Location: Tropical Crops and Germplasm Research
2023 Annual Report
Objectives
Objective 1. Efficiently and effectively regenerate under quarantine, and under tropical, equatorial conditions, genetic resources of grain, legume, and vegetable crops to maintain their safety, genetic integrity, health, and viability. Following seed increase and/or quarantine assessment, release seed supplies of those genetic resources to other USDA National Plant Germplasm System (NPGS) genebanks for maintenance and distribution.
Objective 2. Characterize and evaluate for priority traits the genetic resources of grain, legume, and, vegetable crops regenerated for seed increase and/or quarantine assessment. Record and disseminate evaluation and characterization data via Germplasm Resources Information Network (GRIN)-Global and other data sources.
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
This is the final report for the project 6090-21000-056-000D which terminated in May 2023 and was replaced by 6090-21000-060-000D. Substantial results were realized over the 5 years of the project.
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-Global). Accessions of sorghum, corn, cowpea, Leucaena, cucurbits, Ipomoea and small legumes are being regenerated at St. Croix, U.S. Virgin Islands., and descriptor notes for phenotypic traits are being recorded. During the life of this project the following number of accessions were seed regenerated: 4,115 sorghum, 101 corn, 431 pearl millet, 251 cowpea, 11 cucurbits, 60 Leucaena, 10, Lablab, 20 Macroptillum, 7 Mucuna, 14 Ipomoea. Phenotypic descriptors for all the above accessions were recorded and provided to curators for incorporation into GRIN. All fall/winter 2017 regenerations which would have been reflected in this report were lost due to severe damage from Hurricane Maria.
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 2022-23 season the USDA winter nursery was planted in December 2022 and harvested throughout March, April and early May, 2023. USDA-ARS employees in Puerto Rico took data that included stand counts, flower color and pubescence color. Soybean breeders grew approximately 3877 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 57740 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 Animal and Plant Health Inspection Service (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. Due to Covid19, technicians from North Carolina were not able to assist in planting or harvesting this year. 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
