Germplasm Enhancement of Maize

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Overview
2005 Field Trials
2005 Nursery

GEM - 2005 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.

 

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 2005, 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 2005 trials include a combination of new GEM topcrosses and advanced-generation inbred testing of GEM materials evaluated in previous years.

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2005 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 24 S2+ GEM inbreds crossed to LH185, LH200, or LH283, and six hybrid checks (Table 1).

 

GEM33 had 67 entries and consisted of 61 S5+ families crossed to HC33 and 6 hybrid checks. Most of the hybrids in GEM33 involved BR52051:N04 germplasm. Based on forage yield, 29 GEM33 topcrosses were chosen for nutritional evaluation (Table 2).

 

GEM198 had 68 entries and consisted of 62 S5+ families crossed to LH198 and 6 hybrid checks. Most of the hybrids in GEM198 involved BR52051:N04 germplasm. Based on forage yield, 30 GEM198 topcrosses were chosen for nutritional evaluation (Table 3). Forty-six families that appeared in GEM198 also appeared in trial GEM33.

 

GEM279 had 113 entries and consisted of 108 S4+ families crossed to LH279 and 5 hybrid checks. Much of the germplasm in GEM279 came from CUBA164, CUBA117, and CHIS775 backgrounds. Based on forage yield, 13 GEM279 topcrosses were chosen for nutritional evaluation (Table 4).

 

GEM287 had 104 entries and consisted of 99 S4+ families crossed to LH287 and 5 hybrid checks. Based on forage yield, 20 GEM287 topcrosses were chosen for nutritional evaluation (Table 5). Much of the germplasm in GEM287 came from CUBA164, CUBA117, and CHIS775 backgrounds. Twenty-three families that appeared in GEM287 also appeared in trial GEM279.

 

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All five trials were planted at two WI locations, Madison (May 4) and Arlington (May 23), with two replications at each location. The average planting densities ranged from 27,300 to 30,660 plants/acre. Temperatures were relatively cool early in the season, and seedling emergence was lower than normal. Trial GEM198 at Madison was abandoned due to poor plant stands. Both locations experienced severe drought stress throughout the season, which lead to low forage yields along with excessive root and stalk lodging. The Madison trials were harvested in early to mid-September. The Arlington trials were harvested in late September and early October. For a detailed description of these trials see http://www.silagebreeding.agronomy.wisc.edu.

Nutritional evaluations are not yet completed. Nutritional evaluations will include assessment of neutral detergent fiber (NDF), in vitro true digestibility (IVD), in vitro NDF digestibility (IVNDFD), crude protein (CP), and starch concentration. Based on these values, milk/ton of forage and milk/acre will be estimated based on MILK2000, which 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. Nutritional evaluation will be completed in approximately one month and the results posted on our web site.

 

GEMNEW highlights:  Of the 24 new GEM topcrosses, the forage yield of 5 exceeded 9.49 tons/acre, which was average of the three check hybrids (Table 1). Two of these (AR16026:S17-104-1-B-B X LH283 and FS8B(T):N11a-322-1-B X LH200) had forage yield greater than 10 tons/acre and relatively low lodging scores. Unfortunately, these hybrids also had relatively low dry matter, which indicates that these hybrids may mature too late in the season for Wisconsin conditions, and perhaps a cross to a shorter season tester inbred would be appropriate. Note also the high forage yield of W605S X LH244. (This testcross is also designated “UW EX01” in the 2005 UW Corn Extension report, which can be accessed via http://corn.agronomy.wisc.edu.) W605S, which was released in 2004, was developed from the GEM breeding population AR17026:N1019.

 

GEM33 and GEM198 highlights:  There are a number of hybrids in GEM33 and GEM198 that have considerable potential. Overall, the BR52051:N04 material had excellent lodging scores in both GEM33 and GEM198 trails. In GEM33, seven hybrids involving BR52051:N04 and one related to W605S (65008-2-3-2-1-3) exceeded the mean of the three hybrid checks, and nearly all of these had acceptable dry matter and lodging scores. The GEM198 trial was plagued by poor emergence. Two families from BR52051:N04 and one related to W605S (65008-1-1-3-1-3-B) exceeded the mean of the check hybrids.

 

GEM279 and GEM287 highlights:  Both trials had severe root and stalk lodging, and many entries (those with >50% lodging) were removed from the data set before the final statistical summary. LH279 topcrosses were particularly hard hit by drought stress. Nonetheless, the yield of 11 LH279 topcrosses and 18 LH287 topcrosses exceeded the mean of the four check hybrids. With several exceptions, dry matter was usually lower than desired for most of these high-yielding hybrids, and this indicated that these hybrids may not be suitable for Wisconsin conditions. One GEM line, in particular, CUBA164:S2012-235-1-B-21 had excellent performance, for yield, dry matter, and lodging, across both testers and both locations.

 

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2005 Nursery Activities:

In 2005, 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. In 2005, we visually screened approximately 200 S1 GQS families in the nursery and in a separate stress trial. We will cross the surviving S2 families (~100) to W604S in our 2005/6 winter nursery. These crosses will be evaluated for silage potential in 2006.

In our inbred breeding nursery in 2005, we made additional self-pollinations and selection for approximately 300 advanced families derived from breeding crosses CUBA164:S1517, CUBA164:S2012, CUBA117:S1520, BR52051:N04, CHIS775:S1911b, CHO5015:N15, DKXL370:N11a20, DK212T:N11a12, AR16026:S1719, AR17056:N2025, FS8B(T):N11a-322-1-B-B, AR17026:N1019, UR13085:N0204, and SCRO1:N1310.

 

For additional information, all activities of the UW silage breeding program, including nurseries and yield trials, are available through our web site (http://www.silagebreeding.agronomy.wisc.edu).

 

 

Table 1.  Forage yield evaluation for GEMNEW trial in 2005. Entries marked with “*” will be analyzed for nutritional quality.


 

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Table 2.  Forage yield evaluation for GEM33 trial in 2005. Entries marked with “*” will be analyzed for nutritional quality.


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Table 3.  Forage yield evaluation for GEM198 trial in 2005. Entries marked with “*” will be analyzed for nutritional quality. (Entries with low stand counts dropped from analysis.)


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Table 4.  Forage yield evaluation for GEM279 trial in 2005. Entries marked with “*” will be analyzed for nutritional quality. (Entries with >50% lodging dropped from analysis.)


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Table 5.  Forage yield evaluation for GEM287 trial in 2005. Entries marked with “*” will be analyzed for nutritional quality. (Entries with >50% lodging dropped from analysis.)

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We are grateful to our Cooperators for their support!

 


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Contact us | Home | USDA | ARS | NCRPIS | ISU | Corn Breeding | January 20, 2006