New Sorghums Thrive Under Typical U.S. Day Length

New sorghums that flourish under day length conditions typical in the Unites States could result from a large-scale genetic screening program now being coordinated by Agricultural Research Service scientists and cooperators.

The ARS Plant Genetic Resources Conservation Unit in Griffin, Ga., under the direction of sorghum coordinator Gary Pederson, provided almost 25,000 sorghum accessions to researchers who then evaluated them for a trait known as photoperiod sensitivity. Photoperiod--the cycle of light and darkness a plant receives--is tied to day length, which increases during the long days of the U.S. growing season.

Certain sorghums don’t grow well during these long days in the United States. Only sorghum that is insensitive to day length will reach full maturity and produce harvestable seed in this country.

The sorghum accessions tested were obtained from the ARS national “active collection” of sorghum germplasm. In Texas, scientists grew the plants and evaluated them for their photoperiod sensitivity. This was an ARS collaboration with the Sorghum Crop Germplasm Committee, National Grain Sorghum Producers, and university and industry scientists.

In this cooperative study, scientists determined that 4,193 accessions should be selected because they are less sensitive to day length. That quality was then entered into the Germplasm Resources Information Network for use by researchers worldwide. In spring 2001, seed from these accessions was sent to cooperating private companies so that additional seed could be produced from these plants.

This seed was then sent back to the Griffin lab for processing, cleaning, and counting for distribution during spring 2002 to sorghum breeders and other interested users. The seeds will be grown out at locations in Texas and Kansas this summer for evaluation.

Distribution of seed allows plant breeders to incorporate new genetic diversity into crops and provides growers with cultivars that have desirable genetic traits for various growing conditions.

The national sorghum collection is evaluated and regenerated at Mayaguez, Puerto Rico, and a base collection is maintained in long-term storage at Ft. Collins, Colo.

ARS is the chief scientific research agency of the U.S. Department of Agriculture.