Relationship between Leaf Movement of Trifoliolate Compound Leaf and Environmental Factors in the Soybean Canopy IV. Light intensity on the leaf surface

Kuniyuki Saitoh, Ryuzi Inamura, Kuni Ishihara

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

To clarify the effect of light on the trifoliolate compound leaf movement in the soybean plant, (1) changes in the area of the triangle described by the three tips of the leaflets (ΔT) and leaf inclination angle (ΔT), (2) changes in relative light intensity (RL) on the leaf surface to the horizontal plane, and (3) the relation between light intensity and leaf movement, were examined by irradiating the artificial light vertically above. ΔT decreased to 57% at 60 minutes after irradiation (500 µ E ·−2·S−1) with an increase in β of the three leaflets, and RL decreased to nearly 50%. ΔT decreased with increasing in light intensity above 300 µE · m−2 · s−1, and RL decreased steeply to less than 50% at which the light intensity was above 600 µE · m−2 · s−1. Diurnal changes in RL of upper most expanded terminal leaflets in the potted plants were examined using a small photodiode attached to the leaf surface under the outdoor condition. RL showed more than 100% in the early morning, and decreased during the daytime to below 50%. Similarly, RL decreased to 60% during the daytime in the field experiment. Diurnal changes in leaf xylem water potential (Ψx) in the upper layer of the canopy were compared between the control (moving) and horizntal (pulvini were fixed with aluminum foil) plot. As trifoliolate compound leaf approached the tips of the three leaflets in response to sunlight, the light intensity on the leaf surface decreased and the leaflets maintain the higher Ψx by decreasing transpiration. Clearly, leaf movements play an important role in water stress avoidance, however the light intensity on the leaf surface is maintained above the light-saturated point in the relation between light intensity and photosynthetic rate of the leaflet.

Original languageEnglish
Pages (from-to)616-624
Number of pages9
JournalJapanese Journal of Crop Science
Volume63
Issue number4
DOIs
Publication statusPublished - Jan 1 1994

Keywords

  • Heliotropic movement
  • Leaf inclination angle
  • Leaf xylem water potential
  • Light intensity on leaf surface
  • Soybean
  • Trifoliolate compound leaf

ASJC Scopus subject areas

  • Food Science
  • Agronomy and Crop Science
  • Genetics

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