TOMATO SEEDLING GROWTH IN RESPONSE TO VARIATION IN ROOT CONTAINER SHAPE

Roots of tomato (Lycopersicon esculentum Mill.) seedlings grown in multicelled trays were confined largely to the interface between the growing medium and the inner surface of the cell. Because of the predominance of roots in this area, experiments were done in prototype cells to relate seedling growth to change in this interface area while retaining a constant volume. The cell shapes that were tested included a square cell with 1.36-cm sides and other rectangular cells. All cells were 3 cm in height, but widths decreased incrementally by 0.1 cm from the 1.36 x 1.36-cm square to rectangles with inner cell dimensions of 0.36 x 5.14 cm. With these changing shapes, the interface area increased but cell width decreased to a more narrow cell. Seedling height increased as the cell shape was changed from a square (1.36 x 1.36 cm) to an elongated rectangle (1.74 x 1.06 cm). More narrow cells caused seedling height to decrease; the shortest seedlings occurred in 0.36 x 5.14-cm cells. Root growth was unaffected by change in cell shape. The smoothness of the inner cell surface, however, affected root growth; a rough texture resulted in stubby and reduced root growth but had no effect on shoot growth.