Effect of chitosan molecular mass on germination and in vitro growth of soy

Abstract

Physical-chemical characteristics of chitosan influence the development of crops when applied as a biostimulants. The objective of the research was to determine the influence of chitosan of different molecular masses on the in vitro initial vegetative growth of soybean seedlings. The seeds were disinfected and imbibed for one hour in chitosan solutions at 10, 100 and 500 mg L^-1, with medium molecular mass (Q₁, 100 kDa) and low (Q₂, 25.3 kDa). After 72 hours of incubation the seeds were determined the percentage of germination and the length of the radicle, before placing in containers with sterile Hougland nutrient solution and, cultivated in a room of lights for 10 days (Phase R1). The results obtained showed the biostimulant effect of chitosan, when applied by imbibition of seeds, regardless of their molecular mass and concentration, in the percentage of germinated seeds, while the growth of the seedlings was influenced by the concentration of 500 mg L^{- 1} of chitosan. The application of medium molecular mass chitosan (Q₁) increased the number of leaves, the length of the stem and roots, the radical dry mass and the leaf area of the seedlings. Not influenced on the dry mass of the aerial part was observed, however, Q₂ stimulated the dry biomass, while Q¹, increased the leaf area index (LAI) of the seedlings, by ten times with the concentration of 500 mg L^-1. Both chitosan polymers doubled the root-stem ratio (r/v), in relation to the control plants from seeds embedded in water. The effect of the molecular mass and concentration of chitosan on the biostimulant capacity of soybean seedlings when applied by seed imbibition was demonstrated.