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Abstract
Rooted cuttings of Ilex crenata Thunb. ‘Helleri’ were grown in sand culture with varied Ca and Mg levels in a factorial experiment. No increase in total dry weight was achieved by increasing Ca or Mg rates above 5–10 ppm. Necrosis of shoot apices occurred at 0 ppm Ca. The tissue level of Ca required for optimal growth (0.23–0.38%) was lower than has been reported for broadleaf evergreens. In a 2nd experiment with pine bark, Ca was supplied at 0 and 120 ppm and Mg at 0 and 60 ppm. No differences in dry weight due to added Ca and Mg were observed. In a 3rd experiment, the influence of dolomitic limestone (0, 2, 4, and 8 kg m−3) and gypsum (1 and 2 kg m−3), added to pine bark, on Ca and Mg availability over time was determined. The addition of dolomitic limestone increased Ca and Mg in the growing medium solution, but unamended bark supplied both elements in quantities sufficient for growth of I. crenata ‘Helleri’ The addition of gypsum caused a large initial increase in Ca in the growing medium solution, but levels dropped precipitously thereafter.