SEED QUALITY OF ORGANIC-CERTIFIED CORN HYBRIDSAllen Geyer1, Peter Thomison1*, Deborah Stinner2, Joseph G. Lauer4, Leslie Freehill3, Lori Abendroth3, Roger Elmore3,

Andy Evans1, and Angie Tunink5

1The Ohio State University, Columbus, OH; 2The Ohio State University, Wooster, OH; 3Iowa State University, Ames, IA; 4University of Wisconsin, Madison, WI; 5Organic Crop Improvement Assoc.

INTRODUCTION

Organic farming is one of the fastest growing segments of U.S. agriculture. However, adoption of organic farming differs considerably among crops. Organic fruit and vegetables comprise a much greater percentage of total U.S. crop acreage than field crops, e.g., in 2005, organic carrot production comprised 6 percent of total U.S. carrot acreage, whereas organic corn production comprised only 0.2 percent (ERS-USDA 2005). One obstacle contributing to the low acreage of organic corn is a lack of information on the agronomic performance of corn hybrids and varieties in organic cropping systems. Many organic grain farmers are seeking information and knowledge to help them identify organic hybrids and varieties that perform best under varying environmental conditions.

The USDA National Organic Program (NOP) initiated in 2002 required that certified organic farmers must use certified organic seed unless it is not available. Prior to 2002, organic farmers generally used conventionally produced hybrid corn seed in organic corn production. Several seed companies have now started to market organically produced, untreated corn seed in accordance with the new organic production guidelines.

Some organic farmers have expressed concerns about the seed quality of organically produced seed including organically produced corn seed, and have questioned whether such seed performs as well as the untreated conventionally produced seed they previously used. It is not known whether this problem is due to the seed corn production environment, the conditioning process, or an inherent characteristic of certain hybrids. Organically produced hybrid seed is often more expensive than conventionally produced hybrid seed.

In 2006, the Organic Crop Improvement Association, Research and Education, distributed a survey to farmer members in Ohio, Iowa, and Wisconsin to determine current organic management practices, especially those relating to corn hybrid and variety selection and management (Thomison, et al. 2007). Results of the survey indicated that untreated conventional seed was still widely used. Eighty five hybrids were identified by respondents. Of these, 56 were organically produced, 29 were untreated conventionally produced hybrids (Figure 1).

Seed quality in corn is measured by the standard germination test (AOSA, 2008) which appears on the seed tag and by various vigor tests, especially the cold test (AOSA, 2002). The standard germination test measures seed viability under favorable conditions. The cold test is considered a vigor test and relates better to field emergence under a wide range of conditions (including stress associated with low temperatures) (AOSA, 2002).

MATERIALS AND METHODS

The seed quality of corn hybrids entered in 2007 and 2008 Ohio, Iowa and Wisconsin organic performance trials (Thomison et al., 2009) was assessed using the standard (warm) germination test (AOSA, 2009) and the cold test (tray method) (AOSA, 2002). In both the standard germination test and cold test, four replicates of 50-kernels of each seed lot were evaluated. In addition to organically produced hybrids, a conventionally-produced, untreated hybrid, widely used by organic corn producers in the north central region, and several open-pollinated varieties from public sources (USDA, university and the Michael Fields Institute) were included in the evaluation (Tables 1 and 2 ). Data from each state evaluation were subjected to an analysis of variance. When treatment effects were significant, means were separated using the LSD (0.05).

OBJECTIVEThe primary objective of this study was to evaluate the germination and vigor of organically produced hybrid corn seed which is marketed to organic corn growers in Iowa, Ohio and Wisconsin. In addition, the germination and vigor of untreated conventionally produced hybrid seed and untreated open pollinated seed from public breeding programs and a non-profit organization was also determined.

Hybrid  

State

Year

Organically Produced

Conventionally Produced

Open Pollinated

Iowa 2007 20 1 4

2008 20 1 4

       

Ohio 2007 23 2 7

2008 38 2 7

       

Wisconsin 2007 19 1 4

2008 22 1 4

Table 2. Hybrid and open pollinated entries evaluated in Iowa, Ohio and Wisconsin, 2007-2008.

Fig 2. Seed quality of organically and conventionally produced hybrids and open pollinated varieties. Iowa, 2007-2008.

2007

2008

Fig 3. Seed quality of organically and conventionally produced hybrids and open pollinated varieties. Ohio, 2007-2008.

2007

2008

Fig 4. Seed quality of organically and conventionally produced hybrids and open pollinated varieties. Wisconsin, 2008.

2008

RESULTSResults of the standard germination tests and cold tests for the three states are presented in Figures 2-4. Standard germination was consistently higher than cold test germination. Although organic produced hybrid entries differed for each state and year, standard germination of organically-produced seed, averaged across hybrids, was consistently high both years (>90%). Standard germination of the untreated conventionally produced hybrid seed and the OP varieties was also high. Cold test germination of organically produced and conventionally produced hybrids was lower than standard germination in 2008 than in 2007. This difference was especially pronounced for the 2008 Iowa and Wisconsin seed lots (Plate 1). Cold test germination of organically produced hybrid seed entered in the Iowa and Wisconsin tests in 2008 ranged from 13 to 100% and 33 to 95%, respectively. In Ohio, cold test germination of organically produced hybrid seed ranged from than 68 to 98%. Such differences in seed vigor among seed lots could explain some of the concerns of organic growers regarding the quality of organically produced seed. However, in this evaluation, % cold germination was also low in conventionally produced, untreated-hybrid seed. Cold test germination of conventionally produced, untreated-hybrid seed entered in the Iowa and Wisconsin tests in 2008 was 55% and 38%, respectively. Smaller differences in standard germination and cold test germination were exhibited by OP varieties. Cold test germination of the OP varieties was generally similar to that of organically produced hybrids.

