Plant growth dynamics and root morphology of little-known species of Chenopodium from contrasted Andean habitats

Abstract

Plant morphology determines the access to soil resources, a feature crucial for early growth in annual species. Plant growth and root traits in little-known species of Andean chenopods were compared with the hypothesis that plants from low-resource habitats show traits that enhance resource capture. Three cultivated Chenopodium populations (two populations of the tetraploid Chenopodium quinoa Willd., one population of the diploid Chenopodium pallidicaule Aellen) and one population of their wild tetraploid relative Chenopodium hircinum Schrad. were grown in pots under nonlimiting conditions over nine weeks of early vegetative growth. All populations followed the same sequence of biomass allocation and showed similar maximal values of shoot and root relative growth rates (RGR). Population differences in plant biomass, net assimilation rate, total root length, and specific root length were associated with seed mass ranking and species ploidy level. Chenopodium quinoa produced less branched stems and maintained high root RGR for a longer time than the other two species, and the C. quinoa population from low-resource habitat showed a faster main root growth. These results show that C. pallidicaule developed a plant growth syndrome adapted to cold, high-altitude habitats, while C. quinoa from low-resource habitats showed an improved capacity to explore soil at depth in early growth stages.Résumé : La morphologie des plantes détermine l'accès aux ressources du sol, un élément crucial pour la croissance juvénile des plantes annuelles. La croissance des plantes et les traits racinaires de chénopodes peu connus des Andes ont été comparés avec l'hypothèse que les plantes d'habitats pauvres en ressources présentent des traits qui améliorent la capture des ressources. Trois Chenopodium cultivés (deux populations tétraploïdes de Chenopodium quinoa Willd., une population diploïde de Chenopodium pallidicaule Aellen) et une population de leur parent sauvage tétraploïde Chenopodium hircinum Schrad. ont été cultivés en pots en conditions non limitantes durant neuf semaines de croissance végétative. Toutes ces populations montrent la même séquence d'allocation de la biomasse et des valeurs similaires des taux de croissance relative (RGR) des tiges et des racines. Les différences inter-populations de production de biomasse, taux d'assimilation nette, longueur racinaire totale, et longueur spécifique des racines sont associées à la masse des graines et au niveau de ploïdie des espèces. Chenopodium quinoa produit des tiges moins ramifiées et maintient des RGR de racines plus élevés durant plus longtemps que les deux autres espèces, et la population de C. quinoa issue de l'habitat pauvre en ressources présente une croissance plus rapide de la racine principale. Ces résultats montrent que C. pallidicaule développe un syndrome de croissance adapté aux habitats froids de haute altitude, tandis que C. quinoa de l'habitat pauvre en ressources montre une meilleure capacité d'exploration du sol en profondeur pendant la phase de croissance juvé...

Variation in quinoa roots growth responses to drought stresses

“…Each of these clusters includes genetic materials from different origins, so no geographic pattern in tolerance was detected, a contrast with assertions by Alvarez‐Flores et al. (2014).…”

“…Alvarez‐Flores et al. (2014) also found that quinoa genotypes from dry‐habitat showed longer, coarser and more numerous root segments than wet‐habitat genotypes. Gámez et al (2019) proposed that greater root development and a better stomatal opening adjustment could help maintain seed yield of Rainbow quinoa under drought stress.…”

Root foraging capacity depends on root system architecture and ontogeny in seedlings of three Andean Chenopodium species

“…hircinum, while C. pallidicaule remained limited to the first 40 cm soil layer (Alvarez-Flores et al 2014).…”

Quinoa Abiotic Stress Responses: A Review

“…Finally, root system architecture and its relationship to soil moisture conditions has been studied in quinoa and quinoa relatives. Quinoa roots exhibit faster elongation and abundant and longer external branching of the roots that improve their foraging capacity compared to quinoa relatives C. hiricinum and C. pallidicaule [67,68]. Recently, a root system architecture and dynamics study was conducted in drought conditions, comparing C. hiricinum and C. pallidicaule , a rainy-habitat and a dry-habitat quinoa genotype, respectively.…”