II

I

    

1

III

III

IIIIIIIIIIIII

III

I
I

IIIIII

_I

    

fian—r
'I-U'I
m w _.

      

A COMPARATIVE STUDY OF THE
STRUCTURE AND COMPOSITION OF
SEEDLING AND SCION ROOTS
OF THE APPLE

Thesis for the chréc of M. 5.
Frank N. chetson
1936

 

- (a "VI. Tn . .
23115:”. 1"?“ V. #3:“ '

“$.92 ; '3 yfi.‘ :7.
F {mg ,
4 ‘5

v'

:3

, ‘ a .
‘ .Q .2"; L" v7
‘ , fig?” ~
I 2. I 31.5% ffifl"

 

 

A COMPARATIVE STUDY OF THE STRUCTURE AND COMPOSITION

OF SEEDLING AND SCION ROOTS OF THE APPLE

Thesis

submitted to the Faculty of the M1Chigan State College
of Agriculture and Applied Science
in partial fulfillment
of the requirements
for the degree of
Master of Science

by
Frank Nutter Hew son

June, 1956

0/: HQ ’ 4/73/-
W/flxéezb

A COMPARATIVE STUDY OF THE STRUCTURE AND COMPOSITION

OF SEEDLING AND SCION ROOTS OF THE APPLE

‘{ Introduction

In recent years there has been considerable controversy
.as to whether the root or the stem exerts the greater influence
upon the character of the tree. Batten and his associates (7) believe
that the root system, which in his experiments consists of scion or
adventitious roots arising from the stem of layered shoots, controls
the growth and dominates the scion variety. Roberts (21), on the other
hand, thinks that the stem or trunk has more influence on the character
of the tree-than the seedling roots upon which it was grafted. The
conditions of the experiments were not entirely comparable because of
the difference in the type of root used in the experiments. However,
an understanding of the differences in.the composition of the seedling
and scion roots and the relationship which each bears to the composition
of the stem.mey indicate that both.viewpoints are correct and thus help

to conciliate the two ideas.

a an), {‘s‘ a,
1 {£2 )
.{)i):.)r~d.~a

Review of Literature

A study of the literature has not revealed any direct
references to the prOblem taken up in this thesis, but a short
discussion of the observations recorded by the various writers on
the behavior of seedling and scion-rooted plants may prove of interest.

The idea has long been held by gardeners that seedling-rooted
or grafted plants are more vigorous than those grown on their own roots.
Burbidge (5) cites several observations to prove this point. Cobbett (6),
Malet (15), Thirion (25), Schmidt (22), Rivers (20), "J. T." (9), Bailey
and Munson (2) and Marcille (14) all believe that seedlings are healthier
and produce larger plants than those which are grown on their own adven-
titious roots. On the other hand, many writers — London (12), "Celine" (4),
'J. G.” (8), Bailey and Corbett (1), Pynaert (18), Schneider (25) and
Mblisch (16) claim that plants on their own adventitious roots come into
bearing quicker and are more productive than seedlings. These divergent
opinions can be explained when it is realized that those favoring seedling
roots are chiefly interested in the production of large plants; on the
other hand, those holding that own-rooted plants are better, Judge super-
iority by the amount and precocity of fruiting. This precocity of
fruiting with adventitious-rooted plants is probably due to the greater
maturity of the stems as compared to the roots of these plants, whereas
the vegetative stage in seedling development is a necessary precursor of
maturity and fruit production. It is well known, and has been proved by

flurneek (l7),that fruiting is a dwarfing process, so that own-rooted trees

which produce fruit will naturally be small plants. Recently
Lagassee (10, 11) compared the growth of‘a number of apple varieties
on seedling roots and on their own roots and found that the own-rooted
trees were becoming more uniform.as they grew older, without losing
wanything in.vigor. From his data he concluded that the results were
in favor of scionprooted trees.

The above observations show the need for growing seedlings
and own-rooted plants under identical conditions so that a fair

comparison can be made of the relativesvigor-and precocity of each.

