Effect of air humidity on the development of functional stomatal apparatus

Phaseolus vulgaris L. seedlings were grown under different air humidities simulating conditions during micropropagation (very high humidity duringin vitro cultivation and low air humidity after transferex vitro). The functional stomatal apparatus developed after a short period of growth at low air humidity at the beginning of plant ontogeny or after transfer from high to low air humidity, but not in plants grown steadily under high air humidity. The ability of stomata to regulate gas exchange was not persistent and disappeared after transfer of plants from low to high humidity. The author thanks Mrs. L. Kolčabová for her skilled assistance. The paper is a part of the project supported by the grant No. 501/95/1303 of the Grant Agency of the Czech Republic.