Aims Morphological and ontogenetic variation in root system architecture holds ecological significance, particularly in low-resource habitats where soil rooting is critical for both seedling establishment and water and nutrient uptake. To assess this variation under contrasted agroecological backgrounds, root architecture and rooting patterns were compared in Andean populations of Chenopodium hircinum, Chenopodium pallidicaule and two ecotypes (wet-and dry-habitat) of Chenopodium quinoa. Methods Seedlings were grown in rhizotrons under controlled water and nutrient availability. Root branching and elongation dynamics were characterized during 6 weeks after germination, while leaf area, above and belowground biomass, and specific root length were determined at the end of the experiment. Results Despite large differences in aboveground biomass, all populations showed similar herringbone root systems. The dry-habitat C. quinoa had generally the highest root trait values, with fast taproot elongation, thick roots and long root segments resulting in high total root length and deep root proliferation. Conclusion Irrespective of their contrasting agroecological background, the studied chenopods displayed a similar root system topology. However, from very early development stages, they showed differential root foraging patterns with two extremes: fast and vigourous rooting at depth in the dry-habitat C. quinoa, and shallow and thin root system in C. pallidicaule adapted to shallow-soil and high-altitude habitats.

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The debate on the environmental and social sustentainability of quinoa in its area of major world production (southern highlands of Bolivia) revived with the acceptance by the United Nations of the Bolivian proposal to declare in 2013 as the Year of the Quinoa. Public debate focused on local impacts of quinoa expansion in the Southern highlands of Bolivia, denouncing several negative impacts of quinoa culture such as land degradation, socioeconomic disrupts and biodiversity loss. However, the global or at least the international implications of the expanding quinoa market were less debated and often in caricature, varying between culpability and ingenuity among consumers, while Andean producers were described as trapped by poverty or short sighted greed. If researchers are to make a relevant contribution to the debate on the impact of quinoa expansion on the social and environmental sustainability of the Andean agriculture, is it necessary to re-evaluate present knowledge and ignorance about local Andean production systems integrated with links at the global scales, taking into account local-global interactions.In the present paper are revisited some major ill-founded assertions commonly expressed in this debate and three lines of arguments are used to support the need for a more cautious and ethical approach to quinoa related issues. Key words: debate, biodiversity, socioecological. RESUMEN