Effect of soil phosphorus on vegetative, photosynthetic, water related and nutritional traits of brant’s oak seedlings under different water conditions

Background and objectives:The acceleration in the intensity and duration of droughts in Zagros forests has affected the recovery of native tree species, including the Brant oak (Quercus brantii L.).Despite the importance of phosphorus in increasing drought resistance in different species, there is little information on the role of this element in Brant's oak seedlings with respect to drought. Materials and methods:For this purpose, the main and interaction effects of two factors, soil phosphorus (at five concentrations of zero, 25, 50, 75 and 100 mg/kg) and soil moisture (at three levels of 60, 30 and 10 percent of field capacity), on the performance traits of one-year-old Brant's oak seedlings were investigated.The traits studied include morphological, physiological and nutritional parameters. Results:The results showed that as soil water content decreased, the traits of leaf number, root and leaf fresh weight, relative water content, photosystem II performance, leaf chlorophyll index, and leaf potassium and phosphorus content decreased, while root length and electrolyte leakage rate increased.The increase in soil phosphorus in the heavily irrigated seedlings (60 percent of field capacity) led to the development of aboveground organs and leaf area.In the seedlings that were in a water deficit, this maintained the maximum performance of photosystem II.An increase in soil phosphorus under all water conditions increased the phosphorus and potassium content as well as the chlorophyll index in the leaves of Brant's oak.However, this had no effect on oxidative stress-induced damage to the reducing membrane. Conclusion:The addition of phosphorus increased the resistance of Brant's oak seedlings to drought stress by improving their nutritional status and protecting the photosynthetic apparatus.It was suggested to use higher phosphorus concentrations of phosphorus for future research to investigate the possibility of improving water relations and protection against plasma membrane damage.