Cw. Lee et al., MICRONUTRIENT TOXICITY IN SEED GERANIUM (PELARGONIUM X HORTORUM BAILEY), Journal of the American Society for Horticultural Science, 121(1), 1996, pp. 77-82
Seed geranium (Pelargonium xhortorum) micronutrient toxicity symptoms
were induced by applying elevated levels of B, Cu, Fe, Mn, Mo, and Zn
in fertilizer solution. Beginning at the 3-4 true leaf stage, seedling
plants established in 11-cm (0.67-liter) pots containing peat-lite gr
owing medium were fertilized at each irrigation for 5 weeks with solut
ions containing 0.25, 0.5, 1, 2, 3, 4, 5, and 6 mh I plus the standard
concentration of each micronutrient. The standard solution contained
20 mu M B, 0.5 mu M CU, 10 mu M Fe, 10 mu M Mn, 0.5 mu M MO, and 4 mu
M Zn. All treatment solutions contained a fixed level of macronutrient
s. Visible foliar toxicity symptoms were produced when the nutrient so
lution contained 0.5 raw B, 0.5 mM Cu, 5 mM Fe, 1 mM Mn, 0.25 mM Mo, o
r 0.5 mM Zn. Reduction in dry matter yield was evident when 1 mM B, 2
mM Cu, 3 mM Fe, 2 mM Mn, 0.5 mM Mo, or 1 mM Zn was used in the fertili
zer solution. Leaf chlorophyll contents decreased as Cu and Mn levels
in the concentration range tested increased. Elevated levels of Fe inc
reased tissue chlorophyll contents. The relationship between the nutri
ent solution and tissue concentrations of each of the six micronutrien
ts was determined.