KREZDORN: SEEDS AND POLLEN SOURCE
LITERATURE CITED
growth of young orange trees.
1.
Brams, E. A. and J. G. A. Fiskell.
Relationships
between the inorganic composition of citrus root and ad
jacent soil. Soil Sci. Soc. Amer. Proc. (Manuscript sub
mitted).
2. Fiskell, J. G. A. and E. A. Brams. 1965. Root desorption analysis as a diagnostic technique for measuring:
soil-plant relationships. Soil and Crop Sci. Soc. Fla. Proc.
25: 128-142.
3. Ford, H. W. 1953. Root distribution of chlorotic and?
iron-chelate-treated citrus trees. Fla. Sta. Hort. Soc. Proc.
66:
22-26.
4.
1965.
Leonard, C. D., J. G. A. Fiskell, and R. B. Diamond.
Effect of clay materials, lime, and phosphate on
27-35.
37
Fla. Sta. Hort. Soc. Proc. 78:
5. Nye, P. H. 1966. The effect of the nutrient intensity
and buffering power of a soil, and the absorbing power, size,
and root hairs of a root on nutrient absorption by diffusion.
Plant and Soil 25: 81-105.
6. Smith, P. F. 1956. Effect of phosphate fertilization
on root growth, soil pH, and chemical constituents at dif
ferent depths in an acid sandy Florida soil. Fla. Sta. Hort.
Soc.
Proc.
69:
25-29.
7.
Spencer, W. F. 1958. The effects of phosphate and
lime applications on growth, root distribution, and freeze
injury of young grapefruit trees. Fla. Sta. Hort. Soc. Proc.
71:
106-114.
THE INFLUENCE OF SEEDS AND POLLEN SOURCE ON
THE SIZE OF FRUIT
A. H. Krezdorn
Department
of Fruit Crops
University of Florida
Gainesville
Abstract
The size of 'Orlando' tangelo fruits increased
linearly with the number
of seeds
per
tude of the influence of seeds on the fruit size
of 'Orlando' tangelo the most widely planted of
the interspecific hybrids, (2) determine whether
there is a general relationship of seeds and fruit
sizes for a cross section of varieties grown com
mercially in Florida, and (3) establish whether
the pollen variety influences the fruit size or
seed content of 'Orlando' tangelo.
fruit.
Seedless or sparsely seeded fruits were much
smaller than those which were seedy. Less ex
tensive data showed that for several other varie
Materials and Methods
The data were
obtained over several years
ties of citrus there was a positive relationship
and in some cases were taken from experiments
between fruit and seed size.
designed to determine more than just the rela
tion of fruit size and seed content. Thus, several
experimental approaches were used.
Influence of seeds on fruit size.—Samples of
75 to 100 fruits were selected at random from
an area of about 16 square feet (4 feet x 4 feet)
A wide range of
compatible varieties of pollen had no differential
influence on seed content or fruit size of the
'Orlando'.
Introduction
As a result of breeding programs several in
terspecific hybrids of citrus have been released
that are sexually self-incompatible; i.e., they
do not produce seed when self-pollinated. Most
of these varieties are weakly parthenocarpic and
a few are strongly so. Therefore when inter-
planted with compatible pollinator varieties the
seed content varies tremendously.
Because
these
varieties
are
primarly
mar
keted as fresh fruit and because several of them
characteristically produce fruit that is undesir
ably small, factors influencing fruit size are espe
cially important.
It
was
here to:
the
(1)
purpose
of
the
work
reported
obtain an estimate of the magni
Florida Agricultural Experiment Stations Journal Series
2863.
No.
from each of 6 trees growing adjacent to rows
of pollinator trees. All trees were in commercial
orchards and all fruit was taken from the outer
portions of the canopy. The trees were in good
vigor and 8 to 15 years of age, except for one
group about 25 years old. The equatorial diame
ter and seed count of each fruit was ob
tained and the data subjected to statistical anOther data were obtained from random sam
ples of about 100 fruits sampled from one side
of each of 5 trees for 1, 2 or 3 years. The fruit
obtained was arbitrarily separated into 3 class
sizes designated
small, medium and large.