Material

The material used in this study was grown in the college
orchard of Michigan State College. The seed which produced the trees
was sown in the spring of 1924 in the college nursery. Four average
sized trees resulting from this planting were set out, and in 1928 a
branch from each tree was layered by bending it down to ground level
and mounding it up with earth. In the spring of 1930 this branch was
separated from the parent tree. By this time a sufficient number of
roots had deve10ped to maintain the branch as an individual tree. There
was thus, for comparison, a seedling tree on its natural (seedling) roots,
and one on its scion or adventitious roots. There were four such pairs
of trees planted out so that in each pair the scion-rooted tree was next
to its parent tree. In this study, two such pairs were used, making four
trees in all.

lethodg

Collection and Preparation of material:
The four trees used in this experiment were excavated in

 

December, 1955, sufficient roots being taken for analysis. The mater-

ial was immediately brought inside in.damp sacks and stored in a cool
laboratory. As soon as possible, the roots were washed free from.dirt

and immediately graded according to diameter as follows: 0-1 mm.,

1-5 mm., 5-10 mm. A root which included two or more grades was divided
into the various grades which it included, the finer roots being first
removed, and then the larger ones divided according to diameter. After
all the roots from a tree had been washed and graded, they were cut up
into 1/4 - 1/2'I lengths, placed in covered beakers, and weighed as quickly
as possible. Drying was done at 90 degrees Fahrenheit for one-two hours
and then at 70 degrees Fahrenheit until the material had reached a constant
weight. Samples were ground in an electric grinder and finished by means
of a pestle and mortar until all the material could pass through a 60-mesh
sieve. One-year wood was also collected, dried and ground as above,
except, of course, that it was not washed. Second and third grade roots

(1-5 and 5-10 mm.) and oneeyear old stems were used for analysis.

Mia:
Composition of the material was determined by analysing for

reducing sugars, total sugars, starch, hemicellulose, nitrogen, phosphorous

and potassium. Moisture determinations were also made on the material.

Structure was studied by the use of cross sections, 20
microns in thickness, and stained with safranin and light green. (5)

The Quisumbing and Thomas method (19) was used for heating
the mixture of sugar and Fehlings solution, while the volumetric
thiosulphate method (15) was used for estimating the amount of pre-
cipitated copper. Starch was converted to reducing sugars by the use
of 10 c.c. of saliva and subsequent hydrolysis with concentrated
sulphuric acid.

Preliminary comparisons of three methods for determining the
amount of precipitated copper were made in the winter of 1954-5. These
methods included the Shaffer-Hartman (24), volumetric potassium perman-
ganate (15), and the volumetric thiosulphate method. The alcoholic
extract of fibrous apple roots was used for purposes of comparison. The
results are recorded in Table I and show that the results obtained from
the Shaffer-Hartman method were about double those of either of the
other methods. The high results obtained with the Shaffer-Hartman method
have also been found by other workers in this laboratory. A further
comparison was carried out in the fall of 1955. This time the volumetric
potassium permanganate and the volumetric thiosulphate methods were
compared with the-gravimetric method, using a 0.100 per cent standard
glucose solution. While the gravimetric method gave the greatest recovery,
as shown in Table I, the results obtained by using the volumetric thio-
sulphate method were nearly as high. As in the first preliminary compar-

ison, the volumetric potassium permanganate method gave the lowest result.

Table I

METHODS OF ANALYSIS

 

 

Method 221111152
(£1954-5 il955._,
(Fibrous apple roots) (0.100% glucose
(% Dry Weight) solution)
Shaffer-Hartman 7.981 -
Volumetric Thiosulphate 4.050 0.09456 %
Volumetric Potassium 5.826 0.0886 %
Permanganate
Gravimetric - 0.0955 %

 

The preliminary comparisons of 1954-5 eliminated the Shaffer-
Hartman method for this type of material because it gives results which
were too high. The combined work of 1954-5 and 1955 have shown the
advisability of using the volumetric thiosulphate method in preference
to the potassium permanganate one, as the former gave slightly higher
results than the latter in both.years, and was nearer the figure for the
standard solution in the second comparison.

