INDOLE-3-ACETIC-ACID CONCENTRATION AND ETHYLENE EVOLUTION DURING EARLY FRUIT-DEVELOPMENT IN PEACH

Ethylene evolution was measured from greenhouse-grown 'Jerseyglo' peach fruits beginning 29 days after anthesis. Indole-3-acetic acid (IAA) levels were measured in the pericarp and seed tissues of individual fruits on a single shoot when variable ethylene evolution was noted. Despite hand-pollinating all flowers on the same day, variability within the shoot existed in fruit fresh weight, IAA levels, and ethylene evolution. Seed IAA concentration increased as fruit and seed fresh weight increased and ranged from 106 to 1572 ng. g-1. As pericarp fresh weight increased, IAA levels in this tissue decreased. Ethylene evolution rates ranged from 0.21 to 1.07 nl. g.-1 h-1 and were not correlated with IAA concentration in seed, pericarp, or the whole fruit. High rates of ethylene evolution from the whole fruit occurred prior to increased IAA concentration in the seed. Fruits were excised from field-grown 'Redskin' peach trees beginning 40 days after full bloom. Fruits from field sampled shoots appeared to be more physiologically advanced than the greenhouse-grown 'Jerseyglo' fruits. Pericarp IAA concentration was low, ranging from 2.8 to 6.5 ng. g-1. Seed concentrations accounted for 75% of the IAA found in the fruit and ranged from 239 to 1042 ng. g-1. As with greenhouse-grown samples, whole fruit IAA concentration tended to decrease as fruits increased in fresh weight. © 1990 Kluwer Academic Publishers.