Germplasm Enhancement of Maize

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Larry Darrah
Jim Hawk
Ken Russell
Robert Lambert
Bruce Hibbard
Margaret Smith
Mark Campbell
Dennis West
Javier Betrán
James Coors
Wenwei Xu
Richard Pratt

GEM - 2000 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 testcrosses of S1 lines of UR13085

Larry Darrah

USDA-ARS and Department of Agronomy, University of Missouri, Columbia, MO

Results from evaluating 10 random S1 progeny from 13 GEM populations in 1977 showed that UR13085:S1912 had the best combination of good rind penetrometer resistance and vertical root pulling resistance. UR13085 is of the Cateto Sulino race, characterized very broadly as “tropical flint” or “Caribbean flint” and having orange, hard, flinty kernels. One hundred and twenty S1 progenies were used for testcrossing to two testers in 1998. Testcrosses were made to Mo17 Synthetic(H14)C4 and CarPop(E5)C5. The former is a yellow synthetic made up from various commercial versions of Mo17, and the latter is a population originating with Everett Gerrish, formerly of Cargill Hybrid Seeds, which has a large component of tropical dent Tuxpeño.

For 1999 and 2000, we had 90 testcrosses of UR13085:S1912 S1 to CarPop(E5)C5 and 70 testcrosses to Mo17 Synthetic(H14)C4 for evaluation. Only one location of data was obtained in 1999 because of protracted drought. Two locations were planted in 2000; one at Columbia and a second at Novelty, MO. Severe lodging, due to high natural European corn borer infestation and poor stalk strength, occurred just before harvest at the Novelty site and resulted in discarding of that location’s data. 

At Columbia, trial yields (checks included) averaged 134.4 bu/a for the testcrosses of UR13085:S1912 S1 to CarPop(E5)C5, and 146.8 bu/a for the testcrosses to Mo17 Synthetic(H14). Individual trial results are summarized below:

2000 Testcrosses of UR13085:S1912 S1 
Highest CarPop(E5)C5 testcrosses 160.5 bu/a
Highest 10 CarPop(E5)C5 testcrosses 151.5 bu/a
Average of all CarPop(E5)C5 testcrosses 133.3 bu/a
Check entry B73 ´ Mo17 109.7 bu/a
Check entry Pioneer Brand 3394 173.6 bu/a
LSD 0.05 22.4 bu/a
CV% 10.2
Highest Mo17 Synthetic(H14) testcrosses 182.4 bu/a
Highest 10 Mo17 Synthetic(H14) testcrosses 165.9 bu/a
Average of all Mo17 Synthetic(H14) testcrosses 144.7 bu/a
Check entry B73 ´ Mo17 166.7 bu/a
Check entry Pioneer Brand 3394 176.1 bu/a
LSD 0.05 27.5 bu/a
Nineteen lines from ARO1150:N04 were advanced from S3 to S4, and testcrossed to Missouri’s White Synthetic Tester (all lines), MoSCSSS(R19)C4 (yellow or yellow/white segregating lines), and Mo17 Elite Syn.(R20)C4 (yellow or yellow/white segregating lines) for field evaluation in 2001.

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Testcross and Per se Evaluation of GEM Breeding Population DKXL212:N11a 

James A. Hawk and Teclemariam Weldekidan 

Department of Plant and Soil Sciences, University of Delaware 

We evaluated LH198 testcross of 76 S3 lines from the DKXL212:N11a population at two Mid-Western locations (one rep / location) and at two locations (four reps) in Delaware under both irrigated and dryland conditions. We also advanced and evaluated the lines per se (S4-S5) for agronomic performance and pest resistance in the nursery at Newark, DE.

Based on the testcross results and per se evaluations, we have identified nine lines for further advancement and evaluation on two testers at additional locations for 2001. These lines had comparable yields and grain moisture to the commercial check hybrids and averaged 182 bushels/acre compared to the test average of 168 bushels/acre at the two Delaware locations. Three of the lines had particularly good per se agronomic characteristics (early and synchronous flowering, rapid dry down, short plant height) and overall good plant appearance and pest resistance. These lines may have potential for breeding programs interested in broadening genetic diversity in corn.

