اثر تنش خشكي و گردو‌غبار بر پراكسيداسيون ليپيدي و واكنش ضداكسايشي دو رقم توت‌فرنگي

Evaluation of Lipid Peroxidation and Antioxidant Reaction of Strawberry to Drought Stress and Dust

در ﺳﺎل ﻫﺎي اﺧﯿﺮ ﭘﺪﯾﺪه ﮔﺮدوﻏﺒﺎر ﯾﮑﯽ از ﭼﺎﻟﺶ ﻫﺎي ﻣﻬﻢ در ﻏﺮب و ﺟﻨﻮب ﻏﺮﺑـﯽ اﯾـﺮان ﺑـﻮده ﮐـﻪ ﺳـﺎﻟﯿﺎﻧﻪ ﺧﺴﺎرات ﻓﺮاواﻧﯽ ﺑﺮ ﻣﺤﯿﻂ زﯾﺴﺖ و ﻣﺤﺼﻮﻻت ﮐﺸﺎورزي ﺑﻪ ﺟﺎ ﻣﯽ ﮔﺬارد. ﺑﺮ ﻫﻤﯿﻦ اﺳﺎس، آزﻣﺎﯾﺸﯽ ﺑـﺮاي ﺑﺮرﺳـﯽ اﺛﺮ ﮔﺮدوﻏﺒﺎر و ﺗﻨﺶ ﺧﺸﮑﯽ روي ﺑﺮﺧﯽ ﺧﺼﻮﺻﯿﺎت ﻓﯿﺰﯾﻮﻟﻮژﯾﮑﯽ دو رﻗﻢ ﺗﻮت ﻓﺮﻧﮕﯽ )ﭘﺎروس و ﮐـﻮﺋﯿﻦ اﻟﯿـﺰا ( در ﻃﯽ ﺳﺎل ﻫﺎي 1393-1392 در ﺷﺮاﯾﻂ ﮔﻠﺨﺎﻧﻪ ﻃﺮاﺣﯽ و اﺟﺮا ﮔﺮدﯾﺪ. آزﻣﺎﯾﺶ ﺑﻪ ﺻﻮرت ﻓﺎﮐﺘﻮرﯾﻞ ﺑـﺮ ﭘﺎﯾـﻪ ﻃـﺮح ﮐﺎﻣﻼً ﺗﺼﺎدﻓﯽ ﺑﺎ ﭼﻬﺎر ﺗﯿﻤﺎر )ﺷﺎﻫﺪ، ﺗﻨﺶ ﺧﺸﮑﯽ )1/2- ﻣﮕﺎﭘﺎﺳﮑﺎل(، ﮔﺮدوﻏﺒﺎر، ﮔﺮدوﻏﺒﺎر + ﺗﻨﺶ ﺧﺸﮑﯽ( و 3 ﺗﮑﺮار اﻧﺠﺎم ﺷﺪ. در اﯾﻦ آزﻣﺎﯾﺶ وزن ﺧﺸﮏ اﻧﺪام ﻫﻮاﯾﯽ و رﯾﺸﻪ، ﻣﺤﺘﻮاي ﻧﺴﺒﯽ آب ﺑﺮگ )RWC(، ﺷـﺎﺧﺺ ﭘﺎﯾـﺪاري ﻏﺸﺎء ﺳﻠﻮﻟﯽ )MSI(، ﭘﺮوﻟﯿﻦ، ﮐﺮﺑﻮﻫﯿﺪرات ﻫﺎي ﻣﺤﻠﻮل ﮐﻞ، ﭘﺮاﮐﺴﯿﺪاﺳﯿﻮن ﻟﯿﭙﯿﺪي، ﭘﺮاﮐﺴﯿﺪ ﻫﯿﺪروژن و ﻓﻌﺎﻟﯿـﺖ آﻧﺰﯾﻢ ﭘﺮاﮐﺴﯿﺪاز اﻧﺪازه ﮔﯿﺮي ﺷﺪﻧﺪ. ﻧﺘﺎﯾﺞ ﻧﺸﺎن داد ﮐﻪ RWC و MSI در واﮐـﻨﺶ ﺑـﻪ ﮔﺮدوﻏﺒـﺎر و ﺗـﻨﺶ ﺧﺸـﮑﯽ در ﻫﺮ دو رﻗﻢ ﮐـﺎﻫﺶ ﯾﺎﻓﺘﻨـﺪ . اﻓـﺰاﯾﺶ ﻣﯿـﺰان ﭘـﺮوﻟﯿﻦ، ﮐﺮﺑﻮﻫﯿـﺪرات ﻫـﺎي ﻣﺤﻠـﻮل ﮐـﻞ، ﻣـﺎﻟﻮن دي آﻟﺪﺋﯿـﺪ، ﭘﺮاﮐﺴﯿﺪ ﻫﯿﺪروژن و ﻓﻌﺎﻟﯿﺖ آﻧﺰﯾﻢ ﭘﺮاﮐﺴﯿﺪاز در اﺛﺮ ﺗﯿﻤﺎرﻫﺎي ﮔﺮدوﻏﺒﺎر و ﺗﻨﺶ ﺧﺸﮑﯽ ﻣﺸﺎﻫﺪه ﺷﺪ، ﺑﻪ ﻃـﻮري ﮐـﻪ ﺑﯿﺸﺘﺮﯾﻦ اﻓﺰاﯾﺶ در ﭘﺮوﻟﯿﻦ، ﮐﺮﺑﻮﻫﯿﺪرات ﻫﺎي ﻣﺤﻠـﻮل ﮐـﻞ، ﻣـﺎﻟﻮن د ي آﻟﺪﺋﯿـﺪ، ﭘﺮاﮐ ﺴـﯿﺪ ﻫﯿـﺪروژن و ﻓﻌﺎﻟﯿـﺖ آﻧﺰﯾﻢ ﻫﺎي ﺿﺪ اﮐﺴﺎﯾﺸﯽ در ﺗﯿﻤﺎر ﺗﻨﺶ ﺧﺸﮑﯽ + ﮔﺮدوﻏﺒﺎر ﺑﻪ دﺳﺖ آﻣﺪ. ﺗﯿﻤﺎرﻫﺎي ﮔﺮدو ﻏﺒﺎر و ﺗﻨﺶ ﺧﺸـﮑﯽ ﺳـﺒﺐ ﮐﺎﻫﺶ ﺗﻮﻟﯿﺪ ﻣﺎده ﺧﺸﮏ در ﻫﺮ دو ﺳﺎل ﮔﺮدﯾﺪﻧﺪ. ﺑـﺮ اﺳـﺎس اﯾـﻦ ﻧﺘـﺎﯾﺞ ﮔﺮدوﻏﺒـﺎر اﺛـﺮ ﻣﻨﻔـﯽ ﺑـﺮ ﺧﺼﻮﺻـﯿﺎت ﻓﯿﺰﯾﻮﻟﻮژﯾﮑﯽ دو رﻗﻢ ﺗﻮت ﻓﺮﻧﮕﯽ داﺷﺘﻪ و در ﺷﺮاﯾﻄﯽ ﮐﻪ ﺗﯿﻤﺎر ﮔﺮدوﻏﺒﺎر ﻫﻤﺮاه ﺑﺎ ﺗﻨﺶ ﺧﺸﮑﯽ اﻋﻤﺎل ﮔﺮدﯾﺪ آﺛﺎر ﻣﻨﻔﯽ ﺑﯿﺸﺘﺮي ﺑﺮ ﺗﻮت ﻓﺮﻧﮕﯽ داﺷﺖ. ﺑﻪ ﻫﻤﯿﻦ دﻟﯿﻞ ﻣﯽ ﺗﻮان ﻋﻨﻮان ﮐـﺮد ﮐـﻪ ﮔﺮدوﻏﺒـﺎر ﺗـﺄﺛﯿﺮ ﻣﻨﻔـﯽ روي ﺻـﻔﺎت زﯾﺎﺑﯽ ﺷﺪه داﺷﺘﻪ و ﺗﻨﺶ ﺧﺸﮑﯽ اﯾﻦ اﺛﺮات را ﺗﺸﺪﯾﺪ ﻧﻤﻮده اﺳﺖ.

