Germplasm Enhancement of Maize

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Martin Bohn
Mark Campbell
Marcelo Carena
Michael Clements
James Coors
Major Goodman
Jim Hawk
Bruce Hibbard
Manjit Kang
Richard Pratt
Paul Scott
Margaret Smith
Dennis West
Wenwei Xu

GEM - 2004 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.


Evaluation of Advanced GEM Lines for Multiple Insect Resistance and Fumonisin Concentration

Martin Bohn

University of Illinois, Urbana, Illinois

Project Description: The Western corn rootworm (WCR, Diabrotica virgifera virgifera LeConte) and the European corn borer (Ostrinia nubilalis Hb., ECB) are serious pests of maize in the U.S. causing estimated total costs of two billion U.S. dollars each year due to yield losses and control measures. As a result of insect feeding damage, secondary infections with other pathogens occur and reduce grain quality. Fusarium ear rots of corn, caused by Fusarium verticillioides, F. proliferatum, and F.  subglutinans are of great concern. These Fusarium species produce Fumonisin, a mycotoxin, associated with severe animal and human health disorders. The overall objective of this project is the development of maize varieties with host plant resistance against WCR and ECB as well as an improved Fusarium resistance as major components of an integrated pest management system. The specific objectives are to

  • Evaluate GEM lines for their resistance against WCR as well as first and second generation ECB,

  • Evaluate GEM lines for their resistance against Fusarium species,

  • Determine the association between insect resistance and Fumonisin concentration in GEM germplasm,

  • Study the genetic basis of insect resistance in maize against both insect species by diallel crosses and testcrosses, and

  • Initiate a recurrent selection program aimed to develop new maize lines with improved multiple insect resistant (MIR).

Germplasm Evaluation

Material and Methods: Fifteen GEM base populations, 41 inbreds derived from GEM populations AR17056:N2025 and CUBA117:S1520, as well as nine inbreds with known contrasting levels of insect resistance were evaluated for ECB and WCR resistance and Fumonisin concentration (Table 1). Three separate field trials (GEM1, GEM1-Pop, and GEM2) were conducted in adjacent fields at the Crop Sciences Research and Education Center, University of Illinois, Urbana, Illinois. The experimental design was in all cases a generalized lattice design with four replications and two-row plots for the inbred experiments (GEM1, GEM2) and four-row plots for the population experiment (GEM1-Pop). Rows were 0.75m apart and 5.3m long. Trials were over-planted and later thinned to a final plant density of 64,600 plants ha-1. Plants were manually infested with ECB larvae to ensure an even infestation level for all entries. The artificial infestation with first generation larvae (1ECB) was performed June 16 and 17, 2004 and with second generation larvae (2ECB) July 29 and 30, 2004. The manual infestation was synchronized with the natural appearance of 1ECB and 2ECB moths to simulate natural infestation. For manual infestation, egg masses were applied directly into the plant whorl (1ECB) and into the axils of the first leaf above and below the ear (2ECB). About four egg masses per plant were applied two times at two consecutive days, accounting for about 180 larvae per plant and ECB generation. In the inbred experiment all plants within the first row of a plot were artificially infested with 1ECB egg masses, whereas the second row was infested with 2ECB larvae. In the population experiment 1ECB egg masses were applied to all plants in the first row and 2ECB egg masses to all plants in the third row. The following resistance traits were determined: (1) leaf damage ratings (LDR) using a 1-9 rating scale, as defined by Guthrie and Barry (1989), and (2) stalk damage ratings (SDR) using a 1-9 rating scale, as described by Hudon and Chiang (1991). The WCR treatment was planted in a WCR trap crop area to ensure a high level of infestation. Damage to WCR larval root feeding was measured on five random plants per plot in the line experiment and on ten plants per plot in the population experiment. Root injury was assessed using the Iowa State 0-3 damage rating scale (root damage rating, RDR). The primary ear of each plant of the second row per plot of the GEM2 experiment was manually inoculated with a Fusarium suspension through the silk channel and the husks. The ears were hand harvested, dried, and the bulked seed was ground to facilitate the quantification of Fumonisin using the CD-ELISA method.

Results: The average RDR across all three experiments was 2.6. All evaluated GEM populations and GEM derived S2 families, as well as susceptible and resistant checks showed RDR values larger than 2.14 (see Table 1). For LDR and SDR significant (P > 0.01) differences among populations and between inbreds were found. In the GEM1-Pop experiment LDR means varied between 1.65 (UR10001:N1702) and 3.48 (FS8A(T):N1804). In the inbred experiments GEM1 and GEM2 LDR values ranged from 2.17 (CUBA117:S1520-41-1-B-B) to 3.73 (AR17056:N2025  Select # 2-B-B) and from 1.35 (AR17056:N2025  Select # 6-B-B) to 4.57 (AR17056:N2025-757-1-B-B-B), respectively. Across populations of the GEM1-Pop experiment, SDR means varied between 2.12 (UR10001:N1702) and 6.06 (CASH:N1410). Inbreds of experiment GEM1 showed SDR means ranging from 1.97 (CUBA117:S1520-182-1-B-B) to 5.65 (AR17056:N2025-522-1-B-B-B) and GEM2 inbreds displayed SDR means ranging from 2.63 (AR17056:N2025-566-1-B-B) to 7.00 (CUBA117:S1520-411-1-B-B). Across all experiments, the most resistant GEM derived genotypes were as resistant as the ECB resistant checks. The evaluation of Fumonisin concentrations is currently in progress.

Germplasm Development

A total of 500 S2 lines derived from ten GEM base populations were planted ear to row under trap crop enhanced natural WCR infestation. WCR resistance of each S2 line was determined using row appearance (1-5 rating scale) and the percentage of root lodged plants per row. Out of 500 rows 25 rows were selected with an acceptable appearance rating and less than ten percent root lodging. Within each row individual plants were selected and selfed. The selected S2 families were derived from GEM base populations AR17056:S1216, DKXL212:N11a01, FS8A(T):N1804, and UR10001:N1708b. The S2 lines in this program were randomly derived from the used GEM base populations. A new program was initiated to develop maize germplasm with improved WCR resistance employing a nursery under WCR trap crop. A set of 11 populations was chosen comprising ten GEM base populations and one population improved for multiple insect resistances at CIMMYT. Per population 1,000 plants were grown. In the first step, selection was performed among populations using row appearance and amount of root lodging. In a second step, non-root lodged and early individual plants were selected and selfed. Between ten and 50 individual plants were selected from populations AR16026:N1210, FS8A(S):S0907, UR13085:N0204, CUBA117:S1520, and MIRT_C5Y (CIMMYT).

Conclusions and Future Work

The growing season 2004 in East-Central Illinois was characterized by high levels of WCR infestation. For example, in experiments conducted by entomologists at the University of Illinois Bt hybrids showed a higher than expected damage caused by WCR larvae feeding (for more information see Steffy and Gray, 2004). The natural high occurrence of WCR larvae together with the trap crop enhanced field infestation resulted in high root damage ratings in our germplasm evaluations. All tested genotypes, including the resistant check and the inbreds that showed host plant resistance in the 2003 evaluation, were severely damaged. This result indicates that the available sources of host plant resistance are not yet sufficient to withstand extreme high WCR infestations. However, this high level of WCR infestation was productively used to select new GEM derived S2 lines and GEM base populations with promising levels of WCR resistance. In order to determine the association between testcross and per se performance for WCR resistance, the inbreds of experiments GEM1 and GEM2 as well as the newly selected S2 lines will be tested in the winter nursery 2004 in collaboration with Pioneer and Syngenta. This will allow the evaluation of the per se and testcross performance in the summer season of 2005.


Guthrie, W.D., and B.D. Barry. 1989. Methodologies used for screening and determining resistance in maize to the European corn borer. pp. 122-129. In CIMMYT. Toward insect resistant maize for the third world. Proc. Int. Symp. Methodologies for developing host plant resistance to maize insects. El Batan, CIMMYT, Mexico. CIMMYT, Int., CIMMYT, Mexico.

Hudon, M., and M.S. Chiang. 1991. Evaluation of resistance of maize germplasm to univoltine European corn borer Ostrinia nubilalis (Hübner) and relationship with maize maturity in Quebec. Maydica 36:69-74.

Steffy, K., and M. Gray. 2004. Transgenic Corn Rootworm Hybrid Stumbles in Urbana Experiment; Some Producers Also Report Severe Lodging with Yield Gard Rootworm Hybrids in Commercial Fields. The Bulletin, No. 22, Article 1 ( ).

