Abstract
The culture of leaf vegetable Acmella oleracea L. represents 65% of garden produce of the urban commune of Mahajanga. This is one of the most consumed leafy vegetables and typical Malagasy dishes including that of Majunga population. However, the supply of the local market is never sufficient. The analysis of architectural variability of a species of Acmella oleracea of two origins (from a plain and a plateau) during the two growing seasons of Mahajanga (wet season and dry season), led to a better understanding of the structure and development of this species based on seasonality and draw conclusions on the improvement and production management. The intraspecific variability of architectural features was presented. The calibration of the growth parameters and development in the GreenLab model permitted to calculate the development of the main stem, the meristem development of Acmella oleracea, the topological development parameters and the parameters of the source-sink functions and to retain their intraspecific variability. The development of Acmella oleracea is almost deterministic with a probability of 0.95. The meristems developpement (phyllochron) of Acmella oleracea is not influenced by the environment, it produces one phytomer per week (7 days), regardless of the growing season. The season effect is very marked at the growth and production of biomass which is essentially productive in wet season; in contrary, the origin effect is not important. The various strategies biomass allocation were analyzed and identified by the ratio source-sink, which is a key variable of the model, the season effect is very marked. In addition, the contrubition in the model of growth and development parameters in function of planting densities is discussed in the view of modeling the production of Acmella oleracea.