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GEM
- 2002 Public Cooperator's Report
NOTE: The
information in this report is shared cooperatively. The data are not
published, but are presented with the understanding that they will not be
used in publications without specific consent of the public cooperator.
Please notice that we
didn't include the tables in each GEM public cooperator's report because of
the size of the file. If you need the data, you can download them by
clicking on the zipped file on the previous page or contact the webmaster
for help.
Inbred Line Development and Hybrid
Evaluation in GEM Breeding Crosses
Department of Plant and Soil Sciences, University of Delaware
Objectives
To develop inbred lines
from GEM breeding crosses with good per se and testcross performance,
resistance to abiotic and biotic factors, and adaptation to the Mid-Atlantic
and
Corn Belt regions.
Materials and methods
Four hundred fifty-six S1
families, derived from six Stiff Stalk and seven non-Stiff Stalk GEM
breeding crosses, were self-pollinated. S2 ears were harvested
from selected S1 families based on agronomic and disease
evaluations. Selfing was also initiated on 17 new Stiff Stalk and 10
non-Stiff Stalk GEM breeding crosses. S1 ears were harvested from
selected plants based on plant height, ear placement, maturity, grain
drydown, grain quality, standability, and disease and European corn borer
resistance. Yield trials were conducted on 15 DKXL212:N11a inbreds crossed
to multiple testers (42 entries plus 3 commercial checks) at seven locations
(Georgetown, DE; Hurlock, MD; Ames, IA; Poseyville, FT Branch, MT Vernon,
and Whiteland, IN) with 10 reps. We evaluated seven DKXL212:N11a inbreds for
gray leaf spot resistance in a replicated test at Georgetown, DE and in a
non-replicated observation trial at Blacksburg, VA.
Results
One hundred sixty-two S2
ears were selected from 108 of the 201 Stiff Stalk S1 families
evaluated, and 188 S2 ears were selected from 126 of the 255
non-Stiff Stalk S1 families (Table 1). A higher percentage of
selections were made from the following breeding crosses: CUBA164:S1511b,
DK212T:S0610, DK212T:S0620, DK212T:N11a10, DK888:N11a08b, DK888:N11a08e, and
DK888:N11a17.
Based on per se
evaluations for plant height and maturity, selections were made in 15 of the
17 new Stiff Stalk and six of the 10 non-Stiff Stalk breeding crosses (Table
2). We were not able to pollinate the MDI022:S21 breeding cross due to its
extreme plant height and late flowering. Three hundred sixty-seven Stiff
Stalk S1 ears and 197 non-Stiff Stalk S1 ears were
selected based on grain quality, grain texture, ear size, maturity, insect
and disease resistance, and other agronomic traits.
The top 25 entries in the DKXL212:N11a yield trial are listed in Table 3.
DE4(DKXL212:N11a365-1-1-2-1-1), DKXL212:N11a-197-1-1-1-1, and
DKXL212N11a-2-1-1 yielded well on at least two of the three testers with
yields not significantly different from the commercial check mean.
In the DE gray leaf spot
evaluation, DE3 rated intermediate (3.0) and DE4 resistant (1.0) compared to
the susceptible check B73Ht (5.0) and the resistant check Mo17Ht (1.7) on a
(1-5 scale with 1 most resistant). These lines performed similarly at the VA
observation plot. Hybrid observations at VA indicate that DE4 transmits gray
leaf spot resistance in hybrid combination and had similar resistance to the
resistant hybrid check. We observed premature death on DE4 at the
Georgetown
location that may be related to root rot symptoms.
Conclusions and Future Outlook
Based on the yield results
and per se evaluations, inbred lines DE4 and DKXL212:N11a-197-1-1-1-1 may
have potential for improving both agronomic and disease performance. The 162
Stiff Stalk and 188 non-Stiff Stalk S2’s will be testcrossed in
2002-3 winter isolation blocks, and hybrid evaluations will be conducted
Summer 2003.
