Univrsity of Tehran Press Iranian Journal of Field Crop Science 2008-4811 52 4 2021 12 22 Effect of slow release urea-hydrogel complex on chlorophyll fluorescence and morphological traits of barley under drought stress Effect of slow release urea-hydrogel complex on chlorophyll fluorescence and morphological traits of barley under drought stress 165 177 85556 10.22059/ijfcs.2020.312358.654765 FA Shiva Akbari Department of Agronomy and Plant Breeding Sciences, College of Aburaihan, University of Tehran. Pakdasht. Tehran. Iran. 0000-0001-8664-6141 Iraj Alahdadi Department of Agronomy and Plant Breeding Sciences, College of Aburaihan , University of Tehran. Pakdasht. Tehran. Iran. 0000-0002-8103-2543 Majid Ghorbani Javid Department of Agronomy and Plant Breeding Sciences, College of Aburaihan, University of Tehran.Pakdasht. Tehran. Iran. 0000-0002-1273-2079 Kourosh Kabiri Iran Polymer and Petrochemical Institute. Tehran, Iran Elias Soltani Department of Agronomy and Plant Breeding Sciences, College of Aburaihan, University of Tehran.Pakdasht. Tehran, Iran. 0000-0003-0017-6703 Journal Article 2020 10 24 To study the effect of slow release hydrogel-urea complex (SRHUC) on chlorophyll fluorescence and morphological parameters of barley under drought stress, an experiment was performed in 2017-2018 as <em>factorial</em> in Randomized Complete Block Design (RCBD) with three replications in the greenhouse of Aburaihan campus of University of Tehran. The combination of factorial levels were as fertilization factor containing nitrogen (N) from urea source in five levels of no N application, equivalent 125 and 65 kg.ha^-1 N without and with SRHUC as CU-N₁₂₅, CU-N₆₅, SRHUC-N₁₂₅ and SRHUC-N₆₅, respectivly and drought stress in three levels of 70, 50 and 30% FC. Drought stress decreased flag leaf area and the lowest value (13.12 cm²) belonged to 30% FC. Furthermoreit decreased flag leaf dry weight, total number of tiller and SPAD index. SRHUC-N₁₂₅, SRHUC-N₆₅ and CU-N₁₂₅have showed the highest values of maximum (F_m) and variable (F_v) fluorescences. In 50% FC, N-containing treatmenats had the highest F_v/F_o and SRHUC treatments showed the highest performance index based on absorption (PI_ABS) that were equal to 1.66 and 1.60. In 30% FC, the lowest value (10913) of minimum fluorescence (F_o) was related to SRHUC-N₁₂₅. SRHUC-N₁₂₅ caused the highest flag leaf area (16.8cm²), stem diameter (4.2 mm) and SPAD index (43.6). It can be concluded that better N availability in Goharan cultivar, had favorable effects on chlorophyll fluorescence and growth parameters, especially in drought stress, and SRHUC application might result in more appropriate chlorophyll fluorescence and growth characteristics. To study the effect of slow release hydrogel-urea complex (SRHUC) on chlorophyll fluorescence and morphological parameters of barley under drought stress, an experiment was performed in 2017-2018 as <em>factorial</em> in Randomized Complete Block Design (RCBD) with three replications in the greenhouse of Aburaihan campus of University of Tehran. The combination of factorial levels were as fertilization factor containing nitrogen (N) from urea source in five levels of no N application, equivalent 125 and 65 kg.ha^-1 N without and with SRHUC as CU-N₁₂₅, CU-N₆₅, SRHUC-N₁₂₅ and SRHUC-N₆₅, respectivly and drought stress in three levels of 70, 50 and 30% FC. Drought stress decreased flag leaf area and the lowest value (13.12 cm²) belonged to 30% FC. Furthermoreit decreased flag leaf dry weight, total number of tiller and SPAD index. SRHUC-N₁₂₅, SRHUC-N₆₅ and CU-N₁₂₅have showed the highest values of maximum (F_m) and variable (F_v) fluorescences. In 50% FC, N-containing treatmenats had the highest F_v/F_o and SRHUC treatments showed the highest performance index based on absorption (PI_ABS) that were equal to 1.66 and 1.60. In 30% FC, the lowest value (10913) of minimum fluorescence (F_o) was related to SRHUC-N₁₂₅. SRHUC-N₁₂₅ caused the highest flag leaf area (16.8cm²), stem diameter (4.2 mm) and SPAD index (43.6). It can be concluded that better N availability in Goharan cultivar, had favorable effects on chlorophyll fluorescence and growth parameters, especially in drought stress, and SRHUC application might result in more appropriate chlorophyll fluorescence and growth characteristics. https://ijfcs.ut.ac.ir/article_85556_1827a39385e05c9bc324270042193f02.pdf