Fifty years of citrus developmental research: A perspective

An overview of the conceptual and methodological changes in citrus developmental research during the past half century is provided. Beginning with the hormonal era, the extensive use of plant growth regulators (PGRs) is described and the presumed role of gibberellins in various stages of the reproductive processes is emphasized. Introduction of the sourcesink concept opened the way for alternative, carbohydrate-mediated explanations of productivity and alternate bearing. The potential role of ethylene in citrus abscission and fruit ripening is reviewed. The recent adoption of genetic-molecular approaches paves the way for deeper understanding of citrus developmental enigmas.