INTEGRATING PHYSIOLOGICAL RESPONSES OF FRUIT GROWTH TO GENETICS, ENVIRONMENT AND MANAGEMENT
Patterns of fruit growth and development are usually described by plotting cumulative fresh or dry fruit mass or diameter over time. So the fruit growth pattern of apple is generally described as single-sigmoid while the growth of many stone fruits is described as being double-sigmoid. But just describing the pattern of fruit mass increase does not provide a functional approach to analyzing factors that limit fruit growth. The key to understanding these limitations is to be able to compare fruit growth that occurs under specified limiting conditions with the potential growth that would have occurred without the limitation. Two decades ago my colleagues and I demonstrated that fruit relative growth rate analysis can be used to provide an approximate description of the genetic fruit growth potential of a given fruit cultivar when that cultivar is grown under near-optimal conditions with very low fruit loads. Subsequently we have demonstrated how relative fruit growth rate analysis can be used to develop mathematical models that simulate fruit growth for any given time interval during a growing season. These analyses and models have provided a means to understand the basis of the classical single sigmoid and double-sigmoid growth curves, compare the carbohydrate requirements of fruits of different cultivars during the season and evaluate environmental and management effects on fruit growth and yield. This paper will provide examples of how relative growth analysis has provided understanding of: when fruit growth is source vs. sink limited; how spring temperatures, time of fruit thinning and crop load can influence the timing of these limitations; and how the integration of numerous genetic, environment and management factors ultimately determine fruit size and crop yield.
DeJong, T.M. (2012). INTEGRATING PHYSIOLOGICAL RESPONSES OF FRUIT GROWTH TO GENETICS, ENVIRONMENT AND MANAGEMENT. Acta Hortic. 932, 171-177