دانلود متن کامل مقاله شماره 17
سیستم های تحمل ریزوباکتریها به بیماریهای گیاهی
Understanding the involvement of rhizobacteriamediated induction of systemic resistance in biocontrol of plant diseases
Abstract: range of plant pathogens. To exploit induced systemic resistance, detailed knowledge of the triggering bacterial traits involved and on signal transduction pathways in the plant is necessary. Possibilities to improve effectiveness of induced resistance by rhizobacterial strains are discussed.
Introduction The estimated number of prokaryotic cells in our planet’s soil is 2.6 × 10 29, providing an enormous capacity for genetic
diversity (Whitman et al. 1998) and a great potential for exploitation. One of the uses of prokaryotes from soil is for biological control of soilborne plant diseases (Handelsman and Stabb 1996). Particularly, strains of plantroot- inhabiting fluorescent Pseudomonas spp. have been
studied in detail for their disease suppressive properties. In a recent review, Weller et al. (2002) described the importance of these bacteria in soil suppressiveness against Gaeumannomyces graminis root surface of the plant (Lugtenberg et al. 2001), and effective expression of disease-suppressive traits (Handelsman and Stabb 1996), are generally considered prerequisites for successful suppression of soilborne diseases by rhizobacteria. The mechanisms involved in disease suppression
induced systemic resistance, lipopolysaccharides, Pseudomonas fluorescens, Pseudomonas putida, salicylic
Key words:
تحمل به خشکی در گیاهان گوشنی و ابدار
Salinity Tolerance of Cacti and Succulents
Abstract
The salinity tolerance of golden barrel cactus (Echinocactus grusonii), ocotillo (Fouquieria splendens), saguaro cactus (Carnegiea gigantea), and Gentry’s agave (Agave parryi truncata) was tested. Plants were irrigated with a solution of EC 0.6, 5.0, 10.0, and 15.0 dS/m. Duration of treatments were 18 weeks for saguaro and 26 weeks for the other three species. In general, fresh weight, dry weight, and moisture content decreased with increasing salinity levels, with the exception of saguaro dry weight which was not affected by the treatments, and ocotillo moisture content which increased with increasing salinity. Runoff was collected three times during the experiment and indicated that ion uptake was higher for barrel cactus than the other three species. EC of runoff averaged for all dates and species showed an increase of 17%, 54%, 46%, and 64% over the salinity treatment solutions of 0.6, 5.0, 10.0, and 15.0 dS/m, respectively.
Introduction
Salinity is a problem in many arid regions of the world, including the Southwestern United States. Deteriorating water quality exposes cacti and succulents in urban landscapes to increasing salinity conditions. Unless higher leaching fractions are used, salts will accumulate in the root zone of plants when irrigation water of higher salinity is used. In addition, with drought becoming a common occurrence each year in the arid southwest, it is possible that water restrictions will be imposed in response to drought emergencies, which will cause potential issues of both salinity and drought for plants in urban landscapes. Large numbers of cacti and succulents are already established in Southwest landscapes and many more are planted each year in the rapidly increasing urban developments. Although these plants are generally considered tolerant to drought, no data exists as to their salinity tolerance. It is well established that drought tolerance and salinity tolerance have different mechanisms and therefore tolerance to one stress does not confer tolerance to another. With the likelihood of increasing soil and water salinity in the Southwest, it seems prudent to obtain knowledge regarding the salinity tolerance of commonly planted cacti and succulents. The ive of this research was to determine the salt tolerance of four species of succulents and cacti and to determine ion concentration in runoff.
Materials and Methods
Golden barrel cactus (Echinocactus grusonii), saguaro cactus (Carnegiea gigantea), ocotillo (Fouquieria splendens), and Gentry’s agave (Agave parryi truncata) were transplanted into 2-gallon (5.4 L) containers with a mix of sand and pumice (50/50 vol.). Plants were grown outdoors in full sun at the Campus Agriculture Center of
he University of Arizona in Tucson, Arizona from May to November 2006. Duration of treatments were 18 weeks for saguaro and 26 weeks for the other three species. Plants were irrigated with a fertilizer solution containing 50 ppm N augmented with a 3:1 ratio of sodium chloride and calcium chloride to obtain salinity levels of EC 0.6, 5.0, 10.0, and 15.0 dS/m. Eight replicate plants per species were assigned to each salinity treatment. Plant dry weight, moisture content of shoots and mineral tissue analysis were determined at the end of the experiment. Runoff was captured and analyzed three times at 7-week intervals.
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http://www.uplod.ir/download.php?file=907135
آقطی
Sambucus spp
Elderberry
Caprifoliaceae
معرفی و گیاهشناسی
گیاهی است از خانواده ی Caprifoliaceae که به صورت درخت یا درختچه دیده می شود. دارای برگهای متقابل و به فرم مرکب دارای 5 تا 7 برگچه و فاقد گوشواره است. گلها به رنگ سفید و به صورت گل آذین دیهیم یا خوشه قرار دارند. میوه به فرم سته و به رنگ قرمز یا سیاه است و دارای 2 تا 3 میوه می باشد. ریزوم هایی به رنگ سفید دارد. تمام اندام های گیاه سمی است و بوی ناخوشایندی دارد.
دو گونه از این گیاه دارای اهمیت دارویی هستند: S.ebulus آقطی صغیر و S.nigra آقطی کبیر
S.ebulus در شمال کشور و S.nigra در حوالی همدان، تهران،سمنان و کردستان یافت می شود.
نیازهای اکولوژیکی
در خاک های تقریبا شور می روید و به رطوبت زیاد و ازت فراوان نیاز دارد. در سایه به خوبی می روید ولی نور فراوان باعث افزایش عملکرد اش می شود.
کاشت، داشت، برداشت
بذور آقطی را در مرداد ماه تا شهریور ماه جمع آوری می کنند و این بذور را در پاییز همان سال یا بهار سال بعد در خزانه کشت می کنند. یک سال بعد نهال ها را به زمین اصلی منتقل می کنند.
تکثیر رویشی گیاه بوسیله ی قلمه نیمه خشبی ساقه به طول 20 سانتی متر که در تیر ماه تا شهریور ماه گرفته می شود در خزانه هوای آزاد با رطوبت مناسب ( ترجیحا سایه باشد تا قلمه ها زودتر ریشه دهند) قرار داده می شوند تا ریشه بزنند.
قلمه ها در زمین اصلی به فواصل 100 تا 150 سانتی متر روی ردیف و 250 تا 300 بین ردیف کشت می شود.
برداشت محصول هنگامی است که گلهای قسمت های کناری گل آذین باز شده اند و گلهای وسط به حالت غنچه هستند. میوه ها هم در حالت رسیده برداشت می شوند.
فرآوری
گل ها دارای 1/. تا 2/. اسانس و گلیکوزید سامبونیگرین و فلاونویید ها هستند. میوه ها دارای اسید های آلی و ویتامین های A و C هستند.
عصاره گیری توسط الکل متانل 80 درصد صورت می گیرد. عصاره حاصل پس از جمع آوری توسط تقطیر با بخار آب تغلیظ می شود و سپس در آزمایشگاه حلال از آن تبخیر می شود.
خواص و کاربرد
مواد موثره آقطی دارای اثر آرامبخش، مدر، تقویت کننده عضلات قلب، درمان سرماخوردگی و ... است. گل ها دارای اثر مسهلی هستند.
