VARIATION IN SEED YIELD OF COCKSFOOT (DACTYLIS-GLOMERATA L) IN FINLAND

Variation in seed yield of cocksfoot was studied by using data from trials on seed production of cultivars conducted at the Agricultural Research Centre in 1977-1990. Totally 32 trials of cv. Haka were available from three research sites in Southern Finland. Six cultivars were included in the study. The seed yield ranged from 0 to 697 kg ha-1 for cv. Haka. The average seed yield for cv. Haka was 258 kg ha-1 for the 32 harvests. Second year stands produced on average a higher seed yield (343 kg ha-1) than first (208 kg ha-1) and third (2 16 kg ha-1) year stands. In ten out of the total 32 harvests, seed yield was 150 kg ha-1 or less. The average seed yield of cocksfoot was low compared to seed yield of cocksfoot in Sweden, Norway and Denmark, and compared to seed yield of timothy, meadow fescue and perennial ryegrass in Finland. The reasons for the low seed yield were inadequate floral evocation in the first harvest year when the stand was established with a cover crop, high winter damage due to freezing and/or ice cover and early summer frosts at the panicle growth stage. Early summer drought and pre-harvest shedding also reduced the seed yield in some trials. Cv. Haka had a significantly higher density of panicles and produced significantly higher seed yield than cvs. Tatu, Hera Daehnfeldt, Fala and Frode. The difference between cvs. Haka and Tammisto was neither significant in terms of seed yield nor in panicle density. The correlation coefficient between seed yield and visually evaluated (scale 0-100%) density of panicles ranged from 0.74 to 0.98 for different cultivars and was significant for all cultivars. The correlation coefficient between density of panicles and ground cover in the spring was significant only in cvs. Haka and Tammisto. The data suggest that differences between cvs. Haka and Hera, Fala, Tatu and Frode in seed yield and in density of panicles were due to differences in the fulfilment of floral evocation.