Seed germination and seedling emergence of threehorn bedstraw (Galium tricornutum)

Threehorn bedstraw is an important dicotyledonous weed of winter crops in southern Australia, which can be difficult to control in some field crops. Knowledge of the germination ecology of this weed would facilitate development of effective weed control programs. Seed germination in the laboratory was greater for seeds that after-ripened while buried in the soil relative to those that after-ripened on the soil surface. The timing of greatest seed germination in the laboratory was found to coincide with the period of low temperature in the field. Seed germination of threehorn bedstraw was moderately sensitive to salt stress but moderately tolerant to osmotic stress. Seeds of threehorn bedstraw germinated over a broad range of pH from 4 to 10. No seedlings emerged from seeds placed on the soil surface. Maximum seedling emergence occurred at depths of 1 to 2 cm (89 to 91%) and declined at greater depths.