Changes in the content and accumulation of macroelements in different parts of the quinoa plant biomass Chenopodium quinoa willd.

The aim of the research was to determine the effect of harvest date on the content and accumulation of macroelements in quinoa cultivated for seeds. Chemical analyses of macroelement content were conducted on plant material collected during a field experiment at the Swojczyce Station in 2021 (Poland). Due to similar unfavorable weather conditions during the harvests period of 2021-2022, biomass from a single year only was used for analyses. The biomass was categorized into seeds, infructescence remnants, and stems. Quinoa plant biomass were collected at six 7-days intervals between August 18 and September 21. In the study assessed three quinoa varieties: Zeno, Titicaca, and Vikinga. For each varieties and harvest time, the concentrations of nitrogen (N), phosphorus (P), potassium (K), magnesium (Mg), and (calcium) Ca were determined. Macroelement uptake was calculated in mg per plant. The quinoa exhibited the highest N accumulation in the seeds, and the highest K accumulation in the infructescence remnants and stems. The Titicaca variety demonstrated the greatest uptake of N (over 600 mg), P (80 mg), K (980 mg), and Ca (160 mg) per plant. Magnesium accumulation was most pronounced in the Titicaca and Vikinga varieties (100 mg per plant of each). Plant biomass (r = 0.899) and infructescence remnants N uptake (r = 0.803) was highly correlated with total macroelements uptake. The result of this study should be taken into account when determining quinoa value as a forecrop.