Nine kinds of crop seeds were buried in the field at 1‐, 2‐, 3‐, 5‐, and 7‐inch depths in Saran mesh bags to determine seed longevity and dormancy. Generally, persistence and viability were lowest at the 1‐inch depth and increased with depth, with differential longevity among species. Seeds of perennial ryegrass declined in viability most rapidly; orchardgrass and chewings fescue lost their viability after three winters; Highland bentgrass and Oregon annual ryegrass retained considerable viability; and red clover was highest in viability.

Synopsis Increasing replications or increasing plot size permitted detection of smaller differences in yield of orchardgrass seed. Accuracy of yield estimates changed most rapidly with change in replications. Hence, on a given area, most accurate yield estimates would result with plots of minimum size and increased replications. Plot cost:land cost relationships showed that as land cost increased, optimum plot size decreased. Optimum plot size for close‐drills was about half that for 3‐foot rows.

Thirteen species and varieties of crop seeds were buried in the field at 2.6‐, 5.1‐, 7.6‐, 12.7‐, and 17.8‐cm (1‐, 2‐, 3‐, 5‐, and 7‐inch) depths in Saran mesh bags to study seed persistence and depletion. Persistence and viability tended to increase with increasing burial depth, especially in ‘Dixie’ crimson and ‘Pennscott’ red clovers. Seeds of ‘Illahee’ red fescue were depleted first; none were found in the 2nd year. No viable seeds of Danish commercial orchardgrass, ‘Alta’ tall fescue, or chewings fescue were found in the 3rd year. ‘Linn’ perennial ryegrass retained a trace of vialibity into the 4th year. Oregon annual ryegrass seeds showed viability in the 7th year. Seeds of ‘Highland’ colonial bentgrass, Dixie crimson clover, and Pennscott red clover had considerable viability in the 7th year. Some changes in field history requirements for certified seed production in certain species seem to be warranted.

In a 3‐year experiment we studied the effects of difterent planting rates and of early spring mowing on yields and quality of crimson clover seed. High planting rates generally hastened plant development and maturity. In non‐mowed stands, the 5.6 and 9 kg/ha planting rates resulted, in the best seed yields. Mowing generally increased seed yields, germination, and hard seeds, and it decreased 1,000‐seed weight as compared with non‐mowing. Planting at 13.4 kg/ha plus mowing resulted in the most seed. ]Low planting rates may favor seed production because flowering and maturity are later. Effects of mowing conducive to high seed yields are: decreased lodging; delayed flowering and seed maturity until favorable pollinating and harvesting conditions prevail; and reduced bulk of plant material for threshing.

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