The starch content of tomato leaves grown under glass

Abstract

The starch content of tomato leaves taken from different heights in the canopy was measured in a spring crop grown under glass. Fruit- and leaf-thinning treatments were applied to the crop to induce different source—sink relationships. In control plants, with a full complement of leaves and fruit, leaf starch content (on a unit-area basis) increased with plant height. The removal of all but 3 fruit from each truss caused accumulation of starch in the older leaves but reduced the starch content of younger leaves. Total leaf area was larger in plants with fruit removed, and thus there was more total leaf starch in these plants. Plants with their lower leaves or lower leaves and some fruit removed showed no significant differences in starch level from the control plants. Changes in leaf starch content with time of day were small, and changes in starch content following substantial changes of mean irradiance over the previous 2 days were not detectable. The starch content of the plants is discussed in relation to potential yield.