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Search for useable genetic variation in concentration of total phosphorus in the grain of GEM breeding crosses 

W. Ken Russell

University of Nebraska-Lincoln 

Thirty-two GEM breeding crosses and three adapted F2s were grown in a nursery at Lincoln, Nebraska. The GEM crosses included 20 with a 25% exotic contribution and 12 with a 50% contribution. One F2 had a Stiff Stalk background, a second was of Lancaster origin, and the third was not closely related to either Stiff Stalk or Lancaster. Prior to planting, two soil samples were taken from the plot area. The Bray phosphorus in both samples was high (>63 ppm), so no phosphate fertilizer was applied at any time prior to planting or during the growing season. The nursery was irrigated as needed to prevent obvious drought stress.

Approximately 35 plants per entry were self-pollinated. Selection was practiced only for synchrony between silk emergence and pollen shed and for the absence of smut on the tassel and ear. In the most susceptible entries, approximately 30% of the plants had smut galls at flowering. A sample of grain from the middle of each of 25 well-filled ears from each breeding cross has been ground in a Stein mill and will be evaluated for concentration of total phosphorus in the grain using X-ray analysis.

The concentration of phosphorus in the corn grain is of interest because in many commercial hybrids the level of phosphorus appears to exceed by a factor of two the dietary needs of yearling beef cattle. The excess phosphorus is excreted in the manure and becomes a potential pollutant that causes algae blooms in freshwater supplies. This problem is worsened by the common practice in many large feedlots of supplementing the cattle diet with by-products of the wet-milling industry that contain even higher levels of phosphorus than whole corn. 

Recently, considerable effort by the USDA and private companies has gone into the development of low-phytate corn. Achieving low levels of phytate is important because monogastric animals cannot digest this compound, and much of the phosphorus in normal corn is present as phytate. Low phytate corns hold the promise of eliminating the need to supplement the diet of these animals with phosphorus and also of reducing the level of phosphorus in the manure. 

Cattle, however, are able to digest phytate. Because the concentration of total phosphorus is largely unchanged in the low phytate mutants, these specialty corns will not remedy the problem of too much phosphorus in the diet of corn-fed beef. That is why my long-term goal is to develop corn germplasm with lower levels of total phosphorus in the grain. 

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Development of corn lines from GEM germplasm with improved multiple disease resistance, starch content, and grain yield 

R. J. Lambert 

University of Illinois

Thirty-two S4 lines of BR5101 were grown as testcrosses (BR5101 x ICB#45) at Clinton, and Urbana, IL, and Shelbyville, IN. Two replications were grown at each location. Mean grain yields were 8.9 t ha-1 at Clinton, 10.4 t ha-1 at Urbana, and 8.9 t ha-1 at Shelbyville, IN. Three hybrids were significantly greater than the average for the three locations by about 14% and were 7% greater than the check Pioneer 3163. Stalk lodging at the three locations averaged from 4.0% to 6.3% which is low for this year. All three hybrids were below the mean at each location for stalk lodging.

Twenty-seven S4 lines of BR5101 were selected in nursery (out of 60) that had leaf area infected between 10 to 20% in late August. The average oil content of these lines was 4.1% (range 3.1 to 6.9%), 12.8% for total protein (range 10.7 to 14.4%) and 65.5% for extractable starch (range 65.1 to 69%). The starch values were lower than in 1999 but this could be due to the environment or inbreeding affects producing smaller kernels with harder endosperm. Eight of the BR5101 S4 lines that performed above the mean in testcrosses and had desirable multiple disease resistance levels and starch values per se were sent to Mexico (Mycogen Seeds), to produce hybrids (crosses to DREP150) for testing in 2001.

Forty testcrosses of DREP 150 (DREP 150 S2 x ICB#43) were grown at Clinton, Urbana, IL and Shelbyville, IN. Grain yields varied from 7.7 to 10.0 t ha-1 with an average of 8.8 t ha-1.Stalk lodging was low at two of the three locations. There was a significant GXE for these testcrosses and none of the hybrids showed a non-crossover interaction. None of the testcrosses were in the upper 10% for grain yields at the three locations. Averaged over the three locations two testcrosses yield 17% more than the average for the three locations but were 6% less than check hybrid Pioneer 3163 (10.5 vs 11.2 t ha-1). The GXE interaction could result from testing S2 lines that still carry some dominant genes that are unadapted. Grain yields of several testcrosses at individual locations were above that location mean. Five testcrosses at Urbana, seven at Clinton, and five at Shelbyville, IN were 10% above the means for each location and stalk lodging was below the mean. 

