Effects of Ulva intestinalis Linnaeus seaweed liquid extract on plant growth, photosynthetic performance and water status of two hydroponically grown Lamiaceae species: Peppermint (Mentha × piperita L.) and purple basil (Ocimum basilicum var. purpurascens Benth.)

Abstract

Seaweed extracts are considered as marine biostimulants and have been successfully used in agriculture to improve the growth and tolerance to different environmental stress conditions of many crops. Therefore, the present study was carried out for the first time and aimed to determine the effects of a seaweed liquid extract on growth and photosynthetic performance as well as the water status of hydroponically-grown peppermint and purple basil plants. For this purpose, the experiment was conducted under greenhouse conditions and plants were cultivated in hydroponic systems according to the nutrient film technique. A seaweed liquid extract at 10% was prepared from the green marine macroalgae Ulva intestinalis and then added to the nutrient solution of the hydroponic system. Based on our experimental data, the main results have proven that Ulva intestinalis seaweed liquid extract could be successfully used as a biostimulant in the hydroponic cultivation of peppermint for its enhancing effect on some plant growth and photosynthetic as well as water status parameters. However, it is not recommended to add the seaweed liquid extract of Ulva intestinalis to the hydroponic culture of purple basil since most of the parameters analyzed were shown to be negatively affected by the seaweed liquid extract treatment. Furthermore, the results of this study could be practical for enhancing the production of medicinal and aromatic plants by adding the Ulva intestinalis seaweed liquid extract to the nutrient solution of the hydroponic system.