Shitaka Y, Hirose T
Biological Institute, Graduate School of Science, Tohoku University, Aoba, Sendai 980-8578, Japan Fax: +81-22-217-6699; e-mail:
Oecologia. 1998 Apr;114(3):361-367. doi: 10.1007/PL00008818.
We studied the effects of a change in flowering date on the reproductive output of a short-day annual plant, Xanthium canadense. The flowering date was changed by photoperiodic manipulation to 1 month earlier or later than the natural flowering date. Plants with the natural flowering date attained the highest reproductive output. For those flowering 1 month earlier or later, the reproductive output was decreased by 42% or 23%, respectively. The reproductive output was analyzed as the product of the biomass production during the reproductive period and its allocation to the reproductive organs. Although delay in flowering increased biomass production, it decreased its fractional allocation to the reproductive organs. The highest reproductive output in the natural flowering plants resulted from a compromise between these two effects of flowering. Plants flowering earlier had higher translocation rates to the reproductive organs and accelerated plant senescence. Later flowering caused a reduction in biomass translocation to the reproductive organs and thus extended the reproductive period. These experimental results are discussed in relation to the cost of reproduction and the optimal time for flowering that maximizes the final reproductive output. It is suggested that the natural flowering time maximized the reproductive output while minimizing the cost of reproduction.
我们研究了开花日期的变化对短日照一年生植物加拿大苍耳生殖产量的影响。通过光周期处理将开花日期提前或推迟1个月，使其与自然开花日期不同。自然开花日期的植株获得了最高的生殖产量。对于那些提前或推迟1个月开花的植株，生殖产量分别降低了42%或23%。生殖产量被分析为生殖期生物量生产及其分配到生殖器官的产物。虽然开花延迟增加了生物量生产，但它减少了其在生殖器官中的分配比例。自然开花植株的最高生殖产量是这两种开花效应之间折中的结果。开花较早的植株向生殖器官的转运速率较高，并加速了植株衰老。开花较晚导致生物量向生殖器官的转运减少，从而延长了生殖期。结合繁殖成本和使最终生殖产量最大化的最佳开花时间，对这些实验结果进行了讨论。结果表明，自然开花时间在使生殖产量最大化的同时，将繁殖成本降至最低。