Acknowledgements
We thank the following
cooperators for their assistance in conducting trials: USDA-GEM (Iowa
State
University), Holden Foundation Seeds, Inc.,
Pioneer Hi-Bred Int. Inc., and Mycogen. We also thank Erik Stromberg,
Department of Plant Pathology, Physiology, and Weed Science,
VPI & State University;
Blacksburg,
VA for conducting the gray leaf spot test.
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Silage Evaluation
of Topcrosses with Advanced Lines from GEM Breeding Crosses
Department of Agronomy, University
of Wisconsin
Overview: Approximately 8%
(2,500,000 ha) of all corn harvested in the
USA is harvested as silage
that is fed to ruminants. Most of the silage corn is grown in the northern
Corn Belt and the northeastern
U.S., where the percentage
silage can be as high as 50%. New hybrids are now routinely screened for
silage potential in several states including
Wisconsin,
Michigan, and
New York
because the quality differences among hybrids can have economic consequences
for milk and beef production. Animal rations must be properly balanced, and
nutritional composition has become an important factor for farmers when
choosing which hybrids to plant. Unfortunately, the range in nutritional
value among conventional hybrids is narrow, due to the fact that, until
recently, conventional hybrids have been selected primarily for grain yield.
The GEM project has potential for bringing new germplasm into the
Corn Belt with excellent grain and silage yield, as
well as improved nutritive value.
The UW corn breeding program has been an
active cooperator with the GEM project since 1995, and our objective was
initially to determine if any of the GEM germplasms would contribute to the
development of high-yielding and high-nutritive value silage hybrids. We
started with the evaluation of a number of temperate breeding populations in
per se evaluations. In 1998, we adopted a different strategy, which we have
continued to the present. We now routinely evaluate silage potential of
elite GEM topcrosses with high grain yield and suitable maturity (<
120RM). These hybrids are chosen annually based on excellent grain yield in
GEM evaluations conducted in previous years throughout the U.S. Corn Belt.
If any of these topcrosses have high dry matter yield and good nutritional
quality in our UW trials, the respective GEM parent or breeding population
is included in the UW inbred development nursery for further inbreeding and
selection.
Recent Activities:
Based on results obtained in 2001 (see 2001 GEM public summary reports), two
GEM trials, GEM A and GEM B, were conducted in 2002. The GEM A trial
consisted of the ongoing silage evaluation of elite GEM topcrosses that were
identified in the past year as having high grain yield and suitable maturity
for
Wisconsin. There were 26 entries in GEM A involving breeding populations or
early-generation GEM inbreds topcrossed to LH185, LH198, and LH283. The GEM
B trial consisted of 61 GEM inbreds topcrossed to HC33, LH185, LH198, LH279,
LH287, and LH295. The inbreds involved in the GEM B trial were developed by
the UW silage breeding program and were chosen based on topcross silage
evaluations in previous years.
Both trials were planted at two WI
locations,
Madison (May 7) and
Arlington (May 16), with three
replications at each location. The average planting densities were 29,359
plants/acre (GEM A) and 28, 227 plants/acre (GEM B). Dry conditions
prevailed until mid July, but the
Madison trial was in good shape by
harvest on September 25. Arlington was damaged slightly by drought and the
Arlington
trial also experienced some root lodging, but the plots were in good enough
condition to harvest on October 8. Harvest dates at
Madison and
Arlington
were delayed beyond the optimum dry matter of 30-40% because of weather and
equipment difficulties. Therefore, the average dry matter at harvest was
high (47.3% for GEMA and 49.5% for GEMB).
Nutritional evaluations included assessment of neutral detergent fiber (NDF),
in vitro true digestibility (IVD), in vitro NDF digestibility (IVNDFD),
crude protein (CP), and starch concentration. Based on these values,
milk/ton of forage and milk/acre will be estimated based on the MILK2000
equations (www.wisc.edu/dysci)
developed by the UW Agronomy and Dairy Science Departments. MILK2000 uses
forage composition (NDF, IVD, IVNDFD, CP, and starch) to estimate potential
milk production per ton of forage. Forage yield is then used to estimate
potential milk per acre.
