Amin Abbasi

Potassium as a key element in environmental stress conditions, had fundamental role in plants growth and development. Under water deficit stress conditions, absorption of this element decreases. For this purpose, to evaluate changes in physiological parameters and grain yield of dryland wheat (Baran, Homa, Hashtrood) with application of different levels of potassium sulfate (control, 75 and 150 kg/ha), a factorial experiment based on randomized complete block design (RCBD) with 3 replications was conducted during 2017-18 and 2018-19 growing sessions. Accumulation of potassium (K) increased in varieties by application of potassium sulfate so that, maximum K content was recorded in Hashtrood than other varieties. Also, relative water content, chlorophyll content and NDVI of Hashtrood was more than others. Relative water content and chlorophyll content index of all varieties was increased by application of 75 kg/ha potassium sulfate. Stomatal conductance of Hashtroud by application of 75 kg/ha potassium sulfate was more than Baran and Homa. Photochemical efficiency of PSII and photosynthesis efficiency of studied varieties by application of 75 kg/ha potassium sulfate was higher than other treatments and as a result, grain number, weight and yield was improved. Based on the results, application of the 75 kg/ha potassium sulfate by improving plant tolerance to the water stress, could increase grain yields under dryland areas.