Alleviating the water deficit stress effect on Zea mays L. using an extract of the seaweed Sargassum boveanum

In this study a liquid extract from the seaweed Sargassum boveanum (LE_Sb) was prepared using four different methods and solvents. The optimal method, where the extract was prepared using microwave digestion, was selected, and its spray solution was applied to maize (SC704) plants at different concentrations (0.0%, 1.0%, 1.5%, 2.0%, and 2.5% LE_Sb (_V/V)) and three irrigation levels: non-stress (80% of field capacity (FC), 60% FC, and 40% FC). Water stress (40% and 60% FC) limited plant growth by disrupting physiological and biochemical functions. However, the concentration of 1.5% LE_Sb demonstrated a significant improvement in various traits compared to the 0.0% LE_Sb. This improvement included an increase in shoot dry weight by 15.46%, 27.55%, and 57.52% under conditions of 80%, 60%, and 40% FC. Additionally, there was an increase in the activity of antioxidant enzymes, such as superoxide dismutase (SOD), by 13.27%, 30.42%, and 32.19% under conditions of 80%, 60%, and 40% FC, respectively, which could effectively reduce malondialdehyde (MDA) levels. At the concentration of 1.5% there was an increase in proline content by 20.07%, 19.50%, and 10.40% under conditions of 80%, 60%, and 40% FC, respectively, as well as an increase in soluble sugar content under conditions of 60% and 40% FC compared to 0.0% LE_Sb. The relative water content (RWC) also improved with the 1.5% LE_Sb under 60% and 40% FC conditions, by 29.23% and 25.97%, respectively, compared to 0.0% LE_Sb. These results indicate that a concentration of 1.5% LE_Sb can effectively alleviate the negative effects of water stress on maize plants.