A total of 60 DREP 150 S3 lines were grown in the nursery and selected for multiple leaf diseases and stalk rots. About 5 selfs were made family-1 and well pollinated ears shelled and kernel composition for oil, protein, and extractable starch estimated by near-infra-red-transmission (NIT). Twenty-five of the 60 lines had leaf area infected by multiple leaf diseases of 25% or less in late August. These estimates agree with the stay green estimates at Clinton and Shelbyville for the testcrosses involving these same lines which ranged between 20 to 25%. Bulk kernels from these S3 lines varied in oil content from 3.0 to 6.0% (mean 3.9%), protein 9.3 to 14.4% (mean 11.9%) and extractable starch 63.6 to 72.2% (mean = 66.6%). Twelve of DREP 150 S3 lines had starch values above 69%.Fourteen of the S3 lines were selected based on testcross performance multiple disease resistance and starch values of lines per se. These lines were sent to Mexico (Mycogen Seeds) to produce crosses for testing in 2001. 

Testcross seed from the trials at Urbana, IL were collected from each plot (total 144 samples) and will be assayed for oil, protein, and starch. 

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Evaluation of 25% exotic GEM breeding crosses for and western corn rootworm and European corn borer resistance 

Bruce E. Hibbard and Arnulfo Q. Antonio 

USDA-ARS, Plant Genetics Research Unit, Columbia, Missouri 

In 2000, we evaluated 90 available 25% exotic GEM breeding crosses (half of those available in 1999) plus checks for resistance to western corn rootworm (WCR) larvae and European corn borer (ECB). The WCR trial was conducted in a randomized complete block design with three replicates. Each plot was manually infested with 1,200 western corn rootworm eggs per 30.5 cm. At the time of maximum damage, four roots selected from each of the three replicates were washed of all soil and evaluated for corn rootworm feeding damage using the nodal injury scale (value represents the number of nodes pruned to within 2 cm of the stalk by WCR). First and second generation ECB screening was conducted by infesting ~140 neonate larvae on the first six and last six plants in one 7.6 m row at 10-leaf stage and anthesis, respectively. At the time of maximum damage for first generation, plants were rated using Guthrie’s 1-9 ECB rating scale (1=no damage, 9=severely damaged). Second generation ECB damage was rated by counting the number of tunnels and measuring the length of tunneling near the end of the growing season.

In corn rootworm evaluations, one line, AR16026:n1210 (inventory number 95098) was less damaged than the insecticide control. This line and lines FS8A(T):N1802 (inventory number 950117) FS8A(S):S0907 (inventory number 950114) were significantly less damaged than the susceptible control, B37´H84. These three lines and line UR13085:N0204 (inventory number 950103) were also nominally less damaged than the resistance control, NGSDCRW1(C4)S2. In addition to those already mentioned, 20 lines were more damaged than the susceptible check and 67 lines were less damaged than the susceptible check, but more damaged than the resistant check. 

In European corn borer stalk tunneling evaluations, all entries were less damaged than the susceptible checks WF9 and WF9´W182E. A total of 51 lines were less damaged than the resistant control, Mycogen 7250, for stalk tunneling. In European corn borer leaf feeding evaluations, twelve lines were less damaged than the resistant checks Mycogen 7250 and Pioneer Brand 3184. Seven lines were quite susceptible to first generation leaf-feeding damage by European corn borer larvae and were given ratings equal to that of the susceptible control, WF9. 

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Anthracnose Stalk Rot Resistance from Exotic Maize Germplasm

Margaret Smith 

Department of Plant Breeding, Cornell University 

General Objective: To develop temperate-adapted maize inbreds with both anthracnose stalk rot resistance and good yield potential from GEM accessions.

Specific Objectives: 

1) To continue selfing and selection for anthracnose stalk rot resistance in progenies from the 75% temperate : 25% exotic populations that have adequate testcross yield potential.
2) To evaluate testcross yield potential of the early generation inbred families and select those that are most promising for continued stalk rot selection.

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.

