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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

2021 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, United States 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 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, including meeting SHPO requirements. Animal and Plant Health Inspection Service (APHIS) regulations concerning growouts of quarantine crops in the open field have changed. As a result, quarantine growouts have not been carried out by ARS scientists at Mayaguez, Puerto Rico during the last two years. Conversations to renew the permit are ongoing between the location, Office of National Programs, and key APHIS personnel to have the permit renewed. The USDA frost-free winter nursery serves the breeding efforts of 7 soybean breeders and geneticists on the mainland. ARS scientists at Mayaguez, Puerto Rico in collaboration with these scientists, 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 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 breeding requires 8 calendar years of research. However, ARS scientists at Mayaguez, Puerto Rico 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. This season the USDA winter nursery was planted in December 2020 and harvested throughout March, April and early May, 2021. ARS scientists at Mayaguez, Puerto Rico employees took data that included stand counts, flower color and pubescence color. Soybean breeders grew approximately 3000 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 70,000 plants were grown in the unlighted (normal PR day length) area. For the unlighted plants, 1 pod per plant was harvested manually by ARS scientists at Mayaguez, Puerto Rico, 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. 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.