Information concerning corn plant development within predicted environmental constraints and the possibility of alleviating their negative infl uence by ecological compounds is limited. Thus the aim of our research was to evaluate the physiological activity, growth, and development of corn plants under the expected climate-change conditions and treated with Biojodis (certifi cated extract of humus and active iodine; Jodavita, Lithuania) and Cyanobacteria (a mixture of monocultures of Microcystis aeruginosa MKR 0105 and Anabaena sp. PCC 7120). ‘Cyrkon’ corn plants (Zea mays L.) were cultivated in several simulated predicted climate conditions, including constant or periodically changing temperature and soil moisture content. During the vegetative season they were treated at three-week intervals using Biojodis at concentrations of 1.0, 2.0, or 3.0%, and Cyanobacteria, and then assessed using growth and physiological parameters. The obtained results showed the corn’s different reactions to the applied conditions. Plants that grew at constant or periodically changing different temperatures (0 to 40ºC) or in unsatisfactorily (20% m.c.) or excessively (60% m.c.) watered soils, developed slowly in comparison with those growing at 20ºC and in optimally moistened media (30% m.c.). Watering, spraying, or watering and spraying of corn plants with Biojodis (1, 2, 3%) and a foliar application of Cyanobacteria increased their growth at optimal or unfavourable temperature and in unsatisfactory or excessively moistened soil. The three times spraying with Biojodis (1 or 2%) and with Cyanobacteria was most promising. The plant development changes related to the used compounds and simulated environmental constraints were associated with the changes in indexes of chlorophyll content in leaves, stability of membranes, gas exchange, and activity of acid or alkaline phosphatase and RNase. The above indicates that foliar and soil application of Biojodis and plant sprayings with Cyanobacteria increased growth of corn cultivated under optimal temperature and soil moisture content and partly restored the harmful effects of artifi cial temperature and water stress on plant development and physiological activity. Biojodis also can increase the iodine content in corn and uptake of nutrients from the soil, and thus decrease environmental pollution.