Comparison of Heat and Drought Stress Responses among Twelve Tartary Buckwheat (Fagopyrum tataricum) Varieties.

The use of orphan crops could mitigate the effects of climate change and improve the quality of food security. We compared the effects of drought, high temperature, and their combination in 12 varieties of Tartary buckwheat (Fagopyrum tataricum). Plants were grown at 21/19 °C or 28/26 °C under well-watered and water-stressed conditions. Plants were more discriminated according to environmental conditions than variety, with the exception of Islek that was smaller and produced fewer leaves, inflorescences, and seeds than the other varieties. The combination of high temperature and water stress had a stronger negative impact than each stress applied separately. The temperature increase stimulated leaf and flower production while water stress decreased plant height. Leaf area decreased with both temperature and water stress. High temperature hastened the seed initiation but negatively affected seed development such that almost all seeds aborted at 28 °C. At 21 °C, water stress significantly decreased the seed production per plant. At the physiological level, water stress increased the chlorophyll content and temperature increased the transpiration rate under well-watered conditions. High temperature also increased the polyphenol and flavonoid concentrations, mainly in the inflorescences. Altogether, our results showed that water stress and temperature increase in particular negatively affected seed production in F. tataricum.

Comparison of Plant Morphology, Yield and Nutritional Quality of Fagopyrum esculentum and Fagopyrum tataricum Grown under Field Conditions in Belgium.

Buckwheat is a pseudocereal with high nutritional and nutraceutical properties. Although common buckwheat (Fagopyrum esculentum) is the main cultivated species, Tartary buckwheat (Fagopyrum tataricum) is gaining interest. In this paper, we compared plant growth, yield-related parameters and seed nutritional qualities of two varieties of F. esculentum and F. tataricum under field conditions in Belgium. Fagopyrum esculentum flowered earlier, produced less nodes, less branches, less inflorescences, but more flowers per inflorescence than F. tataricum. The yield was higher in F. tataricum, while the thousand-grain weight was higher in F. esculentum. Yield ranged between 2037 kg/ha and 3667 kg/ha depending on the species and year. Regarding nutritional qualities, seeds of F. esculentum contained more proteins (15.4% vs. 12.8%) than seeds of F. tataricum although their amino acid profile was similar. Seeds of F. esculentum contained also more Mg (1.36 vs. 1.15 mg/g dry weight (DW)) and less Fe (22.9 vs. 32.6 µg/g DW) and Zn (19.6 vs. 24.5 µg/g DW) than F. tataricum. The main difference between seed nutritional quality was the concentration of flavonoids that was 60 times higher in F. tataricum than in F. esculentum. Both species grow well under Belgian conditions and showed good seed quality.

Different drought resistance mechanisms between two buckwheat species Fagopyrum esculentum and Fagopyrum tataricum.

Water availability is one of the main factors affecting crop production and the occurrence of drought periods is expected to increase in the context of ongoing climate change. We investigated the impact of water stress on two pseudocereal species, common buckwheat (Fagopyrum esculentum) and Tartary buckwheat (Fagopyrum tataricum). Plants were grown under greenhouse conditions under two water regimes: control (40-50% soil humidity) and water stress (<20% soil humidity). Although closely related, both species differed by their resistance to water stress. The vegetative growth was affected in F. esculentum but not in F. tataricum as water stress decreased leaf production, leaf fresh, and dry weight, stomatal conductance, transpiration rate, and photosynthesis rate in the former but not in the latter. However, chlorophyll fluorescence parameters were not affected by water stress, whatever the species, and the chlorophyll content increased in water-stressed plants in both species. Oxidative stress was observed in both species in response to water stress, and antioxidant content was increased in F. tataricum. The reproductive phase was affected by water stress in both species: the number of inflorescences and pollen production decreased, mainly in F. esculentum. Seed set was maintained in F. tataricum while this parameter was not investigated in F. esculentum due to its self-incompatibility. Our results suggested that F. tataricum was more resistant to water stress than F. esculentum and that F. esculentum had characteristics of drought avoidance, while F. tataricum exhibited traits of drought tolerance.

Comparison of high temperature resistance in two buckwheat species Fagopyrum esculentum and Fagopyrum tataricum.

In the context of ongoing climate change, expected temperature rise may significantly limit plant growth and productivity of crop species. In this study, we investigated the effects of a sub-optimal temperature on buckwheat, a pseudocereal known for its nutraceutical advantages. Two buckwheat species differing by their reproduction method, namely Fagopyrum esculentum and Fagopyrum tataricum were grown at 21 °C and 27 °C in growth chambers. High temperature increased leaf production mainly in F. tataricum but decreased leaf area in both species. Water and photosynthesis-related parameters were affected by high temperature but our results suggested that although transpiration rate was increased, adaptive mechanisms were developed to limit the negative impact on photosynthesis. High temperature mainly affected the reproductive stage. It delayed flowering time but boosted inflorescence and flower production. Nevertheless, flower and seed abortions were observed in both species at 27 °C. Regarding flower fertility, heat affected more the female stage than the male stage and reduced the stigma receptivity. Pollen production increased with temperature in F. esculentum while it decreased in F. tataricum. Such discrepancy could be related to the self-incompatibility of F. esculentum. Both species increased their antioxidant production under high temperature to limit oxidative stress and antioxidant capacity was higher in the inflorescences than in the leaves. Total flavonoid content was particularly increased in the leaves of F. esculentum and in the inflorescences of F. tataricum. Altogether, our results showed that even if high temperature may negatively affect reproduction in buckwheat, it improves its antioxidant content.