ISHS Acta Horticulturae 812: III International Symposium on Acclimatization and Establishment of Micropropagated Plants
LOWERING PH VALUE WITH ELEMENTAL SULFUR IN THE SUBSTRATE FOR EX VITRO ACCLIMATIZATION |
| Authors: | A.N. Kämpf, C.S. Fior, C. Leonhardt |
| Keywords: | bromeliads, EC value, Vriesea philippocoburgii Wawra |
| Abstract:
The pH value (7.0–8.0) of the irrigation water and of the available substrates represents a limiting factor to the ex vitro acclimatization of native plants, growing naturally in acid soils. This work quantifies the effect of elemental sulfur lowering the pH value of the substrate for ex vitro acclimatization of Vriesea philippocoburgii, a native bromeliad vulnerable to extinction. The substrate was formed by (1:2 v:v) coconut powder and broken expanded clay (1 to 4 mm diameter) prepared with 0, 0.5, 1, 2 and 4 g S/L substrate before planting. The experiment was carried out in a greenhouse under 70% black shade net and intermittent mist. Two hundred and forty micropropagated plants were divided into the 5 treatments (S-concentrations) in 4 blocks, 12 plants/plot. Each plot had also 18 cells filled with substrate without plant. The values of pH and electrical conductivity (EC) were measured every 2 weeks (PourThrough method). The results showed pH values around 7.0 in the control-treatment while S reduced these values in the cells with and without plants. The intensity and the duration of this effect depended on the applied concentration, reaching extremely low pH values (2.1 and 1.3) with 2 and 4 g S/L substrate. Sulfur raised the salinity in substrate due to the formed sulfuric acid, reaching toxic values (5.7 and 25.0 mS/cm) with 2 and 4 g S/L substrate. In these treatments the plants were seriously damaged and survived till the level of 3.0 mS/cm. The addition of 0.5 g S/L substrate provided the best results, sufficient for the acclimatization period (10 weeks). | |
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