اثر گاما- آمينوبوتريك اسيد در القاي مقاومت به سرمازدگي در گياهچه‌هاي خيار (Cucumis sativus L)

The Effect of GABA in Induction of Chilling Resistance in Cucumber (Cucumis sativus L.) Seedlings

ﺑﻪ ﻣﻨﻈﻮر ﺑﺮرﺳﯽ اﻣﮑﺎن اﻟﻘﺎي ﻣﻘﺎوﻣﺖ و ﮐﺎﻫﺶ ﺧﺴﺎرت ﺳﺮﻣﺎزدﮔﯽ در ﮔﯿﺎﻫﭽﻪ ﻫﺎي ﺧﯿﺎر، آزﻣﺎﯾﺸﯽ ﺑﻪ ﺻﻮرت ﻓﺎﮐﺘﻮرﯾﻞ ﺑﺮ ﭘﺎﯾﻪ ﻃﺮح ﮐﺎﻣﻼً ﺗﺼﺎدﻓﯽ ﺑﺎ ﺳﻪ ﺗﮑﺮار در ﮔﻠﺨﺎﻧﻪ داﻧﺸﮕﺎه اﯾﻼم در ﺳﺎل 1397 اﺟﺮا ﺷﺪ. ﻓﺎﮐﺘﻮرﻫﺎي آزﻣﺎﯾﺶ ﺷﺎﻣﻞ ﻏﻠﻈﺖ ﻫﺎي ﺻﻔﺮ، 5، 10 و 15 ﻣﯿﻠﯽ ﻣﻮﻻر ﮔﺎﻣﺎ- آﻣﯿﻨﻮﺑﻮﺗﺮﯾﮏ اﺳﯿﺪ )ﮔﺎﺑﺎ( و دو روش ﮐﺎرﺑﺮد ﺑﺬري )ﭘﺮاﯾﻤﯿﻨﮓ( و ﻣﺤﻠﻮل ﭘﺎﺷﯽ ﺑﺮﮔﯽ در ﻣﺮﺣﻠﻪ ﭼﻬﺎر ﺑﺮگ ﺣﻘﯿﻘﯽ ﺑﻮد. ﮔﯿﺎﻫﺎن ﺗﯿﻤﺎر ﺷﺪه ﺑﺮاي ﻣﺪت ﺷﺶ ﺷﺐ در دﻣﺎي ﺳﻪ درﺟﻪ ﺳﺎﻧﺘﯽ ﮔﺮاد در اﻧﮑﻮﺑﺎﺗﻮر ﻗﺮار ﮔﺮﻓﺘﻪ و ﺳﭙﺲ ﻣﻮرد ارزﯾﺎﺑﯽ واﻗﻊ ﺷﺪﻧﺪ. ﻧﺘﺎﯾﺞ ﻧﺸﺎن داد ﮐﻪ ﻫﻤﻪ ي ﺗﯿﻤﺎرﻫﺎي ﮔﺎﺑﺎ ﺑﺎﻋﺚ ﮐﺎﻫﺶ ﺧﺴﺎرت ﺳﺮﻣﺎزدﮔﯽ در ﮔﯿﺎﻫﭽﻪ ﻫﺎي ﺧﯿﺎر ﺷﺪﻧﺪ. اﮔﺮﭼﻪ در اﮐﺜﺮ ﺻﻔﺎت ﻣﻮرد ﻣﻄﺎﻟﻌﻪ ﺑﯿﻦ ﻏﻠﻈﺖ ﻫﺎي ﻣﺨﺘﻠﻒ ﮔﺎﺑﺎ اﺧﺘﻼف ﻣﻌﻨﯽ داري ﻣﺸﺎﻫﺪه ﻧﺸﺪ وﻟﯽ ﮐﺎرﺑﺮد ﺑﺬري ﮔﺎﺑﺎ در ﮐﺎﻫﺶ ﺧﺴﺎرت ﻧﺎﺷﯽ از ﺳﺮﻣﺎ از ﻣﺤﻠﻮل ﭘﺎﺷﯽ ﺑﺮﮔﯽ ﮐﺎرآﻣﺪﺗﺮ ﺑﻮد. ﺑﻪ ﻃﻮري ﮐﻪ ﮐﻤﺘﺮﯾﻦ ﺷﺎﺧﺺ ﺳﺮﻣﺎزدﮔﯽ، ﻓﻌﺎﻟﯿﺖ آﻧﺰﯾﻢ ﻟﯿﭙﻮاﮐﺴﯿﮋﻧﺎز و ﺑﯿﺸﺘﺮﯾﻦ وزن ﺗﺮ ﺷﺎﺧﺴﺎره ﺑﺪون اﺧﺘﻼف ﻣﻌﻨﯽ دار ﺑﯿﻦ ﻏﻠﻈﺖ ﻫﺎي ﮔﺎﺑﺎ در ﮐﺎرﺑﺮد ﺑﺬري ﻣﺸﺎﻫﺪه ﺷﺪ. ﺑﯿﺸﺘﺮﯾﻦ وزن ﺧﺸﮏ ﺷﺎﺧﺴﺎره )6/77 و 6/68 ﮔﺮم در ﺑﻮﺗﻪ(، ﺷﺎﺧﺺ ﮐﻠﺮوﻓﯿﻞ )20/57 و 21/07 ﻣﯿﻠﯽ ﮔﺮم در ﮔﺮم وزن ﺗﺮ ﺑﺮگ(، ﭘﺮوﺗﺌﯿﻦ ﮐﻞ )1/29 و 1/25 ﮔﺮم در ﮐﯿﻠﻮﮔﺮم وزن ﺗﺮ ﺑﺮگ(، ﭘﺮوﻟﯿﻦ )21/92 و 22/42 ﻣﯿﮑﺮوﻣﻮل در ﮔﺮم وزن ﺗﺮ ﺑﺮگ(، ﻓﻌﺎﻟﯿﺖ آﻧﺰﯾﻢ ﻫﺎي ﮐﺎﺗﺎﻻز )115/67 و 126/91 واﺣﺪ آﻧﺰﯾﻤﯽ در ﮔﺮم وزن ﺗﺮ ﺑﺮگ(، ﭘﺮاﮐﺴﯿﺪاز )0/61 و 0/63 واﺣﺪ آﻧﺰﯾﻤﯽ در ﮔﺮم وزن ﺗﺮ ﺑﺮگ( و ﮐﻤﺘﺮﯾﻦ ﻧﺸﺖ ﯾﻮﻧﯽ )30/22 و 29/72 درﺻﺪ(، ﻣﺎﻟﻮن دي آﻟﺪﻫﯿﺪ )0/65 و 0/60 ﻣﯿﮑﺮوﻣﻮل در ﮔﺮم وزن ﺗﺮ ﺑﺮگ( و ﭘﺮاﮐﺴﯿﺪ ﻫﯿﺪروژن )1/27 و 1/19 ﻣﯿﮑﺮوﻣﻮل در ﮔﺮم وزن ﺗﺮ ﺑﺮگ( ﺑﻪ ﺗﺮﺗﯿﺐ در ﻏﻠﻈﺖ ﻫﺎي 10 و 15 ﻣﯿﻠﯽ ﻣﻮﻻر ﮔﺎﺑﺎ در روش ﮐﺎرﺑﺮد ﺑﺬري ﻣﺸﺎﻫﺪه ﺷﺪ. ﺑﻨﺎﺑﺮاﯾﻦ اﺳﺘﻔﺎده از روش ﭘﺮاﯾﻤﯿﻨﮓ ﺑﺬر ﺑﺎ ﻏﻠﻈﺖ 10 ﻣﯿﻠﯽ ﻣﻮﻻر ﮔﺎﺑﺎ ﺑﻪ ﻋﻨﻮان روﺷﯽ ﮐﺎرﺑﺮدي در ﺟﻬﺖ ﮐﺎﻫﺶ ﺧﺴﺎرت ﺳﺮﻣﺎزدﮔﯽ ﮔﯿﺎﻫﭽﻪ ﻫﺎي ﺧﯿﺎر ﭘﯿﺸﻨﻬﺎد ﻣﯽ ﮔﺮدد

