The Use of Thioxopyrimidine Derivatives as New Regulators of Growth and Photosynthesis of Barley

New synthetic compounds - thioxopyrimidine derivatives as regulators of vegetative growth and photosynthesis of spring barley (Hordeum vulgare L.) variety Acordine were studied. The growth-regulatory effect of new synthetic compounds, thioxopyrimidine derivatives, used in a concentration of 10-6M, was compared with the growth-regulatory effect of a plant hormone auxin IAA (1H-indol-3-yl)acetic acid) or synthetic plant growth regulators, derivatives of sodium and potassium salts of 6-methyl-2-mercapto-4-hydroxypyrimidine (Methyur, Kamethur), N-oxide-2,6-dimethylpyridine (Ivin), used in a similar concentration of 10-6M. The conducted study showed the similarity of the growth-regulatory effects of synthetic compounds, thioxopyrimidine derivatives, the plant hormone auxin IAA, and synthetic plant growth regulators Methyur, Kamethur, and Ivin. Morphometric parameters (average length of shoots (mm), average length of roots (mm), and average biomass of 10 plants (g)) and biochemical parameters (content of photosynthetic pigments chlorophylls a, b, a+b and carotenoids (µg/ml)) of barley plants treated with the plant hormone auxin IAA or synthetic plant growth regulators Methyur, Kamethur, Ivin or thioxopyrimidine derivatives were increased after 4 weeks compared to control plants. The dependence of the growth-regulatory effect of synthetic compounds, thioxopyrimidine derivatives on their chemical structure was analyzed. The use of the synthetic plant growth regulators, derivatives of sodium salt of 6-methyl-2-mercapto-4-hydroxypyrimidine (Methyur), potassium salt of 6-methyl-2-mercapto-4-hydroxypyrimidine (Kamethur), N-oxide-2,6-dimethylpyridine (Ivin) and selected most active synthetic compounds, thioxopyrimidine derivatives for regulating the growth and photosynthesis of spring barley (Hordeum vulgare L.) variety Acordine is proposed.