Relationship Between Tomato Fruit Set and Trophic Competition - A Modelling Approach

Although it has been long recognized that tomato fruit set is linked to the assimilate competition inside plant, quantitative relationship between them have rarely been reported. A reason can be that the dynamic of the internal sink source ratio is hard to measure. In this study, a plant growth model is applied to reveal the ratio between plant assimilate supply and demand (sink-source ratio) at each plant age. GreenLab model was chosen for this purpose. Experiments were carried out in greenhouse with four population densities and the fruit set rate was observed. Results show that (1) for each population density, internal sink-source ratio increase until a peak and then decrease at fruit growing stage; (2) fruit set probability decrease with higher population density; (3) fruit set rate is linearly related with the sink-source ratio for all population densities, with the same coefficient. Discussion is made on the possibility of modeling tomato plasticity including both assimilate allocation and development.