پاسخ‌های فیزیولوژیک گیاه سویا (dpx) به پیش‌تیمار بذر و محلول‌پاشی عصاره جلبک و کیفیت اولیه بذر

تغییراتی که در طی فرسودگی رخ می‌دهد بر کیفیت بذر تاثیر می‌گذارند. با فرسودگی بذر، قدرت بذر اولین جزء از کیفیت بذر است که کاهش می‌یابد و به دنبال آن ظرفیت جوانه‌زنی، رشد و استقرار گیاهچه نیز کاهش نشان می‌دهد. به‌منظور بررسی تاثیر عصاره جلبک دریایی (ascophyllum nodosum) بر بهبود کیفیت گیاهان حاصل از بذرهای زوال‌یافته سویا، آزمایشی در مزرعه تحقیقاتی دانشگاه صنعتی شاهرود طی دو سال زراعی 13981397 و 13991398 اجرا شد. تیمارهای آزمایش شامل کیفیت اولیه بذر در دو سطح (بذر نرمال و بذر فرسوده) و عصاره جلبک دریایی در چهار سطح (شاهد، پیش‌تیمار بذری، محلول‌پاشی برگی، کاربرد توام پیش‌تیمار بذری و محلول‌پاشی برگی با غلظت 3/0 درصد) بودند که در قالب آزمایش فاکتوریل با طرح پایه بلوک‌های کامل تصادفی در سه تکرار سازمان‌دهی شدند. بذور در دمای 41 درجه سانتی‌گراد و رطوبت نسبی 95 درصد به مدت 72 ساعت فرسوده شدند. نتایج نشان داد میانگین ظهور گیاهچه در مزرعه، میزان قند محلول موجود در برگ، شاخص سطح برگ، هدایت روزنه‌ای، عملکرد روغن و عملکرد دانه در گیاهان حاصل از بذور فرسوده کاهش یافت. فرسودگی موجب افزایش در صفاتی از قبیل میزان اسیدهای آمینه آزاد و هدایت الکتریکی غشاء گردید. استفاده از عصاره جلبک به‌صورت پیش‌تیمار بذری در شرایط نرمال و فرسوده موجب افزایش میانگین ظهور گیاهچه در مزرعه به‌ترتیب به میزان 31/15 و 03/55 درصد نسبت به عدم کاربرد عصاره شد. کاربرد توام پیش‌تیمار و محلول‌پاشی عصاره صفات شاخص سطح برگ، هدایت روزنه‌ای، عملکرد روغن و عملکرد دانه را به‌ترتیب 51/34، 72/23، 68/91 و 85/87 درصد نسبت به شاهد افزایش داد. در محدوده پژوهش انجام شده می‌توان کاربرد توام عصاره جلبک دریایی به‌صورت پیش‌تیمار بذری و محلول‌پاشی برگی را به‌عنوان بهترین ترکیب تیماری در جهت بهبود صفات فیزیولوژیک در گیاهان حاصل از بذور فرسوده سویا پیشنهاد نمود.

Physiological Responses of Soybean Plant (DPX) to Pretreatment and Foliar Application of Seaweed Extract (Ascophyllum nodosum) and Seed Primary Quality

IntroductionChanges that occur during aging affect seed quality. Vigor is the first component of seed quality that decreases with aging seed, and followed by a decrease in germination capacity, seedling growth and establishment. The seeds of soybeans are classified in the orthodox seeds. These seeds contain high amount of lipid and protein. Seed viability can only be maintained until few months of storage under normal conditions. One of the important steps in soybean seed industry is maintaining seed quality during storage condition for the planting during next growth season or sales. Lack of a proper storage condition would affect the biochemical and physiological nature of soybean seeds and intensify their aging. Changes that occur during deterioration condition affect seed quality. Through the process of deterioration, seed vigor is the first traits of the seed quality that decreases, followed by a decrease in germination capacity, seedling growth and establishment. Wide range of deteriorative conditions (especially moisture content and temperature) may affect seed quality during storage which may lead to seed aging. Hence, to stimulate germination and increase the establishment of seedlings from ageing seeds, treatment can be done using different materials such as brown seaweed extract. To continue the experiment, normal seeds and aged seeds were sown in June 2018 and 2019 at a depth of 2 cm. Each plot consisted of 4 lines 6 m long with a distance of 50 cm between the lines and 10 cm width on the lines.Materials and MethodsA factorial experiment was performed based on a randomized complete block design with three replications at the research field of Shahroud University of Technology. In this study two sets of seeds including control seeds (unaged) and aged seed were used and brown seaweed A. nodosum (0.3%) was applied for control, seed pretreatment, foliar spray and seed pretreatment+foliar spray. The brown seaweed extract was &Acadian™ Seaweed Powder& (produced in Canada) containing brown seaweed extract (Ascophyllum nodosum), and all the reagent and chemicals for experiments were purchased from Merck (Germany). Soybean seed Var. DPX. was collected from the Mazandaran agricultural research center. The water content of seeds was 12%. The seeds were those that harvested in the same year and kept in a controlled storage room at the temperature between 14 to 17 °C and relative humidity of 30 to 40% at the Agricultural Research and Training Center and Natural Resources of Mazandaran Province. For surface sterilization, soybean seeds were disinfected with 1% sodium hypochlorite for 60 seconds and then washed with distilled water. To prepare aged seeds in the laboratory, the seeds were incubated at 41°C and 95% relative humidity for 72 hours according to the method described previously. For each treatment, 100 g of the soybean seeds were soaked in 20 ml seaweed extract (0.3%) under ventilation condition for 6 hours, following by drying the seeds in the shade.Results and DiscussionIn this study, the results showed that the seed aging reduced the mean daily seedling field emergence, content of soluble sugar, leaf area index, stomatal conductance, oil yield and seed yield and also, increased the electrical conductivity and free amino acids content in the field condition. Whereas, the seed pretreatment with the seaweed extract in normal and aging conditions increased mean daily seedling field emergence 15.31% and 55.03% respectively. The values of leaf area index, stomatal conductance, oil yield and seed yield were increased with application of both pretreatment and foliar spray of seaweed extract, 34.51%, 23.72%, 91.68% and 87.85% respectively. Seed pretreatment and foliar spraying with Ascophyllum nodosum brown seaweed extract at a concentration of 0.3% improved the deteriorated effects and significantly increased seed yield.ConclusionThis study concludes that the seaweed extract is effective to minimize negative effects of aging on seeds performance and has a great positive effect on the physiological and agronomic traits of soybean plant. Among the four methods used in this study, the seeds pretreatment+foliar spray was more effective.