Factors affecting germination and seed production of Eriochloa villosa

Laboratory and field experiments were conducted to determine the effects of light, temperature, oxygen, and seed burial depth on seed germination and seed production of Eriochloa villosa without the interference of a crop. Er iochloa villosa seed germination did not respond to light, although it is p ossible that: experimental conditions were not appropriate for this respons e to develop. Seeds germinated above 10 C and below 45 C, with germination above 85% occurring for temperatures between 20 and 40 C. Seed germination rate and total germination increased as the oxygen concentration increased to the ambient level. Eriochloa villosa seed emerged from 15 cm deep, with maximum emergence from 1 to 4 cm. In the field, emergence was dependent on tillage that affected the vertical distribution of seeds in the soil. Seeds emerged in the reduced-tillage field from between 0.5 and 9 cm deep in soi l, with maximum emergence from 2 cm. A delay in planting greatly reduced th e growth and seed production of E. villosa. Seed production under noncompet itive conditions was reduced by at least 75% when planting was delayed 6 to 8 wk. However, plants that emerged after July 7 still produced approximate ly 3,000 seeds when grown under conditions without intraspecific and inters pecific competition.