Not only light quality but also mechanical stimuli are involved in height convergence in crowded Chenopodium album stands

Authors

  • Hisae Nagashima,

    1. Nikko Botanical Garden, Graduate School of Science, The University of Tokyo, 321-1435 Tochigi, Japan
    2. Graduate School of Life Sciences, Tohoku University, Aoba, Sendai, 980-8578 Miyagi, Japan
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  • Kouki Hikosaka

    1. Graduate School of Life Sciences, Tohoku University, Aoba, Sendai, 980-8578 Miyagi, Japan
    2. CREST, Japan Science and Technology Agency (JST), 102-0076 Tokyo, Japan
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Author for correspondence:
Hisae Nagashima
Tel: +81 022 795 7732
Email: hisae@ceres.ocn.ne.jp

Summary

  • In crowded stands, height is often similar among dominant plants, as plants adjust their height to that of their neighbours (height convergence). We investigated which of the factors, light quality, light quantity and mechanical stimuli, is primarily responsible for stem elongation and height convergence in crowded stands.
  • We established stands of potted Chenopodium album plants. In one stand, target plants were surrounded by artificial plants that were painted black to ensure that the light quality was not modified by their neighbours. In a second stand, target plants were surrounded by real plants. In both stands, one-half of the target plants were anchored to stakes to prevent flexing by wind. The target plants were lifted or lowered by 10 cm to test whether height convergence was affected by the different treatments.
  • Stem length was affected by being surrounded by artificial plants, anchoring and pot elevation, indicating that light quality, light quantity and mechanical stimuli all influenced stem elongation. Height convergence did not occur in the stand with artificial plants or in anchored plants.
  • We conclude that light quality and mechanical stimuli are important factors for the regulation of stem growth and height convergence in crowded stands.

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