نوع مقاله : مقالات پژوهشی

نویسنده

دانشگاه کردستان

چکیده

در نواحی خشک و نیمه خشک، گیاهان اغلب در معرض تنش آبی قرار می‌گیرند. تنش آبی رشد و نمو گیاهان را محدود می‌کند. هدف از این مطالعه بررسی اثر پاکلوبوترازول بر خصوصیات رویشی، فیزیولوژیکی و تبادلات گازی در گلابی رقم "شاه میوه" تحت رژیم‌های مختلف آبیاری بود. نهال‌ها در گلدان‌های بیست لیتری کشت شدند. پاکلوبوترازول به صورت خاکی به مقدار 0، 15/0 و 3/0 گرم در هر گلدان استفاده شد. تیمارهای تنش آبی سه ماه بعد از کشت در گلخانه اعمال شدند. سه تیمار آبیاری شاهد (آبیاری در حد ظرفیت زراعی)، 4/0 و 5/0 مگاپاسکال مکش خاک استفاده شدند. نتایج نشان داد که پاکلوبوترازول تمام صفات رویشی جز وزن خشک ریشه را کاهش داد. پاکلوبوترازول نسبت وزن خشک ریشه به قسمت هوایی را افزایش داد. تنش آبی محتوای نسبی آب برگ، سرعت فتوسنتز، هدایت روزنه‌ای، سرعت تعرق، شاخص پایداری غشاء و مقدار کلروفیل را کاهش و محتوای پرولین برگ، مواد جامد محلول کل و گازکربنیک زیر روزنه‌ای را افزایش داد. اثر متقابل معنی‌داری بین خشکی و پاکلوبوترازول در صفات مقدار کلروفیل، محتوای نسبی آب برگ، پرولین و گازکربنیک زیرروزنه‌ای مشاهده شد. گیاهان تیمار شده با پاکلوبوترازول محتوای آب نسبی بیشتری نسبت به گیاهان تیمار نشده داشتند. آبیاری مجدد در گیاهان تحت تنش دو روز بعد منجر به برگشت تمامی صفات به حالت شد. فقط صفت محتوای نسبی آب برگ کمتر از شاهد بود. به طور کلی نتایج این تحقیق نشان داد که پاکلوبوترازول به گیاه اجازه می‌دهد تا از طریق تغییرات موفولوژیکی و فیزیولوژیکی تنش آبی را تحمل کند.

کلیدواژه‌ها

عنوان مقاله [English]

The Effect of Paclobutrazol on Morphological, Physiological and Gas Exchange Charactersitics of Pear (Pyrus communus cv. Shah Mive) under Different Irrigation Regimes

نویسنده [English]

  • Taimoor Javadi

University of Kurdistan

چکیده [English]

Introduction: Drought is a major environmental stress that affects agricultural systems and induces several physiological, biochemical and molecular responses in plants. Drought inhibits the plant photosynthesis causing changes of chlorophyll contents, damage the photosynthetic apparatus and decreases plant growth and development. Generally, the environmental stresses, especially drought stress, give rise to accumulation of soluble carbohydrates, proline and free amino acids as well as antioxidant compounds. Triazoles are the active ingredient of fungicides (propoconazole, penconazole, epixiconazole) and some growth regulators. The fungicidal properties of triazoles depend on inhibition of the C4-demethylase reactions in sterol biosynthesis of fungi. However, triazole-based fungicides induce a suite of morphological and physiological adaptations and allow plants to tolerate a broad range of environmental stresses including drought, herbicide treatment and elevated temperatures. The growth inhibitor paclobutrazol (PBZ) is a triazole and has been reported to protect plants against several environmental stresses, i.e. drought, low and high temperature. The purpose of this study was to evaluate the effect of palobutrazol on vegetative, physiological and gas exchange characteristics of pear (Pyrus communis cv. ShahMive) under different irrigation regimes.
Materials and Methods: In March, 2011, 1-year-old pear (Pyrus communis cv. ShahMive) saplings 80±2 cm high were planted in 20-l plastic pots filled with loamy sand soil (8% clay, 15% silt, 77% Sand) in experimental greenhouse. Paclobutrazol was added to soil at the same time with sapling cultivation at rates of 0, 0.15 and 0.3 g active ingredient per pot. PBZ was diluted in 500 ml distilled water and solution applied to the soil at the base of the saplings on pots. The control saplings were treated with distilled water of equal volume. Vegetative (stem growth, stem diameter, leaf number, shoot dry weight, root dry weight and plant dry weight), physiological and biochemical (leaf relative water content (RWC), total soluble sugar(TSS), proline and membrane stability index (MSI)) and gas exchange (Photosynthetic rate, sub-stomatal CO2, stomata conductance (gs) and transpiration) characteristics were measured.
Results and Discussion: The results showed that paclobutrazol treatments had significant effect on growth parameters, except root dry weight. Paclobutrazol significantly reduced stem height and stem diameter increment, mean leaf area, shoot dry weight and whole plant dry weight. Root: shoot ratio was increased in paclobutrazol-treated saplings. No significant differences in any characteristic were found between 0.15 and 0.3 g active ingredient PBZ per pot for growth parameter. Waters stress decreased leaf relative water content (RWC), photosynthetic rate, stomatal conductance and transpiration rate, membrane stability index and chlorophyll content and increased leaf proline content, total soluble sugar and sub-stomatal CO2. Significant interaction between PBZ and irrigation regimes was seen for RWC, proline and sub-stomatal CO2. PBZ-treated saplings had higher RWC than untreated ones. The effects of treatments on physiological and gas exchange traits were significant. RWC was high in all non-water-stressed (with or without paclobutrazol) treatments and decreased in water stressed treatments. It was higher in PBZ-treated than PBZ-untreated treatments in similar water stress condition. But there was not significant differences between 0.15 and 0.3 g PBZ in a given water stress condition. For example, RWC was 89.76 and 85.56 percent in -0.4 MPa water stress plus 0.15 and 0.3 gr PBZ treatments, respectively. The results showed that leaf proline content was increased under water stress condition. Leaf proline content of the PBZ-untreated sapling, subjected to water stress increased to 32.13 and 61.82 µmol.gr-1DW in -0.4 and -0.8 MPa water stress conditions, respectively. The PBZ-treated saplings accumulated less proline content than the PBZ-untreated ones. The highest proline concentration was founded in PBZ-untreated and -0.8 MPa water stress treatment. TSS was decreased in water stress treatments. TSS concentration was increased in water stress treatments. The highest TSS concentration was founded in PBZ-treated and untreated -0.8 MPa water stress treatments. PBZ- treated saplings had more TSS than untreated ones in -0.4 MPa treatments. Water stress was decreased leaf chlorophyll (a, b and total) content of saplings. PBZ-treated saplings had higher leaf chlorophyll content than PBZ-untreated ones in non-water stress treatments. The interaction of PBZ treatment and water stress moderated the negative effect of water stress on the chlorophyll b and total chlorophyll.
Conclusions: Generally, the results showed that PBZ allowed plants to tolerate water stress by morphological and physiological traits modification. On the other hand, paclobutrazol stimulated a more efficient stomatal regulation, which affected photosynthesis, but permitted significantly better levels of water status in treated plants.

