GROWTH STUDIES OF NORMAL AND PARTHENOCARPIC TOMATO FRUITS

Abstract

Gaseous exchange by growing tomato fruits is localized in a ring of lenticel tissue that encircles the receptacle and is covered by the calyx. The size of this annular lenticel varies with the size of the fruit.Growth of the fruits of the variety Grand Rapids includes a phase of residual mitotic activity that persists for approximately one week after setting. Cell division is reduced in dwarf or laggard fruits, which are examples of natural parthenocarpy. Under seasonal conditions that are favorable for natural setting, application of 0.2% indolebutyric −50 p.p.m. β-naphthoxyacetic acid to pollinated flowers markedly increases the number and size of fruits obtained with the Marglobe but not with the Grand Rapids variety. The locular pulp of parthenocarpic fruits usually remains green during vine ripening. The green color is largely imparted by chloroplasts that are concentrated in the vicinity of the vascular strands leading to the aborted ovules.