Biomass and mineral nutrient partitioning in relation to seasonal growth of Zantedeschia

Abstract

Dry matter, mineral composition and nutrient contents were measured in component tissues of Zantedeschia elliottiana harvested from a commercial planting at frequent intervals throughout a 7 month growing cycle. The growth cycle was characterised by three distinct phases. During the first phase (5–7 weeks growth), roots and vegetative tissues developed concurrently, tuber dry weights declined to 50% of their starting mass and flowering was completed. In the second phase (about 6–16 weeks after planting), there was rapid growth and maximum nutrient uptake — the dry weight and number of leaves increased to their maximum, new tuberous tissue formed and root growth declined. The final phase was initiated with shoot senescence (16 weeks growth). Tuber dry weights slowly declined in the absence of vegetation and with the onset of dormancy. Seasonal changes in the concentration and content of macro- and micronutrients in roots, tubers, blades, petioles and flowers are described. Between 20 and 56% of the nutrient stored in tubers was removed to support new season's growth in the 5–7 weeks following planting. By contrast, there was minimal remobilisation of Ca, Mn or Na from tubers. Nitrogen and K were the elements required in the greatest amount by Zantedeschia. These results are discussed in terms of fertiliser programmes for commercial production of this crop.