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Project Title: Yield and Quality Evaluation of Amylomaize VII Test Crosses, Continued Development of Amylomaize VII Inbreds Using GEM and Related Studies

Mark Campbell, Anna O’Brien and Peter Howe

Truman State University, Division of Science, Kirksville, MO


High amylose corn generally refers to varieties having greater than 50% of its starch in the form of amylose.  There are, however, a number specific high amylose classes including amylomaize V (50% amylose) and amylomaize VII (70% amylose) which have specific applications in various food and nonfood application.  These varieties are grown mainly for wet milling and used in applications such as production of textiles, gum candies, biodegradable packaging materials and products, adhesives for manufacturing corrugated cardboard, motherboards in digital cameras, as low glycemic/high fiber food additives and other applications requiring starches that crystallize quickly.  It is typical for high amylose corn to yield only 75-80% as much as normal hybrids with lower test weights as well.  About 50,000-60,000 acres of high amylose corn were grown in the US during 2003 with most production and processing done by National Starch and Chemical Co. and Cargill.  A number of smaller independent companies are also involved in production and export.  Development of amylomaize VII corn general involves two steps.  First germplasm is converted with the recessive amylose extender (ae) allele and secondly, quantitative modifier genes must be fixed as well. Until now, most, if not all amylomaize VII germplasm is owned privately.  The only public source, as far as we know, is at Truman State University in which amylomaize VII germplasm as been developed almost entirely using GEM (Germplasm Enhancement of Maize) germplasm or from exotic plant introductions.

General Objectives

The general objective of the Truman plant breeding project is towards the development of amylomaize VII hybrids.  This has involved identification of high amylose modifying genes from three sources including NRC 5357 Zia Pueblo, Cochiti Pueblo NRC 5298 and the GEM source GUAT209:S13, transferring these high amylose modifying genes to GEM lines previously identified as having high yield potential from other GEM cooperators and evaluating of Truman’s amylomaize VII GEM line as hybrids using proprietary amylomaize testers.  A review of the general protocol is outlined in Figure 1.  In addition to field data, the protocol requires a great deal of laboratory starch analysis to monitor the presence of high amylose modifying genes.

Specific objectives from the 2004 GEM SCA

  1. During the summer of 2004 yield evaluations and grain analyses of GEM amylomaize VII testcrosses will be made. 

  2. Additional testcrossing of new GEM-Amylomaize VII lines will be made onto proprietary amylomaize VII testers. 

  3. Continued line development from GEM x amylomaize VII crosses (i.e. recovering ae allele following crossing, identify high-amylose modifiers from laboratory data, etc…) will be accomplished.

  4. Development and evaluation of DSC, NITS and NMR methods for rapid determination of starch properties including structure and content in grain will be made.

Progress on 2004 objectives

Hybrid Evaluation

Table 1 shows results of yield evaluations of test hybrids at two locations including one at Ames Iowa and another at the University of Missouri’s Greenley Memorial Research Center near Novelty, MO.  In addition, a location was planted at Kirksville Missouri in which yield data is not yet available for analysis but will be eventually made.  Also, self pollinations were made in the third rep at the Kirksville location for grain analysis.  We are currently collecting amylose data and total starch and this data will be eventually made available to GEM cooperators.  Some of the F1 seed was analyzed for amylose last spring (2004) prior to planting in order to determine if the amylomaize VII GEM lines and the proprietary amylomaize VII tester would produce amylomaize VII seed.  In many cases amylomaize VII was found however there were some exceptions. Yield data of GEM hybrids was promising.  In most cases, GEM hybrids out yielded the proprietary amylomaize VII (70% amylose) check.  The best crosses were those between non-stiff stalk amylomaize GEM lines and the proprietary stiff stalk tester (n x s).  Some of the GEM lines that are designated as S may also contain some percentage of non-stiff stalk background coming from the ae donors.  This may explain why the S x S type crosses yielded relatively well in some cases

GEM amylomaize line development: 

A number of F3 ears initially evaluated in 2002 as possessing amylomaize VII starch were evaluated in the F4 generation.  This material contains either 50% or 75% GEM germplasm depending on the source of the high amylose modifying genes. Figure 2 (hopfully) will explain the pedigree naming system.

Table 2 shows amylose values determined from F4 ears.  In many cases the F4 ears continue to display the amylomaize VII phenotype, however, in many cases it did not.  This helps to demonstrate that the need for continued amylose screening needs to be done for several generations in order to confidently fix the trait.

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EarlyGEM’: Incorporating GEM Elite Lines in Early Maize

M. J. Carena

Department of Plant Sciences, North Dakota State University

Maize Breeding Program


This report serves to document research conducted under a specific cooperative agreement between ARS and North Dakota State University (NDSU). Additional details of research can be found in the report for the parent project 4296-5050-1510 ‘EarlyGEM: Incorporating GEM Elite Lines in Early Maize’. This project relates to the primary objective of the parent project that includes the evaluation of GEM lines once incorporated in early maize background for grain yield and agronomic performance. We participate in the efforts to broaden the germplasm base of maize. Our research will determine the usefulness of GEM material in the northern Corn Belt. We have defined ‘EarlyGEM’ as the long-term and continuous effort to incorporate GEM elite germplasm into the northern Corn Belt.


General Objective:         Determine the suitability of 25% GEM backcross lines for use as grain hybrids in the northern Corn Belt

Specific Objectives:    1) Obtain 25% GEM genotypes adapted to North Dakota (Phase I already accomplished)
2) Topcross BSSS GEM genotypes (BC1:S2) to a commercial tester and evaluate them across northern environments (Phase II)
3) Identify and incorporate top genotypes into our inbred line development program (Phase III)
                                    4) Determine their potential for release (Phase IV)


NDSU has been an active cooperator with the GEM project since 2000, and the objective was to  initially evaluate and identify GEM lines for adaptation to the northern Corn Belt. The program started with the evaluation of 152 GEM (A, B, and C) released lines for fifteen adaptation traits in 2001. The most adapted (based on agronomic data in Fargo, ND) and top yielding genotypes (based on GEM data accumulated during 1999, 2000, and 2001) were selected and crossed to North Dakota inbred lines ND2000 (released in 2002) and ND99-16 (unreleased) in 2002. Twenty-two GEM genotypes were planted ear-to-row with North Dakota lines in our 2002-breeding nursery. Three different planting dates were used for our lines. Selection within original GEM lines was performed not only for earliness but also for disease resistance and other visual traits we could identify while making crosses. Only the best plants were selected for crossing. Stiff Stalk donors (CUBA117:S1520-388-1-B or GEM3 in our designation, CHIS775:S1911b-B-B or GEM13, CUBA117:S15-372-1 or GEM12, and AR16026:S17-66-1-B or GEM21) were identified for backcrossing in 2003.

Sixty-two rows were planted in 2003 breeding nursery in order to produce BC1 populations. F1s were planted side by side with the recurrent parent (early adapted ND lines). We have discarded later-flowering plants and harvested each BC1 plant from each cross separately. ND99-16 crosses were discarded since their F1s were at least 5 days later than F1s involving ND2000. Other F1s were discarded based on agronomic deficiencies (poor stands, low seedling vigor under cold stress, drought stress, lodging, insect and disease susceptibility, height, and relative maturity). GEM13 x ND2000 showed good adaptation based upon its height and flowering time (67 days after planting). However, F1 plants were not uniform and seedling vigor was below average. GEM12 was also discarded based on poor agronomic traits in the hybrids. The range of ears produced per population was 8-26.

Updated Summary/Discussion

Sixty seeds from each BC1:S0 ear were planted in 2004 breeding nursery on May 7. We decided to make a second round of screening for additional BC1:S0 generations obtained with ND2000 as recurrent parent. Therefore, 182 rows were self-pollinated to obtain 8-10 ears from early and intermediate plants per row. The target was to obtained 100 BC1:S1 ears per population. Rows were screened for seedling vigor (0-9 scale) and checked for uniformity. Plants with below average agronomic characteristics were discarded. Ears were hand-harvested in October 2004. Shelling of individual BC1:S1 lines was performed in November 2004.

GEM S1 selections will be planted across three locations for early generation visual selection in 2005. These locations will include breeding and disease nurseries. S1 selections will be advanced to elite S2 materials and S2 seed from top selected S1 selections will be crossed to LH176xLH177 private tester in the 2005-2006 winter nursery if funds are available or 2006 summer nursery. GEM topcrosses (< 90RM) will be evaluated for grain yield, grain moisture at harvest, root lodging, stalk lodging, test weight, and days to flowering at 6 ND environments. GEM trials will be arranged in simple lattice designs. Target planting densities will be 30,000 plants/acre under dry land conditions and 35,000 plants/acre under irrigated conditions. Based on the results of these early generation trials we will testcross elite S3 families from top breeding populations for evaluation using two testers. S3 families will be advanced and checked for uniformity. Late generation single-cross trials will be conducted with elite S4-S5 lines using at least four testers in order to evaluate their potential as new releases from the NDSU EarlyGEM project.