GEM A highlights. As seen in table 1,
seven testcrosses (indicated in bold) showed potential based on the
milk/acre evaluations, which were all greater than 31,500 lbs/acre. Most of
this production was due to high forage yield. However, one testcross,
BR52051:N04-75-1 x LH198, also had excellent quality (low NDF, high IVD, and
high milk/ton).
GEM B highlights. Six testcrosses were
notable in the GEM B trial (table 2). Most of these had high production
potential based on milk/acre. Three had excellent quality as well based on
their low NDF, high IVD, and high milk/ton (SCRO1:N1310-398-1-B-21 x HC33,
AR17026:N1019-65008-2-3-1 x HC33, and CUBA164:S1517-01113 x LH287).
In our inbred
breeding nursery in 2002, S5+ families were derived from breeding
crosses UR13085:N0204, UR13085:N0207, AR17026:N1013, AR17026:N1019,
SCRO1:N1310-398-1-B, CUBA164:S15-184-1-B, and CUBA117:S1520-156-1-B.
Approximately 200 S3 families were derived from CUBA164:S1517. We
also added three new sets of GEM inbred bulks to our inbred nursery in 2002, CHIS775:N1912-321-1-B-B, CH05015:N15-8-1-B-B, and
DKXL370:N11a20-97-1.
Approximately 300
inbreds from CUBA164:S1517, CUBA164:S15-184-1-B, and CUBA117:S1520-156-1-B
were planted in a crossing block with LH279 as the male pollinator. These
topcrosses will be evaluated for silage potential in 2003.
Based on the GEM A and B evaluations in 2002,
15 inbred have been sent to the winter nursery for increase and additional
testcrosses with LH198 and LH200. After one more year of testing, we should
be able to determine whether any of these families are suitable for release.
For a complete nursery listing, see
http://uwsilagebreeding.agronomy.wisc.edu.
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Developing
Breeding Lines with Anthracnose Stalk Rot Resistance from Exotic Maize Germplasm
Department of Plant Breeding, Cornell
University
Justification
Anthracnose stalk rot (ASR), caused by
Colletotrichum graminicola (Ces.) G.W. Wils., causes stalk rot
problems and contributes to increased lodging in
New York
and throughout many
U.S.
maize-producing areas. The only economically feasible control of ASR is
through resistant varieties and cultural practices that reduce disease
incidence. Recent research has focused on exotic sources for improved ASR
resistance, given the limited resistance available in temperate maize
germplasm. This project aims to develop new maize inbreds with excellent
resistance to ASR (derived from the tropical germplasm sources used) and
good agronomic quality, yield potential, and temperate adaptation (derived
from the proprietary temperate inbreds crossed to the exotic populations).
General Objective
To develop temperate-adapted maize inbreds
with both anthracnose stalk rot resistance and good yield potential from
GEM breeding populations.
Specific Objectives for Current Project
Year
1) Increase seed of S6 (F7) lines
that have shown promising levels of anthracnose stalk rot resistance.
2) Generate testcross seed of these lines
with public and Holden’s testers for multi-location yield evaluation in
2003.
Materials and Methods
The results described
herein represent the latest year of a multi-year inbred development
effort. Results of 1995 per se evaluations were used to select five 75%
temperate: 25% exotic populations with potential for anthracnose stalk rot
resistance. Results of 1996 testcross yield evaluations of these
populations were used to select the four with the best yield potential.