Results: 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 S3 families grown in 1999 and for the S3 plants from which S4 ears were selected are shown in Table 1. Ears were saved from only the more resistant families and the best plants within these families. Plants with very limited stalk rot in the lowermost internode (injection site) were eliminated, as research has indicated that these represent partial escapes rather than truly resistant plants. Yield data based on S2 testcross performance also was considered in selecting which S3 families to maintain (see Table 2 for yield data on some of the better S2 x tester combinations). Some of the very low values listed as minima for means of S3 families in Table 1 represent families where the mean was influenced by several "escapes" and/or families that were dropped based on poor S2 testcross performance. This explains why the minimum values for selected S3 plants are higher than those for S3 family means in two populations. 

Disease resistance ratings on S5 progenies and data from the corresponding yield trials done in the current season have been collected, but remain to be converted, analyzed, and summarized. Field observations suggest that uniform resistance is being achieved and levels of resistance look good in the S5 families. Yield trials showed significant stalk lodging in a few locations, so should provide good selection pressure for standability.

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Development and evaluation of S2 lines from selected GEM germplasm and continued screening of LAMP germplasm for high starch amylose 

Mark Campbell, Heather Yeager, and Gina Garrett 

Truman State University 

The overall objective of last year's workplan was to examine GEM materials together with the recessive amylose-extender (ae) allele in order to identify high starch amylose levels (>65%). The materials used originally included 98 GEM-crosses, temperate accessions from the GEM 50 group (part of the LAMP top 5%) and various other plant introductions. The following report describes starch-amylose values for a number of GEM related materials which are currently at various levels of inbreeding. In general, either GEM crosses or GEM-50 materials were crossed onto the hybrid Oh43 x H99 ae. Seed resulting from these crosses was planted to produce F1 ears that segregated for mutant ae kernels. Mutant kernels were visually selected from these ears and advanced to produce F2 ears which were 50% GEM and 50% Oh43 x H99 ae while being homozygous for the ae allele. When converted to ae, most samples, including the check, will run around 55% amylose, however, for this study we are interested in identifying lines that have at least 65% starch amylose content. For GEM-crosses, numerous selected and random F4 (S2) plants were grown in the 2000 summer breeding nursery from the pedigrees GUAT209:S13 x (Oh43 x H99ae) and CUBA110:N1711 x (Oh43 x H99ae) with many individual ear sample at or exceeding starch amylose values of 70%. In addition, several plant introductions including Zia Pueblo NRC 5357 and Cochiti Pueblo NRC 5298 had ear samples with amylose values equally as high. From GEM-50 materials, F2 ears grown in the 1999 summer nursery were also evaluated. At least two sources appeared to show promising amylose levels (65 - 68%) including CHZM 04 11 x (Oh43 x H99 ae) and CHZM 05 001 x (Oh43 x H99 ae). A complete listing of materials analyzed will be provided at the 2000 GEM Network meeting. Future plans for all GEM materials include continued inbreeding, test-crossing onto commercial high-amylose testers and recombination of lines.

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Summary of GEM research 2000

Dennis West and David Kincer 

University of Tennessee 

Southern Cooperation: 921 yield test plots at Knoxville, TN were used to evaluate testcrosses of GEM germplasm. Dataon yield, maturity, and lodging were forwarded to Raleigh, NC, to the coordinator for the southern region.

Tennessee: F1's from crosses of S2 lines, provided by Dr. M. Goodman, and Tennessee germplasm were advanced to the F2 generation. A few additional lines were obtained in 2000 and crossed with Tennessee Germplasm. 

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Development of food-grade corn germplasm with superior grain quality and adaptation

