Correlation between dynamic tomato fruit-set and sourcesink ratio: A common relationship for different plant densities and seasons?

Abstract

• Background and AimsIt is widely accepted that fruit-set in plants is related to sourcesink ratio. Despite its critical importance to yield, prediction of fruit-set remains an ongoing problem in crop models. Functionalstructural plant models are potentially able to simulate organ-level plasticity of plants. To predict fruit-set, the quantitative link between sourcesink ratio and fruit-set probability is analysed here via a functionalstructural plant model, GreenLab. • Methods Two experiments, each with four plant densities, were carried out in a solar greenhouse during two growth seasons (started in spring and autumn). Dynamic fruit-set probability was estimated by frequent observation on inflorescences. Source and sink parameter values were obtained by fitting GreenLab outputs for the biomass of plant parts (lamina, petiole, internode, fruit), at both organ and plant level, to corresponding destructive measurements at six dates from real plants. The dynamic sourcesink ratio was calculated as the ratio between biomass production and plant demand (sum of all organ sink strength) per growth cycle, both being outputs of the model. • Key Results and ConclusionsMost sink parameters were stable over multiple planting densities and seasons. From planting, sourcesink ratio increased in the vegetative stage and reached a peak after fruit-set commenced, followed by a decrease of leaf appearance rate. Fruit-set probability was correlated with the sourcesink ratio after the appearance of flower buds. The relationship between fruit-set probability and the most correlated sourcesink ratio could be quantified by a single regression line for both experiments. The current work paves the way to predicting dynamic fruit-set using a functional structure model. © 2010 The Author 2010. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved.