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COMPETITION BETWEEN ANNUAL WEEDS (WILD
MUSTARD, WILD BUCKWHEAT) AND SPRING
SOWN SMALL GRAINS (OATS AND BARLEY)

WHEN GROWN IN THE GREENHOUSE

BY

WILLIAM MIN G—CHUAN LIU

A THESIS
Submitted to the School of Graduate Studies of Michigan
State College of Agriculture and Applied Science
in partial fulfillment of the requirements

for the degree of

MASTER OF SCIENCE

Department of Farm Crops

1952

V/N/m.
fag)

ACKNOWLEDGMENTS

The writer wishes to express his sincere thanks to
Professor Boyd R. Churchill for his valuable advice and en—

couragement in making this thesis possible.

TABLE OF CONTENTS

Page
Introduction . . . . . . . . . . . . . . . 1
Review of Literature . . . . . . . . . . . . 3
Materials and Methods . . . . . . . . . . . 7
Results and Discussion . . . . . . . . . . . 11
Summary . . . . . . . . . . . . . . . . 34

Bibliography 0 O O O O O O O O O I 0 O O O 36

IN TRODUC TION

Competition between crop plants and weeds is a most
fundamental factor in the growing of useful plants. If crOp
plants occupy the soil and are vigorous, weeds are excluded
or retarded in their growth. On the other hand, if the crop
stand is thin or lacks vigor, weeds will flourish. Any environ—
mental condition or any proCedure that promotes the growth of
crop plants tends to diminish the ill effects of weeds. Con-
versely, conditions or methods unfavorable to the growth of
useful plants permit the invasion and deveIOpment of a weed
population.

Competition is usually evident in cultivated fields.
Individual crap plants may compete with each other, or they
may compete with weeds. The keenest competition, as between
weeds and crop plants, usually occurs when the individuals
competing are most alike in their vegetative habits, methods
of reproduction, and demands upon the environment.

The chief environmental factors in plant competition
are water, light, and mineral nutrients, their importance

usually being in the order given. There is no conclusive

Z
evidence that root secretions are a factor in plant competition.
Two plants do not compete if water, light, and mineral nutrients
are in excess of the needs of both. Competition begins when
the supply of any one of these factors falls below the require-
ments of both. Thus, if there is an abundance of nutrients and
water, light may be the critical factor; or there may be a suf-
ficiency of water and light for the two neighboring plants but a
deficiency of nutrients, in which instance the latter becomes
the critical factor in competition; or competition may be for
water only, in the event that nutrients and light are ample.

This experiment was designed with the purpose of
studying the effects on the yield of Kent Oats and Moore barley
when in competition with two different weeds at different rates
of seeding. The two weeds used were wild mustard (Brassica
arvensis) and wild buckwheat (Polygonum. convolvulus). The
former has proved to be very competitive in recent experiments
carried out in the greenhouse, and both were found very common

in the spring sown small grain fields.

REVIEW OF LITERATURE

Blackman and Templeman (3) have published a funda-
mental study of competition between cereal crops and annual
weeds in England. CrOp development data on barley and oats
competing with Brassica arvensis and Raphanus raphanistrutn
indicate that nitrogen is an important factor in competition.
The presence of weeds had a greater depressing effect on
cereal yield in wet than in dry springs because the establish-
ment of the weed seedlings and their later growth were ad—
versely affected by a dry spring.

Pavlychenko and Harrington (15) studied competition
between crOps and various species of weeds. They ranked
the crops in order of competing ability as follows: barley,
rye, wheat, oats, and flax. Among the weeds, Avena fatua and
Brassica arvensis were the most vigorous competitors.

Brenchley (4) explained that one of the chief factors
in determining the abundance or scarcity of a particular weed
is the degree of competition it is able to withstand success—
fully, and furthermore, the above-ground struggle for light is

as important as the underground struggle for food and water.

According to Clements, Weaver and Hanson (6), the
problem of competition in field crOps "is centered upon the
relative merits of species and varieties in terms of com-
petitive adaptation to seasonal and annual cycles and to the
tillage and rotation control of factors and reactions." Each
weed and species of crOp has its own merits of competitive
adaption and its own reactions toward its rivals.

The effects of competition were noted in forest com-
munities by De Crescentiuis (9), in the plant kingdom generally
by De Candolle (8), and in nature as a whole by Charles
Darwin (7).