For each of these four populations, 50 S1 ears were grown out
ear-to-row in summer 1997. Eight plants per family were self-pollinated,
injected with approximately 500,000 conidia/plant of Colletotrichum
graminicola, and selected for anthracnose stalk rot resistance at
harvest. In 1998, selected S2 ears were grown out ear-to-row
for another cycle of inbreeding and selection for resistance, and were
testcrossed. Selected S3 ears were grown out ear-to-row for
inbreeding and selection for resistance in 1999, and testcrosses from the
S2 families that gave rise to these selections were evaluated
in yield trials in three New York locations. Yield and resistance data
were used to select S4 ears, which were grown out ear-to-row
for inbreeding and selection for resistance, and testcrossed for yield
evaluation at two or three New York locations in 2000. The same was done
with S5 ears and their testcrosses in summer 2001. In summer
2002, S6 progenies were planted out ear-to-row for sib increase
and crossing to both public and Holden’s testers. Testcross seed will be
used for multi-location yield trials in 2003, to assess yield potential in
combination with both elite commercial testers and with the public testers
that have been used to date in this project.
Progress to Date
Populations selected
based on per se anthracnose stalk rot resistance (evaluated in 1995) and
testcross yield potential (evaluated in 1996) were FS8B(T):N1802,
CH04030:S0906, AR01150:N0406, and GOQUEEN:N1603. Stalk rot resistance
ratings for the S5 families grown in 2001 and for the S5
plants from which S6 ears were selected are shown in Table 1.
Ears were saved from only the more resistant families and the
agronomically best plants within these families. Single plant selection
for stalk rot resistance within families was not made at this point,
assuming that alleles for resistance should be largely homozygous in S5
families. As a result, the standard deviation and range of values for
individual S5 plant selections are higher than they have been
in previous generations when individual plant selection was done. This
variation likely reflects the inherent variability of the screening and
rating technique, combined with the field variability that plagued our
plots during the 2001 growing season.
Yield data based on S5
testcross performance also was considered in selecting which families to
maintain (see Table 2 for yield data on S5 testcrosses
evaluated in 2001; bold indicates the entries derived from S5
families that were selected based on the combination of stalk rot
resistance rating and testcross performance). Yield trial results were
encouraging for some families, particularly those derived from
GOQUEEN:N1603. Poorer performance in other families may be due in part to
the public testers used, which will not give the highest potential
combining ability or the best stalk and root quality. Testing in 2003
(presuming this work is funded) will include both public and Holden’s
testers to evaluate the new inbreds in more competitive combinations.
Publications and
Presentations
None for the current
project year.
Summary of
Accomplishments
The major accomplishment
for this project to date is the development of advanced breeding lines
(nearly finished inbreds) that are showing excellent resistance to
anthracnose stalk rot. Resistance in the best of these materials is better
than that available in currently released
U.S.
inbreds. Simultaneous selection for agronomic performance has identified the
more promising fraction of these resistant selections, although only a few
breeding lines appear to be competitive with current commercial hybrids in
yield and standability. Finally, the process of anthracnose stalk rot
inoculation and selection has contributed to new understanding of the
appropriate basis for selection, by revealing that plants with little stalk
rot in the inoculated internode likely represent partial escapes rather than
truly resistant plants and should not be selected.
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Grain Yield,
Drought Tolerance, and Corn Earworm Resistance of GEM Breeding Crosses
Texas
A&M
University
Agric. Res. and
Ext.
Center,
Lubbock,
Texas
Objectives
To characterize the yield potential,
drought tolerance, and corn earworm resistance of 71 GEM breeding crosses
and to select the best germplasm for developing drought tolerant and CEW
resistant inbred lines.
