Nutritional and management related interactions with iron-deficiency stress response mechanisms

Iron (Fe) deficiency symptoms develop in many agricultural and horticultural settings and generally occur when susceptible genotypes are grown in calcareous soils where Fe availability is limited. However, in some situations, Fe deficiency develops as a result of biological interactions with factors other than limited available Fe. We review physiological explanations for some factors known to interact with iron-deficiency stress. The discussion includes interactions with macronutrients and micronutrients, management factors such as grazing and companion cropping, and symbiotic nitrogen fixation. We also refer to several field observed interactions with Fe deficiency in soybean [Glycine max (L.) Merr.], where physiological explanations are yet to be identified. These include interactions with seeding rate and application of the herbicide glyphosate on glyphosate tolerant varieties. We believe that elucidation of additional physiological answers for field observations are critical to efficient and economic viability of world food production.