Gagan Kumar ¹ Satyabrata Nanda ² Sushil K. Singh ¹ Sanjeet Kumar ¹ Divya Singh ³ Bansh N. Singh ³ Arpan Mukherjee ^3,4*

• ¹ Acharya Narendra Deva University of Agriculture and Technology, Ayodhya, Uttar Pradesh, India
• ² School of Biotechnology, Centurion University, Bhubaneswar, India
• ³ Plant-Microbe Interaction Lab, Institute of Environment and Sustainable Development, Banaras Hindu University, Varanasi, Uttar Pradesh, India
• ⁴ Banaras Hindu University, Varanasi, India

Seaweeds are a natural marine resource containing many bioactive compounds such as amino acids, lipids, carbohydrates, proteins, phytohormones, and antimicrobial compounds. Since ancient times, seaweeds have been used in various sectors, including medicine, food, and the cosmetic industry. Currently, seaweeds are a promising alternative to reduce the application of harmful chemicals in agriculture. Seaweed and its derived products have been utilized for plant growth promotion, immunity enhancement, and the reduction of biotic and abiotic stresses. In the current global scenario, synthetic fertilizers and chemical pesticides are commonly used to increase agricultural crop production to meet the growing demands of the world population. However, these chemicals pose significant threats to the health of people, livestock, plants, soil, and the entire environment. On the other hand, seaweed-based products are emerging as a newer option for stress mitigation and reduction, offering an alternative to synthetic chemicals. This article explains the use of seaweed extracts to increase the tolerance of plants to biotic and abiotic stresses. We also address the functions of various bioactive compounds present in seaweed extracts and the mechanisms by which they promote plant growth and induce defence against different stresses.