Photosynthesis of wheat under field conditions. V.* The effect of sugar elevation on the distribution of photosynthetic activity within the crop canopy

Abstract

The distribution of photosynthetic activity within the canopy of a wheat community was measured at different times of the day Plants In the field were covered by a Perspex assimilation chamber and exposed to ¹⁴CO₂ and light for 15 min., then harvested and dissected. The relative specific activity and dry weight of the parts, and the calculated total carbon dioxide uptake of the community were then used to determine the distribution of photosynthesis within the community. The contribution of the lower leaves and leaf sheaths increased with increasing elevation of the sun up to 67°, while the photosynthesis of the flag leaves approached a maximum when the elevation of the sun was only 28°. The relative contribution of the ears to total photosynthesis decreased from 33 to 13% as the solar elevation increased from 17 to 67°.

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*Part IV, Aust. J. Agric. Res., 22: 1 I (1971).