Effects of selenium application on content, distribution and accumulation of selenium, flavonoids and rutin in tartary buckwheat

Besides its high nutritional value, buckwheat is also rich in many kinds of flavonoids such as rutin and quercetin in its leaves, stems, flowers and seeds, which can serve as very useful resources for high-quality flavonoids. Flavonoids are known for their effectiveness in antioxdant activity and reducing cholesterol levels in blood, keeping capillaries and arteries strong and flexible, and preventing against high blood pressure. It was also used to treat many other chronic diseases, such as cardiovascular diseases. Selenium is one of the indispensable nutrient elements to humans and poultry, but 2/3 of the world lacks it and so does China, 1/3 of which is considered to be critically deficient in selenium. Over 40 kinds of humans and poultry diseases are related to deficiency of Se, this seriously threats the health of humans and the development of animal husbandry. Plant is the key link through which the inorganic Se is converted into organic Se and it is also the most direct Se resource for human beings and poultry. Se application to soil or plant directly can increase Se content in plant, which is the most effective method to improve the deficient Se status of humans. A pot experiment was used to explore the effect of selenium in the form of sodium selenite with five levels (0.0, 0.5, 1.0, 1.5 and 2.0 mg/kg, soil) on distribution and accumulation of selenium,flavonoids and rutin in different organs of tartary buckwheat(Fagopyrum tataricum Gaertn). The results showed when application of Se was in the range of 0.5-2.0 mg per kg soil, tartary buckwheat absorbed and accumulated a large amount of Se by root at seedling stage, and the Se content in all organs of tatary buckwheat were decreased in order of root＞leave＞stem in the 40 days of tartary buckwheat growth, leave＞root＞flower＞stem in Se 0.0 treatment and flower＞root＞leave＞stem in all Se treatments in the 60 days of tartary buckwheat growth, while it was the highest in flower, followed by root, leave, stem and seed at Se 0.0 treatment, flower＞leave＞root＞seed＞stem at Se 0.5 treatment and flower＞leave＞root＞seed＞stem with Se application≥1.0mg per kg soil in the 80 days of tartary buckwheat growth. Treated with Se≤1.0mg per kg soil, the growth, dry matter weight, the content and accumulation of flavonoids and rutin in all organs were enhanced, and the accumulation of flavonoids at the middle and last growing stage was improved and the distribution of flavonoids in different tartary buckwheat organs was not affected. Application of Se at 0.5mg/kg was the best treatment. The accumulation of flavonoids in tartary buckwheat was highest and fastest in the blooming and breeding period (60 d) in all treatments. Excessive Se treatment (1.5-2.0 mg/kg) significantly decreased the growth, dry matter weight, and content and accumulation of flavonoids and rutin in all organs of tartary buckwheat, and restricted the transformation of Se from other organs to seed and the distribution of flavonoids in seed. In summary, for tartary buckwheat planted in low Se soil, Se application less than 1.0mg per kg soil can promote plant growth, increase content and accumulation of Se, flavonoids and rutin in all organs of tartary buckwheat and be friendly to the environment.