The use of Ascophyllum nodosum algae extract as an organic fertilizer to reduce the negative effects of drought stress on the germination of onion seeds (Behbahan native cultivar)

Several studies reported that drought stress in the soil, by reducing the germination indicators, causes a decrease in onion growth and yield. Ascophyum nodosum seaweed extract contains plant growth regulators such as auxin and cytokinin, high and low consumption nutrients, vitamins and antioxidants and can reduce various stresses on plants. For this purpose, different levels of seaweed extract and drought stress were investigated on the germination and growth indices of onion (Behbahan native cultivar). A factorial experiment was performed based on completely randomized design with 3 replications. The investigated factors include: algae extract at 4 levels (0, 3, 6, and 9 percent by volume) and drought stress at four levels non-stress, mild stress, moderate stress, and severe stress (including 0, -0.3, and 0.6 and -0.9 MPa). Drought stress was applied by PEG. The results of this research showed that in conditions non-drought stress, mild stress and moderate stress, the use of Ascophyllum nodosum algae extract (levels of 3% and 6%) caused a significant increase in traits such as germination percentage, germination vigor, seed vigor index, seedling length, plumule length and radicle length. In severe stress conditions, no significant difference was observed between the control levels, 3% and 6%. Considering the development of onion cultivation in Behbahan and the report of negative effects caused by drought stress on onion seeds (Behbahan native cultivar), the use of Ascophyllum nodosum seaweed extract in the soil is recommended to reduce the negative effects caused by drought stress. Algae extract improved the germination indicators, growth characteristics and proper establishment of seedlings , which can increase the yield of this plant.