This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Web of Science (9) Citing Articles via Google Scholar Google Scholar Articles by Kaufmann, M. R. Search for Related Content PubMed PubMed Citation Articles by Kaufmann, M. R. Agricola Articles by Kaufmann, M. R.

Articles

Extensibility of Pericarp Tissue in Growing Citrus Fruits ¹

^a Department of Plant Sciences, University of California, Riverside, California 92502

The tensile force existing in the pericarp of a growing citrus (Citrus sinensis) fruit 17 to 19 centimeters in circumference was sufficiently high to cause a 3% shrinkage of the pericarp when it was excised. When a fruit was cut along the equator to the central axis, shrinkage of the pericarp resulted in the formation of a wedge-shaped gap at the cut. Stretch modulus of the pericarp was determined by measuring the force required to stretch excised strips of tissue to 1% longer than their excised length. Measurements were made on successive layers of pericarp tissue 5 millimeters wide and 1 millimeter thick taken from the fruit equator. All layers required more force for extension at lower temperatures and high water potentials than at high temperatures and low water potentials. The stretch modulus ranged from 0.88 to 2.16 kilograms per square millimeter depending upon the layer, temperature, and water potential. The inner layers, consisting primarily of mesocarp, had stretch moduli only 60 to 70% as great as the outer layer which consisted of exocarp tissue. Measurements of the stretch modulus of tissues from the pericarp support the hypothesis that changes in the tension existing in the pericarp depend upon conditions in the pericarp and are not related to changes in volume or pressure in the juice vesicles.