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Elemental deficiencies of N, P, K, Ca, Mg, S, Fe, Mn, Cu, Zn, or B were induced in plants of Pentas lanceolata `Butterfly Red'. Rooted stem cuttings were planted in 4.87-L plastic containers and fertilized with a complete modified Hoagland's solution or this solution minus the element that was to be investigated. Plants were harvested to measure dry weights when initial foliar symptoms were expressed and later under advanced deficiency symptoms. Deficiency symptoms for all treatments were observed within 7 weeks. The most dramatic expression of foliar symptoms occurred with N (medium green young leaves with interveinal chlorosis on base and tip), S (spindle-like young and recently mature leaves), Cu (purple-brown roots and young leaves with downward pointed leaf tips), and B (multiple youngest leaves arising from shoot tip). At the initial stage, all nutrient-deficient plants had similar dry weights, when compared to the control. Dry weights of plants treated with solutions not containing P were significantly lower when compared to the control under an advanced deficiency. In order to help prevent the development of deficiencies, minimal critical tissue levels have to be determined for adaptation by the greenhouse industry for nutritional monitoring.
Elemental deficiencies of N, P, K, Ca, Mg, S, Fe, Mn, Cu, Zn, or B were induced in plants of Allamanda nerifolia. Rooted stem cuttings were planted in 4.87-L plastic containers and fertilized with a complete modified Hoagland's solution or this solution minus the element that was to be investigated. Plants were harvested to measure dry weights when initial foliar symptoms were expressed and later under advanced deficiency symptoms. Deficiency symptoms for all treatments were observed within 6 weeks. The most dramatic expression of foliar symptoms occurred with N (yellow-green young leaves with necrotic tips), K (downward bending medium-green mature leaves with splotchy chlorosis), S (greenish-yellow young and youngest leaves), and Zn (young leaves with interveinal chlorosis from base to tip). At the initial stage, all nutrient-deficient plants had similar dry weights, when compared to the control. Dry weights of plants treated with solutions not containing N or P were significantly lower when compared to the control under an advanced deficiency. To help prevent the development of deficiencies, minimal critical tissue levels have to be determined for adaptation by the greenhouse industry for nutritional monitoring.