Iron deficiency stress response of Tolmiea Menziesii 1

The popular foliage houseplant, Tolmiea Menziesii (piggyback plant), grown in an all NO₃‐N, half‐strength Hoagland Solution No. 1 without Fe or with 0.5 g/liter Fe₂O₃ became severely Fe chlorotic and caused the nutrient solution pH to rise from 5.1 initially to above 7. Plants supplied 90 μM Fe‐EDTA also raised solution pH but did not become chlorotic. When Fe chlorotic plants were transferred to a solution with 0.5 gAiter Fe₂O₃, modified to contain 25 to 100% of the N as NH₄, the solution pH dropped to between 4.3 and 3.1, and the chlorotic plants regreened. However, if the pH of the modified solution was buffered above 7 with 1 g/liter CaCO₃, no regreening occurred. Solution pH also dropped if the solution lacked N, and there was a temporary regreening of Fe chlorotic plants before N deficiency chlorosis appeared. These solution culture results indicate that Tolmiea should be classified as an Fe inefficient plant.