Relationship between Leaf Movement of Trifoliolate Compound Leaf and Environmental Factors in the Soybean Canopy : IV. Light intensity on the leaf surface
[摘要] 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 (β), (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 μE·m-2s-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 60O 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.
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[效力级别] [学科分类] 农业科学（综合）
[关键词] Heliotropic movement;å‘æ—¥é‹å‹•;Leaf inclination angle;3複葉;Leaf xylem;ダイズ;water potential;葉ã®æœ¨éƒ¨æ°´ãƒãƒ†ãƒ³ã‚·ãƒ£ãƒ«;Light intensity on leaf surface;葉é¢å‚¾æ–œè§’度;Soybean;葉é¢å—å…‰é‡;Trifoliolate compound leaf [时效性]
