Effect of Humic Acid on Morpho-Physiological Characteristics of Turfgrass Under Drought Stress

Outcome appropriate strategy is so essential to reduce the irrigation of the turfgrass in the landspace since to high water requirement of turfgrass growth stages and the limitation of water resources. In the first experiment, the application of polyethylene glycol (0, 2.5 and 5%) and humic acid (0, 250 and 500 mg.l-1) treatments at the germination phase and the application of foliar spraying of humic acid (0, 250 and 500 mg.l-1) and drought stress (100% and 30% of field capacity) in the turfgrass establishment stage in the second experiment was conducted. In the first experiment, although the dry weight of seedlings increased at the presence of different concentrations of polyethylene glycol, most of the indices of germination decreased in comparison to the control. In the second experiment, drought stress in turfgrass caused 10-fold increase in proline, decreasing in relative water content, fresh and dry weight of shoots compared to withouth drought stress in greenhouse conditions. Foliar spraying with 250 mg.l-1 humic acid reduced shoot height and density under drought stress conditions. Therefore, it can be stated that the foliar spraying application of humic acid under field capacity irrigation can improve the physiological conditions, lead to increasing turfgrass density and shoot length nevertheless the use of acid humic foliar spraying was not effective in reduction the drought stress of turfgrass.