L,) and oats (Avena sativa L.), the cultivated barleys are

diploid species. The cultivated barleys have a small

number of chromosomes (n = 7) (49).

There are new research areas that will be signifi­

cant in improving the yielding capability of crop genotypes

in the future. These are (a) ideotype breeding and (b)

employment of exotic germplasm (25). Donald (19) suggested

an optimum model or "ideotype" for wheat production in an

optimum environment, Past plant breeding efforts to improve

yield have been devoted, largely, to ameliorating genetic

characteristics, such as disease susceptibility, in existing

genotypes or to discovering high yielding genotypes through

massive yield testing (18).

Donald (18) proposed the development of plant

genotypes using theoretical models or ideotypes. These

models may be developed using available plant growth data.

19

Preferred ideotypes for wheat and barley have the following

traits: (a) & short, strong culm which reduces lodging,

especially in high-fertility environments; (b) erect leaf

blades which provide for more efficient use of total

available solar radiation; (c) few, small leaves; a

scattered leaf arrangement is advantageous in plant

communities with high illumination, and nitrogen responsive­

ness is more likely with small leaves; <d) a large head

(many florets per spike); the wheat and barley head is

speculated to be a limiting sink for photosynthates; (e)

an erect head, allowing greater illumination for all head

parts;' (f) presence of awns; awns have been shown to

contribute as much as 10% of the grain weight in a head (19,

28); and (cj) appropriate secondary traits to meet stresses

of local environments, such as tolerance to high concentra­

tion of soil salts {18, 19).

The extent to which plant breeders will attempt to

produce genotypes according to various ideotypes will vary

with plant species, philosophies of the plant breeders, and

the specific environmental conditions under which the plants

will be grown. Vogel, Allen, and Peterson (58) demonstrated

how to breed a semidwarf wheat genotype to fit an ideotype

producing a combination of characters consisting of high-

tillering capacity, high lodging and scattering resistance,

coarse awns, medium semidwarf plant height, medium head size,

and short, wide leaves. Ideotype breeding is speculated to

20

be more extensively used for developing plant genotypes

with higher yield potentials for future agricultural

environments. To improve the yielding capacity of plant

genotypes, it is important to plant breeders that new

germplasm must be added to breeding populations (30).

Exotic sources of germplasm have been used as

sources of disease resistance for several decades, but only

recently have breeders systematically exploited exotic

germplasm sources to improve production traits (3 9). Prey

(25) revealed that most plant breeders in the United States

are including exotic germplasm, obtained from composite

crosses, backcrossing, hybridization, and natural selection,

into plant breeding programs to develop new plant genotypes.

Eckebil (21) subjected sorghum (Sorghum bicolor L.

Men.) composites to 4 generations of random mating and

increased grain yields 100% above the check cultivar.

Browning, Frey, and Simons (6) reported that oat breeding

programs in Iowa increased grain yields 30% above ad pted

cultivars, by introducing germplasm from Avena sterilis, a

weedy species that grows in the desert areas that surround

the Mediterranean Sea. The successful use of exotic

germplasm, for improving yield in plant genotypes, has

demonstrated that valuable yield genes do exist in nature

(6). A strong possibility exists that techniques will soon

be available whereby germplasms from very diverse species

and even genera may be combined into viable plants (8),

21

Canlson, Smith, and Dearing (8) used parasexual pro­

cedures to produce interspecific plant hybrids in the genus

Nicotiana. Protoplasts of N. glauca and N. langsdorffi were

isolated, fused, and induced to generate new plants. ' The

biochemical and morphological characteristics of somatically

produced hybrid were identical to those of the sexually pro­

duced amphiploid. Other researchers have obtained callus

tissue from such exotic combinations as barley and wheat but

none of these combinations have produced mature plants (8).

In the future, parasexual techniques may permit plant

breeders to use the total spectrum of germplasm in the plant

kingdom to improve agricultural species for introduction

into new and critical environments.

Wallace, Ozbun, and Munger (59) found that the

following physiological processes were associated with

biological or economical yield in crop plants: (a) relative

growth rate, (b) net assimilation rate, (c) net CO2 exchange

rate, (d) stomatal resistance to CC>2 exchange, (e) enzyme

activityf and {f) dark and photorespiration. Although the

foregoing, physiological processes are heritable, their use

as screening tools in commercial breeding programs is too

costly to be economically feasible at the present time (59).

Nature has provided a tremendous legacy of genetic

variation that may be used by plant breeders in the develop­

ment of new plant genotypes for specific uses by mankind

(34),

MATERIALS AND METHODS

Experiments were conducted at Cyprus Pima Mining

Company and The University of Arizona, Tucson, Arizona to

evaluate and select barley genotypes in a barley composite

cross with a broad genetic base, for use in the revegetation

and stabilization of copper mine tailing disposal berms.

