GULF COAST RESEARCH & EDUCATION CENTER
IFAS, UNIVERSITY OF FLORIDA
5007 60TH STREET EAST ------
BRADENTON, FL 34203 Central Science
Bradenton GCREC Research Report BRA1988-18 August 1988
SEP 26 988
Seedless Watermelon Variety Evaluation University of Florida
Spring 1988 ------
D. N. 4N.aynard and P. R. Gilreath1
The concept of seedless watermelons was described first in the U.S.
literature by Kihara (1) in 1951 based on experimentation that began in
Japan in 1939. Seed for planting seedless watermelons results from a
cross between a selected tetraploid female parent and a selected diploid
male parent. Tetraploid lines are developed by treating diploid ines with
colchicine. The resulting triploid is sterile and does not produce viable
seed. However, small, white rudimentary seeds develop which are eaten
along with the fruit like cucumber seeds.
Fruit enlargement in normal fruit, including watermelon, is enhanced by
growth promoting hormones produced by the developing seed. Growth
hormones are lacking in seedless watermelons so those agents are provided
from pollen. Since flowers on triploid plants lack sufficient pollen,
normal watermelons are interplanted with triploids to serve as
pollenizers. An adequate bee population is necessary for this to occur.
Seedless fruit (from triploid plants) tend to be triangular shaped unless
sufficient pollenizer plants (normal watermelons) and pollinators (bees)
Although the procedure for production of seedless watermelons has been
known for almost 50 years and commercial varieties have been available for
almost 20 years, the interest in and acreage of seedless watermelons has
remained small. Erratic performance, poor seed germination, high seed
costs, and inadequate varieties caused the low interest in seedless
Specialty vegetables are in high demand in the 1980's, and seedless
watermelons offer an attractive alternative for the up-scale consumer and
the food service industry. At the same time, new varieties are being
developed that are superior to those already available.
The object of these trials was to evaluate the performance of seedless
watermelon varieties and experimental lines under west central Florida
1Professor of Vegetable Crops and Manatee County Vegetable Extension
Materials and Methods
Seeds of 16 seedless watermelon varieties or experimental lines (Table 1)
were seeded in a peat-lite growing mix in No. 150 Todd planter flats (1.5
x 1.5 x 2.5 in. cells) on January 26, 1988. After thorough watering, the
flats were covered with polyethylene and placed in a greenhouse maintained
at 800F. At the first sign of emergence the polyethylene was removed, and
the temperature was lowered to 700F night and O00F day.
Soil in the experimental area was sampled before fertilization and
analyzed by the IFAS Extension Soil Testing Laboratory: pH = 7, P = 102, K
= 29, Ca = 1510, Mg = 200, Zn = 10, Mn = 17, and Cu = 6 ppm.
The EauGallie fine sand was prepared in January 1988 by incorporation of
0.36-2.0-0.50 lb N-P205-K20 per 100 linear bed feet (Ibf). Beds were
formed and fumigated with Dowfume MC-33 [methyl bromide:chloropicrin
(66:33)] at 1.5 lb/100 Ibf. Banded fertilizer was applied in shallow
groves on the bed shoulders at 3.5-0-5.0 lb i3-P205-K20 per 100 Ibf after
the beds were pressed and before the polyethylene mulch was applied. The
final beds were 28 in. wide and 6 in, high, and spaced on 9 ft. centers
with seepage irrigation/drainage ditches on 40.5 ft, centers or every 4
The watermelon transplants were set in holes punched in the polyethylene
at 4 ft. in-row spacing. The 24 ft. long plots had 6 plants each, and
were replicated 3 times in a randomized, complete block design. Icebox
watermelons planted on each side of two seedless watermelon beds served as
pollenizers. The row middles were hoed twice for weed control.
Endosulfan was applied for aphid control and chlorothalonil was applied
for downy mildew and gummy stem blight.
Watermelons were harvested three times beginning June 1 and ending June
23. Marketable melons were separated from culls and counted and weighed
individually. Soluble solids determinations were made with a hand-held
refractometer on at least 12 fruit from each entry over two harvests.
Results and Discussion
Temperature and rainfall during the experimental period at the Gulf Coast
Research & Education Center (Table 2) was very similar to the 33-year
Early yields based on the first of three harvests, ranged from 85 cwt/A
for CFREC (Central Florida Research & Education Center-Leesburg) 88-4 to
333 cwt/A for 'Jack of Hearts'. 'Quality' also produced high early
yields. Early average fruit weight ranged from 13.0 lb for CFREC 88-8 to
16.2 lb for 'Jack of Hearts'.
