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ARS Home » Southeast Area » Mayaguez, Puerto Rico » Tropical Crops and Germplasm Research » Research » Research Project #434218

Research Project: Seed Increase, Evaluation, and Phytosanitary Assessment of Quarantined and Tropically-adapted Genetic Resources

Location: Tropical Crops and Germplasm Research

2020 Annual Report

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.

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
Very severe damages to the infrastructure of the station resulted from Hurricane Maria impacting the island of St. Croix, U.S. Virgin Islands, on September 2017. The main building, where offices and work laboratories were located, was completely lost. Storage areas for supplies and materials, shelters for farm equipment and implements, a mechanical shop area, the threshing and processing building, and the irrigation infrastructure also suffered significant damage. The threshing and processing building, and the key irrigation infrastructure were temporarily repaired (“quick fix”) and regeneration efforts on sorghum, corn, and other crops have continued as best as possible, except for the repair of the pond liner and cover, no other repairs have started for various reasons. The USDA frost-free winter nursery serves the research efforts of 7 soybean breeders and geneticists on the mainland. In collaboration with ARS researchers at Mayaguez, Puerto Rico, breeding efforts are carried out to incorporate new genetic diversity from exotic Asian soybean germplasm into advanced soybean germplasm. These research efforts improve seed yield, seed composition and abiotic stress tolerance. Why do ARS researchers at Mayaguez, Puerto Rico, have a winter nursery for soybean? -- Developing new USDA soybean germplasm requires eight seasons of soybean production. The first five are needed to mate the parental stock and develop true-breeding progeny. An additional three years are required to yield test the progeny on the mainland and ‘pick the winners’ for farmer or other commercial use. Normally, 8 seasons of breeding requires 8 calendar years of research. However, ARS researchers at Mayaguez, Puerto Rico, can shorten the process two years by growing extra crops of soybean 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, and Georgia were developed using USDA Puerto Rico winter nursery. This season the USDA winter nursery was planted on December 10, 12 and 16, 2019 and January 2020 and harvested throughout March, April and early May, 2020. ARS researchers at Mayaguez, Puerto Rico, took data that included stand counts, flower color and pubescence color. Soybean breeders grew approximately 3500 individual F1 plants and 14 large bulk-harvested rows of soybean 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, breeders grew approximately 50,000 plants in the unlighted (normal day length) 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 airlifted to North Carolina for spring planting. The winter nursery liaison from Raleigh, North Carolina visited the USDA soybean winter nursery at Isabela, Puerto Rico in early March to confer with the staff on production. Due to Covid19, technicians from North Carolina were not able to assist with harvest this year. Communication with the new LAN Soybean Manager went well. Seed yield of the harvested F1 plants averaged 150 seeds per plant. Leaf samples were taken for DNA analysis from 5 rows mid-way during the growing season.