Effect of Iron Concentration on Growth and Phylloclade Edge Yellowing of Holiday Cactus.

Abstract

<jats:p>Production of holiday cactus has been limited by the common occurrence of marginal chlorosis of the phylloclades, which can lead to losses in crop quality. This work was conducted to determine if poor growth and phylloclade yellowing could be correlated to applied Fe concentration. Rooted cuttings of <jats:italic>Schlumbergera truncata</jats:italic> `White Christmas', `Twilight Tangerine', 'Christmas Charm', and `Lavender Doll' were transplanted into a modified Hoagland's solution, adjusted to a pH of 6.3, containing Fe-EDTA at either 0,10,20,30, or 40 mg·liter<jats:sup>–1</jats:sup> Fe. Plants were grown in a controlled environmental chamber under 16 h daylength for 16 weeks at 22/18C day/night temperature. Plants grown under 0 and 10 mg·liter<jats:sup>–1</jats:sup> Fe had significantly greater fresh weight, height, and root length than plants grown under higher Fe concentrations for all cultivars. Comparison of tissue analysis results revealed a direct correlation between poor growth and levels of Fe within the tissue. There was no correlation, however, between Fe concentration and phylloclade edge yellowing, as yellowing occurred sporadically in all treatments. Comparison studies in the greenhouse of plants grown in peat: perlite medium showed similar trends.</jats:p>