Total yields ranged from 424 cwt/A for ACX 87m103 to 755 cwt/A for CFREC
88-7. Other high yielding varieties were CFREC 88-8, CFREC 88-2, 'Jack of
Hearts', 'Queen of Hearts', CFREC 88-4, and 'Quality'. Average fruit
weight for three harvests ranged from 11.7 lb for 'Fengshan No. 1' to 17.0
lb for CFREC 88-4. There was little difference within varieties in early
average fruit weight or for the entire season.
Soluble solids were uniformly high, ranging frost. a low of 11.5Z for
'Fengshan H1o. 1' to a high of 12.8J for 'Queen of Hearts'. Several
varieties of icebox watermelons in an adjacent trial had lower average
soluble solids (2).
The distribution of seedless watermelon fruit into various size classes is
shown in Table 4. Generally, it is desirable to have uniform-size melons
that can be easily graded prior to boxing. One shipper indicated that
melons weighing about 15 lb each were desirable for packing four to the
carton weighing about 6O lb. Accordingly, varieties producing a high
proportion of fruit in the 10 to 20 lb classes would be more useful than
those producing fruit over a wider range of weights. For example, 90% of
the CFREC 88-7 fruit were within the 10-20 lb weight, whereas only 62. of
the CFREC 88-4 fruit were in this group. If all other factors were
equivalent, the former variety would be superior to the latter,
Variety shape and rind patterns, based on observations in this trial, are
shown in Table 1. Varieties producing oval to oblong fruit may be more
suitable for boxing than varieties producing round melons. Generally, the
striped melons are more attractive for the U.S. market than those with
stripes on a very dark green background or those with a solid dark green
'Tri X 313' has been the standard seedless watermelon variety for some
years, but based on this trial several recently introduced varieties and
experimental lines are higher yielding and have better appearance.
Additional trials are needed to determine the acceptability and
dependability of seedless watermelon varieties for commercial production
1. Kihara, H. 1951. Triploid watermelons. Proc. Amer. Soc. Hort. Sci.
2. Maynard, D. N. and P. R. Gilreath. 1988. Icebox watermelon variety
evaluations, spring 1988. GCREC Res. Rept. BRA1988-00.
3. Stanley, C. D. 1988. Temperature and rainfall report for 1987.
GCREC Res. Rept. BRA1988-11.
The information contained in this report is a summary of experimental
results, and should not be used as recommendations for crop production.
Where trade names are used, no discrimination is intended and no
endorsement is implied.
Table 1. Seedless watermelon varieties, description, and seed source.
Gulf Coast Research & Education Center, Dradenton, FL. Spring
Variety Description Source
ACX 87m103 Round with stripes. Abbott & Cobb
ACX 874503 Round, stripes on dark Abbott & Cobb
CFREC 88-1 Round with stripes. CFREC-Leesburg
CFREC 88-2 Round with stripes. CFREC-Leesburg
CFREC 88-3 Round with stripes CFREC-Leesburg
CFREC 88-4 Elongated with undefined CFREC-Leesburg
CFREC 88-5 Round with stripes. CFREC-Leesburg
CFREC 88-7 Round with stripes. CFREC-Leesburg
CFREC 88-8 Oval with stripes CFREC-Leesburg
Farmers Wonderful Round with stripes Known-You
Fengshan No. 1 Round with dark green rind. Known-You
Jack of Hearts Round with wide stripes. Petoseed
King of Hearts Round/oval with 'Crimson Petoseed
Quality Round, stripes on dark Known-You
Queen of Hearts Oval with Jubilee-type stripes. Petoseed
Tri X 313 Oval with undefined stripes. Northrup King
Table 2. Mean temperature and rainfall at the Gulf Coast Research &
Education Center from March 1, 1988 to June 23, 1988 and
33-year averages (3).
Average Daily Temperature (OF)
1988 33-year average Rainfall (in.)
Month (date) Max. Win. Max. min. 1988 33-year average
March 77 55 77 55 5.27 3.39
April 84 GO 82 60 0.77 1.59
May 87 63 87 64 2.54 3.14
June (23) 90 69 -- 1.75 --
Table 3. Early and total yield, average fruit weight, and soluble solids of seedless watermelon
varieties. Gulf Coast Research & Education Center. Spring 1988.
