THE NINETY‐YEAR PERIOD FOR DR. BEAL'S SEED VIABILITY EXPERIMENT

In 1879 Dr. W. J. Beal selected seeds of 23 different species of locally common plants, mixed 50 seeds of each species with moist sand in unstoppered one-pint bottles, and buried the bottles in a sandy knoll to be unearthed and the viability of the seeds tested periodically. The year 1970 marked the ninetieth year the seed had been buried, and the thirteenth bottle was recovered to test for seed viability. Of the three species which had germinated in the 1960 test (curly dock, Rumex crispus; evening primrose, Oenothera biennis; and moth mullein, Verbascum blattaria), only V. blattaria had viable seed with 20% germination. No other species germinated. All ten seedlings of V. blattaria were grown to maturity, and seeds were then harvested to study the possible deviations from normality and the requirements for seed germination. All seedlings emerging from the first progeny seed appeared normal. The most prominent requirement for germination was light, and this is a possible explanation of why the seeds had remained viable but dormant for so long a period. One-third of the freshly harvested seed germinated in darkness and, furthermore, redrying of dark-moistened seed in the absence of light induced additional germination. Germination of dark-moistened seed was not completely restored when the still moist seeds were subsequently exposed to light. However, when dark-moistened seeds were dried and then remoistened in the light, germination was about 95 %. About 5 % of the seed did not germinate under the conditions used. We find that 5 % of the population of V. blattaria seeds are dormant for unknown reasons, that 30 % will germinate if supplied only with moisture, and that 65 % are inhibited and require light and moisture simultaneously for germination. Supplying this 65 % of the population with moisture in darkness results in the development of a second type of inhibition which is no longer light reversible. It appears that the simultaneous requirement for light and moisture is an important factor in permitting V. blattaria seeds to remain dormant during prolonged burial. THE SPRING OF 1970 marked the 90-year period for the seed viability experiment initiated by Dr. W. J. Beal, then professor of botany and forestry at the Michigan Agricultural College in East Lansing. The experiment is best described by Dr. Beal (1905): "In the autumn of 1879 I began the following experiments, with the view of learning something more in regard to the length of time the seeds of some of our most common plants would remain dormant in the soil and yet germinate when exposed to favorable conditions. I selected fifty freshly grown seeds from each of twenty-three different kinds of plants. Twenty such lots were prepared with the view of testing them at different times in the future. Each lot or set of seeds was well mixed in moderately moist sand, just as it 1 Received for publication 12 May 1972. This work was supported, in part, by The National Science Foundation (GB-18353X). Journal Article No. 5920 from the Michigan Agricultural Experiment Station. We wish to thank Professor J. A. D. Zeevaart and Mr. Donald E. Davis for their help and consultation and for the use of greenhouse facilities supported by the Atomic Energy Commission, Contract AT-(11-1)-1338. was taken from three feet below the surface, where the land had never been plowed. The seeds of each set were well mixed with the sand and placed in a pint bottle, the bottle being filled and left uncorked, and placed with the mouth slanting downward so that water could not accumulate about the seeds. These bottles were buried on a sandy knoll in a row running east and west." During the first 35 years of the experiment, germination tests were performed every fifth year, and every tenth year thereafter (Beal, 1884, 1885, 1889, 1894, 1904, 1905, 1911; Darlington, 1922, 1931, 1941, 1951; Darlington and Steinbauer, 1961). The thirteenth bottle was recovered for testing on April 18, 1970, leaving seven more bottles for future tests. GERMINATION TESTS WITH THE BEAL SEEDSGermination tests were performed in a greenhouse during the summer months of 1970. A soil mixture, consisting of approximately equal parts of well-sifted loam, sand, and muck soil, was steamsterilized for 12 hr under 10-12 lb pressure. Three clean plastic trays, with perforated bottoms