The effect of clearing on reducing power of the alcoholic extract
was determined. Different amounts of neutral lead acetate were used in
clearing the solution and compared with uncleared solution. Di-sodium
phosphate was used as a deleading agent. The results are recorded in
Table II and show the extentto which different amounts of lead acetate
clear the solution and carry down foreign materials which have the power

to reduce copper. Though clearing lowers the results, this is probably

due to the removal of foreign materials which are not sugars and
which should not therefore be included under this heading. Three

cc. of neutral lead acetate was considered sufficient to clear the
solution. Nitrogen determinations were made by the Kjeldahl-Gunning-
Arnold method (15). Phosphorous and potassium analyses were made by
the Experiment Station chemist.

Table II

EFFECT OF CLEARING ON REDUCING POWER OF SOLUTION

 

 

Treatment Reducing sugar
Uncleared 5.88
1 cc neutral lead acetate 5.24

5 cc neutral lead acetate 5.24

 

 

 

 

 

40‘ Legend
f 100:
} Seedling-rooted trees
Scion-rooted trees
} First set 1006 and 1007
so _. _ __ I”
} Second set 1008 and 1009 .. 1008
,‘ .6'
, X
A
.2 i”
20 '
I
I
I
I
10 '7
104
1926 1927 1928 1929 1950 1951' 1952 1955 1954 13:15
1P4;- 1’ nxmmnr rinnm (TIP GMTTM‘P. AHTW corms DWE‘T‘ ADDTI‘ WWWQ

Results

Tree Measurements and Characteristics:
Table III and Fig. I show the various measurements recorded

for the four trees included in this experiment.

Table III

TREE MEASUREMENTS

 

 

 

Tree weight Area Trunk
(portion above' Cros§;Section
No. Type ground level)
(lbs . I 431.421.)..—
1006 seedling-rooted 10.8 ' 24.04
1008 seedling-rooted 24.0 58.52
1009 scion-rooted 11.7 25.78

 

Circumference measurements were taken at one foot above ground level
and afterwards converted into area trunk cross section. The yearly
growth was found by recording the annual rings on four radii at right
angles to one another and averaging these figures. While there was
considerable difference in weight and area of trunk cross section of
seedling and scion rooted trees as between each pair, it is interesting

to note that one seedling rooted tree (No. 1006) and one scion rooted

tree (No. 1009) are comparable as to size and might be used for
comparison. Fig. I shows how the seedlingbrooted trees gained their
lead in 1929 at the expense of the scion-rooted trees, but also shows
how, since 1931, the scion—rooted trees maintained their relative
position after having overcome their original set back. Up to 1950
the scion-rooted tree was attached to the parent seedling tree, and,
being a subordinate branch, could not be expected to attain the same
size as the leader. The parallel growth after 1931 indicates that
after that year the scion rooted tree grew just as well as the seedling
rooted tree, when the difference in age was taken into consideration,
and also shows that the growth rates are somewhat similar.

There was little difference in the general form of seedling
and scion-rooted trees, except that which could be ascribed to differences
in age and size, such as greater abundance of branches in the seedling-
rooted trees. The root system of the scion-rooted trees was characterized
by a horizontal main root (the original layer) from which arose the scion
roots. In contrast, the seedling—rooted trees possessed a well developed
symmetrical root system. In the first pair of trees there was a greater
number of small roots on the seedling-rooted tree (No. 1006) than on the
scion-rooted tree (No. 1007), but in the second pair (Nos. 1008 and 1009)
there was no marked difference. The difference in the first pair was

probably due to the smaller size of these trees, as the second scion-

rooted tree (No. 1009) had about as many small roots as the

corresponding seedling-rooted tree‘(No. 1008).

Moisture :

Percentage moisture determinations are shown in Table IV.

PERCENTAGE DISTURE IN ROOTS AND ‘STEMS OF ALL TREES

Table IV

 

Roots

(Diem) seedling-rooted scion-rooted seedling-rooted scion-rooted

1006

1007

1008

1009

 

 

 

 

 

0-1 mm. 60. 875 62.210 59.611 58. 891
1-5 mm. 61.402 60.181 57.640 57. 866
5-10 mm. 60.051 58.796 56.458 57.517
AVERAGE 60.775 60.596 57 .905 58.091
Stems
(Age)
1 yr. 50.719 50.928 50.951 50. 880
2 yrs . 49.766 50.106 48.988 50.046
5Yrs. 48.626 49.554 47.722 48.401
AVERAGE 49.705 50.125 49.215 49. 776

 

_ 11 -

These figures reveal no differences as between scion and seedling
roots, though they do show a consistent difference between the roots
of the two sets of trees, suggesting that seedling roots may vary in
moisture content. The percentage moisture of the stems is practically
the same, irrespective of which set is considered, or whether seedling

or scion rooted trees are compared.

