The Relationship Between the Rates of Carbon Transport and of Photosynthesis in Tomato Leaves

TLDR: In this article, the carbon balance of a mature tomato leaf was measured over a 6-h period from a tomato leaf and the rate of carbon transport based on this carbon balance was measured under a range of net photosynthetic rates.

Abstract: The rate of carbon transport based on the carbon balance over a 6 -h period from a mature tomato leaf was measured over a range of net photosynthetic rates from 0-1 to 4-9 mg C dm-2 h_1 under light flux densities from 4 to 140 W m-2. A proportional relationship was demonstrated between the rate of carbon transport and carbon fixation when the carbon fixation rate was higher than 2 mg C dm-2 h_1. Below a carbon fixation rate of 1 mg C dm-2 h-1, the rate of carbon export was maintained at 1 mg C dm-2 h_1 at the expense of the breakdown of starch. A highly significant correlation was observed between sucrose concentration and the rate of carbon transport. The sucrose concentration in the leaf appears to be the factor controlling carbon export.