水稲群落の葉群の構造と直達光の透入について

概要

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Biometrical measurements were made to make clear the change in geometrical structure of rice canopy during the growing season. The results were used to clarify the penetration of direct sun-light into the canopy. The penetration of direct sun-light was calculated from Eq. (1) proposed by Ross and Nilson (1965). The geometrical characteristics of the canopy was found to be a vertical foliage-type at about the heading stage and to change the more horizontal one at about the waxy stage of ripening. The effective leaf area function (G_L (w)) that denotes cosine of the angle between leaf normal and sun direction was determined at each layer within the canopy. The special mean (G^^-_L) of the effective leaf area function was also determined by considering the vertical distribution of leaf area density (f_L(z)) and the effective leaf area function (G_L(w)). Both of G_L(w) and G^^-_L were found to change remarkably with the sun altitude (h_0), showing that the types of change are dependent upon the growth stages of rice crops. The ratio (F_d/F_t) between the partial leaf area index of sun-lit foliage (F_d) and the whole leaf area index (F_t), the ratio (_<ab>F_d/F_d) between the partial leaf area index of foliages receiving light on the reverse side (_<ab>Fd) and the sun-lit leaf aera index (F_d), and the extinction coefficient of direct sun-light (k_d) changed by the sun altitude (h_0). The forms of change in these three parameters all depend upon the geometrical characteristics of canopy. It has been pointed out that the vertical foliage-type community is favorable for the photosynthetic activity since the direct sun-light can penetrate into the deeper layer, and that the horizontal foliage-type community is less favorable since the direct sun-light is apt to be absorbed at the upper layers and cannot penetrate into the community so deeply.
日本作物学会の論文
1969-09-30

著者

伊藤綾子
農林省農業技術研究所

水稲群落の葉群の構造と直達光の透入について

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