Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan.
Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan.
Plant Biol (Stuttg). 2021 Jul;23(4):546-555. doi: 10.1111/plb.13236. Epub 2021 Mar 14.
Generally, floral characteristics and pollination are important factors enhancing the quality and quantity of reproductive output for regeneration in plant conservation. However, lack of evidence-based management could decrease fitness under ex-situ conservation. We investigated the capitulum and pollination characteristics of Eriocaulon heleocharioides Satake (Eriocaulaceae), which is extinct in the wild, to develop an evidence-based conservation management plan incorporating previously ignored reproductive characteristics. To evaluate the functional characteristics of capitula, pollen-ovule ratio, and reproductive status (maximum pollination success/florivory damage) were investigated along six flowering sequences of capitulum. To evaluate the effect of plant density on pollen transfer, high- and low-density plots were established. Total deposited pollen on stigma, insect visitation, and visit duration per capitulum were observed. A significantly lower pollen-ovule ratio was observed in the first of six capitula, reflecting higher female functionality. The highest pollination success was found in the second-fourth capitula, whereas florivory increased along the terminal capitula position. High plant density affected the pollen deposited on stigmas via insect visitation and low pollinator visit duration. Different capitula in E. heleocharioides could have different effects: different sexual functionality, enhancement of reproductive output both in quality and quantity through active pollen transfer, and escaping from florivores. High plant density could facilitate outcross-pollen transfer in E. heleocharioides. Multiple perspectives are important for determining potential reproductive success in ex-situ conservation. Thus, density management reflecting capitulum characteristics could improve the efficiency of conservation efforts for E. heleocharioides.
一般来说，花部特征和传粉是提高植物保护再生质量和数量的重要因素。然而，缺乏基于证据的管理可能会降低异地保护下的适应度。我们调查了野外灭绝的谷精草属(Eriocaulaceae)植物头状花序和传粉特征，以制定一个基于证据的保护管理计划，纳入以前被忽视的繁殖特征。为了评估头状花序的功能特征，我们对头状花序的六个开花序列进行了花粉-胚珠比和繁殖状态（最大传粉成功率/花食性损害）的调查。为了评估植物密度对花粉转移的影响，建立了高密度和低密度小区。观察了总柱头花粉沉积、昆虫访问和每一头状花序的访问持续时间。头状花序的前六个中的花粉-胚珠比明显较低，反映出较高的雌性功能。第二到第四个头状花序的传粉成功率最高，而花食性则随着末端头状花序位置的增加而增加。高密度植物通过昆虫访问影响柱头花粉沉积，且访花持续时间较短。E. heleocharioides 不同的头状花序可能有不同的作用：不同的性功能、通过主动花粉转移提高质量和数量的繁殖输出，以及逃避花食者。高密度植物可以促进 E. heleocharioides 异交花粉转移。从多个角度确定异地保护中的潜在繁殖成功率很重要。因此，反映头状花序特征的密度管理可以提高对 E. heleocharioides 保护工作的效率。
