37种杜鹃花属植物在迁地保育下的自然授粉研究

Natural pollination of 37 Rhododendron species under ex situ conservation

关键词:  迁地保育, 自然授粉, 可育性, 综合评价, 杜鹃花属

Key words:   ex-situ conservation, natural pollination, fertility, comprehensive evaluation, Rhododendron

摘要:

该文对主要栽培在四川都江堰龙池基地(海拔1 700 m)及玉堂基地(海拔700 m)和峨眉山生物试验站(海拔805 m)的5亚属15亚组37种杜鹃花属植物的自然授粉开展了为期4 a的数据采集与研究。以绿苗率(Gs)为主要指标, 绿苗系数(Gc)、坐果率(St)和单位可育种子数(Sf)为辅助指标, 初步揭示了迁地保育条件下杜鹃花属植物自然授粉的育性适应及其特征。结果表明:(1)除黄花杜鹃(Rhododendron lutescens)未形成种子外, 受试的其他36个杜鹃花种类均能在其保育地点上不同程度地完成从种子(幼苗)到种子的生命循环, 其中高可育型24种、可育型11种、弱育型1种。(2)上述4项指标, 尤其是保育条件与原生地条件下同种的绿苗率、绿苗系数和单位能育种子数比较, 均能不同程度地反映育性适合度的差异情况。(3)在上述具有不同程度可育性的36种杜鹃花中, 有24种有不同程度的败育现象, 其成因可能为不同程度的自交和花期重叠的同亚组到不同亚组异种间自然交配所引起的遗传不适, 由于遗传选择的限制或胁迫, 这种现象在一些开花个体有限的种类中尤为突出, 因此保证最小存活种群(the minimum viable population, MVP)对于该属植物迁地保育至关重要。(4)杜鹃花属的特定种类可能存在一个受种性制约的单位种子数量幅度和上限, 即不同的类群与种类的单位种子数量存在差异。(5)为探索自交和种间杂交提供了认识起点和参照, 并提出了有关杜鹃花属植物可育性综合评价的指标体系和方法。

Abstract:

In order to evaluate and study the natural pollination fertility of Rhododendron adaptation and characteristics under ex-situ conservation and provide research reference for self and cross fertility, especially aiming at the short of the natural pollination fertility and its multi-index comprehensive evaluation in the past study, this paper revealed the natural pollination fertility characteristics and adaptation of Rhododendron under ex-situ conservation conditions by collecting and analysing the data from the main bases at Dujiangyan(1 700 m above sea level), Yutang 700 m above sea level in Longchi of Sichuan Province and Dujiangyan(700 m above sea level)and Emeishan Biological Test Station(805 m above sea level)in Longchi of Sichuan Province. Thirty-seven species of Rhododendron natural pollination belonging to 15 subsections within 5 subgenera had been carried out for a period of four years with test the green seedling rate(Gs)as the main index, and green seedling coefficient(Gc), rate of capsul set(St)and unit number of fertility seed(Sf)as a secondary indexes. The results were as follows:(1)Except for R. lutescens to not get seeds, the other 36 species went through the life cycle of “from seed(seedling)to seed" to some extent in their conservation sites, among them twenty-two types of high fertility, eleven types of fertility and one type of low fertility.(2)The above four indicators, especially green seedling rate, green seedling coefficient and unit number of fertile seed from comparing the ex-situ conservation and field conditions, could reflect different levels of fertility fitness.(3)Within the 36 fertile species of Rhododendron in different degrees, 24 species of them occur an abortion phenomenon in various degree, and the cause might result in selfing and natural crossing for florescence overlaping of the same or dissimilar subsections with different degrees, which might be caused by genetic discomfort due to genetic selection restrictions or stress, this phenomenon is particularly prominent in some species of flowering individuals limited, so the number of the flowering individuals related most closely to the fertile fitness, ensuring “the minimum viable population(MVP)” for the genus conservation is important.(4)Each species of Rhododendron might exist in a range and upper limit of unit seed number and there are differences in the number among different groups and species.(5)The natural pollination results as the exploration of selfing and inter-specific hybridization offered a starting point of understanding and reference, and the index system and method of fertility comprehensive evaluation about Rhododendron plants was put forward.