SWEET CORN SYNTHETICS AND COMPOSITES
Hawaii Foundation Seeds
Seed Availability: HFS can provide samples of most of these populations. Some are available only from the USDA-ARS
National Center for Germplasm Resource Preservation (NCGRP) in Ft. Collins, CO. Many have been provided to CIMMYT
(International Maize and Wheat Research Center) in Mexico.
PREFACE: Populations most extensively used in tropical breeding (Ref: Brewbaker 2014)
Hawaiian Supersweet #9
(Hi bt COMP 3)
Hawaiian Supersweet Silver
(Hi bt COMP 9)
Hawaiian Sugar
Hawaiian Supersweet #5
(Hi sh2 COMP 2)
1.
SUPERSWEET POPULATIONS BASED ON bt (brittle-1) GENE
Hi bt COMP 3p
Hawaiian Supersweet #9; Composite selected for tenderness and green silk based on earlier Hi bt
Comp 1 and Comp 2 (derived from Hawaiian Sugar variety x bt stock) (Brewbaker, 1977).
Hi bt COMP 4k
Composite based on crosses of Haw'n Supersweet 9 x Suwan 1, segregating resistance to turcicum and
downy mildew
Hi bt COMP 6o
Kalakoa Supersweet, a conversion of Hi bt COMP 3 to purple plant (A B Pl)
Hi bt COMP 9aa
White endosperm conversion of Hi bt COMP 3 (y/y, not y8 or y11) with improved brace roots, kernel
size, fusarium tolerance (= Hawaiian Supersweet Silver)
Hi bt SYN 2i
Synthetic based on 15 sueprior bt inbreds
Hi bt SYN 3i
Synthetic based on 3 outstanding inbreds from bt COMP 3
Hi bt SYN 7p
Synthetic based on selected S5 inbreds from a composite based on bt COMP 3 crossed with hybrids of
temperate x tropical field corn inbreds, selected for lodging and long ear
Hi bt SYN 9g
Synthetic based on crosses of bt SYN 3 x six Hawaii synthetics of field corn inbreds, selected for a
broad range of disease and pest resistance
Figure. Thai brittle-1 hybrid (to left) bred by Dr. Taweesak Pulam (to left) with fellow UH graduate Dr.
Soon Kwon Kim and Prof. Brewbaker. Pulam’s hybrids derive from UH synthetics and dominate the
huge Thai industry. Comparable temperate Chinese hybrid to right.
2. SUPERSWEET COMPOSITES BASED ON sh2 (shrunken-2) GENE
Hi sh2 COMP 2o
Based on crosses of AA8 sh2 x tropical flint and sugary varieties; erect (= Hawaiian Supersweet #5),
broad range of disease and pest tolerance
Hi sh2 SYN 2n
Based on SYN6 x Commercial sh2 hybrids selected for unusual flavor; very temperate in appearance
Hi sh2 SYN 6m
Based on 2 prior SYNs involving 23 Hawaiian Sugar derived inbreds and 5 Mainland inbreds (e.g.,
2256, R819, R839)
3. SWEET CORN POPULATIONS BASED ON su (sugary 1) GENE
Hi su COMP 6g
Stiff-stalked, low-eared composite from AA8 x N28 backcrossed to lines from Hawaiian Sugar, with
genes Ht and Rp (not effective in Hawaii by 1980)
Hi su COMP 10i
Composite based on Hi bt COMP 1 and tropical flints backcrossed to Hawaiian Sugar and selected for
tenderness and Fusarium tolerance
Hi su COMP 12n
Blue-seeded (ACRPr) composite based on BC7 to Hawaiian Sugar
Hi su COMP 13g
Composite based on (Hawaiian Sugar x AA8) x Hi su SYN 3
Hi su COMP 14i
NE-EDR COMP 1i, an exotic disease resistant composite of tropical and temperate sweet corns, under
regional project NE124 (also available in bt and sh2 conversions)
Hi su SYN 3i
Synthetic based on 16 outstanding inbreds from Hawaiian Sugar, that it mimics in appearance and
productivity
Hi su SYN 4h
Synthetic derived from 15 best singlecross hybrids of Hawaiian x Mainland inbreds such as 442, P39,
P51 (formerly = Hi su COMP 1)
Hawaiian Sugar
Open- pollinated variety developed by A. J. Mangelsdorf in 1945 from crosses of Caribbean flints x