Javier Betrán 

Texas A&M University 

Testcrosses of GEM Stiff Stalk S4 lines (derived from DK212T:S11, DK888 S11, DKB830 S11, DK370A, and DKXL380:S11) with LH210, and of GEM Non Stiff Stalk S4 lines (derived from TUXPENO CHIS775 N19, DK212T N11, DKXL370A N11, DKXL380 N11, PE1 N16, DK888 N11, and SCR Gp3 N14) with LH236 were evaluated in 4 Texas environments: Weslaco (subtropical), College Station (transition), Springlake and Dumas (temperate) during year 2000. P3223, P31B13 and DK668 were the commercial checks. DKXL370A N11 x LH236 was the best yielding hybrid (141 bu/a) at Weslaco where yields averaged 123 bu/a. At College Station a hailstorm few days before flowering produced heavy damage in the plants. The average yield was 73 bu/a. The hybrid DKXL380 N11 x LH236 had the greatest yield with 93 bu/a. At Springlake, the average yield was 172 bu/a and the best hybrids were the checks P31B13 (218 bu/a) and P3223 (200 bu/a) followed by Dk212T N11 x LH236 (193 bu/a). At Dumas, the average yield was 178 bu/a with DK668 (218 bu/a) as the best yielding hybrid followed by SCR Gp3 N14 x LH236 (202 bu/a). The best performing hybrids across locations were the checks P31B13 and DK668. Among the testcrosses SCR Gp3 N14 x LH236, DK888 N11 x LH236, and DKXL380 S11 x LH210 showed good yield potential, and desirable maturity, grain moisture content, standability and grain test weights across trials. In general, these GEM testcrosses appear to perform better in transitional areas between subtropical and temperate environments. Selected S4 lines will be advanced and crossed with additional testers during year 2001 for further evaluation and selection.

A composite trial, with a selected group of 1999 GEM testcrosses from experiments 76,83,86 and 89, was conducted in College Station, TX. Due to hail damage the yields were below normal for this location with an average of64 bu/a. The best yielding hybrids were DK888_DK888_N11F1S1 x T8 (104 bu/a) and PE11_BR51_501S11F1S1 x T10 (98 bu/a).

We have developed S2 inbreds for nine breeding populations derived from 50% exotic GEM breeding crosses: 5 Stiff Stalk (CUBA173:S04, AR16021:S09, DKB830:S19, AR16021:S08a02, AR16026:S1704) and 4 Non Stiff Stalk (AR16026:N1209, AR13026:N08c09, DREP150:N2011D, AR17026:N1019). These 9 breeding populations were selected based on agronomic performance and adaptation in trial evaluations during 1998 (100 original GEM crosses at 5 locations) and 1999 (reevaluation of the best 19 crosses during 1998 at 3 locations), and on grain quality traits (e.g. energy dense). Bulks of S2 lines are currently being advanced in our winter nursery in South Texas. 

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Silage Evaluation of Topcrosses with Advanced Lines From GEM Breeding Crosses

James G. Coors


Department of Agronomy, University of Wisconsin


The purpose of our GEM research in 2000 was to estimate silage yield and nutritive value of the most productive GEM topcrosses. We conducted two trials involving GEM topcrosses. The first involved 10 GEM topcrosses and 13 experimental and commercial hybrids that were evaluated at two WI locations, Madison and Arlington. There were three replications at each location. The GEM topcrosses involved inbreds derived from DKXL212, AR16026, and CUBA117 (50% adapted germplasm) crossed to either LH185 or LH198. These breeding crosses had previously been shown to have good grain yield potential.

Planting dates were May 2 (Madison) and May 22 (Arlington), and the trials were harvested on September 15 (Madison) and October 3 (Arlington). Despite excessive rain early in the season, growing conditions at Madison were good to excellent. Arlington did experience some flooding, but the plots were in good condition by the end of the season. 

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 were estimated based on the new MILK2000 equations ( developed 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. 

Several of the GEM topcrosses had excellent forage characteristics (Table 1). In particular, DXL212:N11a-3182-1 X LH198 had the highest forage yield and milk/acre in the trial (9.35 tons/acre and 23,541 lbs milk/acre). One GEM topcross, CUBA117:S1520156 X LH185, also had excellent nutritional characteristics (2,714 lbs milk/ton) mostly due to low NDF and high IVNDF. 

The second trial that involved 20 S2 lines derived from four GEM breeding crosses (75% adapted germplasm),15 S3 lines derived from WQS C0, and synthetic developed for improved silage performance (see, and 5 check hybrids. The GEM breeding populations ARZM17026:N1013, ARZM17026:N1019, URZM13085:N0204, and URZM13085:N0207 were selected from a larger set of 50 breeding populations based on evaluations conducted by the UW silage breeding project in 1995 and 1996. The GEM S2 lines were derived from an initial set of 217 S1 families evaluated for per se nutritional value in 1997 and subsequently selfed and selected for per se agronomic value. Hybrids were evaluated at two locations in 2000, Madison and Arlington, as described above. There were two replications at each location. 