Evaluation and Selection of Barley Genotypes

From 1954 through 1956, 1,000 spring barley

genotypes grown throughout the world were tested at Mesa,

Arizona for adaptation to the environmental conditions in

the southwestern United States, One hundred barley

genotypes were selected and crossed onto a male sterile

California Mariout barley genotype in 1957 to develop

Arizona Barley Composite Cross I. Arizona Barley Composite

Cross If which carried the male sterile gene to enforce

cross pollination each generation, was grown on soil high

in total soluble salts and irrigated with water high in

total soluble salts at Safford, Arizona, from 1958 through

197 2. Each year, natural selection permitted those

genotypes adapted to soil containing high soluble salts,

irrigation water containing high soluble salts, and the

environment in southern Arizona to grow to maturity and

produce seed. The seed produced on those genotypes that

22

23

grew to maturity was harvested, cleaned, and a representa­

tive sample was saved for planting the following year. The

foregoing barley evaluation and selection program was

conducted by A. D. Day, Agronomist, University of Arizona,

Tucson, Arizona.

Physical and Chemical Characteristics of Tailing Soil Material

In 1973, this dissertation research study was

initiated and 1,200 barley genotypes adapted to soil

containing high soluble salts, irrigation water containing

high soluble salts, and the environment in southern Arizona,

from Safford, Arizona, were planted in tailing soil

material at Cyprus Pima Mining Company. The 1,20 0 barley

genotypes were selected based upon their plant height,

vigor, tillering, and per cent ground cover.

Data were collected from four replications on the

following physical and chemical attributes of the tailing

soil material in which the barley genotypes were grown each

year: (a) organic matter, (b) bulk density, (c) pH, (d)

total soluble salts, (e) nitrate nitrogen, {f) available

phosphorus, tg) extractable potassium, and (h) extractable

sodium, The data on the tailing soil material were

obtained following the procedures described by Ludeke

et al. (47).

Fifteen seeds of each genotype were grown in plots

2 0.19 m in size, in a Randomized, Complete Block Design,

24

with four replications. Arivat barley was used as the

check cultivar. Each plot consisted of one row 1.2 m

long. The rows were 15 cm apart. Each of the barley

genotypes were planted in December of each year (1973

through 1975) in planting boxes outdoors. The dimensions

of the planting boxes were 1.2 m deep, 2.4 m wide, and 4,8 m

long. Four replications of 15 genotypes plus one Arivat

check were grown in each planting box. Eighty planting

boxes were required to evaluate the 1,200 barley genotypes

in 1973. Only 15 genotypes survived this initial test and

were selected for seed increase and testing in 1974. The

following data were recorded in May at the end of the

growing season: (a) shoot length, (b) shoot weight, (c)

root length, (d) root weight, (e) heads per unit area, (f)

seeds per head, and (g) grain yield. Root data were

collected by removing the sides of the planting boxes and

washing .all the plant parts from the containers. The roots

were oven-driec at 104 C for 24 hr.

Evaluating Barley Genotypes Growing in Tailing Soil Material

In December 1974, the 15 genotypes selected in 1973

were planted in tailing soil material. Fifteen seeds of

2 . each genotypes were grown in plots 0.19 m m size, in a

Randomized, Complete Block Design, with four replications,

Arivat was used as the check cultivar. The same data

obtained in 1973 were recorded in 1974.

25

In December 1975, the 15 genotypes selected in 1974

were again planted in pure tailing soil material as

described above with Arivat as the check cultivar. The

same data obtained in 1973 and 1974 were recorded in 1975.

Twelve genotypes were selected for seed increase and

testing in 1976.

In December 1976, the 12 genotypes selected in 1975

were planted in pure tailing soil material on the tailing

pond slope. Genotypes were broadcast seeded at the rate of

2 112 kg/ha in plots 37 m in size, in a Randomized, Complete

Block Design, with four replications with Arivat as the

check cultivar. The following data were recorded from each

plot: (a) plant height at the flowering stage, (b) number

2 of heads in 0.56 m , and (c) per cent ground cover 120 days

after planting, by visual estimation. Nitrogen fertilizer

was applied at the rate of 224 kg/ha.

All additional cultural practices, such as irriga­

tion and fertilization, followed throughout the experiments

were similar to those described by Dennis et al. (16) for

barley in Arizona.

All data were analyzed using the standard analysis

of variance and means were compared with the Student-

Newman-Keuls test as described by Stuel and Torrie (54).

Correlation coefficients for shoot length, shoot weight,

root length, root weight, heads per unit area, seeds per

head, and grain yield were calculated because these

26

characteristics are important in the evaluation of plant

material for use in copper mine revegetation and

stabilization.

