Effects of Water Stress, Nitrogen and Potassium on Some Physiological Characteristics and Dry Matter Yield of Blue Panic Grass (Panicum antidotale Retz.)

Severe water shortage is one of the major challenges of agricultural sector in arid and semi-arid region. Optimal use of water resources, along with improving the efficiency of nutrient elements under drought conditions, will increase or stabilize crop yield. Forage production using plant species with low water requirement and adapted to low quality waters is a sustainable strategy for fodder production in dry areas. Blue panic grass (Panicum antidotale Retz.) is a halophytic crop plant, which is water productive and adapted to tropical conditions. This study was carried out to investigate the effects of drought stress, nitrogen and potassium on some physiological characteristics and dry matter yield of blue panic grass in Birjand, South-Khorasan province of Iran.
  This study was conducted as a split-factorial experiment with three replications using a randomized complete block design at the Research Field of Islamic Azad University of Birjand. Irrigation was considered as the main factor at three levels based on cumulative evaporation from evaporation pan class A (70, 140 and 210 mm), nitrogen fertilizer was applied in three levels based on soil test including zero, 50% (100 kg ha-1) and 100% (200 kg ha-1) of recommended N. Potassium was applied in two levels (zero and 100 kg ha-1). Blue panic grass is perennial and in the first year, most of the photosynthetic assimilate are being used for the establishment of the plant; Hence, treatments were imposed in the second year of the experiment. During the growing season, radiation use efficiency and water use efficiency calculated three times during the growing season. Dry matter accumulation was measured at the final harvest. In addition, nitrogen use efficiency and agronomic nitrogen efficiency were calculated based on the consumed nitrogen fertilizer during the growing season and total dry matter harvested during the growing season.
  Results showed that under water stress conditions the radiation use efficiency decreased, while, water use efficiency increased. We concluded that providing enough water and nutrients can increase dry matter production and radiation use efficiency. Application of nitrogen and potassium fertilizers under severe water stress conditions led to an increasing water use efficiency. Application of higher levels of nitrogen reduced nitrogen use efficiency.
  Blue panic grass showed good performance under water stress conditions. Results indicated that application of nitrogen and potassium fertilizers under water stress conditions could mitigate the adverse effects of drought stress and increase nitrogen and water use efficiency.