The Effect of Seaweed Extract (Ascophyllum nodosum) on Quantitative and Qualitative Yield of Soybean

Introduction Seed aging reduces the quality and quantity of agricultural production by reducing quality, viability, and irreversible seed vigor over time. Researchers are increasingly interested in seed aging, which is a serious problem in agriculture. To reduce damages caused during aging, various pretreatment techniques have been studied, including chemical compounds, growth regulators, and antioxidants. Sowing seeds in low osmotic potential osmotic solution is one method of slowing seed aging by osmopriming them. To reduce the negative effects of seed aging, biostimulants such as seaweed extract are used. In order to investigate the effect of seaweed extract on the quantitative and qualitative yield of soybean, an experiment was conducted in the two years of 2018 and 2019 in the research farm of Shahrood University of Technology. Materials and Methods The experimental treatments involved the acceleration of aging in two groups: normal seeds and aged seeds. Additionally, seaweed extract was applied at four different levels: control, seed pre-treatment with a seaweed extract concentration of 0.3%, foliar spraying with a seaweed extract concentration of 0.3%, and a combination of seed pre-treatment and foliar spraying with a seaweed extract concentration of 0.3%. This was conducted as a factorial experiment, employing a randomized complete block design with three replications. A sample of DPX was collected from the Mazandaran Agricultural Research Center. A controlled storage room was used to maintain the seeds at a temperature of 14-17°C and relative humidity of 30-40%. The seeds were harvested the same year as the experiment. In order to apply accelerated aging, the seeds were kept for 72 hours at a temperature of 41°C and relative humidity of 95%. Foliar spraying was done at the beginning of flowering (R1). Results and Discussion  The results showed that accelerated aging decreased the mean daily emergence and germination index by 61.39 and 42.08% compared to the control. The pretreatment of soybean seeds made them more responsive to external stimuli and counteracted stress conditions before they emerged as seedlings. When the seeds were pretreated with seaweed extract, the mean daily emergence and seed germination index increased. The weight of one hundred seeds and the number of pods per plant decreased by 11.64 and 11.38% compared to the control. The combined application of seed pretreatment and foliar spraying in normal and aging conditions had the highest hundred seed weight and the number of pods per plant. In protein-rich crops, seaweed biostimulants can increase protein production. Pretreatment of normal and aged seeds with seaweed extract increased by 1.48 and 1.61 percent of seed protein. In order to improve soybean germination percentage, protein, and seed yield, ellagic acid and seaweed extract should be used individually or combined. Accelerated aging caused a 32.69% decrease in seed yield compared to normal conditions. The combined application of pre-treatment and foliar spraying of seaweed extract had the highest seed yield, which increased by 87.85% compared to the control. Seed aging likely caused a reduction of seed yield by reducing the mean daily emergence, leaf area index, and 100-seed weight. There are three main characteristics (mean daily seedling field emergence, the number of pods per plant, and 100-seed weight) that can explain 85.96% of seed yield variability based on the coefficient of explanation. An analysis of causal connections between seed yield and 100-seed weight showed that seed protein content directly affects seed yield. By increasing the number of pods per plant and the weight of 100 seed, soybean seeds yield may be enhanced by using seaweed extract. Conclusion With its powerful antioxidant properties and anti-aging properties, seaweed extract minimizes the effects of aging on aged seeds. Finally, within the scope of the research, it is possible to suggest the use of pre-treatment and foliar spraying with seaweed extract to increase seed yield and protein percentage in normal and aged soybean seeds.