EFFECT OF SEPARATING GIANT FOXTAIL (SETARIA-FABERI) SEEDS FROM SOIL USING POTASSIUM CARBONATE AND CENTRIFUGATION ON VIABILITY AND GERMINATION

Changes in weed seedbank composition are often monitored by removing s eeds from soil samples. One extraction method accomplishes this by cre ating a slurry of soil and a concentrated inorganic salt solution. Cen trifugation is then used to separate constituents of differing densiti es. We have found that centrifugation of giant foxtail seeds in 3.2 M potassium carbonate solution as conducted in a centrifugation/flotatio n extraction method can reduce viability as measured by germination an d tetrazolium tests. In one experiment, centrifugation/flotation separ ation reduced germination of giant foxtail seeds from 94 to 52%. The l ikely cause of seed damage was the high pH of the potassium carbonate solution in conjunction with the increased hydrostatic pressure due to centrifugation. While centrifugation affected quantitative measures o f seed viability, it did not alter qualitative viability estimates usi ng a pressure test.