Materials and Methods
Seventy-one GEM breeding crosses and three
checks (B73xMo17, Pioneer hybrids 34K77 and 3223) were grown under three
water treatments in Lubbock
in 2002. Of the 71 crosses, 44 had 25%
tropical background while 27 had 50% tropical background. Seeds were planted
on April 18. Under each water treatment, the experiment used a randomized
complete block design with three replications. Each plot consisted of one 15
foot-long row planted 40 inch apart. The stand was thinned to 26 plants per
row (22,646 plants/a). Three water treatments-well-irrigation and two severe
drought stresses (Stress 1 and Stress 2) were in the same field. During the
season, a total of 16.4, 5.2, and 7.0 acre-inch irrigation water were
respectively applied through a subsurface drip irrigation system to the
well-irrigation, Stress 1 and Stress 2. Stress 1 was originally designed to
receive 50% irrigation water of the well-irrigated block from June 21
throughout the season. Due to heavy rain in June, irrigation was withheld
from June 24 to July 28. Watering was restored on July 29 and 0.54 acre-inch
water was applied from July 29 to August 14. In Stress 2, irrigation was
withheld from June 20 to July 29 and 2.66 acre-inch water was applied from
July 29 to August 14. On July 18, 0.30 acre-inch water was applied in Stress
2 to slow down the progress of drought stress. Total precipitation from
January to August was 8.58 inches. In both Stress 1 and Stress 2, soil
drought stress occurred when most
genotypes
were at tasseling stage. Ten days after flowering, drought stress became
severer. Plants in Stress 1 experienced more severe drought stress than
those in Stress 2.
Results and Discussion
Maturity, plant height, CEW
resistance, mold, and yield under well irrigation
Maturity:
There were significant genotypic
differences for days to anthesis and silking. The average days from planting
to pollen shedding ranged from 66 (AR13026:N08a) to 83 (BG070404:D27 and
CHIS462:N08a) with a mean of 73 days. Six genotypes flowered significantly
later than P3223 (RM=116 days): BG070404:D27, BR51675:D27, CHIS462:N08a,
CUBA164:D27, CUBA84:D27, and PRICGP3:N12. None of the GEM crosses flowered
significantly earlier than P34K77 (RM=107 days).
Plant height:
Plant height ranged from 180
(UR01089:N2225) to 294 cm (CUBA84:D27) with a mean of 221 cm. Ten crosses
were much taller than Pioneer 3223 (223 cm): BG07404:D27, BR5150:N11a,
BR51675:D27, CHIS462:N08a, CUBA164:D27, CUBA84:D27, PASCO14: N04,
PRICGP3:N12, and SCRO1:N13.
Corn earworm (CEW)
resistance: The CEW penetration, an indicator of CEW resistance and
measured by CEW ear penetration from ear tip toward the ear base over ten
ears per replication, ranged from 4.0 to 11.3 cm with a mean of 7.5 cm. All
three check hybrids (B73xMo17, P34K77 and P3223) had average CEW ear
penetration. Nine crosses had a significantly lower CEW ear penetration than
the average (7.5 cm), including BG070404:D27 (4.0 cm), DK888:N11a (4.2 cm),
BR51501:N11a (4.6 cm), ANTIG03:N12 (4.8 cm), CUBA84:D27 (5.0), DKXL380:N11a
(5.1 cm), BR51675:D27 (5.2 cm), DK212T:N11a (5.2 cm), and ANTIG01:N16 (5.4
cm).
Grain molds: The average
percentage of molded kernels (mold) was 5.5% ranging from 2.7% to 11.7%. The
molds in AR01150:N0406, AR13026:N08a, AR17026:N1013, BARBGP2:N08a12,
CASH:N1407, DKB844:N11b17, DREP150:N2011d, and GOQUEEN:N16 were
significantly higher than the average. Molds were highly correlated with CEW
penetration (r=0.68**). None of the 74 entries had molds significantly below
the test mean.
Ear length: The ear
length ranged from 15.7 to 22.3 cm with a mean of 19.1 cm. The ears of 11
breeding crosses BR51403:N16, BR51675:N0620, BR52051:N04, CH05015LN1204,
CML329:N18, GOGUEEN:N16, GUAD05:N06, PRICGP3:N1211c, PRICGP3:N1218,
SCRO1:N13, and SCRO1:N1318 were significantly longer than three checks and
test mean.
