Seed production by couch grass (Agropyron repens)

See also Weed Abstr. 18: 1260. The literature is reviewed. Seed samples were collected from >250 fields in many parts of England and Wales near harvest time; the samples came from a wide range of soil types and from 16 different crops (but mostly from spring barley and winter wheat). About 95% of samples contained viable seed and the number of viable seeds per head averaged 13. It was deduced that in some areas A. repens may form 2000-3000 viable seeds/yd2. The mean germination of couch seed (as compared to florets) was >60%. The amount of viable seed produced depends on the crop in which the weed is growing, the density of seed heads, the proximity of different genotypes, the weather and the length of time between the flowering of the weed and crop harvest. The behaviour of the seed and some practical implications of seed production are discussed.-P.K.