Effect of Synthetic and Biological Plant Growth Stimulants and Soil Amendments on the Development of Maize in Various Soil Moisture Conditions

Currently, methods are being sought to reduce the effects of drought. The conducted research tested the effect of potassium polyacrylate, β-cyclocitral, and Rhizophagus irregularis on the development of maize (Zea mays L.). The first of the substances mentioned was mixed with the soil; the others were used as seed dressings. The effect of substances and microorganisms on the height and weight of plants, chlorophyll fluorescence and the gas exchange between the soil and the atmosphere was tested in greenhouse conditions. Plant development was tested at optimal soil moisture levels and in drought conditions. Field experiment determined the effect of the abovementioned preparations on the height of maize, the level of grain yield and seed parameters. The hydrothermal index was calculated for the entire vegetative season of plants. All preparations used had a positive effect on the development of test plants. Significant improvement was found for many parameters compared to the control combination plants, including maize weight and grain yield. This was confirmed for various soil moisture conditions. An increase in grain yield was noted by 0.6–1.3 t ha−1 compared to the control. The tested substances and microorganisms may, therefore, be a good solution for protecting plants against the effects of drought.