RESULTS AND DISCUSSION

Chemical and Physical Characteristics of Tailing Soil Material

The average organic matter, bulk density, pH, total

soluble salts, nitrate nitrogen, available phosphorus,

extractable potassium, and extractable sodium in tailing

soil material at Cyprus Pima Mining Company, Tucson,

Arizona in 1973, 1974, 1975, and 1976 are summarized in

Table 1. The tailing soil material was very uniform in all

soil characteristics tested over the entire 4-year period.

This indicates that the soil medium in which the barley

genotypes were grown was very homogeneous from year to

year and did not contribute greatly to observed differences

in genotypes within and between years. The homogeneity of

the tailing soil material can be explained on the bases

that all'the samples were taken from a representative

mixture of each of the 5 tailing ponds, The nitrogen,

phosphorus, and potassium contents, which are the principal

fertilizer elements needed for plant growth, were extremely

low in tailing soil material. This suggests that tailing

material must be heavily fertilized if it is expected to

support normal plant growth. Tailing was very high in total

soluble salts and pH; however, since this soil medium is

very porous and has a coarse texture, it is probable that

27

Table 1. The average organic matter, bulk density, pH, total soluble salts, nitrate nitrogen, available phosphorus, extractable potassium, and extractable sodium in tailing soil material at Cyprus Pima Mining Company, Tucson, Arizona, in 1973, 1974, 1975, and 1976.+

Total Organic Bulk soluble matter density salts NO3-N P K Na

Year (%) (g/cm3) pH (ppm) (ppm) (ppm) (ppm) (ppm)

1973 0. 61 a 1.09 ab 9.79 b 4,537 a 0.762 b 5.67 a 125 b 118 a

1974 0. 57 a 1.06 b 9.93 a 4,682 a 0.785 a 5.80 b 138 a 123 a

1975 0. 54 a 1.10 a 9.80 b 4,793 a 0.777 ab 6.42 a 137 ab 129 a

1976 0. 51 a 1.08 b 9.95 a 4 # 766 a 0.775 ab 6.15 a 130 b 127 a

+Means in the columns followed by the same letter are not different at the 0.05 level of significance.

29

the salts tended to leach down below the root zone more

rapidly in tailing than in normal agricultural soils (42).

It is believed that as salts are leached below the plow

layer (15 cm) the pH decreases and the soil medium becomes

more suitable for normal plant growth (40).

Since the bulk density of tailing was extremely

low, similar to that of a fine sand, it is believed that

the low bulk density permitted effective leaching of un­

desirable contaminants below the plant root zone over a

relatively short period of time.

Previous studies indicated a low organic matter

content of tailing which made it necessary to incorporate

adequate amounts of plant and/or animal residues to the

surface to improve the water holding capacity, and

structure of the soil material sufficiently to support

plant growth (42), The simplest most economical and ideal

way to incorporate plant residue would be by growing an

adapted barley plant on the tailing slope.

Barley Genotype Results

The average shoot length, shoot weight, root length,

root weight, heads per unit area, seeds per head, and grain

yield for the Arizona barley genotypes evaluated in tailing

soil material at Cyprus Pima Mining Company, Tucson, Arizona

in 1973, 1974, and 1975 are reported in Tables 2, 3, 4, and

5, Fourteen of the fifteen barley genotypes grown in pure

Table 2. The average shoot length, shoot weight, root length, root weight, heads per unit area, seeds per head, and grain yield for the Arizona barley genotypes evaluated at Cyprus Pima Mining Company, Tucson, Arizona, in 1973.

Oven-dry Oven-•dry Seeds Shoot weight Root weight per Grain

Barley length of shoots length of rc iQts Heads head yield (g/m ) genotype (.cm) {g/m^ ) (cm) (g/m ) (no. /m ) (No.) yield (g/m )

Arizona 366 47 abc 236 b 42 b 66 a 73 bed 46 a 4.88 a Ari zona 537 54 ab 251 b 40 b 75 a 84 be 48 a 3.08 cde Arizona 581 59 a 334 a 55 a 79 a 100 ab 45 a 3.67 be Arizona 592 44 bed 242 b 38 be 74 a 73 bed 34 b 3.23 cd Arizona 603 27 f 148 c 17 efg 58 a 58 cd 18 c 2.16 e Arizona 606 37 cdef 118 c 19 ef 69 a 58 cd 24 c 2.24 de Arizona 873 42 bede 137 c 26 de 75 a 117 a 35 b 4,34 ab Arizona 877 49 abc 152 c 29 cde 77 a 94 ab 32 b 4.05 abc Arizona 932 37 cdef 166 c 27 de 69 a 100 ab 31 b 4.71 a Arizona 938 49 abc 223 b 34 bed 69 a 58 cd 19 c 2.24 de Arizona 941 31 def 134 c 21 ef 55 a 58 cd 21 c 2.31 de Arizona 961 32 def 147 c 26 de 62 a 89 b 21 c 2.24 de Arizona 965 29 •ef 132 c 13 fg 58 a 52 d 21 c 2.08 e Arizona 1028 8 f 31 d 7 g 21 b 15 e 5 d 0.57 f Arizona 1104 10 f 34 d 8 g 25 b 15 e 5 d 0.56 f Arivat 6 f 47 d 8 g 15 b 10 e 4 d 0.51 f

+Means in the columns followed by the same letter are not different at the 0.05 level of significance.