Early yieldz Total yield
Weight Avg. fruit Weight Avg. fruit solids
Variety No./AY (cvt/A) wt. (lb.) No./A (cvt/A) vt. (lb.) (%)
CFREC 88-7 1,149 c-ex 170 b-d 14.8 ab 4,965 a 705 a 14.2 b 12.4 ab
CFREC 88-8 1,785 a-c 232 a-c 13.0 b 5,098 a 673 a 13.2 bc 11.9 ab
CFREC 88-2 1,494 a-d 230 a-c 15.4 ab 4,486 ab 646 a 14.4 b 12.0 ab
Jack of Hearts 2,056 ab 333 a 15.2 a 4,521 ab 642 a 14.2 b 12.1 ab
Queen of Hearts 1,611 a-d 253 a-c 15.7 ab 4,657 ab 638 a 13.7 bc 12.8 a
CFREC 88-4 548 e 85 d 15.5 ab 3,713 ab 632 a 17.0 a 12.5 ab
Quality 2,212 a 303 ab 13.7 ab 5,097 a 532 a 12.4 bc 12.2 ab
Farmers wonderful 1,414 a-e 222 a-c 15.7 ab 4,260 ab 522 ab 14.6 b 12.7 ab
CFREC 88-3 1,525 a-d 244 a-c 16.0 ab 4,559 ab 620 ab 13.6 bc 12,7 ab
King of Hearts 1,069 c-e 154 cd 14.4 ab 4,101 ab 555 ab 13.8 bc 12.0 ab
Tri X 313 1,134 c-e 178 b-d 15.7 ab 3,854 ab 541 ab 14.0 bc 12.7 ab
CFREC 88-1 961 de 147 cd 15.3 ab 3,764 ab 527 ab 14.0 bc 12.2 ab
Fengshan No. 1 2,040 ab 253 a-c 12.4 ab 4,368 ab 511 ab 11.7 c 11.5 b
CFREC 88-5 1,197 b-e 188 b-d 15.7 ab 3,645 ab 503 ab 13.8 bc 12.1 ab
ACX 874503 1,993 ab 275 a-c 13.8 ab 3,976 ab 501 ab 12.6 bc 11.9 ab
ACX 87m103 1,463 a-e 218 a-c 14.9 ab 3,029 b 424 b 14.0 bc 12.3 ab
ZEarly yield based on first
YAcre = 4840 Ibf.
Xlean separation in columns
by Duncan's multiple range test, 5%Zevel.
Table 4. Fruit size distribution of the total yield of seedless water-
Gulf Coast Research & Education Center.
Fruit weight (lb.)
<5 5-10 10-15 15-20 20-25 >25
Variety Percentage of fruit
ACX 87m03 0 bz 14 bc 54 ab 20 b-d 4 b 0 b
ACX 874503 0 b 17 a-c 62 a 1I cd 5 b 0 b
CFREC 88-1 0 b 23 ab 44 ab, 22 b-d 11 ab 0 b
CFREC 88-2 0 b 16 a-c 42 a-d 35 a-c 7 b 0 b
CFREC 88-3 3 a 13 bc 46 ab 35 a-c 3 b 0 b
CFREC 88-4 0 b 10 bc 23 d 39 ab 21 a 7 a
CFREC 88-5 0 b 22 ab 25 cd 40 a 5 b 0 b
CFREC 88-7 0 b 6 c 55 ab 35 a-c 4 b 0 b
CFREC 88-8 0 b 17 a-c 55 ab 27 b-d 1 b 0 b
Farmers Wonderful 0 b 5 c 43 a-d 50 a 2 b 0 b
Fengshan No. 1 0 b 30 a 53 ab 15 d 2 b 0 b
Jack of Hearts 0 b 16 a-c 43 a-d 34 a-d 7 b 0 b
King of Hearts 0 b 18 a-c 44 a-c 29 b-d 9 b 0 b
Quality 0 b 30 a 46 a-c 23 b-d 1 b 0 b
Queen of Hearts 0 b 14 bc 48 ab 37 ab 1 b 0 b
Tri X 313 0 b 16 a-c 39 b-d 42 ab 3 b 0 b
z'ean separation in columns by Duncan's multiple range test, 5% level.