From sea to soil: How seaweed extracts benefit vegetable production?

The increasing reliance on inorganic, chemical fertilizers to meet the global food demands has posed a significant threat to human health and the environment. However, there has been a continuous search for eco-friendly alternatives. Recently, a sustainable alternative in the form of seaweed-based bio-fertilizers has garnered considerable attention for their nutrient-rich nature and ease of application. Generally, the seaweeds are classified into red, green, and brown algae, and all of them can be used to prepare seaweed extracts. They are rich in proteins, carbohydrates, vitamins, minerals, and plant growth regulators like auxins and cytokinins etc. Their application in agriculture has been linked to significant improvements in growth, yield, and quality parameters of various crop plants by different researchers. They are particularly useful in vegetable crops and hence can be used to enhance vegetable production worldwide. They have been found quite useful across a variety of vegetable crops. Seaweed extracts are commercially available in their liquid, powder, or granular forms, which are shown to have a variety of benefits, like improvement in nutrient uptake, stimulation of soil microbiota, and boosting of antioxidant properties. Further, the seaweed extracts are also effective in mitigating both biotic and abiotic stress in vegetable crops, including drought, salinity, temperature extremes, insect pests, and plant pathogens, by improving plant defence responses and improving their physiology to enhance stress resilience. Commercially important seaweeds are harvested from coastal regions, where the setting up of such industries is more economical. Various studies consistently demonstrate that integrating the use of seaweed extracts as bio-stimulants with conventional fertilizers can enhance crop performance with reduced environmental concerns. However, there have been some challenges in their application and dosage optimizations, on a plant-to-plant bases. The present review proposes seaweed extracts as non-toxic, bio-degradable bio-stimulants as a promising solution for achieving sustainably in agriculture and improving global vegetable production for ensuring the nutritional security of the increasing human population.