تاثير تنش خشكي بر كيفيت ظاهري، خصوصيات مرفولوژيكي و فيزيولوژيكي ۳ گونه چمن بومي

The Effect of Different levels of Soil Moisture on Visual Quality, Morphological and Physiological Characteristics of Three Native Grass Species

توسعه فضاي سبز شهري و چمنكاري از جمله نيازهاي بشر امروز است كه عامل محدودكننده در اين امر كمبود آب مي باشد. اين كمبود بر توسعه، كيفيت و انتخاب نوع پوشش گياهي تاثير مستقيم مي گذارد. از اينرو آزمايش فاكتوريل بر پايه طرح كاملاً تصادفي براي سنجش مقاومت گونه هاي چمن بومي و انتخاب گونه مناسب روي گونه هاي بومي Brumos tomentellus، Festuca rubra، F .arundinacea و رقم تجاري Super sport (شاهد) و سه سطح رطوبتي ۸۵ درصد (شاهد)، ۶۵ درصد و ۴۵ درصد ظرفيت زراعي در مركز تحقيقات و آموزش كشاورزي و منابع طبيعي خراسان رضوي در شرايط گلخانه انجام گرفت. بر اساس نتايج بدست آمده بيشترين طول شاخساره در تنش خشكي ۶۵ درصد ظرفيت زراعي در گونه F. arundinaceae و كمترين مقدار در چمن سوپر اسپورت، همچنين صفت عرض برگ بيشترين و كمترين مقدار در شرايط تنش به ترتيب در گونه B. tomentellus و چمن سوپر اسپورت مشاهده شد. گونه F. arundinaceae تحت شرايط تنش خشكي بهترين كيفيت ظاهري و بيشترين ميزان كلروفيل a و كل را به خود اختصاص داد. تحت تنش خشكي كمترين نشت يوني (۲۵/۶۶ درصد) در گونه F.rubra، بيشترين مقدار محتواي آب نسبي در گونه F. arundinaceae (۷۷/۸۰ درصد)، بيشترين ميزان پرولين برگ در گونه B. tomentellus و كمترين مقدار در چمن سوپر اسپورت مشاهده شد. با توجه به نتايج بدست آمده ميتوان گفت گونه هاي چمن بومي در شرايط تنش خشكي عملكرد و كيفيت بهتري از چمن هاي وارداتي مانند سوپر اسپورت را دارا مي باشند.

Introduction: Over the last three decades, turfgrass breeders have put significant effort into breeding and developing turf species that have good drought resistance. As water conservation becomes an important issue, an interest is increasing in identifying grasses that require less water. Lack of water resources is most problems to increasing urban green spaces. Plants with good drought resistance are those that are able to survive stress by means of drought avoidance, drought tolerance at leaf water potentials, or both. The efficient use of water is made possible by understanding the effects of soil moisture water on crop development and yield. Drought affects the visual quality, growth rate and evapotranspiration. Researchers reported that turfgrass subjected to drought conditions for short periods could sustain a fairly good appearance by soil moisture about half of its consumptive use whenever soil moisture level falls to near permanent wilting point. Drought stress caused decrease in RWC and visual quality of many grass cultivars. In drought conditions resistance grass showed increase in proline content on their leaves. Therefore the use of native grasses with high strength instead of imported grass with low-resistance is one way to increase landscape areas and reduce costs. The purpose of this study was to be compared native grasses with commercial grass cultivar “Super sport”. Materials and Methods: The objective of this study was to evaluate the effect of soil moisture stress levels included 85% (control), 65% and 45% of field capacity on native species Brumos tomentellus, Festuca rubra and F. arundinacea and commercial cultivars Super sport (control) under greenhouse conditions. Plants were cultured in PVC containers measuring 9 cm in diameter and 60 cm deep. Soil was mixture of 70% loam soil, 20% pit mass and 10% sand. Greenhouse air temperature was maintained between 22 and 28 centigrade degree. All plants were maintained under well watered conditions for 45 day before drought stress. This experiment was conducted as factorial experiment based on completely random design with four replications. Measured parameters were length and width of leaves, chlorophyll a, chlorophyll b and total chlorophyll content, visual quality, electrolyte leakage, RWC and proline content of leaves. Length and width of leaves measured with ruler. Proline content, RWC percent, chlorophyll a, chlorophyll b and total chlorophyll content of leaf, visual quality and leaf electrolyte leakage was measured with standard protocols. Analysis of the data by statistical software JMP 8 and graphs with Excel 2010 was drawn. Results and Discussion: Result of the experiment showed those native species have different response tosoil moisture stress conditions. The highest and lowest length of leaves were observed in 65% field capacity in F. arundinacea and super sport grass, respectively. The results showed that width of leaves of B. tomentellusincreased and decreased in super sport. Under soil moisture stress conditions, F. arundinacea has best visualquality with 7.66 score. Highest chlorophyll a and total chlorophyll were observed in tall fescue grass. The lowest electrolyte leakage under drought stress was obtained from F. rubra with 25.66 percent. RWC content inthe native F. arundinacea increased to 77.80 compared with super sport (control). B. tomentellus under soil moisture stress showed the highest proline content and commercial cultivar (super sport)indicate lowest prolinecontent at 45% field capacity. Selahvarzi and et al. (2009) found that visual quality of tall fescue decrease in drought stress. In drought stress RWC percent decrease in grass species. Proline content was increased in drought stress at Lolium perene cool season grass. Much studies on native cultivar indicated that native turfgrass cultivar have more resistance to drought stress compared with exotic turfgrass cultivars. Conclusions: According to the results, we said native grass species under drought stress conditions have better quality compared with imported grass cultivar Super sport. Visual quality in native grass were suitable for use in urban landscape, that visual quality showed little change in soil moisture stress and leaves were fresh in this conditions. Native grass cultivars were more resistance than imported grass cultivar. This study showed that native grass such as F. arundinacea and F. rubra has low cost to use and these turfgrass need to lower water soil moisture than commercial grass Super sport.