پاسخ‌هاي فيزيولوژيك گياه سويا (DPX) به پيش‌ تيمار بذر و محلول‌ پاشي عصاره جلبك و كيفيت اوليه بذر

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

تغييراتي كه در طي فرسودگي رخ مي‌دهد بر كيفيت بذر تأثير مي‌گذارند. با فرسودگي بذر، قدرت بذر اولين جزء از كيفيت بذر است كه كاهش مي‌يابد و به دنبال آن ظرفيت جوانه‌زني، رشد و استقرار گياهچه نيز كاهش نشان مي‌دهد. به‌منظور بررسي تأثير عصاره جلبك دريايي (Ascophyllum nodosum) بر بهبود كيفيت گياهان حاصل از بذرهاي زوال‌يافته سويا، آزمايشي در مزرعه تحقيقاتي دانشگاه صنعتي شاهرود طي دو سال زراعي 1398-1397 و 1399-1398 اجرا شد. تيمارهاي آزمايش شامل كيفيت اوليه بذر در دو سطح (بذر نرمال و بذر فرسوده) و عصاره جلبك دريايي در چهار سطح (شاهد، پيش‌تيمار بذري، محلول‌پاشي برگي، كاربرد توأم پيش‌تيمار بذري و محلول‌پاشي برگي با غلظت 0/3 درصد) بودند كه در قالب آزمايش فاكتوريل با طرح پايه بلوك‌هاي كامل تصادفي در سه تكرار سازمان‌دهي شدند. بذور در دماي 41 درجه سانتي‌گراد و رطوبت نسبي 95 درصد به مدت 72 ساعت فرسوده شدند. نتايج نشان داد ميانگين ظهور گياهچه در مزرعه، ميزان قند محلول موجود در برگ، شاخص سطح برگ، هدايت روزنه‌اي، عملكرد روغن و عملكرد دانه در گياهان حاصل از بذور فرسوده كاهش يافت. فرسودگي موجب افزايش در صفاتي از قبيل ميزان اسيدهاي آمينه آزاد و هدايت الكتريكي غشاء گرديد. استفاده از عصاره جلبك به‌صورت پيش‌تيمار بذري در شرايط نرمال و فرسوده موجب افزايش ميانگين ظهور گياهچه در مزرعه به‌ترتيب به ميزان 15/31 و 55/03 درصد نسبت به عدم كاربرد عصاره شد. كاربرد توأم پيش‌تيمار و محلول‌پاشي عصاره صفات شاخص سطح برگ، هدايت روزنه‌اي، عملكرد روغن و عملكرد دانه را به‌ترتيب 34/51، 23/72، 91/68 و 87/85 درصد نسبت به شاهد افزايش داد. در محدوده پژوهش انجام شده مي‌توان كاربرد توأم عصاره جلبك دريايي به‌صورت پيش‌تيمار بذري و محلول‌پاشي برگي را به‌عنوان بهترين تركيب تيماري در جهت بهبود صفات فيزيولوژيك در گياهان حاصل از بذور فرسوده سويا پيشنهاد نمود.

Introduction Changes 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 Methods A 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 (un-aged) 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 Discussion In 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 pre-treatment and foliar spraying with Ascophyllum nodosum brown seaweed extract at a concentration of 0.3% improved the deteriorated effects and significantly increased seed yield. Conclusion This 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.