Anatomical changes which take place in conjunction with abscission of cantaloupe fruits (Cucumis melo L. cv. Powdery Mildew Resistant No. 45) include cell separation and cell collapse. Structural modifications in abscission zone cell walls are accompanied by histochemical changes which include losses of pectins and insoluble polysaccharides. Development of a separation cavity is consistently correlated with physiologically defined stages of fruit maturity, and the time of abscission coincides with the peak of the respiratory climacteric. Anatomical and histochemical changes similar to those in cantaloupe also take place in honeydew fruits (Cucumis melo L. cv. Honeydew). However, the abscission zone of honeydews is not structurally well defined, changes are limited to certain parenchyma cells, and the honeydew fruits do not normally abscise. It is suggested that the most desirable growth regulator for use on cantaloupes to accelerate and unify the time of fruit ripening would be one which did not coincidentally accelerate abscission.
Received for publication 13 June 1974. This study was supported by funds from the State Department of Agriculture; Melon Research Board.
Research Morphologist and Lecturer, Department of Vegetable Crops and Department of Agronomy and Range Science.
The author acknowledges the assistance of Mary E. Craig and H. W. Chiu in various phases of this study.