Several of the GEM topcrosses had excellent silage potential. In particular, 67034-2 X LH198 had the highest forage yield and milk/acre in the trial (8.91 tons/acre and 23,648 lbs milk/acre). Several others had above average forage yield as well as nutritional characteristics (e.g., 67003-1 and 66035-1 X LH198) mostly due to high IVNDF. 

In our inbred breeding nursery, approximately 100 S4 families were derived from five breeding crosses (URZM13085:N0204, URZM13085:N0207, ARZM17026:N1013, ARZM17026:N1019, and SCRO1:N1310-398-1-B). Approximately 150 new S1 families were derived from CUBA164:S1517. We tried unsuccessfully to develop new inbreds from CUBA164:S15-184-1-B because of the potential this germplasm showed in 1999. However, only two of approximately 200 seeds planted germinated.

In the upcoming year, superior topcrosses will continue to be evaluated for silage potential. Several of the GEM lines could be very useful for breeders in the northern Corn Belt.

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 GEM Germplasm as New Sources of Drought Tolerance and Corn Earworm Resistance 

Wenwei Xu, Tom Archer, and Lance Bradford 

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

Drought and corn earworm (CEW) are major problems for corn production. In 1999 and 2000, 73 GEM breeding crosses with 25% to 50% tropical germplasm and three check hybrids (Pioneer hybrids 3223 and 34K77, and B73 x Mo17) were evaluated for yield and agronomic performance, pre-tassel drought tolerance, post-tassel drought tolerance, and CEW resistance in Lubbock, Texas. Several GEM crosses were found to have good drought tolerance. Over the two years BVIR103:S04,DKXL380:S08a, DKB830:S19, GUAT209:N19, CUBA117:S15, and CUBA164:S20 had the lowest CEW damage and may be new sources of CEW resistance. CEW damage was positively related to grain mold. The breeding crosses with 50% tropical background had significantly lower CEW damage, less grain mold, and longer ears than those with 25% tropical background or the check hybrids. In 2000, we also evaluated 76 new GEM crosses for drought tolerance and CEW resistance. Breeding for drought tolerance and CEW resistance with selected GEM germplasm is under way.

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Introgression of Grain Quality Traits from GEM Germplasm into Corn Belt Maize

Rich Pratt 

Ohio State University, Wooster 

S2 progeny selections derived from the Germplasm Enhancement of Maize (GEM) FS8A(S):S09 population were made during 1998. 0ne set of 78 selections was made in Iowa by Dr. Pollak’s team, and one set of 100 selections was made in Ohio by Dr. Pratt’s team from duplicate sets of the same 441 FS8A(S):S09 S1 progenies. Thirteen selected lines were in common between the programs. Selected progenies were subsequently testcrossed to elite maize inbred LH185 during the winter. The IA-derived testcrosses were evaluated by the respective GEM cooperators in Iowa (3 locations) and in Ohio (two locations). An industry cooperator conducted field tests at 5 additional locations in 5 states (IA, IL, IN, KS, MO). OH-derived testcrosses were tested in Iowa and Ohio and by an industry cooperator at 5 additional locations in 3 states (IA, IL, IN). All testcrosses also were planted in unreplicated short-row plots with the exception of Wayne Co, Ohio, where two replications were used.

The mean yields of IA-derived and OH-derived experimental testcrosses were approximately 85% (+/-1%) that of the mean of all commercial hybrid checks (IA set check mean = 146.3 bu/A and OH set check mean = 170.9 bu/A). No testcrosses in the top 10% of either set were derived from the common 13 S2 progenies. In both tests, 3 testcrosses arising from the common S2 progenies were represented within one LSD of the commercial check mean. The mean yield of the top two experimental testcrosses within each set was within 96% of the mean yield of the commercial checks.

Kernel compositional and density values of grain samples from the replicated plots near Wooster were determined using a Tecator 1225 near-infrared transmittance grain analyzer and the Composition Systems System One calibration. The highest protein values in Iowa and Ohio testcrosses were 0.7 to 1.0 percentage points higher than the highest check and oil values were 0.3 to 0.4 percentage points higher. Starch composition and density values of testcrosses and checks were nearly identical. Please see tables 1a and 1b. 

During the past summer we performed controlled self-pollinations within selected S2 progenies to produce S3 progenies for characterization and possible release. The highest yielding testcrosses will be crossed to two proprietary inbred testers during the winter season to permit multi-location evaluations of testcrosses in 2001. 


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