The objective of this study was to determine the concentrations of isoflavones in the cultivars and ecotypes of red clover (Trifolium pratense L.) in a whole above ground part of a plant and separately in stems, leaves and flowers at flowering stage. Isoflavones were extracted using acidified aqueous methanol and subsequent analyses of the extracts were carried out by ultra-performance liquid chromatography coupled with a photodiode array detector. Red clover accumulated the highest concentrations of formononetin (51%) and biochanin A (40%) at flowering stage.

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The current study was set out to establish the efficacy of different mitosis inhibitors (colchicine, amiprophos-methyl, trifluralin and oryzalin) used in the production of red clover (Trifolium pratense L.) and alsike clover (Trifolium hybridum L.) polyploids and to assess the agrobiological traits of tetraploid populations. Four cultivars and five wild populations of T. pratense, one cultivar and three wild populations of T. hybridum were used for polyploidization. The effect of conventional soaking of germinating seeds in a colchicine solution was compared with that of colchicine treatment of embryos in an in vitro culture. Colchicine treatment of T. pratense embryos resulted in 3.3 times higher production of tetraploids (teraploid yield 55.0%) compared with colchicine treatment of seedlings, and the production of chimeric plants was 1.9 times lower. The different mitosis inhibitors were characterised by a diverse polyploidization effect. Tetraploid yield depended not only on the mitosis inhibitor used but also on the plant species. Treatment of T. pratense embryos with colchicine, amiprophosmethyl and oryzalin yielded similar results in terms of tetraploid production (31.3-40.7%) and chimeras (14.3-22.4%). The concentration of trifluralin used for the production of T. pratense tetraploids was ineffective. Colchicine solution was more efficient for the development of T. hybridum tetraploids whose yield was 2.5 times as high as that obtained having treated the embryos with amiprophos-methyl. Induced tetraploid populations were compared to reference cultivars in field trials. The two T. pratense populations 'Radviliai 4n' and 'Arimaičiai 4n' stood out in this respect -their plants accumulated higher dry matter contents, produced more inflorescences than those of the reference cultivar and exhibited prolific seed yield capacity. In relation to the agrobiological traits, the tetraploid populations of T. hybridum did not surpass the reference cultivar.

Red clover (Trifolium pratense L.) is very productive in the first two years of harvest but afterwards it tends to thin out dramatically and finally die. In Lithuania, the main disease causing this problem is Sclerotinia crown and root rot (Sclerotinia trifoliorum Eriks.). The present study was aimed to determine red clover resistance to Sclerotinia crown and root rot in the laboratory and field conditions. Investigations were carried out at Institute of Agriculture, Lithuanian Research Centre for Agriculture and Forestry. Resistance of red clover varieties and breeding lines to Sclerotinia crown and root rot was investigated in 2012-2014 in the field under natural and artificial infection conditions. Diploid (43: 20 varieties, 20 breeding lines, 2 wild ecotypes and 1 semiwild ecotype) and tetraploid (41: 24 varieties and 17 breeding lines) red clover was investigated. In the laboratory experiment, red clover seeds were treated with oxalic acid which is the main toxin of Sclerotinia spp. This experiment enabled us to evaluate seedling resistance to Sclerotinia crown and root rot. The same varieties and breeding lines as in the field experiment were investigated. The seedlings were treated with 0, 5, 7.5, 10, 15, 20 and 30 mM oxalic acid concentrations. The most resistant varieties were found to be '

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