生育温度と栽培時期が八重咲きシクラメンにおける弁化雄蕊の形態形成に及ぼす影響

Abstract

This study was conducted to demonstrate the seasonal change of floral organ number and morphology, and the effect of growth temperature on floral morphology in double-flowered cyclamen with petaloid-stamens. In plants grown under seasonal variable temperature, floral organ number and morphology in petaloid-stamen type of double flower changed as time passed, but the degrees of such changes differed depending on the line; there were two types, namely, “variable” and “relatively stable”, in terms of the number of outer and inner petaloid-stamens throughout the flowering period. In the plants grown under different constant temperatures, the rate of complete petals (petaloid-stamens) to the total organs in whorl 3 was greatest at 15°C, followed by the values at 25°C and 20°C. In contrast to complete petals, the rate of incomplete petals (petaloid-stamens) to the total organs in whorl 3 was greatest at 20°C, followed by the values at 25°C and 15°C. The rate of stamen-like organs to the total organs in whorl 3 did not differ significantly among treatments, and the rate of stamens to the total organs in whorl 3 was suppressed only at 25°C. Although the total numbers of stamens and stamen-like organs were similar at 15°C and 20°C, the developed positions of stamen-like organs and stamens were significantly different between 15°C and 20°C. Additional organs including stamens were produced inside the petaloid-stamen at 15°C, while restoration of the stamen was induced at 20°C. In conclusion, floral morphology shows seasonal change, and growth temperature affects the petaloidy of stamen in double-flowered cyclamen. However, the effect on petaloidy differs according to the line.