Effect of burial depth and soil water regime on the fate of Lithospermum arvense seeds in relation to burial time.

CHANTRE, GUILLERMO RUBÉN; SABBATINI, MARIO RICARDO; ORIOLI, GUSTAVO

WEED RESEARCH

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Oxford; Año: 2009 vol. 49 p. 81 - 89

0043-1737

Lithospermum arvense L. is an increasing annual weed in winter crops of the semiarid region of southern Argentina under low impact tillage systems, an agricultural practice that has become popular in recent years. Seed distribution in the soil profile under conventional tillage will change when low impact practices are implemented, thus affecting germination microenvironment. The effect of seed burial depth and soil water regime on field germination, enforced dormancy, innate dormancy and seed decay was studied in relation to burial time in a field experiment. In addition, the effect of burial depth on seed germination and seedling emergence was examined under laboratory controlled conditions. Field germination ranged from 55 to 65% for shallow (2 cm) and from 5 to 30% for deeper (20 cm) buried seeds. Enforced dormancy levels were significantly higher among deeper buried seeds. The amount of innate dormant seeds was reduced to less than 10% after a year of burial. Lithospermum arvense seed banks can be classified as short-term persistent. Germination in the laboratory was unaffected by burial depth while seedling emergence reduction was adequately described by a sigmoidal model. Results indicate that agricultural practices that accumulate L. arvense seeds near the soil surface enhance seedling recruitment. Keywords: winter annual weed, seed bank, field germination, seedling emergence, enforced dormancy, innate dormancy, seed decay.