Within each of these classes the fruit diameter
varied but the largest fruit in a class was much
smaller than the smallest fruit in the next
largest class. The mean seed content was ob-
FLORIDA
38
STATE
HORTICULTURAL
SOCIETY,
1967
Table 1. - Regression coefficients of fruit diameter on seed number,
mean fruit diameter and mean seed number.
1
Mean Fruit
Diam. (mm)
Mean Seed
Number
0.6907
67.2
9.3
Tempie
0.7112
62.1
12.1
3
Temple
0.7234
65.6
14.1
4
Dancy
0.7301
70.1
17.9
5
Temple
0.6876
70.2
18.5
6
Temple
0.459
60.9
17.7
Regression
Experiment
Pollinator
Coefficient (b)
1
Tempie
2
'in all experiments the linear regression analysis indicated high statisti
cal significance (1% level), indicating that there was a linear increase
of fruit diameter with an increase in seed number.
tained for the fruit in each class. Tables of
means are presented but data were not subjected
to statistical analysis since the experiment was
designed only to determine a gross relationship.
Influence of pollen source (variety) on num
ber of seeds per fruit and fruit size.—For 3 suc
cessive years individual flowers on each of 10
'Orlando* trees were hand pollinated with pollen
from a wide range of varieties. On the 4 sides
of each tree 18 flowering shoots were thinned
to 1 flower each and the flowers both depetaled
and emasculated. Two of the 18 flowers at each
location were hand pollinated with one of the
9 pollens used (Table 3). Thus, at each of 40
locations pollen of each variety was applied to
2 flowers.
a block or
and each
turity the
count and
Each location on the tree constituted
replication, each 2 flower units a plot
pollen applied a treatment. At ma
number of fruit produced, the seed
fruit diameter were obtained and the
data was subjected to analysis of variance.
Results and Discussion
Relationship of seeds to the size of fruit of
'Orlando* tangelo.—Fruit size and seed number
for fruit from 6 orchards showed a statistically
significant linear regression of fruit size on seed
number; i.e. there was a linear increase in di
ameter for each unit increase in the number of
seeds per fruit.
Table 1 contains the 6 regres
sion coefficients which are the statistical esti
mates of the increase in fruit diameter (mm)
that can be expected with an increase of 1 seed.
By multiplying the regression coefficient by the
number of seeds one obtains the estimated in
crease in size of fruit.
The number of seeds in 'Orlando* ranged from
0 to 45 although counts above 35 were uncom
mon.
Thus the increase in fruit diameter was
often as much as 20 mm or about 0.75 inch a
very large increase. The numerical value of the
regression coefficients were nearly the same ex
cept for Experiment 5 (Table 1 Fig. 2), in which
the trees were much older and crowded than in
the other experiments. These or other factors
may have attributed to the difference. The simi
larity in the other experiments was attributable
at least in part to the uniformity of vigor and
cropping of the trees used.
The increased size due to seediness is also
quite evident from the data in Table 3, which
was obtained from a controlled hand-pollination
KREZDORN: SEEDS AND POLLEN SOURCE
39
Table 2. - Mean number of seeds per fruit in each of 3 size classes
of several varieties of citrus.
Variety
Experiment
Fruit Size Class
Small
Medium
Large
1
1.21
2.3
3.9
2
1.3
2.1
3.2
3
1.5
2.6
3.0
1
5.2
7.5
10.0
2
6.9
8.7
11.2
1
7.8
9.4
12.2
2
9.4
13.0
15.5
3
10.1
13.0
15.4
1
2.1
3.2
5.0
2
2.6
4.0
6.4
3
2.3
3.7
5.9
1
2.4
6.2
6.2
2
2.1
4.5
6.4
1
8.9
11.6
15.5
2
10.9
12.4
18.0
Robinson
1
3.4
8.9
16.2
Page
1
0.6
9.2
15.7
Hamlin
Parson Brown
Pineapple
Valencia
Marsh
Dancy
"•Each entry is the mean or average number of seeds per fruit of the
fruit in the given size class.
