Ecology and Evolutionary Biology, University of Adelaide, Adelaide, SA 5005, Australia.
Plant Cell Environ. 2010 Sep;33(9):1474-85. doi: 10.1111/j.1365-3040.2010.02190.x. Epub 2010 Jun 7.
Effect of size of inflorescences, flowers and cones on maximum rate of heat production is analysed allometrically in 23 species of thermogenic plants having diverse structures and ranging between 1.8 and 600 g. Total respiration rate (, micromol s(-1)) varies with spadix mass (M, g) according to in 15 species of Araceae. Thermal conductance (C, mW degrees C(-1)) for spadices scales according to C = 18.5M(0.73). Mass does not significantly affect the difference between floral and air temperature. Aroids with exposed appendices with high surface area have high thermal conductance, consistent with the need to vaporize attractive scents. True flowers have significantly lower heat production and thermal conductance, because closed petals retain heat that benefits resident insects. The florets on aroid spadices, either within a floral chamber or spathe, have intermediate thermal conductance, consistent with mixed roles. Mass-specific rates of respiration are variable between species, but reach 900 nmol s(-1) g(-1) in aroid male florets, exceeding rates of all other plants and even most animals. Maximum mass-specific respiration appears to be limited by oxygen delivery through individual cells. Reducing mass-specific respiration may be one selective influence on the evolution of large size of thermogenic flowers.
对 23 种具有不同结构且质量在 1.8 到 600 克之间的产热植物进行了分析，结果表明花序、花朵和球果的大小对产热的最大速率具有影响。15 种天南星科植物的总呼吸速率（，微摩尔 s(-1)）随佛焰花序质量（M，克）而变化。根据，佛焰花序的热导（C，毫瓦摄氏度(-1)）符合 C = 18.5M(0.73)。质量对花与空气之间的温差没有显著影响。具有高表面积暴露附属物的天南星科植物具有较高的热导，这与蒸发有吸引力的气味的需求一致。真正的花朵产热和热导显著较低，因为封闭的花瓣保留了有益于栖息昆虫的热量。在天南星科植物的佛焰花序内的小花或佛焰苞内的小花具有中等热导，符合混合作用。种间比呼吸速率变化不定，但在天南星科植物雄花的小花中达到 900 nmol s(-1) g(-1)，超过了所有其他植物甚至大多数动物的速率。最大比呼吸速率似乎受到单个细胞供氧的限制。降低比呼吸速率可能是对大型产热花朵进化的选择性影响之一。
