[Response of flowering plant seedlings to the action of N-nitroso-N-methylurea].

The influence of N-nitroso-N-methylurea on seedlings of two species of plants--Cucurbita pepo L., Helianthus annuus L.--was investigated. NMU was added in agar-agar, on which seedlings were growing. 0.02% concentration of NMU was used. In addition to the delay in growth and appearance of necrotic regions, also local overgrowth of cotyledons of C. pepo and overgrowth of hypocotyl and the base of cotyledons of H. annuus were observed. A histological analysis has shown that these swellings arise due to two processes: pathological hypertrophy and proliferation.