Seaweed polysaccharides on seed germination of Brassica napus L.

Abstract

Seaweed polysaccharides, when compared to synthetic commercial fertilizers, have been proven to achieve excellent results in plant growth parameters. When applied to the soil directly or sprayed on the foliage, seaweed poly- and oligosaccharides can improve seed germination and plant vigor, increase the uptake of soil nutrients, and protect plants against several abiotic and biotic stresses, by stimulating a plant to produce secondary metabolites and manage its defense pathways. In this study, three different polysaccharides (alginate, agar and carrageenan) were extracted from one brown seaweed, Saccorhiza polyschides, and two red seaweeds, Gracilaria gracilis and Chondrus crispus, respectively, with aim to analyse their impact on Brassica napus L. seed germination. The polysaccharides' chemical structure, mineral profile and other physicochemical properties were assessed. Carrageenan exhibited the best results in seedling growth and germination percentage when compared to alginate and agar. The carrageenan extracted from the tetrasporophyte, non-fructified thalli and female gametophyte of Chondrus crispus exhibited 94.67, 92 and 98.67 % seed germination, respectively. Carrageenan's bioactivities appear to be related with their sulphation level, plus the pH and the conductivity of its solution. The optimum concentration for germination of each polysaccharides' solution was assigned to propose further experiments in turnip greens.