Harnessing phenological traits of wild ancestor Chenopodium hircinum to improve climate adaptation of quinoa

Context: Cultivation of quinoa (Chenopodium quinoa Willd.) is rapidly expanding worldwide. Characterisation of populations of Chenopodium hircinum Schard., its wild ancestor, which thrives in some of the hottest environments in South America, may provide adaptations to new environments. Aims: This study evaluated the developmental patterns of populations of C. hircinum collected from a range of agroecological environments in Argentina, in order to quantify variability among sites of origin and to explore the association between climatic data from environments of provenance and variation in development. Methods: Thirty-three populations of C. hircinum from contrasting sites of origin in Argentina were multiplied in a common-garden experiment under non-limiting conditions of water and nutrient availability. Plants were sampled once or twice weekly (according to parameter) for estimation of the duration of developmental phases, leaf number, and dates of initiation of branching on the main stem. Key results: Significant variation was detected for all phenological traits, and populations were categorised into six groups based on similarity of patterns of variation. We found positive association of the duration of development phases and the number of leaves on the main-stem with maximum temperature during the growing season, and negative association with altitude of origin, consistent with variation in growing-season duration. Conclusions: The finding that late-flowering populations are associated with warmest climates reveals that longer vegetative growth is an adaptive strategy to cope with heat stress in Chenopodium spp. Implications: Time to flowering should be considered in attempts to improve quinoa performance under heat-stress conditions. Further work is needed to understand the genetic basis controlling this response in wild populations of C. hircinum.