Carbon Isotope Discrimination, PEP-Carboxylase Activity and Stomatal Resistance in Various Organs of Zea mays L.

Abstract

In previous researches we had already taken into consideration some structural and metabolic properties of various organs of maize, cv. Asgrow 66, in an attempt to find out how these take part in the productivity of the plant. We found four types of chloroplasts: two already described in the leaf lamina; one with grana and starch in the stem, sheaths and hypsophylls and a very small one in the rachis with all the tylakoids packed in grana. We also found kranz-anatomy to be absent in extralaminar photosynthetic tissues such as leaf sheath hypsophyll and stem (Antonielli, Venanzi 1979). These organs although l3eking kranz-anatomy showed a CO₂-fixation pattern typical of a C₄ plant (Soldatini et al. 1982).To clarify definitely this point we determined the δ ³C values and the PEP-Carboxylase activity in all aerial organs of a maize plant.