Italian ryegrass (Lolium multiflorum Lam.) cv. Tetraflorum sown with different inter-row spacings and seeding rates was grown under the agroecological conditions of Western Serbia. Field experiments were carried out between 2002 and 2006, and biometric characteristics-generative tillers, seed yield, and shoot dry mass-were measured during the first production year. Italian ryegrass was grown with 3 row spacings (20, 40, and 60 cm), using 4 seeding rates (5, 10, 15, and 20 kg ha(-1)). Tiller length was affected by stand density, while 2 other tiller parameters were affected considerably less by the treatments applied. The influence of tiller characteristics on yield components was insignificant. The highest seed yield in the first production year varied with treatment, depending on seasonal conditions. Plant parameters and seed yield were impacted by inter-row spacing, marked, however, by an opposite impact in and and humid weather conditions. Inter-row spacing of 40 cm was the least risky for seed production. While the increase in seed rates (15-20 kg ha(-1)) in stand establishment provided higher seed yields in years with unfavorable weather conditions, the seed rate had either no impact on seed yield, or decreased the seed yield as a result of ryegrass lodging, following seed shedding in the years with favorable weather conditions. Abundant shoot dry mass was obtained with some treatment variants, but there was no linear correlation between seed yield and yield components.
