Iron-deficiency chlorosis evaluation of soybean with tissue culture.

The objectives of this study were: (i) to develop a tissue culture technique for the evaluation of Fe efficiency in soybean, and (ii) to compare the laboratory technique with field Fe chlorosis scores. Nineteen genotypes that had low and high levels of Fe efficiency were evaluated in the laboratory and at five field locations. Friable callus was induced from epicotyl sections, weighed, and placed on two different modified Murashige and Skoog media; one low in α-naphthaleneacetic acid and the other low in Fe. Callus growth was rated as lack of growth compared to respective controls. As an example, Fe-inefficient cultivars ('Asgrow A3205' and 'Pride B216') had significantly reduced growth compared to Fe-efficient germ plasm lines ('All' and 'A14'). Correlation between the laboratory and field chlorosis rating was highest for the low auxin medium (r (2) = 0.78), although correlation for the low Fe medium was also significant (r (2) = 0.72). These results show that in vitro evaluation for Fe efficiency can be a useful tool for plant breeders.