In order to investigate the possibility of chilling resistance induction and reduce the chilling injury of cucumber seedlings, a factorial experimental based on completely randomized design with three replications was conducted in a greenhouse at Ilam University, Ilam Iran in 2018. The experimental factors were included concentrations of 0, 5, 10 and 15 mM gamma-aminobutric acid (GABA) and two methods of application including seed priming and foliar application at four true leaf stages. Treated plants were incubated at 3 °C for six nights and then investigated for different characteristics. Results showed that all GABA treatments reduced chilling injury in cucumber seedlings. Moreover, although there were no significant differences among the different GABA concentrations for most of the studied characteristics, seed priming was better than foliar application. The lowest chilling index, lipoxygenase activity and highest shoot fresh weight were observed in seed priming application of GABA but with no significant differences among GABA concentrations. The highest shoot dry weight (6.77 and 6.68 g.plant-1), chlorophyll index (20.57 and 21.07 mg.g-1 FW: leaf fresh weight), total protein (1.29 and 1.25 g.kg-1), proline (21.92 and 22.42 μmol.g-1 FW), catalase activity (115.67 and 126.9 U.g-1 FW) peroxidase (0.61 and 0.63 U.g-1 FW) and the lowest ion leakage (30.22 and 29.22 %), malondialdehyde (0.65 and 0.60 μmol.g-1 FW) and hydrogen peroxide (1.27 and 1.19 μmol.g-1 FW), were observed in seed priming application of 10 and 15 mM GABA concentrations, respectively. Therefore, seed priming application of 10 mM GABA is recommended for reducing the chilling injury in cucumber seedlings.