Effects of Ascophyllum nodosum extract on sweet pepper plants as an organic biostimulant in grow box home garden conditions

The effects of a commercial Ascophyllum seaweed extract (ASWE) on the growth parameters of sweet pepper plants were studied under grow box home garden conditions in the Caribbean. Grow box cultivation of vegetables in the backyard is very popular in Trinidad and Tobago and the wider Caribbean region. The use of synthetic chemicals should be avoided under home conditions due to the underlying hazards and for biosafety reasons. The application of ASWE at the rate of 0.5% as a foliar spray in sweet pepper plants under grow box home garden conditions improved the plant growth parameters, increased the fruit number, and also enhanced the shelf life of the harvested sweet pepper fruits. Soil drenching of ASWE to plants was less effective compared to foliar application. ASWE foliar spray also reduced the intensity of diseases and pests in plants and further promoted the prevalence of natural enemies. The spraying of ASWE significantly increased the biochemical constituents such as chlorophyll content, reducing sugars, phenol, and amino acids compared to the water control. The activity of the defense-related enzymes (chitinase, β-1,3 glucanase, peroxidase, polyphenol oxidase, phenylalanine ammonia-lyase), and phenolic content was significantly greater in sweet pepper plants treated with ASWE treatment compared to the control. Seed treatment by priming in 0.5% ASWE significantly increased the germination percentage, shoot, and root length of seedlings. The positive effects of ASWE might be attributed to the chemical makeup, native to the seaweed extract, which is believed to contain several organic components, including dissolved nutrients and growth-promoting and diverse functional organic molecules that can induce multiple growth effects in plants. This study demonstrates that ASWE can be readily used under home garden conditions as this would be very conservative to the environment as well as promote the system of organic cultivation.