2013 ASHS Annual Conference

Plectranthus parviflorus has the ability to re-green nitrogen deficient leaves without loss from abscission.  Yellow leaves remain intact and return to a healthy green color when given a complete nutrient supply.  The purpose of this study was to determine the re-greening ability of P. parviflorus and P. ambiguus after various micronutrient deficiencies [iron (Fe), manganese (Mn), zinc (Zn), and molybdenum (Mo)] over 6 months. Fe deficient treatments were switched from deficient to complete twice, Mn treatments were switched once, and zinc and molybdenum have yet to show symptoms of deficiency after 4 months. Fe-deficient plants of P. parviflorus were able to re-green yellow leaves to match control plants on both switches.  P. ambiguus was able to re-green slightly yellowed leaves, but did not re-green leaves with more severe symptoms.  These leaves were eventually lost, and  the axillary buds broke.  Mn-deficient plants of both species did not re-green the yellowing leaves, and upon regrowth some of the yellow leaves abscised.  Yellowed leaves on P. parviflorus remained attached to the plant much longer than P. ambiguus.  To date neither Zn nor Mo deficiency has affected plant growth of either species.  Visual symptomology of roots and shoots including elemental analyses to confirm deficiencies as well as spectral reflectance curves created at the beginning and end of the experiment will be presented.