EN
Perennial forage crops are subjected to numerous stresses throughout the lifetime of meadows and pastures. Biotic and abiotic stresses can be manifested as reactions in vigor or quality of legumes and grasses sod up to complete stand mortality including all intermediate possibilities. Breeding for stress tolerance is complicated largely by the need for a screening procedure that is constant, repeatable, and meaningful. The study and results indicated that the very effective is wide hybridization and fenotypic recurrent selection which significant improvement of resistance for biotic and abiotic stresses. Introduction of foreign genes by plant transformation will eventually allow development of new cultivars from stress - tolerant transgenic plants.