Nageli (14), 1874, suggested that the probable number
of individuals of a competing species in a given habitat is de—
termined by the average life period and average annual increase.

Montgomery (13) studied the competitive abilities of
cereal crops. He found, for instance, that Turkey Red wheat
is much stronger competitor than Big Frame wheat. He states
that a small admixture of the former in a sample of the latter
increased rapidly and in a few years produced ninety percent

of the total stand.

 

5

Kiesselbach (12) found that the yield of plants of a given
variety fluctuated within broad limits as a result of differences
in Spacing or surrounding growth. Aaltonen (l) emphasized the
importance of the underground parts of field crops in com-
petitive reactions.

Sukatschew (17) showed that some biotypes which are
vigorous competitors in open cultures do poorly in dense ones.

Gates (5) estimated that weeds reduce the yield of spring
grain twelve to fifteen percent.

Hopkins (11) and Barnes and Hopkins (2.) have shown by
experiments carried on over a period of years at the Dominion
Experiment Station, Swift Current, Saskatchewan, that the yield
of wheat may be reduced as much as fifty percent as a result
of competition with weeds.

The depressing effect some annual weeds have on grain
yield in Canada was reported by Godel (10). He states that
annual weeds can be economically controlled in cereal craps
in Northern districts of Saskatchewan, by prOper rates of
seeding of the cereals. He suggests the following rates:

Barley - 2—2.5 bushels per acre
Oats — 2.5—3 bushels per acre

The exact rate within those limits will depend on the variety
sown, the condition of the land at seeding, the size of grain
kernels, and the degree of weed infestation of fields.

Robinson (16) studied determination of the effect of an—
nual weeds on certain environmental factors and on yields of
cr0ps. In some cases cr0ps with moderate infestations of
annual weeds yielded less than crOps grown under weed-free

conditions, but this was not always true.

MATERIALS AND METHODS

This experiment was conducted in the greenhouse at
Michigan State College, East Lansing, Michigan, beginning in
December, 1950. Two annual weeds, wild mustard (Brassica
arvensis) and wild buckwheat (Polygonum convolvulus), and two
spring sown small grains, Kent Oats and Moore Barley, were
used for study. Each of the weeds and grains was seeded
alone as checks at six and twelve seeds per pot. Then each
weed was seeded at six and twelve seeds per pot with grain
at the same two rates. Thus there were twenty—four possible

combinations of treatments. They are:

 

 

 

 

Oats 6 alone W. Mustard 6 alone

Oats 12 alone W. Mustard 12 alone

Barley 6 alone ' W. Buckwheat 6 alone
Barley 12 alone W. Buckwheat 12 alone

Oats 6 — W. Mustard 6 Barley 6 — W. Mustard 6
Oats 6 - W. Mustard 12 Barley 6 - W. Mustard 12
Oats 12 - W. Mustard 6 Barley 12 — W. Mustard 6
Oats 12 - W. Mustard 12 Barley 12 - W. Mustard 12
Oats 6 — W. Buckwheat 6 Barley 6 — W. Buckwheat 6
Oats 6 - W. Buckwheat 12 Barley 6 - W. Buckwheat 12
Oats 12 - W. Buckwheat 6 Barley 12 - W. Buckwheat 6

Oats 12 -— W. Buckwheat 12 Barley 12 - W. Buckwheat 12

 

8

The above treatmcnts were replicated four times, making
a total of 96 pots.

The seed was sown in 10—inch clay pots on December 19
and 20, 1950, using quartz sand as the medium. At six plants
per pot the seeding should be approximately equal to 1.104
bushels for oats and 0.736 bushel for barley per acre. The
weeds seeded at six plants and twelve plants per pot were con—
sidered as light and heavy infestation respectively.

Since the grain seeds and weed seeds vary so much in
percentage germination, a germination test was made for each
grain and weed to determine the number of seeds to be sown
per pot. In accordance with the germination test, a reasonable
amount of seeds of each species were seeded. The extra plants
were thinned out later to give the prOper stand.

The depth of planting for the grains was 1—1/2 inches
and for the weeds, 1/2 inch.

After sowing, the cultures were watered regularly and
supplied with a nutrient solution to secure the best growth under
winter and spring greenhouse conditions. The nutrient solution
was fed once a week beginning ten days after the small grains

started to germinate. The amount was five hundred cubic

9
centimeters for each pot until February 23. Then later on, it
was fed twice a week to March 16, and reduced to once a week
again until the end of this experiment.

