Common buckwheat (Fagopyrum esculentum Moench) and Tartary buckwheat (Fagopyrum tataricum (L.) Gaertn.) were grown on five locations with different elevations ranging between 300 and 1200 m above sea level. Plants were sampled four times during the growing season. On the leaves from first, pre-flowering period, and second sampling, flowering period, pigments content (UV absorbing compounds, Chlorophyll a, Chlorophyll b, carothenoids, anthocyanins, rutin and quercetin) and optical properties were measured. 3rd and 4th sampling were conducted in time span of roughly ten days at the end of growing period during harvesting. Plants height, dry steam, leaves and seed (achenes) mass, rutin and quercetin concentration in leaves and seeds were measured. Rutin content in leaves of both Tartary and common buckwheat is high and does not differ much between the two species. The highest rutin content in leaves of both species was observed during the flowering period. Seeds of Tartary buckwheat contain roughly 50-times higher concentration of rutin than common buckwheat seeds. Rutin and quercetin content in different parts of common and Tartary buckwheat are, at least to certain extent, positively affected by altitude. Among all the environmental factors that vary with altitude, lower temperature, especially at the beginning and at the end of the season, and high radiation are the most important factors limiting the plants growth. In the low lands plant growth was decompromised by the lack of precipitation at the height of summer. Rutin concentrations also exhibit a role in plants reaction to dehydration stress. Tartary buckwheat plants seems to cope with drought conditions better that common buckwheat plants. At the end of the growing season, in the case of common buckwheat, sudden drop in rutin concentration was observed on locations with high altitude (1085 and 1200 m a. s. l.). This suggests that stress conditions on locations with high altitude exceeded plants ability to adapt to environmental stress.
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