Yield:
The average yield was 106.9 bu/a ranging
from 43.8 (BARBGP2:N08a12) to 172.2 bu/a (P3223). Three check hybrids P3223,
P34K77, and B73xMo17 were ranked as 1, 6, and 58 respectively. Top 10
yielding GEM breeding crosses were ANTIG01:N12, PRICGP:N1218, ANTIG01:N16,
BR51403:N16, CUBA84:D27, UR11002:N0308b, CUBA164:D27, SCRO1:N13, and
ANTIGO03:N1216. These crosses yielded 134.3 to 152.5 bu/a.
Yield and Stay Green Under
Severe Drought Stress (Stress 1):
Yield:
The average yield was 39.6 bu/a ranging from 9.3 (CHIS462:N08a) to 72.0 bu/a
(AR16026:N12). Top 10 yielding entries include AR16026:N12 (72.0),
UR11002:N0308b (70.9), BR51675:N0620 (68.3), P3223 (66.1), UR13010:N06
(63.3), P34K77 (63.2), CH05015:N1204 (59.7), CUBA110:N1712 (57.8),
CH04030:N0306 (56.9), and DKB830:N11b20 (56.5).
Stay green trait: Stay green was scored
on August 5 and August 10. The average stay green rating over two rating
dates ranged from 2.6 (CUBA84:D27) to 4.6 (B73xMo17) with a mean of
3.8. Fourteen GEM breeding crosses had stay green rating below 3.4,
significantly lower than the average and of course three checks.
Yield and
Stay Green Under Severe Drought Stress (Stress 2):
Yield: The average yield was 44.2 bu/a
ranging from 25.8 (AR17056:N13) to 92.8 bu/a (P3223). Top 10 yielding
entries include P3223, AR16026:N12, UR11002:N0308b, ANTIG03:N1216,
ANTIG03:N12, P34K77, SCROP3:N1411a, DKB830:N11b20, ANTIG01:N16, and
GUAD05:N06. Their yields were between 61.7 to 92.8 bu/a.
Stay green trait: The
average stay green rating over August 5 and August 10 was 3.1 ranging from
2.0 (CHIS462:N08a) to 4.3 (AR17026:N1013). Fifteen entries including P3223
had a rating significantly below the test mean.
Conclusion
The detailed
data are available from the GEM coordinator. Based on the results of three
water treatments, we identified top 15 GEM breeding crosses that showed good
yield potential, earworm resistance, stay green rating, grain mold
resistance, long ear, early maturity, tall plant, upright leaves, or good
husk coverage or a combination of these characters (Table 1). The top 15
crosses are ANTIG03:N12, UR11002:N0308b, AR16026:N12, ANTIG01:N16,
BG070404:D27, PRICGP3:N1218, CUBA84:D27, CUBA164:D27, ANTIG03:N1216,
CH05015:N1204, PRICGP3:N1211c, BR51501:N11a, BR51403:N16, BR51675:N0620, and
GUAD05:N06. The top ranking cross ANTIG03:N12 yielded well under irrigated
and drought stressed conditions, and had good CEW resistance, low grain
mold, good stay green trait, upright leaves, and good husk coverage.
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Use of GEM
Breeding Materials for the Development of
High-Amylose Maize Germplasm (2002 GEM
Report)
Mark Campbell, Nathan Polaski, Amanda Wood, Meghana Kunkala, Derek Lahr
Truman State University,
Division of Science
Overview and
General Objective of the Project
In the
US ,
around 50,000 acres of high-amylose corn are produced. This is processed by
various wet-mills in order to produce high-amylose starch which has a number
of food and industrial applications. High-amylose corn possesses starch
having an amylose content of greater than 50% compared to normal starch (25%
amylose). A number of discrete classifications of high-amylose corn exists
based on their specific amylose content including Amylomaize V (50-60%
amylose) and Amylomaize VII (70-80% amylose). The starch from high-amylose
corn is used in the textile industry, in gum candies, production of
biodegradable packaging material and as an adhesive in the manufacture of
corrugated cardboard. There are a number of new applications of high-amylose
starches especially because of its nuetracuetical value. Specifically it has
a low glycemic index, it serves as dietary fiber and it can be used as a
food coating to minimize fat uptake, and therefore caloric value, of fried
foods.
