Root Restriction Effects on Physiology of Zantedeschia aethiopica

Previous results from ornamental plants suggest that shoot biomass accumulation is a function of roots biomass. The possibility of cropping Zantedeschia aethiopica from seeds in either greenhouse-amended soils or pot substrates allow for quantify the effect of a root restriction on growth and plant quality. The root restriction syndrome has been related to an insufficient cytokinin supply from roots but the physiological mechanisms involved in geophyte ornamental plants are lacking. The aim of this work was to characterize seedling Z. aethiopica growth under two different root restrictions environments (greenhouse-amended soils or pot substrate) and the effect of a single 6, benzyl amino purine (BAP) spray on the hypothesis that the lesser root restriction the higher both post-transplant fresh-dry weight accumulation and leaf area expansion. Results showed a higher fresh-dry weight, leaf area and leaf number in plants from pots with a Sphagnum magellanicum peat-base substrate. A single BAP spray increased responses mainly in pot-grown plants. Positive relationships between the rate of leaf area expansion (RLAE), the leaf appearance rate (RLA), the relative growth rate (RGR), the net assimilation rate (NAR) and root dry weight were found. These results showed that a root restriction related to substrate compaction in pots has a lesser impact on Z. aethiopic plant growth that a root restriction related to compaction in soils, which cannot be overridden by a single 100 mg L-1 BAP spray.