40
FLORIDA
STATE
HORTICULTURAL
SOCIETY,
1967
Table 3. - Number of seeds and size of 'Orlando' tanaelo fruit following
cross-pollination with several varieties.**2
No. Seeds. Per Fruit
Pollen Variety
Fruit Diameter (mm)
1959
1960
1965
Av.
1959
1960
1965
Av.
Hamlin
27.2
29.1
30.0
28.5
85.6
87.2
89.1
87.3
Parson Brown
28.1
29.2
28.1
28.5
85.2
88.1
88.9
88.1
Pineapple
27.5
28.0
30.4
28.6
88.0
87.1
91.2
88.8
Valencia
28.0
30.1
27.1
28.4
87.9
84.6
90.0
87.8
29.1
27.8
30.2
29.0
87.0
85.6
92.1
88.2
Dancy
30.1
29.1
29.0
29.4
84.0
88.1
87.9
87.0
Ponkan
27.8
27.8
29.1
28.2
86.7
87.0
89.9
87.9
30.1
28.0
29.1
29.1
85.4
88.0
87.8
87.1
Robinson
—
—
29.9
29.9
—
—
88.9
88.9
Minneola
0.0
0.1
0.0
0.0
—
68.9
—
69.5
Orlando
0.2
0.1
0.0
0.1
70.1
70.2
—
70.2
Open Pollinated
1.1
1.8
0.6
1.2
70.1
72.5
72.2
71.9
Sweet oranges
Grapefruit
Duncan
Tangerines
Mandarin Hybrids
Temple
^Cross-pollination resulted in 85 to 91% fruit and there was no statisti
cal significance due to source of pollen. Self-pollination and crosspollination with self-incompatible Minneola resulted in only 0-6% fruit.
Open pollinated fruit were produced parthenocarpically and serve as a
comparison.
2There was no statistical difference between mean seed count or fruit
diameter due to compatible pollen varieties.
KREZDORN: SEEDS AND POLLEN SOURCE
41
-80
•
•
•
75
•
•
•
-70
i
UJ
•
•
■
UJ
-65
•
LL
-60
•
•
t
•
* •
•
• 5
r=
0.7706
y ■ 60.78+ 0.691 x
10
15
SEED
PER
20
25
i
30
i
35
■
FRUIT
Fig. I. Regression of fruif diameter on seed number.
experiment. However, the 'Orlando' is weakly
parthenocarpic and blooms heavily. Since the
'Orlando' is incapable of producing seed when
self-pollinated, flowers to which bees do not
transfer pollen from the pollinator variety may
produce appreciable numbers of seedless or few
seeded fruit, and did so on the trees used. This
problem is much more acute for the 'Page'
variety, which produces undesirably small fruits.
As seen in Table 2, the seedy 'Page' fruit is
larger than seedless and few seeded fruit; how
ever, it is doubtful that even cross-pollination
will increase the fruit sizes on the entire tree
sufficiently to overcome the size problem because
the 'Page' is highly parthenocarpic and pro
duces many small seedless fruits.
Moreover in evaluating the commercial appli
cation of increasing fruit sizes through increased
seediness one must use cross-pollination via bees.
The mean fruit size and seed content of fruit
pollinated by hand is usually much greater than
that brought about through bees.
Seedless 'Orlando' fruits as large as the
seedy fruits are frequently produced, but these
generally occur on trees with small crops. Also,
many factors other than seeds affect fruit size.
This is portrayed by the scatter diagrams (Figs.
