Effects of mineral nutrient deficiencies on leaf development, visual symptoms and shoot-root ratio of Spathiphyllum

Effects of deficiencies in N, P, K, Ca, Mg, B and Fe on leaf development, v isual symptoms and shoot-root dry weight ratio were studied in Spathiphyllu m 'Sensation' grown hydroponically. Leaf nutrient contents of treated plant s were analyzed to confirm suspected deficiencies. Leaf number, leaf area a nd chlorophyll content were all significantly reduced in the nitrogen-defic ient plants similar to plants grown in distilled water. The phosphorus-defi cient plants grew slowly but no deficiency symptoms were visible on leaves. Many small yellow specks, usually 2 mm or less in diameter, developed on t he adaxial surface of lower leaves in the potassium-deficient plants. Leaf area, but not leaf number, was significantly suppressed by the calcium-defi cient treatment and the young leaves developed necrotic margins on the midd le and basal leaf blade. Fully expanded leaves in the magnesium-deficient p lants were distorted and had lower chlorophyll contents than the controls. The iron-deficient plants showed interveinal chlorosis on younger leaves. T he boron-deficient plants showed two types of deficiency symptoms: a margin al necrosis at the leaf apex and distorted and crinkled petioles break at t he leaf blade. Shoot-root dry weight ratio was decreased under N, P and Fe deficiencies but was increased under deficiencies of Ca and B. A key was de veloped for the identification of mineral nutrient deficiencies. (C) 2000 E lsevier Science B.V. All rights reserved.