Seed yield of tetraploid red clover as influenced by cover crop management

Red clover for seed production is generally sown under cover crops.The warming climate raises a hypothesis that six-row barley cultivars might be replaced by intermediate cultivars of two-row barley as cover crops for establishing red clover seed production stands.The cover crop spring barley (Hordeum vulgare L.) cultivar 'Maali' was sown with four different cover crop treatments: 1) seeding rate 333 viable seeds per m², fertilisation rate 60 kg ha -1 N; 2) seeding rate 500 viable seeds per m², fertilisation rate 60 kg ha -1 N; 3) seeding rate 500 viable seeds per m², fertilisation rate 90 kg ha -1 N; 4) seeding rate 333 viable seeds per m², fertilisation rate 90 kg ha -1 N. The tetraploid red clover cultivars 'Varte' (early) and 'Ilte' (late) were sown at the rates of 2, 4, 6 and 8 kg ha -1 in four replicates using a randomised complete plot design.The height and density of generative tillers of barley, the grain yield and quality, the number of red clover plants per m² were measured in the sowing year.The seed yield and quality of red clover in the first harvest year were determined.Economic calculations were based on the prices valid in 2013-2014.The nitrogen rate and seeding rate had a significant effect on elongation of generative tillers, as well as increasing plant density, grain yield and protein content.Increased seed rate of the cover crop (500 viable seeds m²) and higher fertilization rate (90 kg ha -1 N) decreased red clover seed yield to 10 %.Increasing of only the seed rate of a cover crop, resulted in up to 4 % reduction in the red clover yield.The higher nitrogen rate (90 kg ha -1 N), when barely was sown at a rate of 500 viable seeds m² and at 300 viable seeds m², resulted in up to 5 % reduction in red clover seed yield.The study showed that it is practical to establish a seed production stand of red clover using a seeding rate of 4-6 kg ha -1 .It can be concluded that two-row barley cultivars are also recommendable cover crops besides the currently used six-row barley cultivars.Economic analysis indicated that it is practical to reduce both the seeding rate of the cover crop and nitrogen rate by one third.