کلیدواژه‌ها [English]

  • Photosynthesis
  • Plant growth retardant
  • Vegetative traits
  • Water stress
1- Asamoah T.E.O., and Atkinson D. 1985. The effects of (2RS,3RS)-1-(4-chlorophenyl)- 4,4-dimethyl-2-(1H-1,2,4 triazol-1-yl) pentan-3-ol (paclobutrazol: PP333) and root pruning on the growth, water use and response to drought of Colt cherry rootstocks. Plant Growth Regulation, 3: 37-45.
2- Berova M., and Zlatev Z. 2003. Physiological response of paclobutrazol-treated triticale plants to water stress. Biologia Plantarum, 46:133-136.
3- Chaney W.R. 2003. Tree growth retardants: arborists discovering new uses for an old tool. Tree care industry. 54:1-6.
4- Chaney W.R. 2005. A paclobutrazol treatment can leave a tree more stress tolerant. Golfdom, Turfgrass Trends. 61: 84-86
5- Conover C.A. 1994. Angel-Wing begonia growth and water requirements affected by paclobutrazol. University of Florida/IFAS, Central Florida Research and Education Centre, Apopka Research Report RH-94-4.
6- Davies T.D., Steffens G.L., and Sankhla N. 1988. Triazole plant growth regulators. Horticaltural Review, 10:63-105.
7- Earl, H. J. (2003). A precise gravimetric method for simulating drought stress in pot experiments. Crop science, 43(5), 1868-1873.
8- Fernandez J.A., Balenzategui L., Banon S., and Franco J.A. 2006. Induction of drought tolerance by paclobutrazol and irrigation deficit in Phillyrea angustifolia during the nursery period. Scientia Horticulturae, 107: 277-283.
9- Fletcher R.A., Gilley A., Davis T.D. and Sankhla N. 2000. Triazoles as plant growth regulators and stress protectants. Horticaltural Review, 24: 56-138.
10- Fletcher R.A. and Nath V. 1984. Triadimefon reduces transpiration and increases yield in water stressed plants. Physiologia Plantarum, 62: 422-426.
11- Gilley A., and Fletcher R.A. 1997. Relative efficacy of paclobtrazol, propinozole and tetraconazole as stress protectants in wheat seedlings. Plant Growth Regulation, 21: 169-175.
12- Gonzalez L., and Gonzalez-Vilar m. 2003. Determination of relative water content. P 207-212. In J. Manuel and Goger R. (eds). Handbook of plant ecophysiology techniques. Kluwer Academic Publishers. London.
13- Irigoyen J.J., and EmerichD.W. 1992. Alfalfa leaf senescence include by drought stress: photosynthesis, hydrogen peroxide metabolism, lipid peroxidation and ethylene evolution. Physiologia Plantarum, 84: 67-72.
14- Kalil I.A., and Rahman H. 1995. Effects of paclobutrazol on growth, chloroplast pigments and sterol biosynthesis of maize (Zea mays L.). Plant Science, 105: 15-21.
15- Lichtenthaler H.K., and Buschmann C. 2001. Chlorophylls and Carotenoids: Measurement and Characterization by UV-VIS Spectroscopy. P. F4.3.1-F4.3.8. In S.J. Schwartz (ed). Current Protocols in Food Analytical Chemistry. New York.
16- Lichtenthaler H.K., and Buschmann C. 2001. Extraction of Photosynthesis tissue: Chlorophylls and Carotenoids. p. F4.2.1- F4.2.6. In S.J. Schwartz (ed). Current protocols in food analytical chemistry. John Wiley & Sons Inc. New York.
17- Mackay, C.E., Hall J.C., Hofstra G., and Fletcher R.A. 1990. Uniconazole- increased changes in abscisic acid, total amino acids, and proline in Phaseolus vulgaris. Pesticide Biochemistry and Physiology, 37: 74-82.
18- Marshall J.G., Rutledge R.G., Blumwald E., and Dumbroff E.D. 2000. Reduction in turgid water in jack pine, white spruce and black spruce in response to drought and paclobutrazol. Tree Physiology, 20: 701-707.