1, 2) which show appreciable deviations of fruit
sizes from the calculated regression line.
The relation of seeds and fruit sizes of varie
ties other than 'Orlando'.—Data in Table 2 show
that increased seediness results in increased
fruit sizes for all varieties. This is not surpris
ing since this relationship has been reported
elsewhere for many multiseeded fruits such as
apples (8), grapes (10), blueberries (4), passion
fruit (1) and several citrus varieties (2, 6, 11).
When single seeded fruits such as peaches have
their seeds killed at an early stage of develop
ment the fruit often grows to maturity but is
FLORIDA
42
STATE
HORTICULTURAL
SOCIETY,
1967
-75
♦
.
-70
-65
•
.
•
cc
LU
H
LU
-60
•
<
•
9
-55
•
•
•
•
•
•
r= 0.7704
^
^^^^
9
•
•
y = 52.77+0.459 x
9
•
•
9
e
•
i
'
IP
15
SEED
PER
20
25
30
35
FRUIT
Fig. 2. Regression of fruif diameter on seed number.
much smaller than fruits with seeds (4).
Seed
less avocados are hardly larger than finger tips
and
trees
are
produced in
large
numbers
on
some
variety used.
Swingle coined the term metaxenia
to indicate the influence of the pollen variety
on all tissue exterior to the endosperm of the
seed, including
(3).
The value of this data is to stress the impor
the fruit wall.
This is
distin
guished from xenia, the influence of the pollen
tance of the role of seeds in determining fruit
source on the characteristics of the endosperm
sizes in a wide spectrum of varieties grown in
and embryo, as is so well demonstrated by the
Florida and stimulate the search for chemicals
different colored endosperms in corn seeds, which
that might substitute for the growth regulatory
show through the translucent fruit wall of the
effect of the developing seed in increasing fruit
corn kernel or caryopsis.
size.
Xenia is common in
on the
certain nut crops (7, 12) where the seed is the
major part of the fruit. Occurrence of xenia
number of seeds and size of fruit,—The possible
is easily accepted because the endosperm results
effect of the variety of pollen used on the char
in a fusion of both the male sperm and the endo
acteristics of the fruit produced has long been
sperm nuclei
a controversial topic largely due to a lack of
different
knowledge of the reproductive process and the
tendency to draw conclusions from gross ob
results from 2 genetic sources.
However the
fruit wall results only from tissue of the female
parent and it is widely accepted that the charac
Influence
servations
of pollen source (variety)
and
poorly
However, Swingle
(13)
designed
and Nixon
experiments.
(9)
demon
strated that the size and sugar content of dates
and the size of seed were influenced by the pollen
teristics
and
genetic
of
thereby is the product of 2
types.
most fruits
Similarly, the
embryo
are not directly influ
enced by the pollen source.
Of course, the pollen
indirectly influences the fruit through its effect
RIEDHART: OIL EMULSION EFFECTS
on the number of seeds produced.
The data in this experiment (Table 3) show
that pollen variety has no influence on the seed
content or the fruit size of the * Orlando', other
than for the incompatible 'Orlando* and
'Minneola' pollens, which resulted in virtually seed
less
fruits that were much
smaller than the
seedy ones. Thus, the 'Orlando' does not exhibit
metaxenia and growers cannot expect the polli
nator variety to directly influence fruit size.
LITERATURE CITED
1. Alkamine, E. K. and G. Giorlami. 1959. Pollination
and fruit set in the yellow passion fruit. Hawaii Agr. Expt.
Sta. Tech. Bull. 59: 1-44.
2.
Cameron, J. W., D. C. Cole, Jr., and E. M. Nauer.
1960. Fruit size in relation to seed number in the 'Valencia'
orange and some other citrus varieties.
Proc. Amer. Soc.
Hort. Sci. 76: 170-180.
3.
