APPLICATION OF EMBRYO RESCUE IN RECOVERING RICE (ORYZA-SATIVA L) GERMPLASM

Conservation of existing germplasm is essential because of the constant erosion of gene pools and native germplasm throughout the world. Conservation of rice (Oryza sativa L.) germplasm, especially accessions in the rice portion of the USDA-ARS Small Grains Collection, is essential because rice is not native to the United States. This study was conducted to determine if rice accessions that did not emerge when seeded in the field could be rejuvenated in the laboratory. Six-thousand rice accessions were seeded at the Rice Research and Extension Center, University of Arkansas, Stuttgart, AR, in 1991. Two-hundred-and-eleven of the accessions, originally introduced from 21 countries, failed to emerge in the field. The viability of these accessions was tested in the growth chamber, on agar medium, and by an embryo culture method. Germination in the growth chamber recovered 27 lines that had been stored for an average of 10.6 yr at Beltsville, MD, and Aberdeen, ID. Fifty-eight additional lines with an average storage age of 15.2 yr were rejuvenated by culturing the grain on agar medium. Embryo culture was used to test the remaining 126 lines, and 76 lines with an average storage time of 19.1 yr survived and produced seeds. All three laboratory techniques recovered rice germplasm that did not emerge in the field. However, embryo culture was superior to grain culture and both of these methods were more effective in rejuvenating rice germplasm than the growth chamber method.