Late-temperate and tropical derived maize germplasm are adapted to North Dakota based on the efforts involved in this project. BC1:S1 lines were 0 to 6 days earlier than the recurrent parent ND2000. This is the first research devoted to germplasm enhancement with tropical material in the northern Corn Belt.

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Evaluation of maize accessions for resistance to Aspergillus ear rot, aflatoxin accumulation in grain, and leaf feeding by Southwestern corn borer

Clements, M.J.1., Windham G.H.1., Williams, W.P.1.,

Maragos, C.M.2., Blanco, M.H.3., and Goodman, M.M.4.

1.USDA-ARS Corn Host Plant Resistance Research Unit, Mississippi State, MS; 2.USDA-ARS Mycotoxin Research Unit, Peoria, IL; 3.USDA-ARS Plant Introduction, Ames, IA; 4.North Carolina State University, Department of Genetics, Raleigh, NC.


BACKGROUND.  Aflatoxin accumulation in corn (Zea mays L.) grain is a concern within U.S. grain markets, and damage from southwestern corn borer (SWCB) (Diatraea grandiosella Dyar) causes economic losses for grain producers in the southern U.S every year.  Inbred sources that contribute genetic resistance to disease and insects, tolerance to environmental stress, and superior agronomics (i.e., standability and yield) to hybrid performance are needed in the southern U.S.

OBJECTIVE.  Assess GEM lines and GEM breeding crosses for resistance to aflatoxin accumulation in grain, resistance to Aspergillus ear rot, resistance to leaf feeding by southwestern corn borer (SWCB), and for agronomic characteristics that are suitable for inbred and hybrid development in the southern U.S. 


EXPERIMENTSSeed for all experiments were planted at Mississippi State, MS.  Experiments were designed as randomized complete blocks with three replicates per year.  Experimental units consisted of one row of each genotype.  Rows were approximately 4 meters in length (±0.5 meter fallow alley), spaced 1 meter apart, and included a maximum of 21 plants.  Primary ears on all plants in trials evaluated for aflatoxin accumulation in grain were inoculated with a propagule suspension of Aspergillus flavus Link:Fr.  Three-point-four milliliters of the propagule suspension (1 x 106 propagules ml-1) were injected through husk leaves into the side of the primary ear on all plants at the R2 (blister) growth stage.  Thirty first-instar SWCB larvae mixed with corn cob grit were distributed in the whorl of all plants of the GEM line SWCB evaluation with volumetric applicators.  Plants were infested at approximately V5 (five true leaves with collars) growth stage and rated for leaf feeding damage 14 days thereafter.

GEM line aflatoxin evaluation. Seed of 87 GEM lines were planted in 2003 and 2004.  Seed of an additional 40 GEM lines were included with the trial in 2004.  Three resistant genotypes (Mp313E, Mp715, and Tuxpan), two susceptible genotypes (T173 and NC258), and four additional genotypes (NC320, Ph9, NC298, and NC300) were included for comparison in both years. 

GEM line SWCB evaluation.   Seed of 127 GEM lines and 9 check genotypes planted in the GEM line aflatoxin evaluation in 2004 were planted in an adjacent trial in 2004.  Six additional genotypes know for resistance (Mp707 and Mp716) or susceptibility (Mp704, Mp708, Ab24E, and SC229) to leaf feeding damage from SWCB were included for comparison.

GEM breeding cross aflatoxin evaluation. Seed of 19 GEM breeding crosses were planted in 2003 and 2004.  Seed of an additional 10 GEM breeding crosses were included with the trial in 2004.  Two resistant genotypes, Mo18W x Mp313E and MP716 x Mp92:673, and two susceptible genotypes, Mp305 x Mp714 and Mp339 x SC212M, were included for comparison in both years, with the exception that MP715 x Mp92:673 was substituted for Mp716 x Mp92:673 as one of the resistant genotypes in 2004. 

GEM testcross aflatoxin evaluation. Seed developed from crosses of 64 GEM lines with one of 3 testers (LH283, hybrid LH132 x LH195, or hybrid FR992 x FR1064), were planted in 2003 and 2004.  Seed developed from crosses of an additional 9 GEM lines with testers LH185 or LH198 were included with the trial in 2004.  Nine testcrosses of GEM lines evaluated in 2003 were not available for evaluation in 2004.


  • Aflatoxin concentration in grain (only 2003 data available as of this report)

  • Severity of Aspergillus ear rot (2003-2004)

  • Severity of leaf feeding damage from SWCB (2004)

  • Maturity (2003-2004)

  • Plant and ear height and percent of main stalk from soil line to the ear (PME) (2003)

  • Kernel and cob color (2003-2004, data not shown),

  • Percent harvestable ears (from a maximum of 21 plants) (2003-2004)

  • Grain weight per ear (2003-2004, or 2004 only)

  • Grain quality (2004)

STATISTICAL ANALYSES.  Data were analyzed with analysis of variance (ANOVA) using the general linear models procedure of Statistical Analysis System software (SAS Institute, NC).  Aflatoxin concentration in grain was transformed to the natural log of the quantity (0.1 + ng aflatoxin g-1 ground corn) to normalize residuals.  Aflatoxin concentration is presented as geometric means (antilogarithm of logarithmic means – 0.1).  Environments and replicates were considered random terms in analyses, while genotypes were considered fixed.  Differences between genotypes were compared with Fisher’s protected least significant difference test (LSD) for all traits except aflatoxin concentration in grain and kernel and cob color.  Differences between genotypes were compared with the least significant ratio (LSR) on geometric means for aflatoxin concentration.


GEM line aflatoxin evaluation.  Aflatoxin concentration in grain was not affected significantly by replicates (P= 0.2392), but was affected significantly by genotypes (P<0.0001) in 2003.  Treatment means for aflatoxin concentration in grain among GEM lines and experimental checks ranged from 9 to 2147 ng g-1 (mean 546 ng g-1) (Table 1).  Aflatoxin concentration was least from the resistant check, Mp313E.  Aflatoxin concentration from another resistant check, Tuxpan, and four GEM lines (coded as lines 1 through 4 for this report) did not differ significantly (P>0.05) from Mp313E.  All four of these lines had Aspergillus ear rot severity that did not differ significantly (P>0.05) from the resistant check, Mp313E, in 2003 and 2004.  These four lines were developed in Raleigh, NC, and are 50% exotic crossed to a private stiff-stalk line.  Although line 1 matured significantly (P<0.05) later than the other three lines in 2003 and 2004, all four lines have agronomic characteristics that are acceptable for environments in the southern U.S.  GEM line 2 had percent harvestable ears that did not differ significantly (P>0.05) from greatest percent harvestable ears in 2003 or 2004.  GEM lines 3 and 4 had percent harvestable ears that did not differ significantly (P>0.05) from greatest percent harvestable ears in 2004 only.  Additionally, GEM line 4 had grain weight per ear that did not differ significantly (P>0.05) from greatest grain weight per ear in 2004.

Grain weight per ear was affected significantly by replicates (P<0.0001) and genotypes (P<0.0001) in 2004.  Treatment means for grain weight per ear from GEM lines and experimental checks ranged from 20 to 90 grams (mean 46 grams).  Grain weight per ear was greatest from GEM line 125.  Grain weight per ear from three other GEM lines (17, 18, and 110) did not differ significantly from line 125.  Line 17 has a stiff-stalk genetic background, while lines 18, 110, and 125 have non-stiff stalk genetic backgrounds.

Grain quality was affected significantly by replicates (P<0.0001) and genotypes (P<0.0001) in 2004.  Treatment means for grain quality from GEM lines and experimental checks ranged from 1 to 5 (mean 3), with 1 being poor grain quality and 5 being excellent grain quality.  Grain quality was greatest for GEM lines 18, 28, 39, 40, and 53.  Grain quality did not differ significantly among lines with greatest grain quality, 32 other GEM lines, and two check genotypes (Tuxpan and Ph9).

GEM line SWCB evaluation.  Leaf feeding damage by SWCB larvae was not affected significantly by replicates (P=0.4410), but was affected significantly by genotypes (P<0.0001) in 2004.  Leaf feeding damage ranged from 3 to 9 (mean 8) (Table 1), with 0 being no visible damage and 9 being severe damage.  Leaf feeding damage was least on the resistant check, Mp716.  Leaf feeding damage from another resistant check, Mp707, did not differ significantly from Mp716.  Leaf feeding damage from SWCB on all GEM lines did not differ significantly from, or was greater than, damage on susceptible checks Mp704, Mp708, Ab24E, and SC229.