In the first two months the temperature in the green-
house was about 700 F. in daytime and 550 F. at night. After
March the temperature was gradually increased to 800 to 900 F.
in daytime and 70° F. at night.

The pots were randomized on the bench in the greenhouse.
A rearrangement of the pots was made on February 28, 1951, to
move the center pots to the side and vice versa. On March 5
the space between pots was expanded on the bench in order to
give enough room for each pot.

The barley and oats were germinated four days after
sowing, wild mustard three days, and wild buckwheat seven
days. On January 3, oats and barley were thinned to'eight and
fourteen plants per pot for the stand of six and twelve. On Jan-
uary 26 they were thinned again to the exact number. The wild
mustard was thinned on January 18 and some transplanting of
seedlings was made for pots having an insufficient number of

seedlings. The wild buckwheat grew slower than the others and

10
was thinned on January 24. All pots were staked with wire on
January 29 and 30.

The wild mustard started to bloom on February 23 and
continued until the end of this experiment. Oats and barley
began to head on March 2, but barley headed more uniformly
later. The wild buckwheat began to flower on March 6, but
finished flowering before the end of this experiment.

The entire experiment lasted for 108 days until April 6,
1951. The barley was harvested at fully headed stage while the
oats ranged from late boot to fully headed stage. .The plants
were harvested by cutting one—half inch above the surface of
the sand. The number of the plants and heads of each pot
was counted. Grain plants and weed plants were weighed sep-

arately, both green weight and oven—dried weight being recorded.

RESULTS AND DISCUSSION

In considering the competition between small grains and
weeds of this experiment, the factors studied have been:
(1) the effect of competition of weeds upon the number of
heads of small grain per plant, (2) effect upon the total yield
of dry weight of small grain per plant and per pot, and (3) ef—

fect upon the moisture content of small grain.

Effect on Number of Heads per Plant

Table I shows the effect of rates of seeding and wild
mustard upon the number of heads of oats and barley per
plant. When oats and barley were grown at the rate of six
plants alone, the number of heads per plant was highest. In—
creasing the rate to twelve plants greatly reduced the number
of heads per plant of both oats and barley. This might be
explained by the competition within the species itself.

The comparison of the effect of wild mustard on heads
of oats and barley per plant is shown in Figure 1.

Adding six additional oat plants to the light rate of

seeding decreased the number of heads per plant more than

TABLE I.

12

Effect of rates of seeding of oats, barley, and wild

mustard upon number of heads of oats and barley
per plant.

 

 

Rates and Mixtures

Heads Per Plant

 

Oats

Barley

 

6

6

12

12

12
12

12
12

plants
plants
plants
plants

plants
plants

plants
plants

plants
plants

plants
plants

plants
plants

plants
plants

plants
plants

plants
plants

oats alone
barley alone
oats alone
barley alone

oats +
wild mustard

oats +
wild mustard

oats +
wild mustard

oats +
wild mustard

barley +
wild mustard

barley +
wild mustard

barley +
wild mustard

barley +
wild mustard

1.63

1.08

1.17

1.17

1.04

1.04

2.29

1.23

1.71

1.92

1.47

1.02

 

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14
the addition of six wild mustard plants. This was also true
for barley. Double the rate of wild mustard plants in general
did not change the number of heads per plant of the crops when
compared with the lighter weed rate.

The effects of wild buckwheat upon the number of heads
per plant of oats and barley was inconsistent, as shown in
Table II. In general, wild buckwheat had very little effect
upon number of heads per plant of the grain crOps. Data in

Table II is shown graphically in Figure 2.

Effect on Yield per Plant

Oats—wild mustard. The dry weight in grams of teps

 

per plant of individual mixtures and their components seeded
alone were used for this study. In'the oats-wild mustard mix—
ture as shown in Table III, when oats and wild mustard were
each seeded alone at six plants per pot, the yield was the
highest. The comparison of the yield was made, taking the
yield of six plants alone as one hundred percent. The table
indicates that when oats and wild mustard were seeded at
twelve plants alone, the yield of both was greatly reduced. It

was also shown that the competition within Species of oats

15

TABLE II. Effect of rates of seeding of oats, barley, and wild
buckwheat upon number of heads of oats and barley
per plant.

