The Journal of Horticultural Science and Biotechnology, 7(2): 170-176(7) (Mar 2002)
Temperature affects plant development, flowering and tuber dormancy in calla lily (Zantedeschia)
V. Naor, J. Kigel

The effects of temperature on plant growth, flowering and tuber dormancy of coloured calla lily were investigated in the two cultivars Calla Gold (CG, hybrid of Z. rehmannii) and Black Magic (BM, hybrid of Z. albomaculata). Four experiments were performed in controlled conditions in a phytotron, under shade (50% of solar radiation) and 16 h daylength. Effects of temperature on plant development and tuber size were studied in Exp. 1 at constant temperature regimes of 17/12, 22/17, 27/22 and 32/27°C (day/night temperature). Dormancy and flowering potential of the tubers produced under these conditions were subsequently determined at the same temperatures in Exp. 2. Effects of temperature shifts during the growth-cycle were studied in Exp. 3 and 4 by transferring plants between low (22/16 or 23/15°C) and high (28/22 or 29/21°C) temperature, and compared with controls grown at constant temperature. After plant senescence and tuber harvest, time-course of bud sprouting and elongation were followed during storage at 20°C, as a measure of tuber dormancy relaxation. CG sprouted and flowered earlier, produced flowers over a wider range of temperatures and had smaller tubers than BM, but the responses of the two cultivars to temperature were generally similar. Leaf production was faster, and flowering and senescence were generally earlier with increasing temperature in the range 17/12 to 32/27°C. In contrast, the proportion of flowering plants was highest at 22/17°C, and tubers were larger at 22/17°C (CG) and at 22/17 - 27/22°C (BM). Plants flowered if the tubers had previously grown at 17/12°C or 22/17°C, while 27/22°C and 32/27°C were inhibitory. Length of the growth-cycle (from tuber planting to plant senescence) was relatively constant in the range 22/16 to 29/21°C, spanning 6-7 months in both cultivars. Temperature during the growth-cycle affected tuber size and its dormancy. Smaller and more dormant tubers were produced the longer the period of the growth-cycle that the plants spent at high (28/22 or 29/21°C) compared with low temperature (22/16 or 23/15°C). Tuber dormancy (time to onset of bud sprouting) was negatively correlated with rate of bud elongation during storage. Sprouting in storage was generally earlier, and bud elongation faster, when tubers were grown at low than at high temperature.

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