High-amylose corn generally yields around
60% of that observed among normal hybrids. In addition, since the
development of high amylose corn has been limited to a few breeding programs
there is an expected yield lag compared to normal corn. It has been
predicted that the volume of high-amylose corn may increase steadily in the
near future because of the number of new applications that have emerged in
the past decade and because of new applications currently being
suggested. For these reasons, it would benefit the starch industry to expand
the germplasm base for this specialty crop. The two primary benefits would
be to 1) identify new sources of modifying genes that, together with the
amylose-extender (ae) gene elevate starch amylose to 70% or greater and 2)
to incorporate GEM germplasm in order to increase genetic diversity which
may lay a better foundation for future improvements in yield and other
desirable agronomic traits.
Specific
Objectives and Results from 2002
A. Inbred Line Development
For the past several years, a number of
exotic populations obtained from the North Central Regional Plant
Introduction Station and from GEM were crossed on to a corn-belt source of
the amylose-extender (ae) mutation (OH43xH9 ae/ae). The material was
advanced to the F2 and screened for amylose content by selecting materials
having 70% amylose or greater. From this work, three sources of germplasm
were found including the populations Zia Pueblo NRC 5357, Cochiti Peublo NRC
5298 and the GEM cross GUAT209:S13. These materials were self pollinated for
a number of generations in order to develop inbred lines with a stable
amylose content of 70 percent or greater. Inbred lines grown in 2001 which
mostly represented the F5 generation of inbreeding were analyzed this past
summer and are shown in Table I. In general a number of inbreds are
displaying consistently high amylose levels. An exception would be for those
lines derived from the Zia Pueblo and Cochiti Pueblo populations. These
lines do not hold up well to inbreeding and in many cases sib-pollinations
were made within families or among families in order to advance the
seed. This may have resulted in the modifying genes not being well fixed in
this material. Efforts were made to cross these onto superior GEM germplasm
in order to preserve the high-amylose modifying genes as explained in the
next section.
B. Initiation of a Backcross Program
Using Selected GEM Lines from Public Cooperators
In order to develop germplasm having desirable
high-amylose modifiers in a high yielding background an effort was made to
begin a backcross into selected germplasm. During the summer of 2001 the
following GEM lines were obtained from Dr. Linda Pollak (USDA/ARS,
Ames, IA) to be used as recurrent
lines since they represented the highest yielding material from this project
at the time (Table II).
During the
winter of 2001/2002 the material was advanced in a winter nursery in
Puerto Rico where F1 ears (segregating F2 Kernels)
were harvested. Mutant kernels were selected from these ears and planted in
a summer breeding nursery during the 2002 growing season where plants were
self-pollinated. Grain from three selected ears per row was analyzed for
starch amylose and the data shown in Table III. From the data it appears
that high-amylose modifiers were recovered and are segregating in many of
the F2 ears from crosses with GEM lines. This indicates that further
backcrossing in these GEM lines may be possibly successful.
Although the
data are limited, the distribution of the amylose values from these crosses
suggests that the inheritance of the modifying genes may be qualitative in
nature and therefore governed by one or a few genes (Figure 1). This is
because the distribution of amylose values appears to be bi-modal in which
amylose values from samples generally are either grouped near 55% or near
70%. Future studies will be necessary to more completely describe the
inheritance of these modifiers.
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OSU Report
– GEM Annual Cooperators Meeting
Ohio State University-Ohio Agricultural
Research Development Center, Wooster,
OH
The breeding line (OSU
43-2) was approved for release by the Director of the OARDC, OSU on
March 24, 2002. Breeder’s
seed was increased by controlled full-sib pollination of the S3
in the 2002 OSU nursery. Seed from over 100 ears was bulked to form the seed
lot for distribution.