Carbogmdrateg:
‘ The results of the carbohydrate analyses are shown in

Table V. A comparison of the amount of reducing sugar in seedling
and scion roots showed in every case a greater amount of this car-
bohydrate in the scion roots than in the seedling roots. The average
ratio between seedling and scion roots was 1.411 for the first set
(Nos. 1006 and 1007) and 1.581 for the second set (Nos. 1008 and 1009),
which is about the same in each case. The reducing sugar content of
the stems of seedling and scion-rooted trees was the same for all trees.
A comparison of these figures also showed that, for roots of equal size,
the reducing Sugar contents of the stems and roots of scion-rooted trees
were more nearly the same than in the case of the stems and roots of
seedling-rooted trees.

The starch analysis also revealed some interesting
relationships. In each pair of trees there was less starch in the

scion-rooted trees than in the corresponding seedling-rooted tree.

- 12 -

Table V.

'CARBOHIDRATE ANALYSES 0F STEMS AND ROOTS

0F SEEDLING AND SCION ROOTED TREES

(All reported as glucose)

(% Dry Weight)

 

 

Carbohydrate Tree
1006 1'00? ' ‘1008 1009 '
seedling scion Ratio seedling scion Ratio Average

rooted rooted rooted rooted

Reducing sugar
Roots 1—5 5.2406 4.4559 1.574 5.2299 4.0875 1.266 1.520

5-10 2.5159’ 5.6410 1.447 0 2.6154 5.9145 1.496 1.4725

 

 

" average 1.411 1.581 1.596

Stone 1 yr. 4.4756 4.4944 1.004 4.2687 4.2266 0.990 0.997

Total sagars
Roots 1-5 4.5179 5.0988 1.181 4.7272 4.9949 1.056 1.119

5-10 5.5644 5.9276' 1.167 5.7776 4.0227 1.065 1.116

 

" average 1.174 1.061 1.117

Stems

Starch

4.2945 4.8492 1.129 4.8056 4.5814 0.955 1.041

Roots 1-5 6.7966 6.5585 0.9556 8.5465 6.2252 0.728 0.852

5-10 7.4115 6.5611 0.858 8.8776 6.9604 0.784 0.821

' average 0.897 0.756 0.826

Hemi—cellulose
Roots 1-5 12.1025 12.7516 1.052 15.9808 12.6890 0.908 0.980

5—10 15.7685 15.5740 0.986 12.7282 15.9542 1.094 .1.040

 

 

' average 1.019 1.001 1.010

Stems

14.5745 15.7611 .944

 

- 15 _

This difference really confirms the reducing sugar analysis, in that
starch is converted to glucose. The less starch there is in a certain
tissue, the more glucose one would expect to find. The sum total of
reducing sugar and starch are about the same in seedling and scion roots.
The slightly higher figure for the combined carbohydrates in No. 1005
was due to the larger amount of starch in this tree, probably on account
of its larger size.

Comparisons of total sugars and hemiecellulose reveal no
consistent differences between seedling and scion roots, apart from the
slightly larger amount of total sugars in scion roots consequent upon

the greater amount of reducing sugar in the scion roots.

nitrogen:
There was no significant difference in amount of nitrogen

in the seedling and scion roots, or~betweenthe two pairs of trees, as
shown in Table VI. The difference in amount of nitrogen in the stems

of the first and second pair cannot be explained.

Table VI.