GEM breeding cross evaluation.  Aflatoxin concentration in grain was not affected significantly by replicates (P=0.4784), but was affected significantly by genotypes (P=0.0002) in 2003.  Treatment means for aflatoxin concentration in grain among GEM breeding crosses and experimental checks ranged from 38 to 1087 ng g-1 (mean 440 ng g-1) (Table 2).  Aflatoxin concentration was least from the resistant check, hybrid Mp313E x Mo18W.  Aflatoxin concentration in grain from five breeding crosses (CUBA84:D27, BG070404:D27, ANTIG01:N16, CUBA164:D27, and BR51403:N16) did not differ significantly (P>0.05) from Mp313E x Mo18W.  All five of these breeding crosses had severity of Aspergillus ear rot that did not differ significantly (P>0.05) from Mp313E x Mo18W in 2003 and 2004.  Genotypes did not differ significantly for grain weight per ear (P=0.1885, mean 127 grams) in 2003; however, four of five breeding crosses associated with least aflatoxin concentration in grain (CUBA84:D27, BR51403:N16, ANTIG01:N16, and CUBA164:D27) had grain weight per ear that did not differ significantly (P>0.05) from greatest grain weight per ear in 2004.  Although one breeding cross, CUBA164:D27, matured significantly (P>0.05) later than the experimental mean in 2003 and 2004, all five of these breeding crosses have maturities that are acceptable for the southern U.S.  Of note, three of these five breeding crosses were developed with a private inbred coded as D27.  Genotypes did not differ significantly for percent harvestable ears (P=0.3078, mean 66%) in 2003 and 2004.

GEM testcross evaluation.  Aflatoxin concentration in grain among all testcrosses of GEM lines and experimental checks ranged from 38 to 920 ng g-1.  Aflatoxin concentration was least from the resistant check, Mp313E x Mo18W.  Aflatoxin concentration in grain differed significantly (P=0.0131) among testcrosses developed with GEM lines and FR992 x FR1064 (Table 3), but not among testcrosses developed with GEM lines and LH283 (P=0.2023, mean 303 ng g-1, data not shown) or LH132 x LH195 (P=0.1695, mean 274 ng g-1, data not shown).  Aflatoxin concentration did not differ significantly (P>0.05) between Mp313E x Mo18W and GEM testcrosses [(7541-10DKXL380N11 F2S2) x (FR992 x FR1064)] and [(Cr1-239PE_1_N16 F2S3) x (FR992 x FR1064)].  GEM testcrosses developed with FR992 x FR1064 did not differ significantly for severity of Aspergillus ear rot (P=0.1540, mean 7% of the ear with symptoms) or for grain weight per ear (P=0.2449, mean 140g), however, these testcrosses did differ significantly for maturity (P < 0.0001).  GEM testcrosses [(7541-10DKXL380N11 F2S2) x (FR992 x FR1064)] and [(Cr1-239PE_1_N16 F2S3) x (FR992 x FR1064)] matured relatively early (1388 to 1409 MGDU50) for environments in the southern U.S.


GEM lines in this study will be evaluated for agronomic characteristics and resistance to aflatoxin accumulation in grain as testcrosses developed with commercial inbreds Holden’s LH195 and LH210 in 2005.  Ear to row and recurrent selection programs are currently underway with several of the most promising lines and breeding crosses.

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Development of Inbreds, Hybrids, and Enhanced GEM Breeding Populations with Superior Silage Yield and Nutritional Value

James G. Coors, Dustin T. Eilert, Patrick J. Flannery

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. 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.

In 2004 we continued to evaluate silage yield and nutritive value of the most productive GEM topcrosses identified in grain yield evaluations conducted over the past several years by the GEM project. These hybrids are chosen annually based on maturity and 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. The 2004 trials include a combination of new GEM topcrosses and advanced-generation inbred testing of GEM materials evaluated in previous years.

2004 Field Trials

GEMNEW consisted of the silage evaluation of elite GEM topcrosses that were identified in the past year as having high grain yield and suitable maturity (<120RM) for Wisconsin. GEMNEW included 17 breeding populations or early-generation GEM inbreds topcrossed to LH185, LH198, LH200, LH244, or LH287, as well as four population crosses involving WQS C2, and several hybrid checks.

GEMADV consisted of promising S4+ GEM lines from breeding populations ARZM 17026:N1019, URZM13085:N0204, and SCRO1:N1310 crossed to HC33, LH198, LH227, and/or LH244. The inbreds involved in the GEMADV trial were developed by the UW silage breeding program and were chosen based on topcross silage evaluations in previous years.

GEM198 consisted of 48 promising S3+ GEM families crossed to LH198. The trial consisted of testcrosses involving 22 S5 families derived from CHO5015:N15-8-1-B-B and 26 S3 families derived from DKXL370:N11a20-97-1. All 48 families were the same as those appearing in GEM244.

GEM244 consisted of 49 promising S3+ GEM lines crossed to LH244. The trial consisted of testcrosses involving 23 S5 families derived from CHO5015:N15-8-1-B-B and 26 S3 families derived from DKXL370:N11a20-97-1. Forty-eight families were the same as those appearing in GEM198.

All four trials were planted at two WI locations, Madison (May 7) and Arlington (June 3), with three replications at each location for GEMNEW and GEMADV, and two replications at each location for GEM198 and GEM244. The average planting densities ranged from 31,000 to 34,000 plants/acre. Temperatures were relatively cool throughout the season until late August and September, but the plots were in excellent condition at harvest. The Madison trials were harvested in late September. The Arlington trial was harvested in mid October, after the first frost. For a detailed description of these trials see

Due to the late harvest dates, nutritional evaluations are not yet completed for these trials. Reported herein are forage yield and dry matter summaries for all four trials. Nutritional evaluation will be completed in approximately one month and the results posted on our web site.

GEMNEW highlights:  Of the 17 new GEM topcrosses, the forage yield of 7 exceeded 9 tons/acre, which was the cutoff for quality evaluation (Table 1). Two of these (FS8B(T):N11a-322-1  X LH198 and DK212T:S11 F2S4 2111-01  X LH185) had relatively high forage yield and high % dry matter that were equivalent to the hybrid checks indicating that they were well adapted to Wisconsin conditions. A third testcross (AR17056:N2035-421-1 X LH244), while somewhat later maturing than desired, had excellent forage yield.

GEMADV highlights:  There are a large number of topcrosses in GEMADV that have considerable potential. One hybrid in particular, AR17026:N1019-65008-2-3-2-1-1 X LH244, had the highest mean forage yield in the trial. A related hybrid, AR17026:N1019-65008-2-3-2-1-1 X LH227 was entered in the 2004 UW corn performance trials conducted by the UW Corn Extension program, and both yield and quality analyses have been completed. In the southern zone (Arlington, Lancaster) late-maturity trial with a total of 42 hybrids, the forage yield of AR17026:N1019-65008-2-3-2-1 X LH227 was statistically equivalent to the best hybrid in the trial, and the predicted milk/acre was the highest in the trial (38,800 lbs/acre). This topcross is designated “UW EX01” in the 2004 UW Corn Extension report, which can be accessed via We had similar results for AR17026:N1019-65008-2-3-2-1 X HC33 in 2003. We will formally initiate release of AR17026:N1019-65008-2-3-2-1-1 in December.

In 2004 we increased seed quantities for crosses of AR17026:N1019-65008-2-3-2-1-1 with HC33, LH198, LH244, LH332, and TR7245 so that those interested can evaluate this GEM inbred in multiple testcrosses.

GEM198 and GEM244 highlights:  The combined performance of the 48 LH198 and LH244 topcrosses is presented in Table 3. Most of the CHO5015:N15 topcrosses were discarded based on low forage yield. Most of the DKXL370:N11a20 families had excellent yield potential but need re-evaluation as topcrosses to earlier maturing testers. Twenty-five of the 26 DKXL370:N11a20 topcrosses are currently undergoing nutritional evaluation.

2004 Nursery Activities:

In 2004, we continued our new breeding effort for the GEM Quality Synthetic (GQS), developed from GEM breeding populations CUBA164:S1517, CUBA164:S15, and CUBA117:S1520. Since GQS is approximately 75% Stiff Stalk, inbred lines from GQS may well produce silage hybrids with high forage yield as well as superior nutritional quality when crossed to inbred lines from our Wisconsin Quality Synthetic, which is a non-Stiff Stalk breeding population. We will continue breeding GQS using the same S2-topcross system used for WQS. We are currently developing approximately 300 S1 families from GQS during the 2004/5 winter nursery. These will be visually screened in the summer of 2005 and S2 families topcrossed to a non-Stiff Stalk tester in the 2005/6 winter nursery.

In our inbred breeding nursery in 2004, we made additional self-pollinations and selection for 382 advanced families derived from breeding crosses CUBA164:S1517, CUBA164:S2012, CUBA117:S1520, BR52051:N04, CHIS775:S1911b, CHO5015:N15, DKXL370:N11a20, AR17026:N1019, UR13085:N0204, and SCRO1:N1310.