Golden Bantam variety; selected for tolerance to maize mosaic virus
4. SUPERSWEET COMPOSITE BASED ON bt2 (brittle-2) GENE
Hi bt2 COMP 1m
Supersweet #6)
Composite based on crosses of lines from Hawaiian Sugar with bt2 genetic stock (= Hawaiian
5. NE-EDR COMPOSITES, GERMPLASM RESERVOIRS FOR DISEASE RESISTANCE
NE-EDR su1
Composite based on 10 elite temperate sweet corn hybrids and 10 tropical, elite sugary-1 populations
bred at U. Hawaii (see above), followed by 13 cycles of recurrent mass selection
NE-EDR bt1
Composite based on NE-EDR su1 Cycle 8 crossed to HibtCOMP3 followed by 5 cycles of
backcrossing and 10 of selfing and recurrent mass selection; A superior germplasm resource
NE-EDR sh2
Composite based on NE-EDR su1 Cycle 8 crossed to temperate sh2 hybrids, followed by 5 cycles of
backcrossing and 5 of sibbing in Hawaii and 4 of sibbing in Florida
6. WAXY (Vegetable corn) COMPOSITES
Hi wx COMP 1e
Composite based on varieties and inbreds from SE Asia, selected for use as green vegetable (“mochi”)
Note: Suffixes a, b, c, etc. indicate the cycle of population improvement. AA8 is an inbred derived from Hawaiian Sugar. All
composites and synthetics have the Mv allele for resistance to Maize Mosaic Virus, and varying levels of general resistance to fusarium
kernel and seedling rot, common and polysora rusts, Northern leaf blight, MDMV, physoderma stalk rot, and earworms.
Relevant Publications:
Brewbaker, J.L. 1977. Hawaiian Super-sweet #9 corn. HortScience 12:355-356.
Brewbaker, J.L. 1998. Disease-resistant tropical sweet corn populations. HortScience 33:1262-1264.
Brewbaker, J.L. and B.T. Scully. 2002. NE-EDR su1 and NE-EDR bt1, disease-resistant sweet corn populations with sugary 1 and brittle 1
endosperms. HortScience 37:600-602.
Scully, B.T., J.L. Brewbaker, J.K. Pataky, W.F. Tracy and M.E. Smith. 2001. NE-EDR sh2; A yellow shrunken 2 sweet corn population
with disease resistance from exotic sources. HortScfience 36:1149-1151.
Brewbaker, J. L. 2014. Breeding tropical vegetable corn. Plant Breeding Reviews 2014.
Performance data of Hi syns and comps.
Name
Gene
Color
KD mm
KW mg
KRN
EL cm
PH cm
EH cm
MMV
Rust Fus
HibtSYN2
HibtSYN2
HibtSYN3
HibtCOMP3
HibtCOMP4
HibtCOMP6
HibtSYN7
HibtCOMP8
Hibt2COMP1
Hish2SYN6
Hish2COMP2
HisuSYN3
HisuSYN4
HisuCOMP6
HisuCOMP10
HisuCOMP12
HisuCOMP13
bt1
bt1
bt1
bt1
bt1
bt1
bt1
bt2
sh2
sh2
su1
su1
su1
su1
su1
su1
Y
Y
Y/W
Y
Y/W
Y/W
Y
Y
Y
Y
Y
Y
Y
Y/W
B
Y
9.9
10.0
9.8
9.4
7.9
10.5
9.4
8.6
8.9
9.5
10.0
9.8
9.6
9.4
10.0
9.2
125
101
125
112
123
142
117
146
95
158
193
234
195
211
171
139
14.7
14.7
13.4
13.2
13.8
14.5
13.5
13.5
12.9
13.5
14.1
13.4
13.7
13.6
13.5
13.9
12.3
11.3
11.9
10.8
9.5
12.5
12.0
11.2
11.5
14.2
13.1
12.0
13.1
13.6
13.0
12.9
179
169
179
182
197
195
184
191
189
190
212
203
207
203
202
197
56
56
70
75
76
79
68
63
76
77
94
79
74
80
75
77
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
2
2
3
2
4
4
3
5
4
4
4
4
5
3
4
4
Mean
Haw'n Sugar
Jubilee
su1
su1
Y
Y
9.4
8.9
10.8
154
222
158
13.6
12.9
14.8
12.2
13.7
12.5
195
206
138
76
93
49
R
R
S
3.6 47
5 24
8 93
39
41
13
55
60
63
57
69
77
44
54
52
41
19
30
26
MMV = maize mosaic virus; Rust = common rust (scores 1 good - 9 bad), Fus = Fusarium ear/kernel rot, % reduction under severe
infection. KD = Kernel depth, KW = kernel weight, KRN = kernel row number, EL = ear length, PH/EH = plant/ear height
(2015 web\sweetcorn syns&comps.doc)