Table 3. The average shoot length, shoot weight, root length, root weight, heads per unit area, seeds per head, and grain yield for the Arizona barley genotypes evaluated at Cyprus Pima Mining Company, Tucson, Arizona, in 1974,

Oven-dry Oven-dry Seeds Shoot weight Root weight per Grain

Barley length of shi Dots length of roots Heads- head yield genotype (cm) (g/nr 2 ) (cm) (g/m2) (no. /m ) (No.) (g/m2)

Arizona 366 46 cd 230 c 42 b 65 e 68 def 44 a 4.87 a Arizona 537 52 be 251 b 34 c 72 cd 63 ef 33 b 2.93 h Arizona 581 60 a 337 a 55 a 74 be 89 abc 47 a 3.62 e Arizona 592 43 e 232 c 35 c 67 de 75 cde 32 b 3.19 f Arizona 603 26 i 149 f 13 f 56 f 63 ef 19 d 2.17 k Arizona 606 38 f 114 h 18 e 69 de 63 ef 23 c 2.26 j Arizona 873 46 d 132 g 26 d 80 a 95 a 34 b 4.10 c Arizona 877 54 b 149 f 27 d 77 ab 89 ab 31 b 3.94 d Arizona 932 35 f 166 e 26 d 68 de 79 abed 32 b 4.69 b Arizona 938 50 cd 233 c 36 c 65 e 58 f 22 c 2,33 i Arizona 941 43 e 179 d 26 d 65 e 79 bed 31 b 3.10 g Arizona 961 32 g 168 e 28 d 67 de 95 ab 23 c 2.30 ij Arizona 965 29 • h 126 g 12 f 58 f 63 ef 23 c 2.10 k Arizona 1028 15 j 55 k 12 f 32 h 26 g 10 f 1.14 m Arizona 1104 17 j 68 j 13 f 47 g 32 g 14 e 1.33 1 Arivat 12 k 97 i 17 e 31 h 32 g 7 g 1.05 n

+Means in the column followed by the same letter are not different at the 0,05 level of significance.

Table 4. The average shoot length, shoot weight, root length, root weight, heads per unit area, seeds per head, and grain yield for the Arizona barley genotypes evaluated at Cyprus Pima Mining Company, Tucson, Arizona, in 1975.+

Oven-dry Oven-•dry Seeds Shoot weight Root weight per Grain

Barley length of sh( ?ots length of roots Heads head yield genotype (cm) (g/m' h (cm) (g/rn2) (no./m ) (No.) (g/m2)

Arizona 366 43 c 209 c 35 be 68 ab 74 cde 43 a 4.94 a Arizona 537 54 a 243 b 41 b 60 ab 95 abc 31 b 3.53 de Arizona 581 59 a 324 a 51 a 69 ab 89 bede 41 a 3,64 de Arizona 592 41 cd 222 be 31 cd 64 ab 68 cde 30 b 3.24 ef Arizona 603 23 e 138 de 17 ef 58 ab 58 e 14 d 2.21 g Arizona 606 38 cd 127 de 17 ef 72 a 84 cde 22 c 2.38 g Arizona 873 44 be 135 de 25 de 79 a 116 a 30 b 4.69 be Arizona 877 52 ab 126 de 23 de 68 ab 116 a 31 b 3.99 ab Arizona 932 39 cd 164 d 23 de 62 ab 84 cde 29 b 4,63 g Arizona 938 45 be 221 b 32 cd 61 ab 63 de 22 c 2.31 g Arizona 941 42 c 199 c 30 cd 65 ab 105 ab 33 a 3.01 f Arizona 961 35 cd 150 de 26 d 59 ab 63 de 30 b 2.27 g Arizona 965 31 d 119 e 13 fg 57 ab 58 e 22 -c 2.16 g Arizona 1028 8 f 28 9 6 g 22 c 16 f 5 e 0.57 h Arizona 1104 11 f 36 « 3 8 g 28 c 21 f 6 e 0.59 h Arivat 11 f 74 : f 13 fg 38 cb 32 f 8 e 0.75 h

•f Means in the column followed by the same letter are not different at the

0,05 level of significance.

Table 5. The average shoot length, shoot weight, root length, root weight, heads per unit area, seeds per head, and grain yield for the Arizona barley genotypes evaluated at Cyprus Pima Mining Company, Tucson, Arizona, in 1973, 1974, and 1975 (3 year average).

