Changes of soluble protein contents in leaves of 25-day-old tobacco plants
treated with different chitosan compounds and concentrations. Treatments were
applied by foliar spray (A) (SEx = 0. 0131), soil drench to the plant rhizosphere (B)
(SEx = 0. 0373) 72 h before foliar extraction or by soil drench to the substrate at
seeding (C) (SEx = 0. 0092). Data are means ± SE of triplicate samples from one
representative of two independent experiments. Different letters among treatments
indicate significant differences in Tukey’s test (p 6 0.05).