EFFECT OF AIR HUMIDITY ON THE DEVELOPMENT OF FUNCTIONAL STOMATAL APPARATUS

Phaseolus vulgaris L. seedlings were grown under different air humidit ies simulating conditions during micropropagation (very high humidity during in vitro cultivation and low air humidity after transfer ex vit ro). The functional stomatal apparatus developed after a short period of growth at low air humidity at the beginning of plant ontogeny or af ter transfer from high to low air humidity, but not in plants grown st eadily 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.