Oven-dry Oven-dry Seeds Shoot weight Root weight per Grain

Barley length of shoots length of roots Heads head yield genotype (cm) (g/m2) (cm) (g/m ) (no./™2) (No.) (g/m )

Arizona 366 45 d 225 c 40 b 66 e 74 def 44 a 4.91 a Arizona 537 53 b 248 b 38 be 72 cd 79 cde 37 b 3.18 g Arizona 581 59 a 332 a 54 a 74 be 95 be 44 a 3.65 e Arizona 592 43 e 232 c 35 cd 68 de 74 def 32 b 3.23 f Arizona 603 25 i 109 h 16 ef 57 f 58 ef 17 d 2.18 k Arizona 606 38 f 119 h 18 ef 70 de 68 ef 23 c 2.29 i Ari zona 873 44 d 135 g 26 de 78 a 111 a 33 b 4.25 c Arizona 877 52 b 143 f 26 de 74 be 100 ab 31 b 3.99 d Arizona 932 37 f 165 e 25 de 66 e 89 bed 31 b 4.67 b Arizona 93 8 48 cd 226 c 34 cd 65 e 58 ef 21 c 2.29 i Arizona 941 37 f 171 d 26 de 62 e 79 cde 28 b 2.79 h Arizona 961 33 g 158 e 27 d 63 e 89 bed 25 c 2.27 i Arizona 965 30 •h 126 g 13 fg 58 f 58 ef 22 c 2.11 k Arizona 1028 10 k 38 j 8 g 25 h 22 g 7 f 0.76 m Arizona 1104 13 j 46 j 10 g 33 g 22 g 8 e 0.83 1 Arivat 10 k 73 i 13 g 28 h 26 g 6 g 0.75 n

+Means in the column followed by the same letter are not different at the 0.05 level of significance.

34

tailing produced taller plants than did the Arivat check

2 over the 3 year period. The shoot production (g/m ) of

15 barley genotypes grown on tailing was compared with

shoot production from the cultivar Arivat, when grown1 under

similar environmental conditions. From 1973 through 1975,

13 genotypes produced an average of from 50 to 357% more

shoot growth than did Arivat. Tall vegetation is desired

on tailing material because it improves the aesthetic

appearance of the tailing pond slope, eliminates wind

erosion, and reduces the kinetic energy of falling rain

and/or sprinkler irrigation water which checks water

erosion in its early stages of development.

An environmental agronomist is interested in

maximum shoot growth per unit area because this indicates

the relative amount of organic matter that the genotypes

will provide for incorporation into the surface soil waste

material. In general, as the amount of organic matter

added to the surface material is increased, the water

holding capacity is increased and the texture and structure

is improved. In problem soils, such as tailing material,

the addition of large amounts of organic matter greatly

reduces soil crusting at the surface.

The average root length and root weight per unit

area of 15 barley genotypes were compared with the root

length and root weights of Arivat barley, when grown in pure

tailing, from 1973 through 197 5, Twelve genotypes produced

35

from 23 to 208% longer roots and 13 genotypes produced from

108 to 179% more total root material than did Arivat. Long,

extensive root systems are required to hold plant material

in place on steep tailing pond slopes prior to incorporation

within the surface 15 cm of soil material. Well developed

root systems are more efficient in extracting soil nutrients

and tend to produce larger plants and more organic matter

per unit area. It is likely that extensive root systems

growing in a soil improve aeration which in turn insulates

the soil material against excessively high and/or low soil

temperatures during periods of unfavorable environmental

conditions (7).

Whenever plant cover is needed on a disturbed land

area, it is essential to use species that tiller profusely

under the environmental conditions existing on the site in

question. By counting the number of heads per unit area, it

is possible to effectively estimate the tillering potential

of a plant genotype, The average number of heads produced

per unit area by 15 barley genotypes grown in tailing was

compared with the number of heads per unit area obtained

from Arivat, under similar growing conditions, from 1973

through 1975. Thirteen genotypes produced from 120 to 320%

more heads per unit area than did Arivat, These data

suggest that the foregoing genotypes had the ability to

tiller more profusely in tailing soil material than did

Arivat. Genotypes that produce many tillers per unit area

36

are likely to produce a more uniform surface mulch to

protect young perennial grass seedlings, while they are

becoming established, than do genotypes that produce few

tillers per unit area.

