二倍体菘蓝开花习性及传粉特性研究

菘蓝是药材板蓝根和大青叶的基原植物,依赖种子繁殖。通过田间观测和人工授粉实验,对民乐县栽培菘蓝开花时序和传粉生物学系统进行研究,旨在为其种子繁育和杂种优势利用提供科学和技术依据。研究表明,菘蓝为无限花序,单株表现异向开花习性,花序从植株顶部向下,单花从花序基部向上依次开放。花两性,雄蕊6,4枚长,2枚短,花萼和花瓣均为4,花萼绿色,花瓣黄色,子房上位,1室。单花寿命6~7 d,异常气候可缩短至3~4 d,群体开花期30 d左右。即将开放的花蕾柱头已成熟,花瓣刚露出花萼后开花当天,花粉鲜黄而散,末花期子房膨大,花粉干枯。短角果结种子0~2粒。自然结籽率95.0%,不去雄和去雄套纸袋均不结实,同株异花去雄授粉结籽率仅4.0%,去雄套纸袋异株异花授粉结籽率72.0%,去雄不套袋结籽率53.3%,自交不亲和指数为0.96~1.00。不去雄套网袋结籽率5.0%,去雄后提高至13.7%,访花者主要有食蚜蝇、黑蜂等。说明菘蓝具有较强的自交不亲和性,不存在无融合生殖现象,属典型的异花授粉类型,需传粉者,传粉媒介以虫媒为主,风媒为辅。

Studies of the flowering habits and pollination for diploid Isatis indigotica

Isatis indigotica is the primary ingredient of traditional Chinese drugs ‘Banlangen’ and ‘Daqingye’, and its cultivation relies on seed propagation. This research examined the flowering habit and pollination biology of I. indigotica cultivated in Minle county. The work included field observation and an artificial pollination experiment, in order to provide scientific and technical information to support seed production and heterosis utilization in this crop. It was found that the plant had an infinite inflorescence consisting of an upright main stem bearing raceme-like branches with new branches above as older matured branches below and 10-20 individual flowers per branch opening in an acropetal sequence over a flowering period of some 30 days. Flowers are bisexual with 6 stamens, four of which are long and two of which are short. There are 4 green calyces, 4 yellow petals with ovary superior, and 1 locule. The flower lifespan was 6-7 days but was shortened to 3-4 days under adverse climate conditions. The stigma matures just prior to the flowers opening. When the petals are just emerging from the calyx tube, bright fresh yellow pollen grains become visible and are dispersed by the flowering day. Anthers then begin to wither, and the ovary expands at the end of the flowering stage, growing a short pod with 0-2 seeds. Seed set was 95.0% for plants under natural conditions. Under covered conditions with paper bags, seed set was very low (approximately 4%) both with and without castration, but was 72.0% when plants were cross-pollinated after castration. When plants were cross-pollinated after castration, but the inflorescence was unbagged, seed set was 53.3%. The self-incompatibility index was assessed as 0.96-1.00. For bagged racemes, seed set was 5.0% without castration and increased to 13.7% after castration. The most common flower pollinator visitors were Episyrphus balteatus and Apis mellifer but various other insect species also visited. These results indicate that I. indigotica has strong self-incompatibility without apomixis, and can be considered a typical cross-pollinating plants needing pollinators, pollinated mainly by insects but supplemented by wind.