Location: Tropical Crops and Germplasm Research
2024 Annual Report
Objectives
1. Maintain the safety, genetic integrity, health, and viability of priority genetic resources through seed increases and release of quarantined NPGS accessions of grain genetic resources.
2. Generate phenotypic evaluation and morphological characterization data for genetic resources cultivated for regeneration and/or release from quarantine and incorporate those data into the GRIN-Global information management system.
Approach
Select and treat seed for freedom of signs and symptoms of pathogens; conduct annual disease surveys; inspect and verify status of plants (PPQ); grow quarantined and/or photoperiod-sensitive crops, report new diseases, maintain low pest levels, bag heads prior to anthesis; identify diseases and take regulatory action; record key descriptor information for entry into Germplasm Resources Information Network (GRIN), harvest seed and examine for disease symptoms; and return seed to National Plant Germplasm System (NPGS).
Progress Report
Research in this project is service oriented and assists ARS curators with the introduction of new germplasm, seed regeneration and increase, and recording of descriptor notes for entry into the Germplasm Resources Information Network (GRIN). Accessions of sorghum, corn, cowpea, cucurbits, and Ipomoea are being regenerated at St. Croix, U.S. Virgin Islands and Isabela, Puerto Rico, and descriptor notes for phenotypic traits are being recorded.
For the first time in several years a quarantine planting was grown at the facilities and seed regenerated and released for the first time for breeding programs thanks to the Animal and Plant Health Inspection Service (APHIS) permit being renewed after significant restrictive hurdles were cleared with APHIS.
The USDA frost-free winter nursery serves the breeding efforts of 7 public soybean breeders and geneticists on the mainland. In collaboration with these scientists, breeding efforts are carried out to incorporate new genetic diversity from exotic Asian soybean germplasm and wild soybean (G. soja) into U.S. adapted elite soybean lines. These research efforts improve seed yield, seed composition and abiotic stress tolerance. Why do we have a winter nursery for soybean? – Developing new soybean germplasm/cultivars requires eight to nine years. The first five are needed for developing the hybrid progeny and several generations of inbreeding of the hybrid progeny to get the stable inbred progeny. An additional three to four years are required to yield test the progeny in the mainland and ‘pick the winners’ for release.
Normally, 8 seasons of soybean breeding requires 8 calendar years of research. However, we can shorten the process two years by growing extra seasons of the early breeding material at the USDA-ARS Research Farm at Isabela during the mainland’s off-season for soybean (November through April). This Isabela site is an excellent winter nursery environment for soybean breeding. The importance of the winter nursery is highlighted by the fact that all of the USDA soybean germplasm released from North Carolina and most public germplasm from Mississippi, Tennessee, Georgia and occasionally few other states were developed using USDA Puerto Rico winter nursery.
During the 2023-24 season the USDA winter nursery was planted in December 2023 and harvested throughout April and May, 2024. USDA-ARS employees in Puerto Rico took data that included stand counts, flower color and pubescence color. Soybean breeders grew approximately 2143 individual F1 plants under extended light conditions. Extended light simulated summer day length on the mainland and increased plant height so that plants produced adequate yields. In addition to the lighted area, approximately 47,000 plants were grown in the unlighted (normal PR daylength) area. For the unlighted plants, 1 pod per plant was harvested manually, following the single seed descent method of soybean breeding. After harvest and prior to APHIS inspection, all seeds were shelled, cleaned manually and diseased seed were discarded. After seed inspection, seed were boxed and mailed to North Carolina ahead of spring planting. Communication with the winter nursery staff members went well. Seed yield of the harvested F1 plants and the return on the single seed descent lines were better than the previous year. Despite the mounting challenges from COVID-19, the staff members of the winter nursery did a commendable job to achieve such excellent results.
Accomplishments