Thirteen genotypes produced from 183 to 633% more

seeds per head and from 18 0 to 552% more grain than did

Arivat. The number of seeds per head and grain yield are

plant growth characteristics that indicate the relative

ability of a plant genotype to reproduce itself under

adverse environmental conditions. The primary purpose for

growing barley on tailing pond slopes was to produce

vegetative growth for use as organic matter in improving

the surface 15 cm of soil material. If it were possible

to develop a genotype that produces high seed yields under

these unusual growing conditions, specialized harvesting

equipment could be designed to harvest the seed crop

without jeopardizing the use of organic matter for soil

improvement. If the barley seed crop were grown directly

on the tailing soil material, for a number of years,

natural selection would tend to improve the overall adapta­

tion of the genotype for mine waste reclamation. Natural

selection would allow the more favorable genotypes to

establish themselves and provide a means for evaluation and

selection by the plant breeders.

In 1976, the 12 barley genotypes that performed

best during the previous 3 year period were evaluated,

37

extensively, for shoot length, number of heads per unit

area, and per cent ground cover 12 0 days after planting,

when grown directly on tailing pond slopes (Table 6).

Arivat was used as the check cultivar. All 12 genotypes

produced from 61 to 261% taller plants, from 83 to 136%

more heads per unit area, and from 168 to 2 92% more ground

cover 120 days after planting than did Arivat, when grown

under the foregoing conditions. The 197 6 data clearly

indicated that the observations made from 1973 through 1975

were valid and that the 12 barley genotypes selected were

more adapted for the revegetation of tailing pond slopes

than was Arivat.

Correlation Coefficients for Barley Genotypes

Shoot weight was positively correlated with shoot

length, root length, root weight, numbers of heads per unit

ground area, numbers of seeds per head, and grain yield

(Table 7). When barley genotypes were selected for high

forage production selection was taking place for these

associated factors. Coefficients with shoot length, root

length, and number of seeds per head were higher than the

coefficients with root weight, number of heads per unit

area, and grain yield.

Root length was positively correlated with shoot

length, root weight, number of heads per unit ground area,

number of seeds per head, and grain yield (Table 7). The

38

Table 6. The average shoot length, heads per unit area, and ground cover for the Arizona barley genotypes evaluated at Cyprus Pima Mining Company, Tucson, Arizona in 1976.+

Ground cover 120 days

Shoot length Heads after planting Barley genotype (cm) (no,'/m2) (%)

Arizona 366 53 b 81 cd 84 d

Arizona 537 61 a 90 b 97 a

Arizona 581 53 a 96 a 98 a'

Arizona 592 46 a 67 fg 84 d

Arizona 603 29 h 42 k 67 h

Arizona 606 40 f 52 j 70 g

Arizona 873 48 c 81 cd 97 a

Arizona 877 52 b 62 gh 91 b

Arizona 932 41 ef 87 be 86 cd

Arizona 938 52 b 73 ef 80 e

Arizona 941 43 e 58 hi 77 f

Arizona '961 36 g 77 de 88 c

Arivat 18 i 23 1 25 i

Means in the columns followed by the same letter are not different at the 0.05 level of significance.

39

Table 7. Correlation coefficients for shoot length, shoot weight, root length, root weight, heads per unit area, seeds per head, and grain yield for the Arizona barley genotypes evaluated at Cyprus Pima Mining Company, Tucson, Arizona, in 1973, 1974, and 1975.*

Oven-dry weight

Variable of shoots

Oven-dry Root weight ength of roots

Heads . per unit Seeds . ground per Grain

area head yield

Shoot length

1973 0.912 1974 0.810 1975 0.839

Combined 0.85 9

Shoot weight

1973 1974 197 5

Combined

Root length

1973 1974 1975

Combined

Root weight

1973 1974 1975

Combined

0. 920 0.813 0. 857 0. 867

0. 966 0. 924 0. 961 0. 952

0. 928 0.867 0.814 0.868

0.806 0.594 0.668 0.708

0.799 0. 582 0.681 0.705

0.828 0.698 0.847 0.798

0. 693 0. 510 0. 697 0.608

0.731 0.511 0, 636 0. 635

0,875 0,847 0.846 0. 851

0. 902 0. 854 0.855 0,878

0, 860 0,788 0.807 0.823

0. 889 0.822 0.844 0. 856

0,825 0,772 0.766 0,792

0.816 0.728 0.815 0.792

0.702 0. 549 0.654 0.644

0,758 0.626 0.681 0.693

0,823 0,751 0,762 0.780

Heads per unit ground area

1973 1974 1975

Combined

Seeds per head

1973 1974 1975

Combined

0.812 0,712 0,764 0,763

0.886 0.730 0.800 0. 816

0,877 0,866 0.880 0.872

*A11 correlation coefficients were significant at the 0,05 level.

40

correlations with shoot length, shoot weight, and number of

seeds per head were higher than the correlations with root

weight, number of heads per unit area, and grain yield.

These data suggest that when a plant breeder selects plants

with long roots he is also selecting plants with long

shoots, high forage potential, and many seeds per head.

The correlations between root weight and shoot

length and number of heads per unit area were higher than

the correlations between root weight and shoot weight, root

length, number of seeds per head, and grain yield.

