Studies on the Leaf Orientation-Adjusting Movement in Soybean Plants : II. Fundamental pattern of the leaf orientation-adjusting movement and its significance for the dry matter production

Abstract

Since the leaf orientation-adjusting movement is after all the alteration in the leaf inclination the author devised the analytical method based upon the value of actual measurment of the three elements for determining the leaf orientation: φ (azimuth of leaf), θ (main angle of leaf inclination) and ψ (sub-angle of leaf inclination) given in fig. 1 and 3, and applied the devised analytical method to the soybean leaf acting a typical adjusting movement, thus attempted to make investigations into the fundamental pattern of the leaf orientation-adjusting movement and its significance for the dry matter production. 1. The author took the alteration in the leaf inclination (i.e., leaf orientation-adjusting movement) as the change in the horizontal system of co-ordinate at the intersection between the normal on the leaf surface and the celestial sphere, and proposed such method which clarifies the change by using figure drawing and calculation based upon the value obtained from the actual measurement of the three elements necessary for the determining the leaf inclination. The method to draw figures was indicated in fig. 2 and 4 and the calculation was made by using the following expression. 1) The expressions to find out the horizontal system of co-ordinate P (intersection of the normal on the leaf surface with the celestial sphere) : x=-cos φ sin θ cos ψ + sin φ sin ψ y=-sin φ sin θ cos ψ - sin φ cos ψ z=cos θ cos ψ (1) 2) The expressions to find out φ' (azimuth) and θ' (altitude) of the normal on the leaf surface: φ'=tan-1y/x θ'=sin-1z (2) 3) The expressions to find out the angle α of the direction of the sun (or the brightest light in the sky) with the normal on the leaf surface: α=cos-1 (cos φs cos θs·x+sin φs cos θs·y+sin θs·z) (3) where φs : Azimuth of the sun θs : Altitude of the sun Notes : Azimuth : Oo : south, + : the east circuit line, and - : the west circuit line Main-angle of leaf inclination (θ) : + : upward inclination, - : downward inclination Sub-angle of leaf inclination (ψ) : + : turning-up to the left direction from the leaf base to the leaf apex, - : turning-up to the right direction from the leaf base to the leaf apex 2. The soybean plant was grown in a pot in isolation. By taking Madison variety acting a typical adjusting movement as a sample, the actual measurement was made extending over the duration from early to mid-September, 1965, in order to measure the three elements necessary for determining the leaf inclination for each of the leaflets in the compound leaf according to the selected hours on fine days and according to the climatic conditions at the same hours. Basing upon the value obtained from this actual measurement, the changes in the co-ordinate of normal on the leaf surface were observed by the figure drawing and calculating methods. Thus the fundamental pattern of the leaf orientation-adjusting movement was investigated. As to the changes in the three elements measured according to the selected hours on fine days, at first, the changes in each leaflet was observed according to the selected hours (changes in the compound leaf on the uppermost node are given in fig. 5), and the changes were classified according to the selected hours (fig. 6). α was also obtained by using tha calculating method (fig. 7). The changes due to the climatic conditions were observed also in the same ways (figs. 9 and 10). 3. The survey results indicated that, in the case of isolated individual small in the leaf number, as in the case with the present report, a remarkable adjusting movement was shown by the entire leaves. [the rest omitted]