Effect of planting depth and density, leaf removal, cytokinin and gibberellic acid treatments on flowering and rhizome production in zantedeschia aethiopica

Zantedeschia (Fam. Araceae), a genus of 6 or 7 species, are all native to South Africa, They generally grow in wet, marshy land often at the edge of forests. Z. aethiopica is used in Israel for cut flower production, as well as for rhizome propagation. The crop is mainly grown in unheated greenhouses during winter and early spring. Annual production of Z. aethiopica has increased rapidly over the last few years. This paper reports results of a series of studies on the influence of planting depth and density, leaf removal and growth regulator treatments (gibberellic acid (GA) and benzyl adenine (BA)) on flowering and rhizome production. The objective was to define optimum growing procedures for the production of high yields of top quality Z. aethiopica flowers and rhizomes during the December to May winter growing season in Israel. We found that flower yield was high when rhizomes were planted at a depth of 10 cm below the soil surface. Deeper planting (20 cm) yielded highest rhizome weights, whereas planting at 10 cm, yielded the highest number of rhizomes. Changing planting density did not affect the number of flowers produced per plant, but close planting resulted in longer flower stems. Leaf removal increased flower yield. Dipping rhizomes in 350 ppm BA followed by a dip in 350 ppm GA3 increased flower yield five fold over the control. However, a dip with only BA, yielded the same number of flowers, as the combined treatment. Although many malformed or green flowers developed as a result of GA3 treatments, combination treatments with BA or BA alone reduced the extent of this problem.