Evaluation of Maize Leaf Gas Exchanges with Application of Mycorrhizal Biofertilizer Under Drought Stress Conditions

To study the effects of arbuscular mycorrhizal fungi (AMF) on photosynthesis، stomatal conductance، transpiration and leaf temperature of maize (Zea mays L.) under well-watered (I1)، moderate drought stress (I2) and severe drought stress (I3) conditions، two field experiments were conducted in agricultural research station in Khorramabad، Iran in 2011 and 2012. Each experiment was carried out as split-plot factorial based on randomized complete block design with three replications. Irrigation was imposed at three levels based on 70% (I1)، 50% (I2) and 30% (I3) field capacity، as the main plot. Mycorrhizal biofertilizer (Glomus intraradices) was applied at two levels of control or without application (M1) and application of 100 kgha-1 (M2) as the sub plot. Phosphorus fertilizer was also applied at three levels of control or without application (P1)، application of 75 kgha-1 (P2) and 150 kgha-1 triple superphosphate (P3)، as the sub plot. The results of combined analysis showed that، mycorrhizal biofertilizer application and different irrigation treatments significantly affected the measured traits. Mycorrhizal biofertilizer application led to improved photosynthesis، stomatal conductance، transpiration and leaf temperature، as much as 20، 3. 3، 9. 2 and 4. 2%، respectively. Photosynthesis، stomatal conductance and transpiration as affected by different irrigation regimes were decreased by increasing drought stress، but leaf temperature was increased by increasing drought stress. Different P fertilizer levels also significantly affected photosynthesis. Measured traits in AM plants had priority than non AM plants، as a consequence of enhancing nutrient uptake، extension of the root system and water status of the plants.