 

 

Heads Per Plant

 

Rate 5 and Mixture s
Oats Barley

 

6 plants oats alone 1.63
6 plants barley alone 2.29
12 plants oats alone 1.08
12 plants barley alone 1.23

6 plants oats +
6 plants wild buckwheat 1.25

6 plants oats +
12 plants wild buckwheat 1.58

12 plants oats +
6 plants wild buckwheat 1.10

12 plants oats +
12 plants wild buckwheat 1.19

6 plants barley +
6 plants wild buckwheat 2.50

6 plants barley +
12 plants wild buckwheat 1.83

12 plants barley +
6 plants wild buckwheat 1.19

12 plants barley +
12 plants wild buckwheat 1.19

 

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TABLE III. Effect of competition upon the yield of dry weight
per plant of oats and wild mustard.
Oats Wild Mustard
dry wt 3st: dry wt. 3.13:3:
gms./ p alone gms./ p. alone
6 oats alone 8.11 100.0
12 oats alone 4.07 50.2
6 wild mustard alone 5.88 100.0
12 wild mustard alone 3.67 62.4
6 oats, 6 wild mustard 5.23 64.6 2.52 42.9
6 oats, 12 wild mustard 4.94 60.9 1.81 30.8
12 oats, 6 wild mustard 3.49 43.0 1.23 20.9
12 oats, 12 wild mustard 3.46 42.7 0.58 9.9

 

 

18
itself was greater than when infested by wild mustard. Where
oats were infested by wild mustard, the heavier the rate of
wild mustard used, the more the reduction in the yield of
oats.

Wild mustard reduced the weight per plant less in the
heavy than in the light rate of oat seeding. The dry weight
per plant of wild mustard was reduced more by the addition
of oats than by the addition of more wild mustard. The yield
of wild mustard was suppressed by the oats of different rates
of seeding. Figure 3 shows the effect of competition upon the

yield of dry weight per plant of oats and wild mustard.

Oats—wild buckwheat. The results with wild buckwheat

 

as shown in Table IV were more or less the same as that of
oats—wild mustard mixture.

It is evident from Tables III and IV that oats suppressed
the yield per plant of wild buckwheat more than it did wild
mustard. Figure 4 gives a general trend toward the yield of
dry weight per plant of oats and wild buckwheat as well as

their effect on each other.

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TABLE N. Effect of competition upon the yield dry weight per

plant of oats and wild buckwheat.

It fit Oats Wild bukwluut
dry W" 3:; dry Wt‘ 2:11:
gms./p. alone gms./ p ° alone

6 oats alone 8.11 100.0

12 oats alone 4.07 50.2

6 wild buckwheat alone 3.13 100.0

12 wild buckwheat alone 1.61 51.4

6 oats, 6 wild buckwheat 7.12 87.8 0.23 7.4

6 oats, 12 wild buckwheat 7.24 89.3 0.28 9.0

12 oats, 6 wild buckwheat 4.07 50.2 0.21 6.7

12 oats, 12 wild buckwheat 4.29 52.9 0.18 5.8

 

 

 

 

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'12' Wt he

‘Effett of cafipéextibh upon the yieLdor dry
'weight'per plant of cats and wild buckwheat.

2/

——-- —.- -.—¢- -———.-~m-— ——m-I

‘

 

22

Barley—wild mustard. Table V shows that the yield per
plant of barley was affected more by barley itself than by wild
mustard. Wild mustard had less effect on the yield per plant
of 12 barley than it did on 6 barley. Increasing the rate of
seeding of wild mustard, according to the data, tends to de—
crease the yield per plant of barley. It should be noted, how—
ever, that the yield of 12 barley when in mixture with 6 wild
mustard was slightly higher than when 12 barley was grown
alone. .

A considerable reduction in the yield of wild mustard
due to the effect of barley has been observed, the more barley
in the mixture, the more was the suppressive effect; the effect
being even greater than that due to wild mustard itself.

Figure 5 shows the effect of various mixtures on the

yield of dry weight per plant of barley and wild mustard.

Barley—wild buckwheat. Table VI reveals that the yield

 

of wild buckwheat per plant was reduced very much by barley.
Wild buckwheat, on the other hand, exerted less effect on the
yield of barley than barley did itself. These results in general

agree with the barley-wild mustard mixtures.

TABLE V.

23

Effect of competition upon the yield dry weight

per plant of barley and wild mustard.

