Chinese Bulletin of Botany ›› 2016, Vol. 51 ›› Issue (5): 594-600.DOI: 10.11983/CBB15194

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The Schedule of Pollen Presentation and Pollination Adaption in an Early Spring Ephemeral Plant Gagea nigra

Rongqian Zheng1, Zhenzhen Hou2, Aiqin Zhang1*   

  1. 1College of Life Sciences and Technology, Xinjiang University, Urumqi 830046, China
    2Xinjiang Jiuzhou Fumigation Limited Liability Company, Kashi 830011, China
  • Received:2015-11-02 Accepted:2016-01-22 Online:2016-09-01 Published:2016-09-27
  • Contact: Zhang Aiqin
  • About author:

    # Co-first authors

Abstract:

Gradual pollen presentation is an adaptive strategy in flowering plants that limits pollen removal with high pollinator visitation rate. High visitation rates may favor plants presenting pollen gradually in many small doses and potentially enhance male reproductive success given that pollen grains could be donated to more different individuals. Here we studied the pollen presentation schedule and pollination adaptation of an early spring ephemeral plant, Gagea nigra, by investigating flower characteristics, pollinators and breeding systems in a natural population in Xinjiang Province, northwestern China. (1) The flowering period of single flowers was about 5 to 7 days; flowers open during the day and close at night. The anthers release pollen in the sequence of one by one and split longitudinally like a zipper, lasting 4-6 days. (2) The breeding system of the species was mainly outcrossing and partial selfing. Flies and hoverflies were the main pollinators, with mean visitation rate was 0.141±0.078 times per flower per hour. (3) During pollen presentation, the pistils continued to grow. Thus, the position of stigmas experienced three stages: below stamens, as high as stamens and higher than stamens. In the middle stage, with stamens and stigma at a similar height, the opening and closing of the single flowers during the day and night push the stamens and the stigma closely, thereby facilitating automatic self-pollination. (4) Under a scarcity of pollinators, the gradual pollen presentation in G. nigra extended the period of pollen release, elongating the time for pollinator visits that may reduce the risk of pollination failure, instead of an adaptation to abundant pollinators. Such a gradual pollen presentation strategy in terms of waiting for pollinators and risk of spreading may be widespread in many early spring flowering plants in Xinjiang.

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