Approximately 130 advanced-generation inbreds from breeding populations CHIS775:S1911b, CUBA164:S1517, CUBA164:S2012, and CUBA117:S1520 were crossed to two testers, LH287 and LH279. Thirty-two advanced generation inbreds from breeding populations BR52051:N04 and ARZM 17026:N1019 were crossed to HC33 and LH198. These testcrosses will be evaluated in 2005.

For additional information, all activities of the UW silage breeding program, including nurseries and yield trials, are available through our web site (

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Raleigh, NC, November 2004 Progress Report

Major Goodman

North Carolina State University

This report summarizes the research conducted under specific cooperative agreements between the ARS and N.C. State University. Additional details will be reported at the December, 2004, cooperators meeting and the December, 2004, TSG meeting.  This subproject is concerned with nine aspects of the overall GEM effort. (1) The development of GEM families from Breeding Crosses. (2) Making topcross seed of the families. (3) Setting up appropriate experiments to compare the topcross families with commercial and experimental checks. (4) Providing seed for these experiments to 15 additional GEM collaborators. (5) Growing the experiments ourselves at several locations. (6) Analyzing and summarizing our own and our collaborators data. (7) Selecting the better materials for subsequent-year trials. (8) Conducting GLS tests on the more advanced materials. (9) Increasing seed of better families, providing it to Ames and other GEM cooperators and to the NCRPIS.

Tables 1 and 2 attached report the results for advanced trials (2nd-year and 2nd-tester) with more promising entries that were grown both by us (2 replications, five locations) and by our cooperators (one replication per location).  Table 3 presents the plot totals for cooperative yield trials coordinated by N.C. State in 2004 (totaling 14,506 plots, of which 6,342 were at N.C. State locations) and Table 4 presents the GEM trials grown only by N.C. State (6,912 plots).  The latter mostly represent trials of advanced inbred lines from GEM materials, but one experiment, K8 in Table 5, represents a direct yield trial of GEM Breeding Crosses.  A similar trial in 2003 revealed a very great spread in yield potential among Breeding Crosses and greatly influenced our choices of materials for nursery work in 2004. From two-years' of direct yield-trials of Breeding Crosses the following looked best (rank order):

1. PE11:S11a (BR51501) 2. CL‑00331:N18 3. FS8B(S):S03
4. BR105:S16 5. DKB830:S19 6. FS8B(T):N11a
7. RN07:S20 (BR51721) 8. SE32:N11c (BR52051) 9. PASCO14:S11a 
10. GUAT209:N11c  11. CML329:N18 12. BG070404:D27
13. PE27:D27 (BR51675) 14. CUBA84:D27 15. PE01:S02
16. RN07:N20 17. CUBA164:D27 18. MDI022:N21
19. FS8B(T):N18 20. SCR0GP3:N20 21. CL‑G1607:S18


Perhaps most important, the following were identified as likely being of very low priority (ranked from worst to merely bad):

1. CML325:N13 2. CHIS462:N08a 3. CML247:N17a
4. CML247:N18 5. CUBA117:S15 6. CML247:N17b
7. SANM126:S12 8. DK888:S08a 9. FS8B(S):S17b
10. DKXL370:S08a 11. GUAD05:N06 12. MDI022:S21
13. DKXL380:S08a 14. NEI9008:S17a 15. CML247:N17c
16. CML323:S17a 17. NEI9008:S17b 18. CHIS740:S14
19. CML323:S17b 20. NEI9008:S17c 21. NEI9008:N08
22. CML287:N13 23. DKXL370:S08c 24. CL‑G1501:S17b
25. PASCO14:S21 26. NEI9004:S28  

The total number of GEM yield trial plots coordinated or conducted by N.C. State in 2004 is 21,418, with 13,254 actually grown by N.C. State.

In 2004, over 1250 GEM rows were grown in the regular nursery, an additional 850+ were grown in isos (700 early-generation materials, 150 inbreds).  Nursery work involves 17 new Breeding Crosses (populations that have not previously been tested in any form).

GEM topcrosses were grown at 2 locations (525 plots) for GLS ratings.  In addition to the GEM work described above, we have been testing potential new, more modern testers for the past two years.  We are reasonably happy with our Stiff Stalk tester, FR992.FR1064, with LH132.LH195 as alternate.  However, we would like to replace FR615.FR697 as our non-Stiff Stalk tester, and midwestern favorites like LH185 and LH287 will not work in the South.  We sent Experiment A1 (which involves testers under current consideration) to several of our more northern cooperators this year, but none of the alternate testers were better than FR615.FR697.  We did identify TR7322.NC320 as an acceptable alternative.

Finally, we have begun routine screening of available tropical lines, as so little data are available to choose among them for use in GEM or other research.  A summary of that work is to be submitted as an invited article for the 50th anniversary issue of Maydica and will be discussed at the December, 2004 meetings.


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Inbred Line Development and Hybrid Evaluation in GEM Breeding Crosses

James A. Hawk and Tecle Weldekidan

Department of Plant and Soil Sciences

University of Delaware


Identify GEM breeding crosses and lines with desirable agronomic characteristics, resistance to abiotic and biotic stresses, and high, consistent yield performance.

Materials and Methods:

One hundred seventy three GEM breeding crosses were evaluated for adaptability, maturity, flowering synchrony, standability, plant and ear height, pest resistance, stay green, grain quality, and drydown. Inbreeding was also initiated on ten new Stiff Stalk and two non-Stiff Stalk GEM breeding crosses. Four hundred plants per population were selfed. S1 ears were harvested from selected plants based on agronomic traits, disease and European corn borer (ECB) resistance. Eight hundred thirty-nine S1 families, derived from seven Stiff Stalk and five non-Stiff Stalk GEM breeding crosses, were self-pollinated. Two breeding crosses (one Stiff Stalk and one non-Stiff Stalk) were grown to initiate a breeding methodology study comparing the GEM protocol, mass selection, and a modified single seed descent procedure. Yield tests were conducted on 235 Stiff Stalk lines crossed to LH185 and/or a Pioneer non-Stiff Stalk tester and 103 non-Stiff Stalk lines crossed to a Pioneer Stiff Stalk tester at two irrigated and one dryland locations in Delaware (two reps/location), one location (one rep) at Ames, Iowa and one location (one rep) at Mt Vernon/Fort Branch, Indiana. The lines were also advanced and evaluated per se for agronomic performance.


The GEM breeding crosses recommended for line development will be summarized by the GEM coordinator based on performance at Delaware, Iowa, and Illinois.

Based on per se evaluations for plant height, ear placement, stalk and root strength, ear traits, maturity, disease and ECB resistance, 873 S1 selections were made from 10 Stiff Stalk and 198 S1 from 2 non-Stiff Stalk breeding crosses (Table 1).

Using the GEM breeding protocol, 250 S1 ears were kept from each breeding population. With the mass selection method, 160 S1 ears were selected from each population based on stalk and root strength, plant height, ear placement, maturity, grain drydown, grain quality, and disease and European corn borer (ECB) resistance. For the modified single seed descent method, three kernels were bulked from each of the 160 S1 ears (from the mass selection method) and will be advanced to S 2’s in a winter nursery.

Four hundred seventy S2 ears were selected from 286 of the 651 Stiff Stalk S1 families evaluated, and 166 S2 ears from 102 of the 188 non-Stiff Stalk S1 families (Table 2). A higher percentage of selections were made from the following breeding crosses: AR01150:S0121, DKXL212:S0912, AR03056:N1625, BR51721:N2012 and DK212T:N11a10.

Yield test results are listed in (Tables 3-12). The top 10-20% lines will be advanced. S2 lines from selected breeding crosses will be testcrossed and hybrid evaluations will be conducted summer 2005. 


Hawk, J.A., Weldekidan, T., and Frey, T.J. 2004. Utilization of exotic germplasm for improving agronomic, disease resistance, and grain quality traits in Corn Belt maize.  Ninth Interregional Corn Improvement Conference, St Louis, MO.

Acknowledgements: We thank the USDA-GEM Project at Iowa State and Mycogen Seed for collaboration in conducting yield trials and Holden Foundation Seeds, Inc. and Pioneer Hi-Bred Int. Inc. for making testcrosses.


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Breeding for Corn Rootworm Resistance in Maize

Bruce E. Hibbard

USDA-ARS, Columbia, Missouri

General Objective:  To develop elite populations useful for derivation of corn rootworm resistant lines and to serve as the basis for future molecular genetics research on the dissection of the basis of corn rootworm resistance.

Approach:  In 2003, 12 GEM populations were evaluated for resistance to corn rootworm larval feeding.  Based upon feeding damage and other agronomic characters, we brought 4 of these populations, UR13085:N0215 (4 families), CHIS775:N1912 (14 families), DK212T:S11 (10 families), and BR52051:N04 (7 families) to our winter nursery and self pollinated in the winter of 2003-4. 

