Leaf orientation in barley, lupin, and lucerne stands

Abstract

The height above ground and orientation (vertical angle and azimuth) of leaf surfaces in stands of barley, lupin, and lucerne were measured with a modified point intercept method. The final segment of the pin was geared to rotate horizontally and vertically, allowing it to be orientated parallel with the leaf surface at the point of contact. Individual surfaces could be measured with an accuracy of ±2° and ±0.2 cm, but measurements were grouped into larger angle and height classes. Frequency in 36 height, azimuth, and vertical angle classes is given for the three stands. Mean leaf vertical angles in barley varied rrom 44° (to the horizontal) near the top of the stand to 53° near ground level. The corresponding values for lupin were 27°–37° and fop lucerne 35°–31°. In all stands there was a wide range of slopes. Azimuths of leaf surfaces were not uniformly distributed—barley surfaces had a net southerly azimuth, whereas lupin and lucerne tended to have net northerly azimuths and in lucerne this changed during the day.