Ontogenic changes in the construction costs of leaves, stems, fruits, and roots of tomato plants
1998
Gary, C. | Le Bot, J. | Frossard, J.S. | Andriolo, J.L.
The construction cost of a plant tissue, i.e. the amount of photoassimilates used in the synthesis of a unit weight, varies with its biochemical composition. Crop modellers use standard values published for a few groups of cultivated species. Yet, there are also intraspecific variations in the construction cost in relation with the development of the plant or organ. This research aimed at analysing the ontogenic changes in the construction cost of leaves, stems, roots, and fruits of tomato plants and the specific contribution of the mineral content to these changes. For that purpose, samples were harvested from the vegetative phase to the beginning of fruit production. The estimation of the construction cost was based on the contents of carbon, nitrogen and ash. In leaves, the construction cost decreased with the physiological age whereas, in stem internodes, it varied with the sympod number. These ontogenic changes could partly be explained by different accumulations of minerals. In contrast, the construction cost and the mineral content of fruits and roots remained fairly stable. On a whole plant basis, the construction cost of the bulk of each category of organs varied much less. Most of the increase in the mean construction cost of the whole plant during the experiment was due to changes in the allocation ratio between the vegetative parts and the fruits. Attention of crop modellers is drawn to the importance of a precise estimation of the construction cost and to the existence of ontogenic changes at the whole plant and organ levels.
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