In 2004, we evaluated 37 S1 ears from the four families of UR13085:N0215, 128 S1 ears of the 14 families of CHIS775:N1912, 80 S1 ears of the 10 families of DK212T:S11, and 84 S1 ears of the 7 families of BR52051:N04.  Each ear was evaluated in three replications for corn rootworm damage along with checks.  Selected ears for UR13085:N0215 (9/37), CHIS775:N1912 (19/128), DK212T:S11 (14/80), and BR52051:N04 (15/84) were bulk random mated.  Those lines with the least damage were also selfed toward the development of inbred lines.

Materials and Methods:   Cultivars were planted in a randomized complete block design with 9 kernels planted in a 1.8 m plot, each replicated three times.  The University of Missouri South Poultry Farm, approximately 1.6 km east of Columbia, MO was used for experiments.  A trap crop of corn of varying maturities was planted the previous year.  Conventional herbicide and fertilizer regimes for Missouri growing conditions (atrazine @ 1.3 lb ai/acre and metolachlor @ 0.8 q ai/acre) were used.  All plots were mechanically infested with western corn rootworm eggs.  Eggs were placed in 0.15% agar suspension and applied at a rate of 600 viable eggs per 0.3 m of corn row using equipment modified after Sutter and Branson (1980).  Eggs used in the experiment were supplied from the USDA-ARS Brookings, SD laboratory.  Plots were planted on May 10, infested on May 21, when seedlings were approximately at the two-leaf stage (Hibbard et al. 1999).  On July 6, when maximum damage had occurred (when approximately two-thirds of the western corn rootworm larvae had pupated in infested border rows), plots were dug (Praiswater et al. 1997), and four roots from each plot (the average for which was considered one replication) were removed.  Roots were washed and rated using a linear scale (0 to 3) based upon the number of nodes pruned (Oleson et al. 2005).  The data were analyzed with proc GLM in SAS followed by a Fisher’s Least Significant Difference numerical range test. 

Results:  The combination of natural infestation from the trap crop and manual infestation provided an extremely high level of corn rootworm pressure at the University of Missouri South Poultry Farm in 2004.  Overall, the level of corn rootworm damage exceeded that which was desired with control roots (nearly 2.5 nodes of damage).  Average corn rootworm damage ratings from 329 S1 ears are presented in Table 1.  The DK212T:S11 population had the highest proportion of roots with damage less than the susceptible control.  Each of the other populations also had plants with reduced damage compared to the susceptible control.  Selected entries within each population were bulk random mated.  Those lines with the least damage were also selfed toward the development of inbred lines.

References Cited

  • Hibbard, B.E., B.D. Barry,  L.L. Darrah, J.J. Jackson, L.D. Chandler, L.K. French, and J.A. Mihm. 1999. Controlled field infestations with western corn rootworm (Coleoptera: Chrysomelidae) eggs in Missouri: Effects of egg strains, infestation dates, and infestation levels on corn root damage.  J. Kans. Entomol. 72: 214-221.

  • Praiswater, T. W., B.E. Hibbard, B. D. Barry, L. L. Darrah, and V. A. Smith.  1997.  An implement for dislodging maize roots from soil for corn rootworm (Coleoptera: Chrysomelidae) damage evaluations.  J. Kans. Entomol. Soc. 70: 335-338.

  • Oleson, J. D., Y-L. Park, T. M. Nowatzki, and J. J. Tollefson.  2005.  Iowa state node-injury scale to evaluate root injury by corn rootworms (Coleoptera: Chrysomelidae).  J. Econ. Entomol. (In Press).

  • Sutter, G.R. and T.F. Branson.  1980.  A procedure for artificially infesting field plots with corn rootworm eggs.  J. Econ. Entomol. 73: 135-137.

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Project Title: Identifying Resistance to Infection by Aspergillus flavus and Fusarium in GEM Breeding Crosses and Advanced Breeding Lines

Manjit S. Kang

Department of Agronomy and Environmental Management

Louisiana State University Agricultural Center, Baton Rouge, LA 70803-2110

(Specific Cooperative Agreement No. 58-3625-3-126)

The purpose of this research was to identify sources of resistance to infection by Aspergillus flavus and Fusarium verticillioides in selected GEM breeding crosses and advanced breeding lines.

2003 Experiments:

A total of 30 breeding crosses and 41 breeding lines were planted in two replications of a randomized complete-block design on April 23, 2003 at the Ben Hur Plant Science Farm near Baton Rouge, LA. Plots consisted of two rows (20 ft long with 40 in row spacing). One row was inoculated with A. flavus and the other with F. verticillioides in the summer of 2003.  Five to six ears were harvested in each row and bulked by fungal species.

Evaluation of Resistance to Aspergillus flavus:  The media-free incubation technique developed by Li and Kang (in press) was used to evaluate genotypes for percent kernel infection (PKI). A total of 144 kernels per replication was evaluated using 48-well culture plates. Surface-sterilized kernels were placed in wells of the plates and plates were sealed with cellophane tape to prevent any contamination.  After a 10-day incubation period, the number of infected kernels was recorded.  Examples of highly susceptible, intermediate, and resistant genotypes are shown in the attached figures.

Analyses of variance were conducted via SAS. Data were transformed via the log transformation to normalize the data.  The results (transformed and non-transformed) for year 2003 are shown in Tables 1 and 2 for breeding crosses and in Tables 3 and 4 for advanced breeding lines. Transformation of data reduced CVs and improved the chances of detecting real differences among genotypes.  Genetic differences among crosses were not significant at the 5% or lower level when data were not transformed (Table 1). The mean PKI varied among crosses from 2.8 to 58.7% (Table 2) and among lines from 5.6 to 77.1% (Table 4). Nineteen crosses (PKI between 2.8 and 30.8%) did not differ in their PKI and would be classified as relatively resistant to A. flavus infection. For the breeding lines (Table 4), 21 lines (PKI between 5.6 and 44%) were relatively resistant and not significantly different from one another. The check GT-MAS:GK was relatively resistant to infection.

On the basis of the results in Table 2 and 4, top five and bottom five genotypes (crosses and lines) will be evaluated for aflatoxin, although little or no correlation between PKI and aflatoxin can be expected.

2004 Experiments:

Thirty GEM crosses and 41 breeding lines were planted at the Ben Hur Farm on April 6. Inoculations with A. flavus and F. verticillioides were accomplished in July 2004. Experiments were harvested in August. The A. flavus samples have already been processed for PKI in the same manner as done in 2003. Two-year data analyses should provide information on genotype-by-year interaction relative to the materials tested. We expect statistical analyses will be finished by January 2005.

Some of the genetic materials tested in 2003 and 2004 for A. flavus were related to those tested in 1995/96. A preliminary analysis indicated that some of the genotypes judged to possess resistance to A. flavus in 1995/96 were found to be resistant in 2003/04. This part will be expanded in a final report.

Fusarium Evaluations for 2003 and 2004:

We are currently evaluating the materials inoculated in 2003. The 2004 samples will be processed soon thereafter. We are developing a technique for PKI determination for Fusarium. Results will be provided as soon as evaluations have been completed.


Li, R., M.S. Kang, O.J. Moreno, and L.M. Pollak. 2004. Relationship among Aspergillus flavus infection, maize weevil damage, and ear moisture loss in exotic x adapted maize. Cereal Res. Commun. 32: 371-378.


  • Mr. Ruming Li, LSU Graduate Student

  • Dr. Michael H. Blanco, USDA, GEM Program, Iowa State University, Ames, IA

  • Dr. H.Abbas, USDA, Stoneville, MS.

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Optimization of Protein and Oil Value-Added Traits and Their Combination with Elite Ames and Southern Gem Lines

Rich Pratt

Ohio Agricultural Research and Development Center

The Ohio State University, Wooster, OH

BACKGROUND:  This project was initiated in 2003.  High protein and high oil GEM breeding lines, and their sister lines or other closely related lines with desirable agronomic performance, were identified by examination of existing data sets.  Selected lines arising from both the northern (ISU) and southern GEM (NC State) projects were selected and evaluated at two locations in 2003.  Several lines with high trait values e.g. 14.5% protein in line 02GEM00305 PE001n16F2S2-431-B, and their crosses to other desirable lines, were selected for further examination in the 2004 nursery.  Controlled self-pollination of the F1s was performed to provide new high-trait X high trait F2 populations and high-trait X high agronomic performance F2 populations.  These populations will provide high selectable variation for 1) a favorable balance of agronomic and grain quality traits and 2) extreme trait expression per se.

OBJECTIVE: The objective will be to verify the reported phenotypes of the selected lines and then to initiate selection within lines, and within newly generated populations to identify lines with a good balance of agronomic and grain quality traits and lines with extreme trait expression per se. 

