Seaweed fertilizer improved drought tolerance of tomato seedlings in sandy soil

Global climate change has increased atmospheric transpiration and evaporation and decreased rainfall, and these changes have exacerbated water deficit-induced restrictions on agricultural production in arid and semi-arid areas. To test the influence of seaweed fertilization, a product of Qingdao Bright Moon Seaweed Group Co., Ltd®., on tomato drought response in sandy soils, on tomato drought response in sandy soils, a pot experiment was conducted in a greenhouse to measure biomass and leaf parameters, including chlorophyll concentration, relative water content, and carbohydrate and nitrogen content, under two water-availability scenarios including 85 ± 5% field water content and without irrigating treatment (chemical fertilization under well-watered conditions (WW), chemical fertilization under drought-stressed conditions (WD), seaweed fertilization under well-watered conditions (WW + SF), and seaweed fertilization under drought-stressed conditions (WD + SF)). The results showed that under water deficit stress, seaweed fertilization increased soil urease activity (429%) and soil ammonium nitrogen content, thereby increasing the nitrogen content available to the plants. Seaweed fertilization also enhanced the leaf proline content and water content of the plants, and decreased oxidative damage (low malondialdehyde content, which is lower 43.8% compared with WD). In addition, seaweed fertilization increased the leaf nitrogen content and reduced the nonstructural carbohydrate contentto maintain a relatively low total nonstructural carbohydrate/nitrogen (C/N) ratio. Taken together, seaweed fertilization-induced changes improved drought resistance in tomato seedlings and these results suggested that seaweed fertilization has the potential to improve crop drought resistance in sandy areas.