Experimental design, treatments and crop management
A split plot design based on randomized complete blocks with
three replicates was used. Two sowing dates (20 February and 25
March) were assigned to main plots. The sub-plots were devoted to
zinc foliar spray (100 ppm, as zinc sulfate) alone and in combinations
with humic acid (500 ppm) or/and chitosan (150 ppm) as well
as a control (only sprayed with tap water), sprayed in doses of up to
0.143 L m−2. Soluble humic acid as potassium-humate (80% humic
acid, 11–13%K2O) was used.Alocal commercial product of chitosan
(2-amino-2-deoxy-ˇ-d-glucosamine) namely Chito-Care® with a
degree of deacetylation of 85% was used. Humic acid and chitosan
were dissolved in tap water to get the targeted concentrations