APPROACH: All selected lines were planted in the field near Wooster, Ohio in replicate tests.  A split-application of nitrogen fertilizer was made to ensure adequate supply of N late in the season.  Controlled pollinations were made to provide uniform grain samples and to produce F2 populations for further trait enhancement.  Notes were made concerning agronomic traits and disease reactions.

PRELIMINARY OBSERVATIONS:  Controlled pollinations were successfully obtained in the majority of lines.  Some southern GEM lines were too late in maturity to mature grain.  Grain samples have been harvested and dried but compositional analysis has not yet been performed.

ADDITIONAL WORK:  Approximately 300 S1 progenies obtained from the GEM breeding population GOQUEEN:N1612 were evaluated for anthracnose stalk-rot resistance, resistance to foliar pathogens, and general agronomic performance.  Self-pollinations have been performed on desirable plants to produce S2 progenies. 


Pratt, R.C.,  L. M. Pollak, and K. T. Montgomery. 2004.  Registration of Maize Germplasm Line GEMS-0002.  Crop Science (Submitted).

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Amino Acid Analysis of GEM Germplasm

Paul Scott and Mike Blanco

The objective of this study was to determine the environmental stability of the amino acid content of selected GEM germplasm.  Lysine, Tryptophan, Methionine, Proline, Leucine and Threonine were measured using a microbial method.  In addition, an index of amino acid balance was calculated based on content the nutritionally limiting amino acids.  Grain was produced in 2003 and 2004 from seed produced in 2002.  The experiment consisted of 19 GEM hybrids and 52 GEM inbreds. 

Correlations between 2003 data and the 2004 data were determined for each amino acid and are summarized in Table 1.  The correlations between years are somewhat low, underscoring the importance of multienvironment testing when breeding for amino acid content.  Fortunately, the nutritionally limiting amino acids Met, Trp and Lys had the highest correlations of the study. 

Comparison of the GEM samples to normal (B73, Mo17 and B73xMo17) and high (B45o2 for Trp and Lys, B101 for Met) check samples is presented in Table 2.  29 GEM accessions outperformed all of the normal checks for Met, while only one GEM accession outperformed all of the normal checks for Trp and one outperformed all of the normal checks for Lys.  Encouragingly, one GEM line, DKXL212:N11a-139-1-1-B-B-B, was the top ranked sample in the index ranking (Met + Trp + Lys + 0.5 Thr), outperforming both of the high ranking checks.  This line has unusually well-balanced amino acid content and will be particularly interesting for further study.   

Three other parts of this project are in progress:

  1. Variability in F2 families

  2. Screening more GEM accessions

  3. Comparison of microbial amino acid analysis results with AOAC standard method.

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2004 Annual Report: United States Germplasm Enhancement of Maize Project

Margaret Smith

Department of Plant Breeding and Genetics, Cornell University

Project Title:  Developing Breeding Lines with Anthracnose Stalk Rot Resistance from Exotic Maize Germplasm


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) Evaluate S6 inbreds derived from GEM populations and their testcross progeny for anthracnose stalk rot resistance in replicated plots for a second year to confirm resistance levels.

2) Evaluate these same inbreds as testcrosses to both public and Holden’s testers for yield potential and agronomic quality in replicated yield trials at three New York locations.

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, S5 and S6 progenies were planted out ear-to-row for sib increase and testcrossing.  Twenty-seven lines and testcrosses of each to two testers (one public line cross and one Holden’s tester) were planted in two replications at Aurora NY in summer 2003 for stalk rot evaluation as described above.  Most of these testcrosses also had sufficient seed for yield evaluation at three New York locations. These same studies were repeated in summer 2004 for all the progenies where seed supply was adequate.  Final yield plots have just been harvested and final stalk rot ratings are still being taken, so data analysis and interpretation from the 2004 season is yet to be done.

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.  From these populations, a total of 27 lines have been selected based on per se anthracnose stalk rot resistance and testcross yield potential.

Mean anthracnose stalk rot ratings for the inbreds and their testcrosses, evaluated at Aurora NY in summer 2003, are presented in Table 1 (stiff stalk-related inbreds) and Table 2 (non-stiff stalk-related inbreds).  The ratings presented are the stalk rot means for internodes two through eight, reflecting our interest in identifying plants that were clearly exposed to the pathogen (e.g., not escapes and thus showing 50% or more stalk rot in the injected internode) but in which spread up the stalk was minimal (e.g., low disease in internodes two through eight). 

Among the stiff stalk-related GEM lines (Table 1), line 253 appears to have the best per se resistance and reasonable resistance in testcross combination with RD6501/RD6502.  Line 250 has the best resistance in this group of GEM lines on both of the testers, and is reasonably resistant in the per se evaluation.  In general, crosses to RD6501/RD6502 were much more resistant than crosses to LH176/LH177; RD6501/RD6502 is moderately resistant itself. 

Among the non-stiff stalk-related GEM lines (Table 2), line 212 had the best per se resistance and was among the most resistant in both testcross combinations.  Line 222 also looked very promising both per se and in crosses.  Line 261 produced the most resistant hybrids on both testers, even though it did not look that resistant in the per se evaluation.  These are all FS8B(T)- related progenies.  Line 266 also produced very resistant crosses on both testers.  Among these materials, the LH198 crosses were generally more resistant than the B73/CD1 crosses (the latter is quite susceptible).

Yield data were collected at two sites for all testcrosses that had sufficient seed in 2003.  (A third site was lost due to extremely wet weather in May that delayed planting, combined with early heavy snowfall in November that lodged the entire field before it was dry enough to harvest.)  Both sites suffered quite a bit of stalk lodging.  At Kingston, excellent moisture during the growing season resulted in very big, tall plants.  High winds in early fall (including the edges of a hurricane) caused considerable stalk lodging.  Yield data from this field had quite high CVs.  Our Albion location had better yield CVs (although not as good as we would like) but cool conditions in October resulted in slow dry-down and high grain moistures at harvest.  A mean over locations is provided for those hybrids that had sufficient seed to go in both locations, but note that the Albion yield data is more reliable than the Kingston yield data.

Among the stiff stalk-related GEM lines (Table 3), Lines 195, 199, and 250 appear to have the most competitive yields.  Some of them also had excellent standability on the LH176/LH177 tester compared to the commercial checks.  Line 250 is especially interesting as it was one of the best in this group for anthracnose ratings, both per se and in testcrosses. 

Among the non-stiff stalk-related lines (Tables 4A and 4B), lines 222 and 263 looked good over locations on the LH198 tester; lines 263 and 229 looked good over locations on the public line cross tester;  and line 266 looked good at the Albion location on the LH198.  Line 270 looked very promising on the LH198 tester at Kingston (seed was insufficient to include it in Albion), but the variability in the Kingston data gives limited confidence in this yield measurement.  Of this group, line 222 is especially interesting as it had some of the best anthracnose stalk rot ratings both per se and in testcross combinations.

Summary of Accomplishments:

The major accomplishment for this project to date is the development of advanced breeding lines (nearly finished inbreds) that are showing strong resistance to anthracnose stalk rot.  Resistance in the best of these materials is comparable to that available in currently released U.S. inbreds.  Simultaneous selection for agronomic performance has identified the better fraction of these resistant selections in terms of yield, maturity, and standability.  A few lines have emerged that appear to have good resistance, both per se and in testcrosses, and good yield potential and agronomic quality.


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Breeding Maize Lines with Exotic Germplasm

Dennis West

Plant Sciences Department

University of Tennessee, Knoxville, 2004

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.  Diversification of the U.S. maize germplasm base may contribute decreased vulnerability to bio-terrorism.


  1. Outstanding new lines from GEM accessions were identified from yield trials in 2004.

  2. Crosses between GEM accessions and adapted germplasm were advanced by self-pollination and selection in 385 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 2004, 793 experimental GEM hybrids were evaluated in 16 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 tale 1.  Several experimental hybrids were competitive with commercial check hybrids included in these trials.  An experimental hybrid in trial W87 yielded 20 bu/a more than the average of 4 check hybrids.  The best lines from these GEM accessions will be selected for further testing and incorporation into breeding for new value-added parental lines.  Inbreeding and selection was continued in populations resulting from crosses between GEM lines identified in previous trials.

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Characterization and Utilization of GEM Breeding Crosses, Topcrosses, and Advanced Lines for Drought tolerance, Grain Mold resistance, and Corn Earworm Resistance

Wenwei Xu

Texas A&M University Agric. Res. and Ext. Center, Lubbock, Texas


(1) To conduct multi-location yield trials of the topcrosses between the GEM inbred lines and Holden’s (LH185, LH198, LH200, LH247, and LH283) or public tester lines; (2) to advance and characterize new inbred lines developed from GEM breeding crosses; (3) to perform first-year field evaluation of 41 new GEM breeding crosses for drought tolerance, grain mold resistance, and CEW resistance; and (4) to characterize the 16 new recommended lines by Dr. Blanco for drought and heat tolerance and CEW resistance.

