Cell Division and Elongation in the Exocarp of Tomato Fruits Grown in Systems In vitro and on the Vine

Abstract

Summary The growth in vitro of tomato fruits, cultured in the usual, closed way and in an especially developed open system, was compared with the growth of fruits grown in vivo . The area of exocarp cells was measured histologically at different stages of fruit development. In vivo , cell divisions continued until about 14 days after anthesis, thereafter fruit growth was by cell enlargement only, a mature fruit having an average weight of 106 g in summer and 63 g in winter. In the fruits cultured in the open system cell division also proceeded until about 14 days after anthesis, but cell enlargement was less intensive, resulting in a mature fruit with a weight of 57 g. In fruits in the closed system, cell enlargement was strongly restrained, the final fruit weight attaining only 38 g. Because fruit development in the open system approaches that of fruits on the plant, it is concluded that the open system can be used to study fruit growth and development unaffected by the complicating influences of the rest of the plant.