Page 162 - 广西植物2024年1期
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1 5 8                                  广  西  植  物                                         44 卷
                 Abstract: Ottelia cordata is a kind of rare and endangered submerged plant that grows in freshwater wetlands in northern
                 Hainan Islandꎬ from Haikou to Wenchang in China. This species is known for its beautiful appearance and the distinct
                 “flower river” landscapeꎬ which makes it a high ornamental value. With the intensification of human activitiesꎬ the
                 habitat of O. cordata has been sharply reduced and fragmentedꎬ leading to its endangerment. In order to explore the
                 reproductive characteristics and reproductive laws of O. cordataꎬ the flower morphologyꎬ sex ratioꎬ pollen viabilityꎬ
                 stigma receptivityꎬ reflectance spectrumꎬ pollen limitation and apomixisꎬ and the types and behaviors of pollinators in
                 O. cordata were analyzed. That isꎬ the pollination biology of O. cordata were studied for its further in ̄situ and ex ̄situ
                 conservation. The results were as follows: ( 1) The flowers were dioecismꎬ and the sex ratio of female and male
                 individuals was about 1 ∶ 2ꎻ the morphologies of male and female flowers were similarꎬ and the female flowers were
                 slightly larger than the male. (2) O. cordata had high pollen viability and stigma receptivity in budding and blooming
                 phases. (3) Apis cerana was the main pollinator of Ottelia cordataꎬ which visited male flowers more frequently than
                 female flowersꎬ with higher pollination efficiency. (4) The distance between the color loci of pistils and stamens was
                 significantly higher than the discrimination threshold of Apis cerana. (5) The fruit setting percentage under natural
                 pollination was similar to that under artificial pollination (95. 29% and 98. 42%ꎬ respectively)ꎬ and there was no
                 apomixis and low pollen limitation in the natural population of Ottelia cordata. In conclusionꎬ the deceptive pollination of
                 O. cordata simulated by both sexes is imperfect. Pollinators can visually distinguish female and male flowers. Howeverꎬ
                 the large number of male flowers of O. cordata attracted many insects to visit flowersꎬ which increases the probability of
                 “mistake” pollination and is enough for the reproductive needs of female flowers. Thereforeꎬ future ex ̄situ conservation
                 and artificial population restoration should pay more attention to population sizeꎬ sex ratio and the number of local
                 pollinators.
                 Key words: dioecismꎬ deceptive pollinationꎬ breeding systemꎬ pollen limitationꎬ Hydrocharitaceae




                湿地生态系统作为全球三大生态系统之一ꎬ                                水 菜 花 隶 属 于 水 鳖 科 ( Hydrocharitaceae) 海
            不仅在涵养水源、抵御洪水、补给地下水等方面具                             菜花属( Ottelia) ꎬ雌雄异株ꎬ一 年 生 或 多 年 生 沉
            有独特的水调节功能ꎬ同时在生物多样性维持、调                             水植物( Wang et al.ꎬ 2010) ꎮ 水菜花一年四季均
            节局域气候、固碳、净化水质等方面还具有诸多生                             可开花ꎬ其单花花期通常约为 1 dꎮ 花单性ꎬ雌雄
            态功 能ꎬ 被 誉 为 “ 地 球 之 肾 ”ꎮ 但 是ꎬ 人 类 世                异株ꎻ花瓣 3 枚ꎻ雄佛焰苞内有雄花 10 ~ 30 朵ꎬ
            (Anthropocene)以来的快速经济发展和城市化进                       而雌花内仅 1 花ꎻ雄蕊 12 枚ꎬ花柱 9 ~ 18( Wang
            程ꎬ以及随之带来的全球气候变暖、水体富营养                              et al.ꎬ 2010) ꎮ 水菜花花多而大、花期较长、辐射
            化、外来物种入侵等一系列环境问题导致湿地急                              对称、花粉量大ꎬ符合典型的泛化传粉系统( 张大
            速退化ꎬ湿地水生植被种类减少ꎬ大量珍稀濒危物                             勇ꎬ2004) ꎮ 水菜花对水体变化较为敏感ꎬ对生境

            种面临着灭绝的风险( 李伟ꎬ2020ꎻFluet ̄Chouinard                 要求极为苛刻ꎬ喜生长在清澈洁净的流水沟渠及
            et al.ꎬ 2023ꎻ祝惠等ꎬ2023)ꎮ 海南岛是我国唯一                   池塘中( 于丹等ꎬ1998ꎻ Chen et al.ꎬ 2012) ꎮ 随着
            的热带大陆型岛屿ꎬ设立了海南热带雨林国家公                              人类对淡水湿地的开发、外来生物的入侵、水资
            园ꎬ然而海南湿地尤其是淡水湿地并未得到同等                              源的污染ꎬ适宜水菜花生长的环境越来越少ꎮ 目
            重 视ꎮ 养 殖 场 随 意 排 污、 凤 眼 莲 ( Eichhornia             前ꎬ仅零星分布于缅甸、泰国、柬埔寨和中国南方
            crassipes)和大薸( Pistia stratiotes) 快速入侵等事件          地区ꎬ在我国广西种群灭绝后ꎬ现仅分布在海南
            依然时常发生ꎬ严重威胁着该地区水菜花( Ottelia                        北部火山岩淡水湿地( 何景彪等ꎬ1991ꎻ 于丹等ꎬ
            cordata)、邢 氏 水 蕨 ( Ceratopteris shingii)、 野 生 稻    1998ꎻ Chen et al.ꎬ 2012ꎻ 韦毅刚ꎬ2019ꎻ Shen et
            (Oryza rufipogon ) 等诸多珍稀濒危水生植物的生                   al.ꎬ 2021) ꎬ可作为海南淡水湿地的“ 伞护种” 开
            长ꎮ 其中ꎬ国家二级保护植物水菜花的个体数量                             展保育工作ꎮ
            仅 4 年时间(2017—2020) 就下降了 11%( Shen et                   水菜花花瓣洁白、一抹淡黄点缀在花中央ꎬ一
            al.ꎬ 2021)ꎬ生存状况极不乐观ꎮ                               簇簇、一丛丛随波荡漾在清澈的溪面ꎬ在海南淡水
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