Differences in Yield of Diploid and Tetraploid Red Clover in Lithuania

The research was carried out in 2003-2011 at the Institute of Agriculture, Lithuanian Research Centre for Agriculture and Forestry. The fresh forage, dry matter (DM) and seed yields of red clover diploid and tetraploid populations and cultivars were determined. In total 58 diploids and 35 tetraploids were evaluated during four cycles in the study period. The average DM yield of diploids was 16.6 t ha -1 and of tetraploids was 17.8 t ha -1 . The tetraploid average DM yield surpassed that of diploids by only 6.5%. The seed yield was very low over the period. The average seed yield of diploids was 110.4 kg ha -1 . The average seed yield of tetraploids was 94.9 kg ha -1 . The diploid average seed yield was higher than that of tetraploids by 16.3%. The highest negative impact on seed yield was due to wet weather in the seed harvest year, which was favourable for development of diseases on above-ground plant parts. The study showed that tetraploid red clover had no significant advantage over diploid red clover in DM yield under Lithuanian conditions. Variation in seed yield showed that production of diploid red clover seed is less problematic. It seems that only directed disease resistance breeding can improve seed yield as well as forage yield of red clover.