An urgent task of modern agriculture and biotechnology is the development of new environmentally friendly plant growth regulators to increase the growth and yield of plants and protect them from abiotic and biotic stress factors. Synthetic plant growth regulators Ivin, Methyur and Kamethur based on pyridine and pyrimidine derivatives are the most promising environmentally friendly biologically active compounds. Our laboratory, field and in vitro studies have proven their high efficiency in growing important agricultural, industrial, and floricultural crops. These synthetic plant growth regulators exhibit high growth-regulating activity when used at low non-toxic to human and animal health concentrations ranging from 10-5M to 10-8M. The practical use of synthetic plant growth regulators Ivin, Methyur and Kamethur for intensifying the growth and development of agricultural, industrial, and floricultural crops, increasing their productivity, and improving crop adaptation to stress factors is proposed.