Potential of Chitosan Supplementation for Remediation of Iron Deficiency Chlorosis in Soybean (Glycine max).

Chitosans are polysaccharide molecules derived from chitin, which is found in fungal cell walls and crustacean exoskeletons. Chitosans’ agricultural applications include boosting disease resistance, increasing crop growth and enhancing nutrient uptake, including microminerals. Iron (Fe) deficiency chlorosis is an important problem in agriculture, namely in soybean production. Here, we evaluated the potential of low molecular weight chitosan in remediating iron deficiency chlorosis in a soybean variety inefficient in iron uptake (Glycine max cv. Dieckmann Green-Yellow). Soybean seedlings were hydroponically grown for 14 days in Fe-sufficient (30 µM) and Fe-deficient (5 µM) conditions, with or without low molecular weight chitosan supplementation (0.02 g/L). Chitosan supplementation did not affect plant growth, but lessened foliar chlorosis when plants were grown in Fe-deficient conditions. Chitosan supplementation was associated with increased (P < 0.01) concentration of chlorophyll a (29% and 11%) and chlorophyll b (40% and 29%) in Fe-sufficient and Fe-deficient conditions, respectively. Additionally, chitosan supplementation modulated the concentration of several minerals in different plant parts. However, in chitosan-treated plants, Fe concentration increased (P < 0.05) in roots, but not in leaves. This was accompanied by a significant increase in root Fe-chelate reductase gene expression (4.9-fold; P < 0.05) and activity in Fe-deficient plants supplemented with chitosan. In summary, low molecular weight chitosan could potentially be used in iron deficiency chlorosis remediation but further studies are necessary to characterize the underlying mechanism of chitosan-mediated chlorosis improvement.