The effects of drought and UV-B stresses on physiological and biochemical changes in some linden (Tilia sp.) species in Türkiye

It is known that environmental stresses will become more severe and widespread due to global climate change. Drought and UV-B radiation are two critical environmental stressors that can suppress or activate plant defense mechanisms. In this study, drought and UV-B stresses were applied to Tilia cordata Mill., Tilia platyphyllos Scop., and Tilia tomentosa Moench. seedlings that grow naturally in Turkey. The morphological, physiological, and biochemical changes of these stress applications on the seedlings of these species were determined. Within the scope of the study, seedling height, root collar diameter, number of lateral branches, number of leaves, leaf height, leaf area, relative water content (RWC), xylem water potential, electrolyte leakage (EL), chlorophyll a, b, total carotenoid amount, chlorophyll fluorescence, photosynthesis efficiency (transpiration, stomatal conductivity, net photosynthesis (assimilation) rate, intrinsic water usage efficiency, intercellular CO2 ratio, ambient CO2 ratio, intercellular CO2 to ambient CO2, water usage efficiency, proline content and total carbohydrate amount were measured. As a result, it was determined that there are differences between species and stress applications of each species in terms of physiological and biochemical characteristics.On the other hand, while ambient CO2 ratio and proline and total carbohydrate amount increased, relative water content, xylem water content, total carotenoid, chlorophyll a, b, chlorophyll fluorescence, net photosynthesis rate, and stomatal conductivity were determined to decrease. Apart from this, it was determined that the effect of drought on the study parameters was more dominant than the effect of UV-B, and the effect of UV-B alone was generally insignificant. The study results generally showed that Tilia tomentosa species was the most tolerant species, and Tilia platyphyllos species was the most susceptible species against drought and UV-B stresses.