تاثیر پیش‌تیمار بذر آفتابگردان(helianthus annuus l.) با پلاسمای سرد بر عملکرد و اجزای عملکرد آن در رقابت با علف‌های هرز

پیش تیمار بذر گیاه زراعی با پلاسمای سرد از طریق تسریع جوانه‌زنی بذر می تواند قابلیت رقابت آن را با علف های هرز افزایش دهد. به منظور ارزیابی تاثیر پیش تیمار بذر با پلاسمای سرد بر عملکرد و اجزای عملکرد آفتابگردان در حضور علف های هرز، آزمایشی به صورت فاکتوریل در قالب طرح بلوک های کامل تصادفی با سه تکرار در سال زراعی 95-1394 در مزرعه ی تحقیقاتی دانشگاه صنعتی شاهرود انجام شد. فاکتورهای آزمایش شامل: پیش تیمار بذر در شش سطح، شاهد (بدون پیش تیمار)، خیساندن بذر در آب به مدت 10 ساعت، پیش تیمار بذور با پلاسمای سرد به مدت 15 و 30 ثانیه، خیساندن بذر در آب مقطر به مدت 10 ساعت + پلاسمای سرد به مدت 15 و 30 ثانیه و روش کنترل علف‌های هرز در سه سطح: عدم وجین، وجین تمام فصل و کاربرد  تریفلورالین (1200 گرم ماده موثره در هکتار) بودند. نتایج نشان داد که اثرمتقابل بین فاکتورهای آزمایشی بر تعداد دانه در طبق، عملکرد بیولوژیک و دانه، شاخص برداشت، عملکرد روغن آفتابگردان وزن خشک علف های هرز معنی دار (0.01 >p ) بود. در حضور علف های هرز، روش های مختلف پیش تیمار بذری سبب افزایش معنی دار در تعداد دانه در طبق و عملکرد بیولوژیک آفتابگردان شد. همچنین، پیش‌تیمار بذر با پلاسمای سرد به مدت 30 ثانیه عملکرد روغن و دانه را به ترتیب به میزان 68.8 و 58.5 درصد در حضور علف های هرز نسبت به تیمار شاهد (عدم پیش تیمار در حضور علف های هرز) افزایش داد. براساس نتایج این پژوهش، پیش تیمار بذر با پلاسمای سرد می تواند صفات رشدی و عملکرد آفتابگردان را از طریق بهبود قابلیت رقابت آن با علف های هرز افزایش دهد.

Effect of Pretreatment of Sunflower (Helianthus annuus L.) Seed with Cold Plasma on its Yield and Yield Components in Competition with Weeds

Introduction: Sunflower (Helianthus annuus L.) is a major worldwide oilseed crop that develops slowly during the initial weeks after planting. Weed competition with sunflower during the first four weeks after crop emergence can reduce sunflower yield significantly. Promoting seed germination is the most direct way to improve sunflower growth and competition with weeds. Pertreatment of seed by cold plasma through accelerating seed germination can increase competitive ability of plant with weeds. Cold plasma treatment significantly increased wheat growth and yields. Thus, increasing plant growth can improve competitive ability of it with weeds. The aim of this study was to investigate the effect of cold plasma treatment on growth and yield of sunflower in competition with weeds. Materials and Methods: This experiment was carried out as factorial based on randomized complete block design with three replications at Shahrood University of Technology (latitude of 36° 25 ’N and longitude of 54° 57’ E with an elevation of 1345 m) in 2016. Experimental factors were including cold plasma at six levels: control, hydropriming of seeds for 10 hours, pretreatment of seeds with cold plasma radiation for 15 and 30 seconds, hydropriming of seeds for 10 hours + cold plasma radiation for 15 and 30 seconds and weed control at three levels: control (no weeding), weeding all season and application of trifluralin (1200 g. a.i. ha1). Dielectric barrier discharge plasma jet was operated in ambient air under sterile conditions in the laboratory of Faculty of Physics, Shahrood University of Technology. After seed priming in distilled water for 10 hours, sunflower seeds were taken in petri plates and treated with the plasma for determined times. Seeds were planted in the field immediately after cold plasma treatment. Seed number per head, 100 seeds weight, harvest index, biological, grain and oil yield of sunflower and weed dry weight were recorded. Statistical analyses of data were performed with statistical software MSTATC. Significant differences between means refer to the probability level of 0.05 by LSD test. Results and Discussion: The results showed that seed number per head, biological and grain yield, harvest index, oil yield and weed dry weight significantly affected by interaction effects of treatments. Results showed that biological, oil and seed yield of sunflower decreased by 62.76, 56.11 and 55.86% in weedinfest than weedfree treatments respectively. Seed number per head and biological yield of sunflower significantly increased by using different pretreatments methods than control in the weedinfest conditions. Also, pretreatment of seeds with cold plasma for 30 seconds increased oil and seed yield of sunflower by 68.8 and 58.5 percent respectively in the weed infest treatment than control. The plasma treatment of soybean seeds up to 2 min showed positive effects on their germination rate and seedling growth. Cold plasma has essential roles in a broad spectrum of developmental and physiological processes in plants, including reducing the bacterial bearing rate of seeds, changing seed coat structures, increasing the permeability of seed coats, and stimulating seed germination and seedling growth. In addition, plasma treatment also could improve the physiological metabolism of the plant, such as dehydrogenase activity, superoxide dismutase and peroxidase activities, photosynthetic pigments, photosynthetic efficiency and nitrate reductase activity. It seems that hydropriming technique and cold plasma irradiation with improving seed germination and seedling early growth can led to more and faster germination and better competition of sunflower plants with weeds.  Conclusion: Based on our results, pretreatment of seeds by cold plasma and hydropriming in addition to reducing weed biomass, could significantly improve the growth characteristics and yield of sunflower through increasing crop competitive ability with weeds.