Studies of the Physiology of Coffea Arabica

Abstract

In a previous communication (Nutman, 1937) examples have been given of the daily march of assimilation of Coffea Arabica leaves in the field, showing that there is a marked midday drop in assimilation rates when the leaves are exposed to direct sunlight, but not when they are shaded, nor during cloudy weather. It was concluded that this drop in assimilation was not due to the water relations of the leaf or of the plant as a whole, nor to an excessive accumulation of assimilates in the leaf, nor to a solarization effect. It was suggested that stomatal changes might explain the observed phenomena" and, if so, stomatal aperture should be directly correlated with light at low intensities inversely correlated at high intensities.