The correlations between number of heads per unit

area and shoot length, root weight, and grain yield were

higher than the correlations between number of heads per

unit area and shoot weight, root length, and number of seeds

per head (Table 7).

The correlations between number of seeds per head

and shoot length, shoot weight, root length, and grain yield

were higher than the correlations between number of. seeds

per head and root weight and number of heads per unit area.

The correlations between grain yield and number of

heads per unit area and number of seeds, per head were

higher than the correlations between grain yield and shoot

length, shoot weight, root length, and root weight.

The correlation coefficients obtained from combined

values for shoot length, shoot weight, root length, root

weight, heads per unit ground area, seeds per head, and

41

grain yield for barley genotypes grown in planter boxes from

1973 through 1975 were all positively correlated with shoot

length, heads per unit ground area, and ground cover for the

same genotypes grown directly on the tailing berms in'

197 6 (Table 8), The foregoing positive correlations indi­

cate that it is possible to evaluate a large number of

barley genotypes in planter boxes and select elite genotypes

for tailing berm evaluation, with confidence that the

selected genotypes will respond on tailing berms the same

as they responded in planter boxes. Shoot length, shoot

weight, and grain yield were the plant growth variables that

were easiest to evaluate on the tailing slopes. Since the

foregoing plant characteristics were positively correlated

with ground cover, a plant breeder may use these variables

as screening tools and be relatively certain that he will

be selecting those genotypes that will provide the most

desirable vegetation on tailing disposal berms. Shoot

length, shoot weight, and grain yield may be used effectively

as the principal screening plant growth variables in future

breeding programs designed to select elite genotypes for

the revegetation and stabilization of copper mine tailing

disposal berms.

Although indigenous plants and cacti may be used to

stabilize tailing ponds, the sparse vegetation that they

provide is inadequate to effectively control wind and water

erosion (Figure 6), After the tailing pond is constructed,

42

Table 8. Correlation coefficients obtained from average values for shoot length, shoot weight, root length, root weight, heads per unit area, seeds per head, grain yield, and ground cover for the Arizona barley genotypes evaluated at Cyprus Pima Mining Company, Tucson, Arizona, in 1973, 1974, 1975, and 1976.*

Correlation coefficients

Variable

Planter boxes Shoot length Heads per unit ground area

Ground cover 120 days

after planting

Shoot length 0,884 0. 910 0.896

Shoot weight 0.857 0,612 0.878

Root length 0.862 0.624 0.618

Root weight 0.625 0.839 0,643

Heads per unit ground area 0. 715 0. 668 0. 606

Seeds per head 0,773 0. 610 0.687

Grain yield 0.810 0,720 0.755

*A11 correlation coefficients were significant at the 0,05 level.

Figure 6. Tailing pond stabilization with indigenous plants and cacti — Although indigenous plants and cacti may be used to stabilize tailing ponds, the uneven vegetation that they provide is inadequate to effectively control wind and water erosion. The high density plant cover that grasses provide is more desirable and successful in stabilizing fine tailing soil material than indigenous plants and cacti.

Tailing pond stabilization with indigenous plants and cacti

44

barley may be planted to stabilize the slope and to provide

organic matter, which may be incorporated into the surface • i

soil material, to provide a suitable soil medium for "the

establishment of perennial grass species (Figure 7).

The data presented in this dissertation clearly show

that barley composite crosses, developed using a variety of

genotypes collected from throughout the world for use as

parents, have very broad genetic bases from which it is

possible to select specific genotypes for use in solving

unusual environmental pollution problems. The present

research study, which was designed to evaluate the

possibility of selecting barley genotypes in Arizona Barley

Composite Cross I for use in copper mine waste reclamation,

verified that this composite had real potential for the

foregoing purpose, The 12 barley genotypes selected at

Cyprus Pima Mining Company were better adapted to growing

in tailing soil material than was Arivat. Further research

is needed to evaluate these elite genotypes in large scale

tests made directly on tailing pond slopes to determine

which genotype or combination of genotypes should be

released for general use by the copper mining industry to

produce initial plant cover and organic matter to incorporate

into the surface 15 cm to provide a suitable soil medium

for the establishment of perennial grasses, shrubs, and

trees.

Figure 7. A tailing pond stabilized with barley — After the tailing pond is constructed, barley may be planted to stabilize the slope and provide organic matter, which may be incorporated into the surface soil material, to provide a suitable soil medium for the establishment of perennial grass species. The barley plant has a fibrous root system that is capable of holding the fine tailing soil material in place.

Figure 7. A tailing pond stabilized with barley. Ul

46

When perennial grasses, shrubs, and trees are grown

together on tailing ponds, they provide an appealing and

permanent form of vegetation that effectively stabilizes

tailing soil material {.Figure 8) . A variety of carefully

selected plant materials provides attractive landscaping

for essential service roads in copper mining areas

(Figure 9). The effective stabilization of tailing soil

material, using a variety of carefully selected plant

species, converts unsightly copper wastes into attractive

man-made structures that blend nicely into the surrounding

landscape (Figure 10).

