The effect of pretreatment and foliar spraying of seaweed fertilizer (Ascophyllum nodosum) on the improvement of pigments, qualitative traits and grain yield of soybeans obtained from aged seeds

This experiment was conducted to investigate the effect of seaweed fertilizer on the improvement of physiological traits of soybeans in the research field of Shahrood University of Technology Faculty of Agriculture during two crop years, 2018–2019 and 2019–2020. The experiment was carried out factorially in the form of a randomized complete block design in three replications. The experimental factors included accelerated aging in two levels (control seeds and aged seeds) and seaweed fertilizer in three levels (control: no treatment, seed pretreatment and foliar spraying with a concentration of 0.3% seaweed fertilizer). Results showed that accelerated aging in the first and second years of the experiment caused a decrease of 15.11 and 13.33% in the amount of chlorophyll a in leaves of plants obtained from these seeds. In both years, the foliar application of seaweed fertilizer in normal and aging conditions caused a significant increase in the amount of chlorophyll a to a significant level. Accelerated aging in seeds caused an increase of 35.13, 12.46 and 22.22 percent of carotenoid, flavonoid and anthocyanin in the leaves of plants obtained from these seeds, respectively. Accelerated aging decreased by 0.86%, 0.90% and 33.18% of seed oil, protein and yield. The maximum levels of oil and protein were 19.74% and 38.31%, respectively, which belonged to foliar spraying and seed pretreatment treatments. Using seaweed fertilizer as seed pretreatment and foliar spraying increased yield by 36.49% and 21.67%, respectively, compared to the control. Finally, pre-treatment of seeds with seaweed fertilizer can be suggested to improve the effects of seed aging and increase yield in the soybeans.