TOTAL NITROGEN
(% Dry Weight)

 

 

TREE STEM ROOT
1 yr. 1.5 mm. diam. 5.10 mm. diam.
1008 0.955 .0.625 0.662
1007 0.891 0.606 0.566
1008 0.671 0.579 0.568
1009 0.564 0.675 0.559

 

.V—v—

-14..

lflneral Contents:

Table VII. shows the analysis of roots and stems
of seedling and scion-rooted trees for phosphorous and potassium.
In every comparison between seedling and scion roots, there is a
larger amount of both phosphorous and potassium in the scion roots
than in the seedling roots. There is also a closer relationship
between scion roots and stems than between seedling roots and stems
on the basis of mineral composition. The composition of the stems
serves as a valuable check on this relationship, for in every case
the mineral composition of comparable seedling and scion-rooted trees

is the same.

Structure:

A somewhat hasty Observation of the cross sections
prepared from the four trees did not reveal any outstanding structural
differences between seedling and scion roots as regards proportion of

xylem to phloem, thickness of cell walls, cu~ root origin.

- 15 _

Table VII

MINERAL ANALYSES

 

 

 

of
STEIB AND ROOTS 0F SEEDLING AND SCION ROOTED TREES
,Iineral Tree
1006 1007 1008 1009
seedling scion Ratio seedling scion Ratio
rooted rooted rooted rooted
(% Dry (% Dr5r (% Dry (1» Dry
weight) Height) Weight) Weight)
Phosphorous
Roots 1-5 0.118 0.148 1.254 0.076 0.114 1.500
' 5-10 0.092 0.168 1.826 0.108 0.114 1.055
" average 1.540 1.277
Stems 1 yr. 0.186 0.184 0.9891 0.102 0.104 1.0196
Potassium
boots 1.5 0.459 0.507 1.1046 0.285 0.459 1.6070
" 5-10 0.557 0.517 1.4481 0.551 0.589 1.1085
” average 1.2764 1.5577
Stems 1 yr. 0.509 0.479 0.9410 0.599 0.400 1.0025

 

 

-16..

W

The results of this investigation have revealed a difference
between seedling and scion-rooted trees used in this experiment in
respect to the amount of reducing sugars and starch, phosphorus and
potassium. While it was at first thought that the difference in size
of the trees light explain these differences, a combined study of
Tables III and V suggests that such is not the case. Trees No. 1006
and 1009 are about the same size, the first being seedling-rooted and
the second-being scion-rooted - No. 1006 being one year older than
No. 1009. Comparison of the amount of reducing sugar of the roots of
these two treesreveals the same relationship as between the original
pair, which are very different in size. Again, with the starch content,
the same‘relation3h1p_holds between Nos. 1006 and 1007 as between Nos.
1006 and 1009. The relationship between seedling and scion roots in
respect to phosphorous and potassium are somewhat variable, though in
each set there is a larger amount of those elements in the scion-rooted
tree than in the seedling-rooted tree. A study of these results would
suggest that size and age of the tree affect the mineral composition
to a greater extent than they do the carbohydrate composition. The
smaller sets (Nos. 1006 and 1007) have larger amounts of each mineral
while the ratio between seedling and scion roots varies according to

size of root and size of tree. The ratio of phosphorous in seedling

-17..

to phosphorous in scion roots 1-5 mm. in diameter is higher in the
larger set (Nos. 1008 and 1009). On the other hand, in the case of
roots 5-10 mm. in diameter, it is higher in the smaller set of trees
(Nos. 1006 and 1007). This relationship also holds for the potassium
analyses.

Thompson (26) has shown that while there are certain differ-
ences in the phosphorous and potassium content of roots of various
ages, these differences are not directly correlated with age after the
first two to three years of growth. During these early years, however,
there was a slight increase in mineral composition of the roots. One
might therefore expect to find larger amounts of phosphorous and
potassium in the seedling roots than in the scion roots. The results
reported herein are, however, Just the reverse and serve to confirm
the differences revealed by the carbohydrate analyses.

A comparison of the figures for phosphorous and potassium
indicate that these minerals fluctuate together in the same direction,
roots having large amounts of P also having large amounts of K. This
is shown rather well by comparing the ratios of comparable sets. Such
results are contrary to those found by Wallace (27, 28) but conform
to those of Thompson (26).

