Sandler-Ziv, D., Department of Ornamental Horticulture, Institute of Plant Sciences, Volcani Center, Bet-Dagan 50250, Israel
Gilad, Z., Jordan Valley R and D Authority, Jordan Valley, 91906, Israel
Achiam, M., Jordan Valley R and D Authority, Jordan Valley, 91906, Israel
Luria, G., Agricultural Extension Service, Ministry of Agriculture, Bet Dagan 50250, Israel
Kamenetsky, R., Department of Ornamental Horticulture, Institute of Plant Sciences, Volcani Center, Bet-Dagan 50250, Israel

The colored calla lily (Zantedeschia) is a tuberous plant with alternating growth and rest periods. It is a popular ornamental crop worldwide, suffering, however, from a low propagation rate and susceptibility to bacterial soft-rot Pectobacterium carotovorum. Commercially, multiplication is achieved using seed or tissue culture, and about 2-3 years are needed to obtain tubers of flowering size. The main objective of this study was the development of an effective propagation system by cutting technique, incubation, intensive growth and a shortening of the propagation cycle. Uniform mother tubers of 'Black Magic', 50 g, were used for the experiments. Cutting techniques affected production of new tubers: division of the mother tuber into 10, 15, 20 or 25 segments resulted in 8, 12, 15 and 18 propagation units respectively. During the two week incubation period at 28-30°C, the bigger segments usually produced roots, and, following the growing period of 5-6 months, these segments formed significantly larger new tubers, as compared to the non-rooted, smaller propagation units. Cultivation of the propagation units in perlite, heated to 22°C, increased the growth rate and resulted in the production of larger tubers. Following the growth stage, the newly-formed tubers were collected, stored and subjected to the regular protocol for flowering. The propagation process continues for 6-8 months and is comprised of several major stages, each with specific conditions.