Increased Fe‐efficienchy in sotbeans through plant breeding related to increased response to Fe‐deficiency stress. II. Mineral nutrition

Abstract

Iron efficiency in A7 soybean [Glycine max (L.) Merr.] was increased through plant breeding, and it was determined in a companion paper that A7 soybean responded to Fe‐deficiency stress by increased exudation of H and reductants at a lower Fe concentration than the Fe‐efficient Hawkeye (HA), A2, and Bragg, and the Fe‐inefficient Pride B216 (Pride), Anoka, and T203 soybean cultivars. The objective of this paper was to assess how soybean response to Fe‐deficiency stress affected the general nutrition of the plant. Response to Fe‐deficiency stress (H ion and reductant extrusion) was not a good index of total Fe taken up by the plant at higher levels of Fe. For example, as the Fe concentration in solution increased, Bragg took up much more Fe and Mn into both tops and roots than did the other cultivars tested. Pride behaved very much like Bragg and if grown where the supply of Mn is plentiful may develop Mn‐toxicity symptoms. With the addition of Fe, both Cu and Zn concentration decreased in tops and roots of all cultivars. Under these same conditions, Ca, K, and P concentrations in top leaves were about the same in all cultivars tested. These data show that Fe‐efficiency relates to the ability of the plant to make Fe available under Fe‐deficiency stress conditions, and not to the ultimate Fe concentration in the plant material when adequate Fe is supplied or made available.

Key words:

• Copper
• Glycine max (L.) Merr
• Iron Content
• Leaves
• Magnesium
• Manganese
• Roots
• Zinc