Effects of Leaf Movement on Radiation Interception in Field Grown Leguminous Crops. I. Peanut(Arachis hypogaea L.)

The effects of leaf movement of peanut on radiation interception were examined. A peanut cultivar (c.v. Nakateyutaka) was planted at three planting densities (20 cm, 30 cm and 40 cm equidistant spacings). In the treatment plots, the upper layer of the conopy was covered horizontally with a nylon net to restrain the movement of the leaflets. Intercepted radiation of each leaflet was measured by integrated solarimeter films for two consecutive days. It was observed that the leaflets of the upper layer oriented paraheliotropically to the sun rays in midday. Intercepted radiation per unit leaf area and unit ground area of the control were larger in the 20 cm spacing, almost similar in the 30 cm spacing and smaller in the 40 cm spacing as compared with the treatment. The leaf movement of the upper layer of the canopy played a significant role in radiation interception in the 20 cm plot, no discernible effect in the 30 cm plot and a rather adverse role in the 40 cm plot. Leaf area of the 20 cm spacing was concentrated densely at the upper layer. Leaf area of the 30 cm and 40 cm spacing was larger at the middle layers. It was assumed that effectiveness of the leaf movement of the upper layer would depend mainly on spatial leaf area distribution and density.