Involvement of Fe3+(dipyridyl)3compounds in Fe3+reduction reactions

Abstract

Abstract Much of the methodology used in the measurement of rhizosphere iron reduction involves the chelation of ferrous ions by BPDS (batho‐phenanthrolinedisulfonic acid) and other related dipyridyl derivatives. This technique was applied to monitor the rates of iron reduction by the root system of citrus seedlings at both slightly alkaline and acidic pH. The results of this Study demonstrated unusual effects of these dipyridyl compounds on the rates of iron reduction. These effects included a strong dependence on both the concentration and the type of the dipyridyl compound present. Also affecting the rates of iron reduction were the presence of divalent metal ions. Iron (Fe3+) chelates of HEDTA and EDDHA, both of which are common sources of soluble iron in nutrient solutions, dramatically iniibited iron reduction by the cituus roots. These feateres of the iron reduction reactions, monitored by the use of dipyridyl compounds, are consistent with the involvement of Fe3+ (dipyridyl)3‐type chelates as the actual electron acceptors. This role of dipyridyl compounds, such as BPDS, in rhizosphere iron reduction measurements, demonstrates the need to accurately evaluate the actual electron‐transfer activities being monitored.