Matthies Diethart
Unit of Plant Population Biology, School of Plant Biology, University College of North Wales, LL57 2UW, Bangor, Gwynedd, UK.
Oecologia. 1990 May;83(1):105-116. doi: 10.1007/BF00324641.
This study examines the effect of different densities and the removal of all neighbours at different stages of development on all components of reproduction in the inbreeding annual Thlaspi arvense L. A 64-fold increase in density significantly reduced all repooductive components. The number of flower buds per plant was decreased most strongly; the order of decreasing plasticity among the other components was number of capsules per flower, individual seed weight, ovule number per capsule, flowers per flower bud and seeds per ovule. Removing neighbours at all stages of development increased seed yield of plants in comparison to the control without density reduction, but patterns of plasticity depended strongly on time of treatment. The main effect of the removal of neighbours at the vegetative stage was to increase the number of flowers per plant, but the number of ovules per capsule and seed weight increased also, and abortion of capsules decreased. Removing neighbours at the onset of flowering initially failed to affect flower number per plant, instead it resulted in a strong reduction of capsule abortion and an increase in seed weight. However, several weeks after flowering had initially ceased, fresh lateral inflorescences were produced, resulting in a second flush of reproduction. Removing neighbours at the stage of fruit ripening resulted at first only in an increase in seed witht, but later a second reproductive phase occurred. Fresh lateral branches were produced, but the apical meristem was also reactivated. The overall pattern of plasticity among all reproductive components in response to a removal of neighbours was the same as in response to density. The position of a capsule along the inflorescence influenced its number of ovules, the rate of seed abortion and the mean weight of seeds, with the type of effect depending on the developmental stage at which neighbours were removed. Significant negative correlations were found between the mean weight of seeds and the number of seeds in a capsule under all treatments.
本研究考察了不同密度以及在近交一年生植物遏蓝菜发育的不同阶段去除所有邻株对其繁殖各组分的影响。密度增加64倍显著降低了所有繁殖组分。单株花芽数量减少最为显著；其他组分可塑性降低的顺序依次为每花荚果数、单粒种子重量、每荚胚珠数、每个花芽的花数以及每个胚珠的种子数。与未降低密度的对照相比，在发育的所有阶段去除邻株均提高了植株的种子产量，但可塑性模式强烈依赖于处理时间。营养生长阶段去除邻株的主要作用是增加单株花数，但每荚胚珠数和种子重量也增加了，并且荚果败育减少。开花初期去除邻株最初并未影响单株花数，反而导致荚果败育大幅减少和种子重量增加。然而，在最初开花停止几周后，产生了新的侧生花序，从而形成了第二轮繁殖。在果实成熟阶段去除邻株起初仅导致种子重量增加，但随后出现了第二个繁殖阶段。产生了新的侧枝，并且顶端分生组织也被重新激活。所有繁殖组分对去除邻株响应的可塑性总体模式与对密度响应的模式相同。沿花序排列的荚果位置影响其胚珠数、种子败育率和种子平均重量，效应类型取决于去除邻株时的发育阶段。在所有处理下，均发现种子平均重量与一个荚果中的种子数之间存在显著的负相关。
