Phosphorus Efficiency of Sirvan and Sivand Wheat Cultivars Under Drought Stress Conditions in a Calcareous Soil

Phosphorus deficiency and drought stress are limiting factors in wheat yield. Drought stress has different effects on the uptake, utilization and use efficiency of soil phosphorus in wheat cultivars. The purpose of this study is to investigate the response of growth and development, uptake and efficiency of phosphorus in Sirvan and Sivand wheat cultivars at three moisture stress levels of 50, 70 and 95% of soil field capacity (FC) and two phosphorus levels of 0 and 25 mg kg-1. The results showed that addition of phosphorus increased shoot dry weight, phosphorus utilization efficiency, root length and area, and soluble sugars by 42, 61, 84, 47, and 66%, respectively, and decreased electrolyte leakage by 64% under stress conditions of 50%FC. Besides, the phosphorus application of 25 mg kg-1 under drought stress conditions of 50%FC increased the shoot dry weight of the Sirvan variety by 75% compared to the Sivand variety. This increase can be due to the effect of phosphorus on metabolic activities inside the plant, which has led to an increase in root growth, soluble sugar production and cell wall resistance, and a decrease in electrolyte leakage. Therefore, the positive changes observed in different traits and indices due to the use of phosphorus increased the resistance of the Sirvan cultivar compared to Sivand under drought stress conditions. According to the results of phosphorus efficiency and some root morphological and physiobiochemical characteristics, Sirvan cultivar showed a good response to phosphorus fertilizer in modulating the effect of drought stress.