The effect of salicylic acid on photosynthetic resistance of Ocimum basilicum and Thymus vulgaris to drought stress under elevated climate conditions

The aim of this research was to investigate the effect of SA on photosynthetic response of basil (Ocimum basilicum L.) and thyme (Thymus vulgaris L.) under current and warmed climate conditions. The plants were grown in automatically controlled climatic conditions under current (400 ppm CO2, 21/14 °C, day/night) and warmed (800 ppm CO2, 25/18 °C) climates, and well-watered and drought stressed conditions. Half of the plants were sprayed with 2mM SA, other – with distillated water. There was obtained, that warmed climate increased the growth of both investigated plant and the effect was more pronounced for basil. Drought stress was decreasing growth parameters of basil, while for thyme the opposite tendency was detected. Salicylic acid effect on dry biomass of both plants was week and statistically insignificant in almost all treatment variants, with exception for basil grown under warmed climate, when dry biomass of plants sprayed with SA increased and decreased significantly (p<0.05) for well-watered and drought stressed plants respectively, compare to non-sprayed. Drought decreased photosynthetic rate of both plants (p