Three-dimensional modelling of salt stress effects on the tomato canopy development
Final Report Abstract
Salt stress causes important morphological alterations on plants, with tremendous implications for light interception and crop productivity. It is therefore important to include morphological information in strategies aiming to overcome salinity-induced yield reduction. This is especially true for spatially heterogeneous crops such as tomato. The purpose of this project was to develop an integrated understanding of salinity-induced morphological alterations significant for the tomato productivity. We conceptualized an architectural model of the tomato growing under various levels of salt stress using L-system formalism. Plant development was modeled as an integration of organ appearance, expansion, senescence as well as geometrical details such as 3-D organ positioning, orientation and shape. Each of these events was modeled depending on salinity, temperature, vapor pressure deficit or light. The effects of these environmental factors on canopy development were investigated in five experiments, four of which were used for model parameterization and one for model evaluation. The model was then used as a research tool to first evaluate the value of morphological traits under non-stressed conditions in different temperature environments. In a second step, the effects of salinity on canopy traits and ultimately crop productivity was investigated. The dynamic functional-structural plant model (FSPM) constructed on the basis of four experiments predicted the organ growth, organ size and shoot dry mass over time with high accuracy (> 85%). Trait analyses showed that, in comparison with the reference canopy, shoot dry mass is substantially influenced by leaf angle and to a lesser degree by internode length, leaf curvature, leaf length/width ratio, curvature ratios and leaf arrangement. Tomato canopies at low temperature had higher canopy density and were more clumped due to higher leaf area and shorter internodes. Interestingly, dry mass production and light interception of the clumped canopy was more sensitive to changes in architectural traits. The complex interactions between architectural traits, canopy light interception, dry mass production and environmental conditions can be studied by the dynamic FSPM, which may serve as a tool for designing a canopy structure which is “ideal” in a given environment. Modelling salinity effects required an adjustment of light use efficiency to get correct estimates of dry matter production. This allowed a separation of architectural and nonarchitectural effects on the reduction of dry matter production due to salinity. It was interesting to note that the architectural effects decreased with time. Obviously, the continuing accumulation of salt in the tissues increasingly diminished photosynthesis. Of the architectural traits, leaf number and leaf angle appeared to have the highest impact on dry matter production, while internode length had very little influence. The parameter describing salinity effects on expansion affected dry matter production mainly under high temperature conditions.
Publications
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2009. A framework for three-dimensional modelling of salt stress effects on the tomato canopy development. In 45. Gartenbauwissenschaftliche Tagung, Berlin. BHGL-Schriftenreihe,152. Poster
Nguyen TMN, Kahlen K, Stützel H
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2010. Effects of salinity on architectural traits of tomato. SEB Main Meeting, Prag, Tschechische Republik. Proceedings. 361. Poster
Nguyen TMN, Kahlen K, Stützel H
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2010. Modeling leaf growth of tomato under salt stress. In 46. Gartenbauwissenschaftliche Tagung. Hohenheim: Universität Hohenheim. BHGL-Schriftenreihe, 151. Poster
Nguyen TMN, Kahlen K, Stützel H
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2010. Modeling of salt stress effects on tomato leaf morphology. In DeJong T, Da Silva D. FSPM2010 - 6th Workshop on Functional- Structural Plant Models. Davis: University of California. 288. Poster
Nguyen TMN, Kahlen K, Stützel H
