Plant Growth and Development, Yield and Reproductive Quality of Seeds in Fagopyrum tataricum (L.) Gaertn. Differ Depending on Foliar Silicon Addition in a Three-Year Experiment

Tartary buckwheat is the second most economically important species of the genus Fagopyrum for human nutrition. It has higher nutritional and nutraceutical value than common buckwheat. Tartary buckwheat is considered a species that is well adapted to adverse conditions such as drought, cold and aluminum toxicity. Despite its high stress tolerance, the yield of Tartary buckwheat varies considerably from year to year. The present study was conducted to assess the effect of silicon application on the growth, development, yield, and seed reproductive quality of Tartary buckwheat cultivated in northeastern Poland from 2022 to 2024. The experiment included three genotypes of Tartary buckwheat (of Chinese, Slovenian, and Polish weedy origin). The silicon biostimulant was applied as three foliar sprays at 250 g ha−1 each, at 21-day intervals starting from the three-leaf-unfolded stage (BBCH 13). The use of silicon resulted in a 29% increase in the air-dry mass per plant, an increase in the number of inflorescences and seeds per plant, an increase in the bulk density of achenes, and a reduction in the mean germination time (MGT) of a single seed. The biostimulant did not affect the average yield of achenes or their germination. The main factors that strongly differentiated the plant characteristics and yield of Tartary buckwheat were weather conditions across years of the study and Tartary buckwheat genotypes.