PHOTOSYNTHETIC CHARACTERIZATION AND LEAF ANATOMY OF CHENOPODIUM ALBUM AND CH. HIRCINUM (CHENOPODIACEAE) IN A HIGH-ALTITUDE VALLEY IN NORTHWESTERN ARGENTINA

Background and aims: Chenopodium album (exotic) and Ch. hircinum (native) are weeds in different environments in Argentina. They tolerate various stress conditions so may have interesting traits for Ch. quinoa selection. This study aims to investigate the leaf anatomy and physiological photosynthetic behavior of former species to identify desirable traits for the improvement of quinoa. M&M: Leaf morphological and physiological characteristics were evaluated in the targeted species growing spontaneously in a high mountain valley (1,995 m a.s.l., Tucuman, Argentina). Results: Ch. hircinum exhibited higher net photosynthetic assimilation, stomatal conductance, internal CO2 concentration, nocturnal respiration, and light compensation point. Ch. album showed higher concentrations of protective pigments and carotenoids, along with superior carboxylation capacity and intrinsic water use efficiency as well as a leaf blade with smaller isodiametric palisade mesophyll cells, higher percentage of intercellular air spaces and a greater density of bladder cells. These attributes allow Ch. album the capacity to survive in high mountain environments. Conclusions: The attributes observed in both species provide valuable insights for targeted improvements in Ch. quinoa cultivation.