Analyse comparative et modélisation de la croissance et du développement de tubercules andins dans les Andes en Bolivie

Abstract

In conditions of high genetic diversity and environments such as the mountainous zones in the Bolivian Andes, modern tools of analysis as the simulation models are necessary for a better crop management. The Andean tubers (AT) such as potato (Solanum tuberosum ssp.), oca (Oxalis tuberosa), isaño (Tropaeolum tuberosum) and papalisa (Ullucus tuberosus) are neglected millenarian crops, although they are conserved and compose the more important rotation of crops in the production systems. Our objective was to contribute to the knowledge of AT, assessing the variability of the phenotypical stability. It was also to describe quantitatively their growth and development with an agrophysiological characterization to use this information in LINTUL potato model validation under favorable and real agroecological conditions of growth in the Bolivian highland. The analysis of stability allows us to interpret in a simple and rapid manner the behavior of different genotypes in the environments where they are grown. This gave us criteria about the capacity of a given cultivar to increase and adapt its yields in function of a given environment more or less favorable. This method however presents limitations for explaining yield determination when other parameters inherent to yield determination as ground cover, light use efficiency and harvest index have to be taken into consideration. We characterized the growth attributes of the AT. We found large differences in the performances of assimilate production and different combination of attributes typical for each species. The definition of these characters can help us to structure our actions for constructing models of growth for these species or programs of variety improvement (ideotypes) which perform better in terms of tuber yield. The LINTUL potato model allowed us to detect a slowing down in the initial phase of ground cover by the foliage which results in a failure of reaching 100% soil cover and indicates less favorable conditions for biomass production. It remains to evaluate the adaptability of this diverse genetical material to different environmental conditions related chiefly to changes of temperatures (cold and warmer zones) and to investigate whether zones with better conditions could be found. An important constraint to reach higher potential performances is the temperature (average of 11°C) which could be responsible for yield levels reaching only half of the potential production under other latitudes.Doctorat en sciences agronomiques et ingénierie biologique (AGRO 3)--UCL, 200