Increasing the efficiency and effectiveness of curation of the USDA-ARS world rice collection

Authors: McClung, Anna; Bockelman, Harold; Jia, Melissa; Edwards, Jeremy

Submitted to: Rice Technical Working Group Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 1/19/2018
Publication Date: 10/16/2018
Citation: McClung, A.M., Bockelman, H.E., Jia, M.H., Edwards, J. 2018. Increasing the efficiency and effectiveness of curation of the USDA-ARS world rice collection. Proceedings of 37th Rice Technical Working Group Meeting, February 19-22, 2018, Long Beach, California. p 79. Electronic Publication.

Interpretive Summary:

Technical Abstract: The world rice collection is part of the USDA-ARS National Small Grains Collection (NSGC) that includes the cereal crops wheat, oats, barley, and rye, as well as related wild species. The Oryza accessions include 12 species that comprise 9% of the NSGC collection. Over 19,000 rice accessions originating from 114 countries are in the collection. Seed of these accessions are rejuvenated, the plants and grain are phenotyped, and the data are made public through the Germplasm Resource Information Network (GRIN) website. All rejuvenation and phenotyping activities are performed at the Dale Bumpers National Rice Research Center (DBNRRC) in Stuttgart, AR and the harvested seed is provided to the NSGC in Aberdeen, ID where it is cleaned, stored, and distributed to the public. Each year the DBNRRC rejuvenates nearly 2000 accessions that have depleted seed reserves or seed quality has deteriorated due to length of storage. These accessions are grown either at the Stuttgart location or using winter nursery facilities. The rice collection has been characterized for some 42 traits over the years, many of these in response to recommendations by the Rice Crop Germplasm Committee. However, the whole collection has not been completely characterized for all traits. Over 60% of the collection has been phenotyped for such traits as grain amylose content, alkali spreading value (ASV), grain dimensions, plant height, days to heading, lodging, allelopathy, and salt tolerance. Other traits like grain aroma, protein content, parboiling loss, straighthead susceptibility, sheath blight tolerance, and ratoon ability have been characterized on a few hundred to a few thousand of the accessions, usually due to the difficulty or expense associated with analyzing the trait. The DBNRRC has endeavored to improve the efficiency and effectiveness of curation activities for the rice collection by implementing a number of new quality assurance procedures that utilize genotyping, bar-coding, and new field management methods. Because of the tremendous diversity of the collection, managing materials in the same field environment that differ by 120 days to heading, grow to over 160 cm in height, and are extremely susceptible to lodging, can be very challenging. We now organize planting of the accessions in the field according to previous data regarding days to heading. This facilitates data collection and harvest on the earliest maturing accessions first. In addition, because of the susceptibility to lodging, we have limited the amount of nitrogen fertilizer applied to the field to 56 kg/ha and have increased the space between accession-plots to 0.6 m to prevent the possibility of seed mixtures at harvest. Because of the large number of accessions that are rejuvenated each year, only a single field plot is included of each. However, plots of the US adapted varieties Presidio (early maturing, semidwarf) and Rondo (late maturing, medium height, lodging susceptible) are repeated throughout the field and height and heading data are collected as means of assessing field variability and the relative adaptation of the NSGC germplasm to the southern US growing environment. Field books are made that include previous phenotypic data on the accessions as means of verification that planting or seed mix-ups have not occurred. Accessions that have been in storage for nearing 20 years are grown to assure distribution of seed sources with good viability. In the past, these were planted in the field without any prior knowledge of viability resulting in many plots with failed plant stands, an inefficient use of labor and research facilities. Over the last two years, we have implemented a new germplasm tracking program to increase the efficiency of curation activities. Accessions are received from NSGC at the beginning of the year, to allow time for germination tests. Bar-codes are ge