In recent years, dust has been identified as a major source of adverse environmental and agricultural effects in west and southwest of Iran. Reducing light penetration, decreasing photosynthesis, changing stomatal performance, and reducing flowering are some of the adverse effects of air pollution on plants. Strawberries have a shallow root system, high leaf area, and are sensetive to drought stress. Kurdistan province is the major producer of strawberries in Iran. Since in Kurdistan dust occurs mostly in the spring and during the strawberry flowering and fruit production, we investigated the interaction effect of dust and drought stress on some physiological characteristics of two strawberry cultivars (cvs. Paros and Queen elisa) during 2013-2014. Materials and Methods The experiment was conducted based on a completely randomized design with four treatments (control, -1.2 MPa soil water potential as drought stress, dust and dust + drought stress) and three replications. In this experiment, leaf relative water content, membrane stability index, proline, soluble carbohydrates, lipid peroxidation, hydrogen peroxide, peroxidase and ascorbate peroxidase activity were evaluated. Results Results showed that relative water content and membrane stability index decreased in response to dust and drought in both cultivars. Also, the amount of malondialdehyde, hydrogen peroxide, and activity of antioxidant enzymes increased by dust and drought treatments. Most increase was obsereved in the proline and total soluble carbohydrates, hydrogen peroxide, malondialdehyde, and the activity of antioxidant enzymes was obtained by dust + drought stress. Drought stress + dust had the highest levels of POD and APX. There was a significant difference between the two cultivars, so that Paros cultivar had higher activity of POD and APX compared to queen elisa. Dust and drought treatments reduced shoot and root dry weigth in both years and both cultivars. Discussion Probably due to the stress caused by dust, the total leaf soluble sugars increased in the first year. In this condition, the plant can continue to absorb water from the soil by increasing the soluble carbohydrates through osmotic regulation. In the second year, the long-term reduction in photosynthesis led to a reduction in total soluble carbohydrates, due to prolonged exposure to dust or damage to light absorption pigments resulting from dust accumulation and its negative effects on stomatal function. Dust and drought stress decreased relative water content (RWC) through decreasing water absorption by the strawberry plants, and the decrease of water led to the increase of H2O2. With the increase of H2O2 in dust and drought stress, membrane lipid degradation increased and led to the increase of malondialdehyde (MDA). The increase of MDA indicates cell wall destruction, which is accompanied by the decrease of memberan stability index MSI). MDA increased in all treatments in Queen Eliza cultivar, which could indicate the higher sensitivity of this cultivar to dust and drought stress. In this study, Paros showed higher antioxidant enzyme activity accompanied with lower H2O2 content and consequently a lower MDA, thus, more resistance to drought and drought stress. In conclusion, dust had negative effects on evaluated characteristics, and drought stress exacerbated these effects. Adverse effects of dust and drought were observed on dry matter production in both years. Reducing the dry matter of the roots and the shoot might be due to increased free radicals, reduced leaf water content and, consequently, loss of photosynthesis of the leaf.