Though it is fully realized that results based on such a
small number of trees cannot be given too much consideration, the

constant relationship between the various trees with different grades

- 18 -

of roots has in itself considerable significance. A study of Fig. I
shows that the growth rates of the seedling and scion-rooted trees
have been practically the same during the last few years, and that
differences in.the composition of the roots do not appear to be due
merely to differences in growth rates. That no differences were found
in the hemi—cellulose content of the different roots is not surprising,
as this form of carbohydrate is only used for nutritional purposes
when all the other reserve materials (chiefly starch) are exhausted.
The fact that there is a larger amount of reducing sugar in the scion
roots than in the seedling roots shows that the scion roots bear a
closer relationship to the stem than do the seedling roots. This fact
also suggests that scion roots have reached a greater degree of seasonal
maturity than have the seedling roots. This resemblance in composition
of scion roots and stems may throw some light on the hitherto contra-
dictory results of Hatton and Roberts. If stems and scion roots have a
somewhat similar composition, it is quite possible that they might
exert a similar influence on the behavior of the tree grown thereon,
and that in reality Hatton and Roberts are working with comparable
material.

The lower amount of starch in the scion roots would be
expected if the reducing sugar content is higher, as these carbohydrates

are closely associated with each other.

-19..

Conclusion§

The roots of seedling and scion-rooted trees from the
same seedling differed in respect to reducing sugar, starch,
phosphorous, and potassium. The results suggest that the relative
size of the trees was not a factor influencing the amounts of these
substances and indicate that there is a real difference between
seedling and scion roots and a similarity between scion roots and
stems. This similarity in composition may help to reconcile the

differences of opinion as regards stem and scion root influence.

2.

(N

4.

5.

6.

_ 20 _

Summag:

Two pairs of scion and seedling rooted trees were compared in
respect to moisture, reducing sugars, total sugars, starch,

hemi-cellulose, nitrogen, phosphorous and potassium.

No consistent differences were found in total sugars, hemi-cellulose

or nitrogen.

Scion roots had more reducing sugar, phosphorous, and potassium

and less starch than seedling roots.

The composition of scion roots in respect to reducing sugars,
phosphorous and potassium bore a closer relationship to the

composition of stems than did the seedling roots.

No difference was observed in the structure of seedling and

scion roots.

The bearing that the findings here described may have on the
question of stem and scion root influence on the behavior of

the tree is discussed.

_ 21 -

Acknowledgments

The writer wishes to express his thanks to Mr. R. C.
Palmer, Superintendent of the Dominion Experimental Station at
Summerland, B. C. for helpful criticism during the early part of
the work; to Mr. D. J. Strachan for his assistance in preparing
and planting the material; and to Professor V. R. Gardner for his
criticism of the manuscript. Especial thanks are due to Professor
F. C. Bradford for providing the material at Michigan State College,

and for so much valuable advice during the course of the investigation.

- 21 -

Acknowledgments

The writer wishes to express his thanks to Mr. R. C.
Palmer, Superintendent of the Dominion Experimental Station at
Summerland, B. C. for helpful criticism during the early part of
the work; to Mr. D. J. Strachan for his assistance in preparing
and planting the material;' and to Professor V. R. Gardner for his
criticism of the manuscript. Especial thanks are due to Professor
F. 0. Bradford for providing the material at Michigan State College,

and for so much valuable advice during the course of the investigation.

1.

2.

5.

4.

6.

7.

8.
9.

10.

11.

_ 22 -
REFERENCES
Bailey, L. B., and Corbett, L. 0.,
Exp. Sta. Bul. 45. 1892.
Bailey, L. H., and Munson, W. M.,
Exp. Sta. Bul. 21:79-80. 1890.

Burbidge, F. W., Grafted and Own-rooted Trees.
and Improvement of Cultivated Plants. pp. 57-70.

"Celine”, Treatment of the Cobaea écandens.

Cabinet. pp. 192-5. 1855.

Chamberlain, C. J., Methods in Plant Histology, The University
of Chicago Press, Chicago, Illinois.

Cobbett, London's Gard. Hag. III.:565:4.

Tomatoes. Cornell Agri.

Tomatoes. Cornell Agri.
Propagation
1876.

Floricultural

D ‘1 'M ._....___.._

1955.

1828.

Hatton, R. G., The Influence of Vegetatively Raised Rootstocks

Upon the Apple, with.Special Reference to the Parts Played

by the Stem and Root Portions in.Affecting the Scion.

of Pom. and Hort. Sci. IX: No. 4:265-77.