19- Monge E., Madero P., Val J., and Blanco A. 1993. Effects of paclobutrazol application and fruit load on microelement concentrations in peach leaves. P. 319-323. In M.A.C. Fragoso and M.L. van Beusichem (eds). Optimization of plant nutrition. Kluwer Academic Press. Dordrecht.
20- Morgan J. 1986. The effect of N nutrition on the water relations and gas exchange characteristics of wheat (Teriticum aestivum L.). Plant Physiology, 80: 52-58.
21- Neill S.J., and Burnett E.C. 1999. Regulation of gene expression during water deficit stress. Plant Growth Regulation, 29: 23-33.
22- Ozmen A.D., Ozdemir F., and Turkan I. 2003. Effects of paclobutrazol on response of two barley cultivars to salt stress. Biologia Plantarum, 46: 263-268.
23- Paquin R., and Lechasseur P. 1979. Observations sur une methode de dosage de la praline libre dansles extraits de plants. Canadian Journal of Botany, 57: 1851-1854.
24- Poole R.T., and Conover C.A. 1992. Water use and growth of eight foliage plants influence by Paclobutrazol. University of florida, Central Florida Research and Education Center-Apopka.
25- Ranney T.G., Bassuk N.L., and Whitlow T.H. 1989. Effect of transplanting practices on growth and water relations of Colt cherry trees during reestablishment. Journal of Environmental Horticulture, 7: 41-45.
26- Ronchi A., Farina G., Gozzo F., and Tonelli C. 1999. Effects of triazolic fungicide on maize plant metabolism: modifications of transcript abundance in resistance-related pathways. Plant Science, 130: 51-62.
27- Sairam R.K., Veerabhadra R.K., and Srivastava G.C. 2002. Differential response of wheat genotypes to long term salinity stress in relation to oxidative stress, antioxidant activity and osmolyte concentration. Plant Science, 163: 1037-1046.
28- Sanchez-Blanco M.J., Ferrandez T., Navarro A., Banon S., and Alarcon J.J. 2004. Effects of irrigation and air humidity preconditioning on water relations, growth and survival of Rosmarinus officinalis plants during and after transplanting. Journal of Plant Physiology, 161: 1133-1142.
29- Senaratna T., Mackay C., Mckersie B., and Fletcher R. 1988. Uniconazole- induced chilling tolerance in tomato and it relationship to antioxidant content. Journal of Plant Physiology, 133: 56-61.
30- Sopher C.R., Krol M., Huner N.P.A., Moore A.E. and Fletcher R.A. 1999. Choloroplastic changes associated with paclobtrazol-induced stress protection in maize seedlings. Canadian Journal of Botany, 77: 279-290.
31- Still J.R. and Pill W.G. 2004. Growth and stress tolerance of tomato seedlings (Lycopersicon esculentum Mill.) in response to seed treatment with paclobutrazol. Journal of Horticultural Science and Biotechnology, 79: 197-203.
32- Swindale L.D., and Bidinger F.R. 1981. The human consequences of drought and crop research priorities for their alleviation. P. 2-13. In L.G. Paleg and D. Aspinal (eds). The physiology and biochemistry of drought resistance in plants. Academic Press: Sydney.
33- Wang, S.Y., and Faust, M.1986. Effect on growth retardants on root formation and polyamine content in apple seedlings. Journal of the American Society for Horticultural Science. 111: 912-917.
34- Wood B.W. 1984. Influence of paclobutrazol on selected growth and chemical characteristics of young pecan seedlings. HortScience, 19: 837-839.
35- Zhu L., van Peppel A., Li X., and Welander M. 2004. Changes of leaf water potential and endogenous cytokinins in young apple trees treated with or without paclobutrazol under drought conditions. Scientia Horticulturae, 99: 133-141.
CAPTCHA Image