摘要
【目的】凤丹(Paeonia ostii)为我国新型食用油原料树种,了解其繁育系统与传粉生物学有助于成功繁殖凤丹。【方法】分别采用TTC法和联苯胺-过氧化氢法对凤丹的花粉活力与柱头可授性进行检测,利用杂交指数估算、花粉胚珠比(P/O)、去雄套袋人工控制授粉等检测繁育系统,同时野外观测昆虫访花习性。【结果】凤丹单花期4 d,群体花期17～19 d,呈现集中开花模式。花粉不具黏附性,柱头为湿型,雄蕊与柱头存在一定的空间分离。花粉寿命4 d,花粉活力第1天最高(65.21%),第2天略微下降,第3～4天急剧下降;柱头可授性在第1天较强,第2～3天最强,第4～5天开始减弱,随后逐渐失去可授性,至第8天完全失去可授性。花粉活力与柱头可授期重叠。单花具雄蕊(211±10)枚,总花粉量为159.7×10~4～576.3×10~4粒,单花胚珠数(67±3)枚,花粉胚珠比为58 940,杂交指数为4。人工控制授粉试验表明异交结果率与单果种子数量显著高于自交,不存在无融合生殖、自花自动授粉和风媒传粉。传粉昆虫有蜂类、蚁类、甲虫与蝇类,其中中华蜜蜂、意大利蜜蜂与黄熊蜂为主要传粉昆虫。【结论】凤丹繁育系统以异交为主,自交部分亲和,传粉过程需要传粉者。
【Objective】Paeonia ostii is a shrub that is native to China and planted widely in the southern and northern regions of the country. The seed of P. ostii is abundant in monounsaturated fatty acids, including α-linolenic acid(ALA), a necessary fatty acid that the human body cannot produce. Thus, the seed of P. ostii is an excellent raw material for a new type of edible oil. There are nearly 20 species of Paeonia plants, most of which are native to China. Due to its large-sized flower, many Paeonia species are cultivated as ornamental plants. Most Paeonia plants have poor fecundation ability. Compared with other Paeonia plants, the fruit-set value of P. ostii is relatively high, which provides a possibility for its large-scale seed production. However, the breeding system and pollination biology of the plant still remain unclear.【Method】This study examined the breeding system and pollination biology of P. ostii, through its floral biology, pollen viability, stigma receptivity, breeding system and major pollinators. The life of a single flower and the population were observed. Pollen viability was tested with the TTC staining method, in which red pollen was regarded as viable while black and pink pollen were regarded as inviable. Stigma receptivity was determined with benzidine and hydrogen peroxide, which allowed the identification of air bubbles and produced a range of color intensities, with darker colors representing stronger stigma receptivity. The breeding system was detected by applying an out-crossing index, a pollen ovule ratio(P/O), and artificial pollination using emasculation, pollination and bagging. The major pollinator species and their foraging behavior in the field were also observed.【Result】① The anthesis of a single flower and population of P. ostii was 4 and 17-19 d, respectively. The blooming period of the population showed a mass flowering pattern. During flower opening, the filaments became elongated, loosened and moved away from the stigma, which created a relative spatial separation between the stamen and stigma. The surface of the pollen was dry and smooth. Many pollen grains fell on a floral disc when shaking the flower. The surface of the stigma was wet and sticky.② The flower of P. ostii was protandrous. Anthers began to release pollen after the petals were completely open. Pollen was released from the top(on the 1st morning) to the bottom(by noon the 2nd day) during anthesis. The life span of the pollen grain was four days. Pollen viability was the highest on the 1st day [(65.2±2.6)%] and showed a weak decreasing trend on the 2nd day [(57.4±2.5)%]. Pollen viability decreased sharply on the 3rd [(43.9±1.8)%] and 4th days [(19.5±2.2)%]. The color of anther locules was yellow on the 1st and 2nd days, dark yellow on the 3rd day, and completely brown on the 4th day. The filament wilted and began falling off gradually by the evening of the 4th day. The stigma receptivity was strong on the 1st day and peaked during the 2nd to 3rd days. The surface of the stigma gradually became dry and the stigmatic receptivity had a decreasing trend on the 4th and 5th days. The stigma then gradually lost receptivity, until it had basically disappeared on the 8th day. During flowering, the stigma stayed close to the style before opening, expanded after opening, and became receptive gradually. Mucus could be observed on the surface of the stigma on the 2nd day. Mucus flew from the surface to the bottom of the stigma and could condense into a transparent gel on the 4th afternoon. Thus, the expression of male function(pollen viability) and female function(stigma receptivity) overlapped.③ Numerically, a flower produced(211 ± 10) stamens, 159.7×10^4-576.3 × 10^4 pollen grains, and(67±3) ovules. The pollen ovule ratio was 58∶940. The out-crossing index was 4, due to the large flower diameter[(15.3 ± 0.2) cm] and relative separation between the male and female functions. Through emasculation, bagging and the artificial pollination test, we found that the fruit set and seeds per fruit resulting from xenogamy pollination were significantly higher than that from selfing. No apomixis, wind pollination, or automatic self-pollination were found. No significant differences were found in the fruit set and seeds per fruit between open and xenogamy pollinations.④ The flower of P. ostii is nectarless and the only reward for visitors was pollen grain. Each plant could produce( 3.5 ± 0.1) flowers(ranging from 2 to 5 flowers). Thus, a plant displayed an average of 0.8 flowers each day. Petals could keep fresh after the filament wilted, which enlarged the floral display. The floral morphology of P. ostii was not specialized and could be visited by different types of insects. Visitors to the flower of P. ostii included bees, ants, beetles and flies, of which Apis cerana, A. mellifera and Bombus flavescens were the most abundant pollinators. The bees foraged pollen and flew quickly among different flowers, which implied a quick pollen transfer. The quantity of beetles was also relatively high, and they could carry a large amount of pollen grain due to their dense short hair. However, the beetles often foraged on the flower for up to several hours and were thought to affiliate self-pollination of the plant. Thus, the bees were the major pollinators of the flower of P. ostii.【Conclusion】The breeding system of P. ostii is dominated by out-crossing, with partial self-crossing, and the pollination process requires pollinators. The major pollinators included honey and bumble bees.
作者
罗长维
陈友
张涛
LUO Changwei;CHEN You;ZHANG Tao(Chongqing City Management College,Chongqing 401331,China;College of Life Sciences, Chongqing Normal University, Chongqing 401331,China)
出处
《南京林业大学学报（自然科学版）》
CAS
CSCD
北大核心
2019年第3期37-44,共8页
Journal of Nanjing Forestry University：Natural Sciences Edition
基金
重庆市科委基础与前沿研究计划项目(cstc2015jcyjA80011)
重庆市教委基金项目(KJ1731421)
关键词
凤丹
花粉活力
柱头可授性
杂交指数
花粉/胚珠比
人工控制授粉
传粉昆虫
Paeonia ostii
pollen viability
stigma receptivity
out-crossing index
pollen-ovule ratio(P/O)
artificial pollination
pollinator