”LG." , Lobelia cuttings.

”J.T.', Seedling Deodars.

The Garden XXI.:82.

The Garden XXVII.:551.

Jour.
Dec. 1951.
Feb. 4, 1882.

1885. 5

Lagasse: F. 8., A Comparison of the Variability in Growth of

Several Varieties of Apple Trees Growing on Seedling Roots

and upon Their Own Roots.

A.S .H.S. 28: 475-484 .

1952.

Lagasse, F. 8., The Circumferential Variability of Five Varieties

of Apples Trees on Seedling and Scion Roots.

1955.

A.S eHeSe 30: 577-810

12.

15.
14.

15.

16.
17.
18.

19.

20.

22.

- 23 -

Loudon, - Magnoliaceae. Arboretum et Frut. Brit. I.:259-91.

Mdlet, - Seedlings and Cuttings. Jour. Soc. Imp. et Cent.
d'hort (Paris) II.: 555. 1865.

Marcille, R. Notes on the Tunis Varieties of Olives. Bul.
Dir. Agr. et. Com. (Tunis) 41: 511-27. 1906.

methods of the Assoc. of Official Agricultural Chemists. 1950.

Molisch, - Pflanzenphysiol. als. Theorie der Gartneri. Jena:
256-62. 1922.

Murneek, A. E. Is Fruiting of the Apple an Exhaustive Process?
Proc. Am. Soc. Hort. Sci. 1925 pp. 196—200.

Pynaert, Ed. Le Fruit de la Passiflora. Rev. de 1'hort. belge
et étre. 11.: 105-5. 1894.

Quisumbing, F. A., and Thomas, A. W. Conditions Affecting the
Quantitative Determination of Reducing Sugars by Fehling’s
Solution. Elimdnation of Certain Errors Involved in Current
methods. Jour. Amer. Chem. Soc. 45: 1505726. 1921.

Rivers, T. Francis, Apples on Their Own Roots. The Garden
XXI.: 550-1. May 15, 1882.

Roberts, R. H. Some Stock and Scion Observations on Apple Trees.
Wisconsin Agri. Exp. Sta. Res. Bul. 94. 1929.

Schmidt: Beitrage und Bemerkungen zur Cultur Neurer Oder Besonders
Werthvoller Coniferen. Wiener Obst. u. Garten. Zeit II.:

564-79. 1877.

25.

24.

25.

26.

27.

28.

-24..

Schneider, N. Les Luculia. Rev. hort. 82: 429.51. 1910.
Shaffer, P. A., and Hartman, A. F., The Iodometric Determination
of Copper and Its Use in Sugar Analysis. Jour. Biol. Chem.

45: 549-90. 1920.

Thirion: Precocity of Cuttings. Jour. de la Soc. Imp. et Cent.
d'hort. de Fr. 2 ser. T. III.: 150-1. 1869.

Thompson, R. C. The Relation of Fruit Growing to Soil Fertility.
Ark. Agri. Expt. Sta. Tech. Bul. 125. 1916.

Wallace, T., Experiments On'The Manuring of Fruit Trees. 1.
Jour. Pom. and Hort. Sci. 4: 117-140. 1924-5.

Wallace, T., Experiments on the Manuring of Fruit Trees. II.

Jour. Pom. and Hort. 801. 5: 1-55. 1925.

.a‘...

...V in. T

 

.1119: ‘Béit: .

y . x . .1.K!1.E$iw£‘§tth . . -

1%: (ELL-l. ":63.
it???

115;;‘. 3,": v
9.7-1.3 g .

35?.

u . ' t .
12.,
.L' :14, ,\

‘g‘{

.. we- W
.. . fifths" ‘34»)
J )W )3: 4" ‘D $311;
‘I‘Kxg'kk ”3“; ‘S‘fii
Mui‘lz (HA-‘5'u41
u flu};
01962" ‘
fut. .
be
Jigr‘ 1.11“.

[Llhtaw

T “k.
.925? ..

\
fig“
‘9" ”gt-:3"

‘4'”;
Jo

"4 ..
A! ,r?
h w

 

5 2127

\flilfiflflxum