CONCLUSIONS• The standard germination of organically produced hybrid seed was generally high (>90%).

• Seed quality of organically produced hybrids was comparable to a conventional check.

• Seed vigor of organically produced seed was highly variable among seed lots.

• Standard seed germination and cold test germination of OP seed similar to hybrid seed.

• Low vigor associated with organically produced seed may contribute to reduced and/or uneven stands if conditions are cold and wet at planting.

Plate 1. Differences in cold test results for two seed lots.

Low vigor (4% germination

High vigor result (100% germination)

ACKNOWLEDGEMENTSThis project was supported by a 2006 North Central Region Sustainable Agriculture Research and Education Grant.

REFERENCES

AOSA. 2008. Rules for testing seed. Association of Official Seed Analysts, Las Cruces, NM.

AOSA, 2002. Seed vigor testing handbook. Association of Official Seed Analysts, Las Cruces, NM.

ERS-USDA. 2005.Organic Production. http://www.ers.usda.gov/data/organic/#

National Organic Program (NOP). 2003. USDA-AMS, Washington D.C. (http://www.ams.usda.gov/nop)

Thomison, P., R. Elmore, J. Lauer, D. Stinner, K. Delate, S. Newman, and A. Geyer, 2007. Organic corn production practices across the Corn Belt. In Agronomy Abstracts, ASA, Madison WI.

Thomison, P., D. Stinner, J. Lauer, L. Frehill, L. Abendroth, R. Elmore, A. Geyer, and R. Minyo. 2009. Evaluation of the agronomic performance and grain quality of organic certified varieties and hybrids. In Agronomy Abstracts, ASA, Madison WI.

9997

94

91

80

85

90

95

100

% G

erm

inat

ion

Standard Germination Test Cold Test

Organically Produced Open Pollinated

98-100a

84-99a

LSD (0.05)=NS

LSD (0.05)=6

98 99 94

67

55

88

0

20

40

60

80

100

% G

erm

inat

ion

Standard Germination Test Cold Test

Organically Produced Conventionally Produced Open Pollinated

93-100

13-100

98 99

90

9596

87

80

85

90

95

100

% G

erm

inat

ion

Standard Germination Test Cold Test

Organically Produced Conventionally Produced Open Pollinated

93-100a

86-99a

99-100

93-99

83-98

69-98

LSD (0.05)=3LSD (0.05)=6

LSD (0.05)=6

LSD (0.05)=4

96 97

92 90

86

83

75

80

85

90

95

100

% G

erm

inat

ion

Standard Germination Test Cold Test

Organically Produced Conventionally Produced Open Pollinated

86-100

68-98

96-98

86-87

72-98

61-92

LSD (0.05)=4

LSD (0.05)=4

97 99 95

78

38

84

0

20

40

60

80

100

% G

erm

inat

ion

Standard Germination Test Cold Test

Organically Produced Conventionally Produced Open Pollinated

92-100a

93-98

33-95a

70-95

LSD (0.05)=3LSD (0.05)=7

2007• Blue River Hybrids (4)a • Cornelius (3)• Great Harvest Organics (4) • Pioneer Int’l Hybrid Inc. (1)• Prairie Hybrid Seeds (5) • Viking (4)• Iowa State University (1)• Michael Fields Agricultural Institute (3)

2008• Blue River Hybrids (4)• Cornelius (3)• Great Harvest Organics (5)• Pioneer Int’l Hybrid Inc. (1)• Prairie Hybrid Seeds (4)• Viking (4) • Iowa State University/USDA (1)• Michael Fields Agricultural Institute (3)

Table 1. Organic corn performance test entries.Iowa

Ohio2007

• Blue River Hybrids (8)• Doebler’s (3)• Great Harvest Organics (3)• Merit Seed Company (3)• Pioneer Int’l Hybrid Inc. (2)• Prairie Hybrid Seeds (5)• Viking (1)• Iowa State University (1)• Michael Fields Agricultural Institute (3)• Ohio State University (3)

2008• American Organic Seed and Grain (5)• Blue River Hybrids (9)• Doebler’s (2)• Great Harvest Organics (5)• Master Choice Hybrids (3)• Merit Seed Company (4)• Pioneer Int’l Hybrid Inc. (2)• Prairie Hybrid Seeds (5)• Welter Seed Company (5)• Iowa State University/USDA (1)• Michael Fields Agricultural Institute (3)• Ohio State University (3)

2007• Blue River Hybrids (3)• Brunner (5)• Cornelius (2)• Foundation Direct (3)• Prairie Hybrid Seeds (3) • Pioneer Int’l Hybrid Inc. (1)• Viking (3)• Iowa State University (1)• Michael Fields Agricultural Institute (3)

2008• Blue River Hybrids (5)• Foundation Direct (8)• Prairie Hybrid Seeds (3)• Pioneer Int’l Hybrid Inc. (1)• Viking (4)• Iowa State University/USDA (1) • Michael Fields Agricultural Institute (3)

Wisconsin

aNumber in parentheses indicates number of entries

66%

34%

ConventionallyProduced Seed

OrganicallyProduced Seed

- 85 hybrids planted- 8 hybrids accounted for most of acreage planted- 20% treated w/ organic fungicide or biostimulant

Fig 1. Source of seed used in organic corn production in Iowa, Ohio and Wisconsin (Thomison et al. 2007)

* Presenting author

aNumbers within bars represent range in germination/vigor among entries

aNumbers within bars represent range in germination/vigor among entries

aNumbers within bars represent range in germination/vigor among entries