Materials and Methods

Objective 1: Thirty-seven crosses of GEM lines with five Holden lines and 60 crosses between GEM lines and public lines were evaluated tested at four Texas High Plains sites (Etter, Lubbock, Halfway, and Hereford) and three south Texas sites (College Station, Beeville and Corpus Christi).  The hybrids were tested in subsets with a two-row plots and two-replication.

Objective 2: F4-F8 generations from selected GEM breeding crosses were selfed and evaluated in replicated trials for overall agronomic traits, drought tolerance, heat tolerance, earworm resistance, spider mite resistance.

Objective 3: Forty-one GEM breeding crosses and three checks (Garst 8285 and Pioneer hybrids 34K77 and 3223) were grown under three water treatments in Lubbock in 2004.  Planting date was April 22.  Under each water treatment, a randomized complete block design with three replications was used.  Each plot was a 15 foot-long row with 40-inch row-spacing.  The stand was thinned to 22,646 plants/a.  Three water treatments (100% ET, 50% ET and V-10 drought stresses) were in the same field, and each received a total of 13.4, 5.3, and 7.88 acre-inch irrigation water during the season.  Total precipitation from planting to August 30 was 10.67 inches.  Detailed watering schedule is shown in Table 1.  The 50% ET irrigation provides a mild stress throughout the season.  In V-10 drought stress, irrigation was withheld from June 24 to July 15 to create a severe drought stress around the flowering time.  Plants in V-10 showed moderate to severe drought stress symptom around flowering time.  The year 2004 is the wettest in history with 33 inches of year to Nov. 29 rainfall in comparison to normal 18 inches.

Objective 4: Sixteen new recommended lines by Dr. Blanco and three check lines were grown under well-irrigated and V-10 drought stressed conditions in Lubbock, TX (see Section 1 for details).  Under each water treatment, a RCB design with two replications was used.  Plants in V-10 drought stress experienced moderate stress with a 30% yield reduction.  Plant height, stage green rating and other agronomic data were collected during the growing season.  The CEW feeding damages were measured on 10 ears.

Results and Discussion

Performance of GEM Topcrosses:

Among the 60 crosses between GEM lines and public lines, Tx204 x B110 and Tx205 x B110 were the best.  Their yield average yield was 213 and 208 bu/a, 9-10% higher than the check means (Table 2).  Inbred lines Tx204 and Tx205 were developed from AR01150:N0406 by my program.

Table 3 and 4 show the yield and other agronomic traits of GEM linex by Holden’s lines under well-irrigated and drought stressed conditions in Texas.  The best crosses were (DKB844:S1601-517-1-B-B-B-1 x LH283 (Table 3), Tx205 x LH198, AR16035:S02-443-1-B-B-1-1 x LH185, and CUBA164:S20)F7-1C x LH185 (Table 4).

Advancing and characterizing new inbred lines developed from GEM breeding crosses:

Inbred lines Tx204 and Tx205 developed from AR01150:N0406 were officially released in August 2004, and are available to interested public and private researchers royalty free from Wenwei Xu.  Tx204 has white cobs, while Tx205 has red cobs and shows a better combing ability.  Both lines above-average early vigor, upright and dark-green leaves, green silks, 3-5 primary tassel branches, 16-18 rows of semi-dent yellow and long kernels.  Their maturity, plant and ear height are similar to B73.  Both lines have strong silk emergence and silk 1 day earlier than pollen shed-a favorable trait for drought tolerance.  Both lines have low leaf firing, an indicator of good heat tolerance.  They are moderately resistant to earworms and drought stress but susceptible to Banks grass mite and two-spotted spider mite.

Other lines at F4-F8 generations are being advanced and characterized for overall agronomic traits, drought tolerance, heat tolerance, earworm resistance, mite resistance.  Lines from AR03056:N0902, SCROGP3:N2017, SCROPG3:N1411a, and FS8A(T)N1801 are promising and will be released as more data confirm the results.

Evaluation of 41 GEM breeding crosses for yield and stress tolerance:

CEW resistance, grain mold, and yield of GEM breeding crosses under well irrigation in 2002 and 2004:  The average yield was 123.4 bu/a ranging from 76.2 (CHIS740:S14) to 187.4 bu/a (P3223).  The average yield of check hybrids P3223, P34K77, and Garst 8285 was 181.9 bu/a.  UR11003:S17b, UR13010:N0613, CML323:N15, UR13085:N0204, NS1:S08, AR17056:S19 yielded 161.9 to 153.9 bu/a, statistically equal to the check means.   The yield of some crosses may be affected by the high green snap that occurred on June 18 when a storm with over 50 miles wind struck the field.  This was the first time we had such high level of green snap damage (Table 5).

There was a significant difference among the entries in all other traits.  The CEW penetration, an indicator of CEW resistance and measured by larval penetration from ear tip toward the ear base over ten ears per replication, ranged from 5.1 to 9.1 cm with a mean of 7.3 cm.   UR0571:S04, GUTA209:N11c, and CHIS740:S14 had CEW damage below test mean (7.3 cm).  GUTA209:N11c has lowest grain mold (1%).  High grain mold is usually correlated high mycotoxin (aflatoxin and fumonisin) contamination.  Several crosses have long ears and large kernels (Table 5).

Yield and stay green of GEM breeding crosses under 50% ET drought stress: The average yield was 81.6 bu/a ranging from 21.7 (CHIS740:S14) to 154.2 bu/a (P3223).  The average yield of three checks was 143.0 bu/a, a 21.4% reduction of the 100% ET yield.  Top 5 yielding breeding crosses include UR13085:N0204, AR16026:N1210, AR13026:N08a04, CML323:N15, and AR17056:S12.  Under this stress condition, one should consider the crosses with lower barren plants, better ear rating, lower stay green rating value, and low grain mold. Most of the top yielding crosses tend to have these characters (Table 6).

Yield and stay green of GEM breeding crosses under V-10 drought: The average yield was 70.1  bu/a ranging from 11.7 (DK888:S08b) to 152.3 bu/a (P3223).  The average yield of three checks was 133.5 bu/a, a 26.6% reduction of the 181.9 bu/a under 100% ET.  Although the total irrigation in this block received more irrigation water (7.88 acre-inches) than the 50% ET (5.39 acre-inch), a more severe drought stress during the flowering time cause higher yield reduction (Table 7).

Recommendation: A combined analysis of all data from three water treatments, I developed an imperial selection index.  The best five crosses are UR13085:N0204, CML323:N15, BR52051:N0417, UR13010:N0613, AR16026:N1210, AR13026:N08a04, and GUAT209:N11c (Tables 5-7).

Characterization GEM Lines for Drought and Heat tolerance and CEW Resistance

The CEW penetration ranged from 4.1 to 11.9 cm with a mean of 8.8 cm.  All 16 GEM lines were susceptible to CEW.  The CEW resistant check C3S1B73-3 had 4.1 cm feeding damage.  CUBA164:S2012-444-1-B-B had least CEW damage among the GEM lines (Table 8).  All lines except AR03056-lines had good husk coverage.

A typical susceptible response to high temperature is leaf firing.  CHIS740:S1411a-783-2-B-B was highly susceptible to heat stress with 65% plants showed leaf firing.  Traits associated with drought tolerance include leaf firing, visual rating before restoring water, stay green rating, ears per plant.  The yield was not collected due to high variation of yield under drought stress.

CUBA164:S2012-444-1-B-B, FS8B(T):N11a-110-1-B-B, DKXL370:N11a20-199-2-B-B-B, DKXL370:N11a20-234-2-B-B-B, and UR11003:S0302-937-1-B-B were better than the other 11 GEM releases for most of the stress traits measured. The best line was CUBA164:S2012-444-1-B-B; it had no leaf firing, low CEW damage, low grain mold, low percent of barren plants, good drought and stay green rating.

Publications and Field Days

Field days:

Two field days were held in 2004:  May 12 at Weslaco, TX and August 10 at Halfway, TX.  Attendees represented the Texas Corn Producers Board, the High Plains Underground Water Conservation District No. 1, seed companies, extension specialists and other scientists.  The GEM project and germplasm (breeding crosses, inbred lines, and topcrosses) were discussed and demonstrated.


Wenwei Xu and Mike Blanco.  2004.  Identification of useful tropical x temperate GEM germplasm for corn production in semi-arid regions.  ASA-CSSA-SSSA Annual Meetings Abstract No. 6171. Seattle, WA. Oct. 31-Nov. 4, 2004.

Germplasm Releases:

Tx204 and Tx205


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