It has been released to
GEM cooperators as GEMS-0002 following the GEM protocol.
The line was selected
from the GEM FS8(A)S:S09 population. The genetic composition of the
population is estimated to be approximately 50% BSSS related, 21% tropical,
18% southeastern
U.S. ,
and 11% diverse
Corn Belt (with a high proportion of inbred
C103A). The breeding program was conducted through a collaborative effort
between OSU/OARDC, the USDA-ARS maize research group at ISU, Golden Harvest
Seeds, Inc., and through in-kind support provided by other private sector
cooperators.
Mid-silk date of the
GEMS-0002 is approximately one week earlier than that of B73 in
Ohio, and it produces moderate amounts of pollen. Plant height
is quite moderate (avg = 133.2 cm) and ear placement is slightly below
mid-plant height (avg ear height = 55.8 cm). Cob color is white and ears
generally display 12 kernel rows (average 12.5, range 10-16). Ear width is
approximately 3.8 cm (range 3.5 to 4.4 cm). Ear length is approximately 13.2
cm (range 11 to 15 cm). Kernels of GEMS-0002 are yellow to yellow-orange in
color and are slightly dented to flinty and have a 100 kernel wt. of 21.7
g. Grain protein composition is somewhat elevated (approx. 2 to 2.5 points
above B73) and average density is 1.35 g/cc. The line has not been exposed
to high levels of foliar or stalk-rotting diseases and definitive
information concerning its susceptibility to pests and diseases is
unknown. Testcross performance of OSU 43-2 (GEMS-0002) was presented in last
year’s annual report.
GEMS-002 is intended as
a breeding resource for the improvement and diversification of elite,
non-‘Lancaster Sure-Crop’ related inbreds. The line is unique in that it has
a relatively high proportion of tropical germplasm yet is able to impart
earliness to hybrids. It has potential as a source of germplasm in breeding
programs throughout much of the U.S. Corn Belt. It is recommended that it be
introduced into breeding programs by crossing with elite inbreds followed by
modified pedigree selection. Using this method, it is anticipated the
agronomic characteristics can still be improved since only one cycle of
selection has been practiced.
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Breeding Maize Lines
with Exotic Germplasm
Plant Sciences and Landscape Systems,
University of
Tennessee, Knoxville
Objective
Develop
new parental maize lines with desirable milling and grain
quality characteristics from GEM populations.
Justification
Incorporation of genes from exotic
germplasm populations for selection has the potential to produce new maize
lines that exceed the performance of those currently available for
characters such as grain quality components (milling traits, carbohydrate,
protein, and oil) and stress tolerance.
Accomplishments
1) Outstanding new lines from GEM
accessions were identified from yield trials in 2002.
2) Crosses
between 24 GEM accessions and adapted germplasm were advanced by
self-pollination and selection in 427 nursery rows.
Research Approach
Evaluate maize lines from GEM accessions in
topcross yield trials in
Tennessee. Select superior lines/populations from topcross
trials and cross these with elite adapted lines. Self-pollinate and select
in segregating populations of crosses between GEM and adapted lines.
Results
In 2002, 883 experimental
hybrids were evaluated in 15 yield trials in
Tennessee.
These hybrids were crosses
between GEM lines and adapted germplasm. Results from this single replicate
trial at
Knoxville, TN
are shown in table 1. Several experimental hybrids were competitive with
commercial check hybrids included in these trials. An experimental hybrid in
trial Wj9 yielded 50 bu/a more than the average of 8 check hybrids, and a
testcross in trial W89 produced 47 bu/a more than the check average. The
best lines from these GEM accessions will be selected for further testing
and incorporation into value-added breeding for new parental
lines. Inbreeding and selection was continued in populations resulting from
crosses between GEM lines identified in previous trials.
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Germplasm
Enhancement
of
Maize
