Photosensibilite des bromes annuels (Bromus L. spp.)

Photosensitivity of annual bromes (Bromus L. spp.) Increased awareness by fanners of the problem of brome grasses in cereals stimulated work to sec if the germination characteristics of these species could explain their field behaviour. This paper reports on the response of bromes to light in particular. Twelve annual species were tested: six of the sub-genus Bromus and six of the sub-genus Anisantha Koch; Bromus cartharticus Vahl was included because it can behave as an annual. Response to light was very marked especially at low temperatures when it inhibited germination. The species were compared on the basis of their geographical origin. Negative responses to light were very important for the sub-genus Anisantha Koch and for samples from the Mediterranean area. The intensity and persistence of the phenomenon indicates it could play a significant role in determining the behaviour of these grasses under natural conditions.