Figure 8. A tailing pond stabilized with perennial plant species — When perennial grasses, shrubs, and trees are grown together on tailing ponds, they provide an appealing and permanent form of vegetation that effectively stabilizes tailing soil material.

Figure 8. A tailing pond stabilized with perennial plant species

Figure 9. A landscaped service road — Carefully selected plant material provides attractive landscaping for essential service roads in copper mining areas. The large trees provide shade for the slower growing desert shrubs, and indigenous grasses.

48

Figure 9, A landscaped service road.

Figure 10. A vegetatively stabilized tailing pond — The effective stabilization of tailing soil material using a variety of carefully selected plant species converts unsightly copper wastes into attractive man-made structures that blend nicely into the surrounding landscape. These tailing pond slopes are vegetatively stabilized and are no longer susceptible to wind and/or water erosion.

SUMMARY

Experiments were conducted at Cyprus Pima Mining

Company and The University of Arizona, Tucson, Arizona to

evaluate and select barley genotypes from a barley composite

cross with a broad genetic base, for use in the revegetation

and stabilization of copper mine tailing disposal berms.

Tailing soil material was very high in total soluble

salts and pH. Since this soil material is basically silica

sand, liberal applications of sprinkler irrigation water

leach undesirable salts below the root zone in tailing more

readily than they can be leached in agricultural soils. The

low organic content of tailing makes it necessary to

incorporate plant material into the surface 15 cm to

improve this waste soil material sufficiently to support

plant growth.

Fourteen of the 15 selected barley genotypes grown

in tailing soil material produced taller plants than did

the Arivat barley check each year for a 3 year period. From

197 3 through 1975, 13 genotypes produced an average of from

50 to 3 57% more shoot growth, when grown in tailing, than

did Arivat.

When grown in tailing soil material 12 barley

genotypes grew from 23 to 2 08% longer roots and 13 genotypes

50

51

produced from 108 to 179% more total root material than did

Arivat. In general, as root length increased, the stability

of the plants growing on the surface also increased.

Fifteen genotypes produced from 120 to 320% more

heads per unit area, when grown in tailing soil material,

than did Arivat. The genotypes with many heads per unit

area produced a more uniform surface mulch, for the protec­

tion of perennial .grass seedlings, than did genotypes

with fewer heads per unit area.

When grown in pure tailing, 13 barley genotypes

produced from 183 to 633% more seeds per head and from 180

to 552% higher grain yields than did the Arivat check, It

was encouraging to find genotypes that could reproduce

themselves when grown in copper mine wastes. Specialized

equipment was required to harvest a seed crop from barley

grown on steep tailing pond slopes.

In 1976, 12 barley genotypes produced from 83 to

136% more heads per unit and from 168 to 292% more ground

cover 120 days after planting than did Arivat, when grown

directly on tailing pond slopes.

Shoot weight was positively correlated with shoot

length, root length, root weight, number of heads per unit

area, number of seeds per head, and grain yield. Root

length was positively correlated with shoot length, shoot

weight, root weight, number of heads per unit area, number

of seeds per head, and grain yield. Hoot weight was

52

positively correlated with shoot length, shoot weight, root

length, number of heads per unit area, number of seeds per

head, and grain yield. Number of heads per unit area was

positively correlated with shoot length, shoot weight,

root length, root weight, number of seeds per head, and

grain yield. Number of seeds per head was positively

correlated with shoot length, shoot weight, root length,

root weight, number of heads per unit area, and grain

yield. Grain yield was positively correlated with shoot

length, shoot weight, root length, root weight, number of

heads per unit area, and number of seeds per head.

Correlation coefficients indicated that it is possible to

evaluate a large number of barley genotypes in planter

boxes and select elite genotypes for tailing berm evalua­

tion, with confidence that the selected genotypes will

respond on tailing berms the same as they responded in

planter boxes,

Previous studies have revealed that indigenous

plants and cacti may be utilized to stabilize tailing ponds

but the sparse vegetation that they provided was inade­

quate to effectively control wind and water erosion (4 2),

After tailing ponds were constructed, barley was planted

to stabilize the slopes and provide organic matter to be

incorporated into the surface 15 cm, which provided a more

suitable soil medium for the establishment of perennial

grass species. Plant breeding techniques such as male

53

sterility, composite crosses, natural selection, hybridiza­

tion, evaluation, and seed increase were utilized effectively

in selecting barley genotypes adapted to copper mine

wastes. The foregoing breeding procedure has the potential

for saving the mining industries millions of dollars in

the revegetation and stabilization of their waste products

in the years ahead.

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