Development of sprayable sodium alginate-seaweed agricultural mulches with nutritional benefits for substrates and plants

Abstract

Sprayable agricultural mulch suspensions were prepared from the combination of sodium alginate (Alg) and three different concentrations of the seaweed Undaria pinnatifida (A) microparticles: 0.5, 1, and 2 wt.%. Growth parameters were measured in tomato plants cultivated under each type of mulches, including polyethylene (PE) as a control treatment. The aerial fresh and dry weights (FW and DW, respectively), chlorophyll (Chl) content, green canopy cover, and the anthocyanin content were determined in tomato plants at the end of the bioassays. The soil temperature and moisture were measured during the experiment. Besides, the impact of the different mulch treatments on soil microorganisms was assayed by measuring the relative abundance of bacteria, fungi, and actinomycetes. Results indicated that the percentage of A in the mulch formulation was crucial to confer it with biostimulant properties. Alg with 1 wt.% of A provided a significant increment in FW and DW and the Chl level of tomato plants, demonstrating that the developed formulations represent a useful material for horticulture production.