Flowering time of Hippeastrum can be controlled by applying specific thermal regime to large sized bulbs. Due to high-energy costs, the aim of this study was to examine the possibility to reduce soil heating and keep high bulb growth rate by increasing the CO2 concentration. Two sets of experiments were carried out in a controlled greenhouse at the North-Western Israeli Negev Desert. In both experiments, bulbs of different initial sizes were grown under two levels of CO2 concentrations (ambient, 350 ppm and elevated, 1000 ppm) combined with different minimum soil temperature regimes. In the first experiment three temperature regimes (16°C, 22°C and 24°C) were tested, while in the second experiment only one minimum soil temperature regime (22°C) was investigated. In both experiments, raising CO2 concentration from the ambient level to elevated one, or increasing soil temperature resulted in a higher bulb growth rate. Temperatures, CO2 concentration and initial bulb size significantly influenced the final diameter of the bulbs. A significant difference in final bulb diameter was obtained only between the 16°C treatment and the 22°C and 24°C treatments, but not between the two high temperatures tested. The area of the largest leaf was significantly affected only by the soil temperature treatments. No effect of CO2 concentration on leaf area development was detected. The number of leaves, however, was affected by the CO2 but not by the temperatures. Bulbs grown under elevated CO2 had a higher flowering rate compared to ambient CO2. This was effective both in shortening the period of time from replanting until flowering and by the significant high number of flowers compared to the ambient CO2 conditions.
|Number of pages||11|
|State||Published - 1 Dec 2001|
- Bulb size
- Leaf area
- Number of leaves