Seed and pollen deposition on Salvia przewalskii

Generalized pollinators visit multiple co-flowering plant species and may transfer heterospecific pollen grains. Recent studies have indicated that the effect of heterospecific pollen (HP) on reproduction success is variable and depends on the identity of donor and recipient species. However, few studies have documented variation in HP receipt and evaluated the reproductive effects of HP receipt across geographic locations under natural conditions. We investigated the spatial variation of pollen deposition across eight sites and how the pollen receipt related to seed set of Salvia przewalskii, a subalpine perennial herb in Hengduan Mountain in southwest China. We found that stigmatic pollen loads substantially varied among sites for several metrics, including quantities of conspecific and heterospecific pollen, the proportion of HP, and species composition of HP donors. Five different plant families were the most common HP source at one or two sites, and the proportion of HP ranged from..., Field collections occurred from July 25 to August 19, 2021, during peak flowering of Salvia przewalskii. We collected 2.9 (median, 3) stigmas per plant, with a range from 1 to 10 stigmas due to variation in plant size. Because the wilted corolla and pistil usually abscise, we secured the corolla to the corona with a single horizontal pin at the corona’s midpoint to keep it from falling off. For each site, we performed a given procedure (labeling, stigma collection or seed counts) for all flowers on the same day. After three or four days, when the corolla wilted, we removed the stigma with clean forceps and stored it in a microcentrifuge tube containing 70% ethanol. In most cases, the style abscised naturally, which indicated that the fertilization had already occurred, and germinated pollen exines were still affixed to the stigma. Ten days after stigma collection, we counted the developed and undeveloped seeds of each flower, which were readily distinguishable based on size. This approa...,

泛化传粉者会访问多种共花期植物物种，并可能传递异种花粉粒。最近的研究表明，异种花粉（HP）对繁殖成功的影响存在差异，且取决于供体和受体物种的身份。然而，很少有研究记录自然条件下不同地理位置间HP接收量的变化，也未评估HP接收对繁殖的影响。我们研究了八个样点间花粉沉积的空间变异，以及花粉接收量与甘西鼠尾草（Salvia przewalskii）结实率的关系——这是一种分布于中国西南横断山区的亚高山多年生草本植物。我们发现，在多个指标上，柱头花粉负荷量在样点间存在显著差异，包括同种花粉和异种花粉的数量、HP的比例以及HP供体的物种组成。五个不同的植物科在一到两个样点中是最常见的HP来源，且HP比例范围从……野外采集于2021年7月25日至8月19日进行，正值甘西鼠尾草的盛花期。我们每株植物采集了2.9个柱头（中位数为3），因植株大小不同，采集数量范围为1至10个。由于枯萎的花冠和雌蕊通常会脱落，我们用一根水平别针将花冠固定在副花冠（corona）中部，以防其掉落。对于每个样点，我们在同一天对所有花朵执行特定流程（标记、柱头采集或种子计数）。三到四天后，当花冠枯萎时，我们用干净的镊子取下柱头，并将其存放在装有70%乙醇的微量离心管中。在大多数情况下，花柱会自然脱落，这表明受精已完成，且萌发花粉的外壁仍附着在柱头上。柱头采集十天后，我们统计了每朵花的发育种子和未发育种子，二者可根据大小轻易区分。该方法……