Limiting Factors in Photosynthesis: I. USE OF IRON STRESS TO CONTROL PHOTOCHEMICAL CAPACITY IN VIVO

The possibility of using Fe stress as an experimental tool in the study of limiting factors was explored. Results show that Fe stress decreased the chlorophyll (Chl) a, Chl b, carotene, and xanthophyll content of leaves of sugar beets (Beta vulgaris L.) and that the maximum rate of photosynthetic CO₂ uptake (P_max) per unit area was linearly related to Chl (a + b) per unit area. Measurements of noncyclic ATP formation by isolated chloroplasts at light saturation indicate that photosynthetic electron transport capacity decreased concomitantly with pigment content under Fe stress.