A Comparison of the Metabolism of the Ear and Accompanying Tissues in Zea mays L

Abstract

Summary All aerial organs metabolically related to the ear in maize are able to fix 14 CO 2 both in the light and in the dark. In the light extralaminar tissues fixed at rates from 5 (leaf sheath) to 650 (rachis) fold lower than leaf lamina (32 mg CO 2 · h -1 · g -1 f.w.). In the dark hypsophylls fixed at a higher rate than leaf lamina. In all organs most 14 C is fixed into the aspartate plus malate pool. The results indicate the importance of dark CO 2 fixation in organs outside the leaf lamina, a central role being played by C 4 acids and particularly by malate. Leaf sheath and hypsophylls show a fixation pattern typical of a C 4 and do not photorespire, although they do not possess kranz-anatomy.