 

 

 

 

Barley Wild Mustard
dry w.t' git: 1'” Wt' filafit:
gms./p. alone SJ ° alone

6 barley alone 7.97 100.0

12 barley alone 4.31 54.1

6 wild mustard alone 5.88 100.0
12 wild mustard alone 3.67 62.4
6 barley, 6 wild mustard 6.89 86.5 1.39 23.6
6 barley, 12 wild mustard 6.02 75.5 0.98 16.7
12 barley, 6 wild mustard 4.58 57.5 0.70 11.9
12 barley, 12 wild mustard 3.44 43.2 0.43 7.3

 

 

- wfi‘fi

 

7a4.. . .\

‘75 of 6 plants'alone'
23

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u I
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a I
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. . . . . . 9

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24

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I

 

 

6 fifloao 12 alone 6 b

j .
ageley

12mm. 6mm.

I

6 barley l2 Barley 1:2 barley

12 w. m.

Figure 5? Effect, of competition upon the yield of d
neight‘ per plant of barley and wild mustar

u-ua-‘- -u. ‘-

1

 

25

 

 

 

 

 

TABLE VI. Effect of competition upon the yield dry weight
per plant of barley and wild buckwheat.
¥ Barley Wild Buckwheat
dry Wt' 21:51: dry Wt‘ flit:
gms./ p. alone gm s./ p ° alone
6 barley alone 7.97 100.0
12 barley alone 4.31 54.1
6 wild buckwheat alone 3.13 100.0
12 wild buckwheat alone 1.61 51.4
6 barley, 6 wild buckwheat 8.26 103.6 0.31 4.2
6 barley, 12 wild buckwheat 6.59 82.7 0.09 2.9
12 barley, 6 wild buckwheat 3.81 47.8 0.09 2.9
12 barley, 12 wild buckwheat 3.97 49.8 0.08 2.6

 

26

It will be noted from data in Tables III, IV, V, and VI

that barley was a stronger competitor than oats and that wild

mustard was a stronger competitor than wild buckwheat. The
grain craps were stronger competitors than the weeds.

The yield of dry weight per plant of barley—wild buck—

wheat mixture is shown in Figure 6.
Effect on Total Yield per Pot

Total yield of small grain per pot is shown in Table VII.

The total dry weight of oats per pot was essentially the
same for the six—plant and twelve—plant rates. The twelve-
plant rate of barley exceeded the six—plant rate by approximately
eight percent (Fig. 7).

Adding six wild mustard or six wild buckwheat to the
light rate of seeding of either oats or barley decreased the
total yield of small grain per pot much more than the addition
of six weeds to the heavy rate of grain seeding.

Wild mustard decreased grain yields more than wild
buckwheat.

Wild buckwheat had an adverse effect on oats yield when

the latter was planted at the higher rate. Yields of barley

 

.n—- —-I-'- p. —-—-— y'- —-1

 

,o-- «—

4 a»- vi '8“-

 

- //01r

”’0‘ "Barley

_ :

82$-

% of 6 plants alone

. . \ . _ ; . ‘x 1'
. .. '

0“
‘_‘...--

 

 

6w. b. 12w.b. 6w.b.‘ law. b.

V

 

i‘ I t Figure 6. Effect of competition upon the yield of dry
1 , . ‘weight per plant of barley and wild buckwheat.

 

‘ o

I. a 1 u ' t
I I
0“...— — - .u..- .uw“-—_-—-— — aha-*u-_h. -. A - —-——-.—~.

6: one [lZTaione- 6 barley 6 barley 12 barley l2 barleytw

 

Hi.

my.“ “'14;

{It

 

 

 

 

28
TABLE VII. Effect of competition upon the total dry weight

per pot of small grain in different rates of

seeding when in mixture with weeds.

Yield of total

dry wt. (Gms./Pot)
Oats Barley
6 crop alone 48.66 47.82
12 crop alone 48.84 51.72
6 crop, 6 w. mustard 31.38 41.89
6 crop, 12 w. mustard 29.64 36.12
12 crOp, 6 w. mustard 41.88 44.96
12 crOp, 12 w. mustard 41.52 44.28
6 crop, 6 w. buckwheat 42.72 43.56
6 crOp, 12 w. buckwheat 43.44 44.54
12 crop, 6 w. buckwheat 48.84 45.72
12 crop, 12 w. buckwheat 51.48 47.64

 

 

.4

 

 

- ~——. -—.— v..- .0-“
- I

I

I

I

 

w.