Chandler, W. H. 1950. Evergreen orchards. Ch. 2,
pp. 208-242. Lea and Febiger, Philadelphia.
43
4. Darrow, G. M. 1942. Seed size in blueberry and re
lated species. Proc. Amer. Soc. Hort. Sci. 28: 438-440.
5. Havis, L.
1938.
Seedless peaches as a result of
freezing injury. Ohio Agr. Exp. Sta. Bimon. Bull. 23 (195):
215-219.
6.
Krezdorn, A. H. and F. A. Robinson. 1958. Unfruitfulness in 'Orlando' tangelo.
Proc. Fla. State Hort. Soc.
21:
86-91.
33:
4-6.
7. McKay, J. W. 1938. The immediate effect of pollen
on the fruit of the chestnut. Proc. Amer. Soc. Hort. Sci.
36: 293-298.
8. Murneek, A. E. and G. C. Schowengerdt.
1935. A
study of the relation of size of apples to number of seeds
and weight of spur leaves.
Proc. Amer. Soc. Hort. Sci.
9. Nixon, R. W. 1928. The direct effect of the pollen
on the fruit of date palm. J. Agr. Res. 36: 97-128.
10.
Olmo, H. P.
1946.
Correlation between seed and
berry development in some seeded varieties of Vitis vinifera.
Proc. Amer. Soc. Hort. Sci. 48: 291-297.
11.
Oppenheimer, H. R.
1948.
Experiments with un
fruitful "Clementine" mandarin in Palestine.
Agr. Res.
Sta., Rehovot, Israel, Bull. 48: 1-63.
12.
Romberg, L. D. and C. L. Smith. 1946. Effects of
cross-pollination and sib-pollination on the dropping, the
volume and the kernel development of pecan nuts.
Proc.
Amer. Soc. Hort. Sci. 47: 130-138.
13.
Swingle, W. T. 1928. Metaxenia in the date palm.
J. Heredity. 6: 257-268.
INFLUENCE OF OIL EMULSIONS ON ABSORPTION
OF CARBON DIOXIDE BY CITRUS
J. M. RlEDHART
Materials and Methods
Kennecott Copper Corporation
Leaves of nursery grown trees of Citrus
sinensis, Osbeck, variety Valencia, were utilized
Special Products Division
Waterbury, Connecticut
as a source of plant material.
Introduction
In a recent investigation using infra-red CO2
analysis it was shown that pure paraffinic hydro
carbons
applied
to leaves
Osbeck, variety Valencia,
of
Citrus
sinensis,
depress CO2 absorp
tion; and, that the recovery from the depressive
effect correlates with the dissipation of the hy
drocarbons
(1).
Because of the differences in the physical and
the chemical properties and the methods of ap
plication
of
the
pure
paraffinic
hydrocarbons
used in the above study, it was considered haz
ardous to extrapolate from the
results
to the
performance of a field application of a typical
oil emulsion, also,
on CO2
absorption.
The present investigation was initiated in
to obtain specific data concerning the
effects of a typical oil emulsion on CO2 absorp
tion under as near normal conditions as practical.
order
Determinations
of CO2 absorption were made using continuous
infra-red CO2 analysis with sequential multi
point sampling, as described previously (1). Air
from the atmosphere, at thirty liters per hour,
was passed over leaves placed in water-cooled
plastic chambers, through a dririte drying col
umn, a flow meter, and a Hartmann & Braun
URAS Infra-red CO2 analyzer. A switching
unit permitted sequential sampling from several
sampling points for five minute periods. A purge
pump maintained a constant flow at thirty liters
per hour over leaves not being channelled
through the analyzer.
Apparent photosynthesis, CO2 absorption,
was measured by the amount of CO2, in ppm,
removed from the air stream in daylight. Res
piration, CO2 evolution, although recorded dur
ing the dark period has been disregarded in
the present investigation.
All measurements were made on, outdoor
growing plants. The leaves were enclosed in