长柱紫茎的花部特征与繁育系统

【目的】研究长柱紫茎Stewartia rostrata的花部特征和繁育系统，为紫茎属Stewartia种群更新、人工扩繁及园林推广应用提供科学依据。【方法】以3年生长柱紫茎为材料，观察(测)长柱紫茎的花部特征和昆虫访花特性，测定花粉活力和柱头可授性，测算杂交指数和花粉胚珠比，分析其传粉生物学及繁育系统特征。【结果】(1)长柱紫茎居群花期为5月初至5月中下旬，约17 d，单花花期约2 d。(2)花粉活力开放当天最强，单花开花24～32 h，花冠和雄蕊易脱落，脱落后花粉极易失去活力。(3)开花前柱头已具有可授性，可授期达7 d，花粉强活力与柱头强可授性具1～2 d的相遇期。(4)花蕾期柱头高于花药，开花后花药高于柱头；无论开花前后，雄蕊与雌蕊均具有一定的空间分离。(5)长柱紫茎杂交指数为4，花粉胚珠比为2 108.0～195 525.0，繁育系统以异交为主，需要传粉者，部分自交亲和。(6)传粉昆虫以熊蜂Bombus sp.为主。【结论】长柱紫茎花粉寿命短，传粉昆虫单一，传粉易受阴雨天气影响，繁殖过程有较大限制；集中开花模式、花粉量大、柱头5裂及可授期长等花部特征是保障繁殖成功的基本表现。...

Floral syndrome and breeding system of Stewartia rostrata

  Objective  The objective is to study the floral syndrome and breeding system of Stewartia rostrata, so as to provide a scientific basis for its population renewal, artificial reproduction and garden popularization and application.   Method  Taking 3-year-old S. rostrata as material, the characteristics of pollination biology and breeding system were observed and analyzed by observing the floral syndrome and insect visiting characteristics, measuring the pollen viability and stigma acceptability, and calculating the hybridization index (OCI) and pollen-ovule ratio (P/O).   Result  (1) The flowering period of the population was about 17 days from early May to mid and late May, and the single flowering period was about 2 days. (2) The pollen vitality reached the highest on the day of opening, and the single flower bloomed for 24?32 h , the corolla and stamens were easy to fall off, and the pollen was easy to lose vitality after falling off. (3) The stigma was receptive before flowering, lasting for 7 days. The strong pollen vitality and stigma receptivity had a meeting period of 1?2 days. (4) Stigma was higher than anther in bud stage, and anther was higher than stigma after flowering. Both before and after flowering, stamens and pistils had a certain spatial separation. (5) The OCl of S. rostrata was 4 and P/O was 2 108.0?195 525.0. The breeding system was mainly outcrossing and some self compatibility was required for pollination. (6) Bombus sp. was the main pollinator.   Conclusion  S. rostrata has short pollen life, single pollinating insect, and pollination is easily affected by cloudy and rainy weather, so the reproductive process is greatly limited. The floral syndromes such as centralized flowering mode, large amount of pollen, 5-lobed stigma and long receptive period are the basic manifestations of reproductive success. [Ch, 5 fig. 1 tab. 31 ref.]