#6 p/anl‘: a/«ime. “ ‘

 

 

2!

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. 1

z. .' , ,_ -

d . ; I l . L ..

i. . . . I: } I .' . .

«" Iii—H: . ‘ .Y,. I ..... - ‘ -'.

‘ .' ' ' '. .' I I l . . 1.. ,

' ‘ -. . t. . .

f ‘ ~.

O - K; _.i ' I . _ . .I
uuuuuuu ' .fl 4 7' ‘Y I 5 ' A. "

;~ 6941;: a .3" l 2"” 7:17.; an» M; a '12.; "421.wa

. , elm a . an. mm (1% 6!? .A. 02H .6» fill/.4; 12 .A.

1' ~ . ' ‘.

. Y ‘ ' \. .

. ' I 2 .

2 ' " ' '
T I . , I

Figure :71

‘ i

Meet 61‘ competition upon the total yield of
dry weight per pot of small grain in different
rates of Seeding when in mixture with weeds.

.
-a—n—‘n -——-

 

 

 

30
from the higher rate were reduced slightly by the addition of
wild buckwheat.

Barley had more resistance to the weeds than oats.
Figure 7 shows yield of each rate and mixture expressed

in terms of percentage of the lighter rate of planting.
Effect on Percentage of Moisture

A study was made of the moisture content of oats and
barley at different rates of seeding and in mixture with weeds.
Both crops andweeds were harvested at the same time, although
among them they did not show uniformity in degree of maturity.
Tables VIII and IX show that the cr0ps with heavy rate of seeding
contained less percentage of moisture per plant. The percentage
of moisture of oats and barley in light rates of seeding was de—
creased by the infestation of wild mustard as compared with the
grains grown alone, which resulted in hastening the maturity of
the cr0ps.

The percentage of moisture of wild mustard was not
affected when in mixture with oats; but in the presence of
barley the percentage of moisture was increased, which resulted

in delayed maturity of the wild mustard.

.l.‘ --.4133‘ 1......mv«».w...i_~u‘.p. .
~. | ‘. ' . n'.

31

TABLE VIII. The percentage of moisture content per plant of
oats, barley, and wild mustard in different rates
of seeding.

 

 

Percentage of
Moisture per Plant

 

 

Grain Weed
Oats 6 alone 81.03
Oats 12 alone 76.64
Barley 6 alone 77.73
Barley 12 alone 74.15
W. mustard 6 alone 80.86
W. mustard 12 alone 81.25
Oats 6, w. mustard 6 79.21 80.60
Oats 6, w. mustard 12 77.69 80.13
Oats 12, w. mustard 6 80.74 80.66
Oats 12, w. mustard 12 78.15 80.73
Barley 6, w. mustard 6 75.18 80.88
Barley 6, w. mustard 12 76.39 82.65
Barley 12, w. mustard 6 75.77 85.07
Barley 12, w. mustard 12 74.02 83.71

 

 

32

TABLE IX. The percentage of moisture content per plant of
cats, barley and wild buckwheat in different rates
of seeding.

 

Percentage of
Moisture per Plant

 

 

Grain Weed
Oats 6 alone 81.03
Oats 12 alone 76.64
Barley 6 alone 77.73
Barley 12 alone 74.15
W. buckwheat 6 alone 78.84
W. buckwheat 12 alone 77.36
Oats 6, w. buckwheat 6 80.73 71.95
Oats 6, w. buckwheat 12 78.37 75.65
Oats 12, w. buckwheat 6 77.69 69.12
Oats 12, w. buckwheat 12 78.07 75.00
Barley 6, w. buckwheat 6 78.05 72.34
Barley 6, w. buckwheat 12 77.12 81.25
Barley 12, w. buckwheat 6 77.00 77.50
Barley 12, w. buckwheat 12 74.87 72.41

 

 

 

-r— —_ —_.I.' “-9--an .IF

33

Wild buckwheat had little effect on the percentage of
moisture of either oats or barley. Oats in this experiment
tended to decrease the percentage of moisture of wild buckwheat,
resulting in earlier maturity. The effect of barley upon the

maturity of wild buckwheat was variable.

 

g" ;_“ -_'.'.~

SUMMARY

Oats, barley, wild mustard, and wild buckwheat were
grown in the greenhouse at different rates of seeding for studying
the competition between small grain and weeds.

1. The effects of competition upon the number of heads

’ ’-h’.‘..“.€-J"'l-“M ..
A ' A I

and dry weight per plant within the species of small grain
itself were greater than by weeds.

2. Wild mustard had more effect on the number of
heads and dry weight per plant of small grain than wild buck—
wheat.

3. The rates of infestation of weeds in general did
not change the number of heads per plant of the small grain.

4. Weeds had less effect on the yield of dry weight per
plant in the heavier rate of seeding of small grain than in the
lighter rate.

5. The heavier infestation of wild mustard caused more
reduction of the yield of dry weight per plant of small grain.

6. The total yield of dry weight per pot of small grain
was not decreased by increasing the seeding rates, but by the

infe station of weeds .

35
7. The higher rate of seeding of barley increased the
total yield of dry weight per pot about eight percent.
8. Wild mustard decreased crop yields more than
wild buckwheat.
9. Barley had more resistance to the weeds than oats.

10. The moisture content per plant of small grain
grown alone was decreased by increasing the seeding rate.

11. Wild mustard caused earlier maturity of small
grain with light seeding rate.

12. Wild mustard was delayed in maturity by the pres—
ence of barley and wild buckwheat was hastened to maturity by
the presence of oats.

13. The competing ability among these four plants
ranked as follows: barley, oats, wild mustard and wild buck—

wheat.

-_D'1‘K':Qr .m‘l ' mam
. 4 I

 

1L“:

BIBLIOGRAPHY

Aaltonen, V. T.

Ueber die raurnliche Ordnung der Pflanzen auf dem Felde
und im Walde.
Act. For. Fenn. 23: 7—85, 1923.

Barnes, 5., and H0pkins, S. E.
Soil Moisture and Crap Production.
Dom. Dept. of Agric. Bull. 130 N. S. 27—30, 1930.

Blackman, G. E., and Templeman, W. G.

The Nature of the Competition between Cereal Crops and
Annual Weeds.
Jour. Agr. Sci., 28: 247-271, 1938.

Brenchley, W. F.
Weeds on Farm Lands.
London: Longmans, Green Co. 1920. (Pages 159—174.)

Cates, H. F.
The Weed Problem in American Agriculture.
U. 5. Dept. Agr. Yearbook. 1917.

Clements, F. E., Weaver, J. E., and Hanson, H. C.
Plant Competition.
Carnegie Inst. Wash. 1929.

Darwin, C.

The Origin of Species. London, 1859.

The Variation of Animals and Plants under Domestication.
2nd Ed. New York, 1876.

De Candolle, A. P.
Essaie élémentaire de Géographie Botanigue.
26-28. 1920.

De Crescentus, Petrus.
Handschrift. 1305.

10.

ll.

12.

13.

14.

15.

16.

17.

37

Godel, G. L.

Relation between Rate of seeding and Yield of Cereal
CrOps in Competition with Weeds.
Sci. Agr., 16: 165-168, 1935.

Hopkins, E. S.

Report of the Dominion Field Husbandman, Ottawa 37.
1926; 34-35. 1927; 43—46. 1928; 57—59. 1929; 43~44.
19300

Kiesselbach, T. A.

Studies Concerning the Elimination of Experimental
Error in Competitive CrOp Tests.
Neb. Agr. Exp. Sta. Res. Bull. 13. 1918.

Montgomery, E. G.
Competition in Cereals.
Neb. Agr. Exp. Sta. Bull. 113. 1912.

Nigeli, C. 1874.

Verdrangung der Pflanzenformen durch ihre Mitbewerber.
Sitzb. Akad. Wise. Munchen, 11.: 109—164.
Bot. Mitt. 3: 205-260. 1881.

Pavlychenko, T. K., and Harrington, J. B.
Competitive Efficiency of Weeds and Cereal Crops.
Can. Jour. Res., 10: 77—94. 1934.

Robinson, R. G.

Annual Weeds, Their Viable Seed POpulation in the Soil,
and Their Effect on Yields of Oats, Wheat, and Flax.
Jour. Amer. Soc. Agron. 41: 513-518. 1949.

Sukatschew, W.

Einige experimentelle Untersuchungen uber den Kampf
ums Dasein zwischen Biotypen derselben Art.
Zeits. Indukt. Abs. Vererb. 47: 54-74. 1927.

ROOM USE ONLY

 

 

145 6894

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