Farzaneh Garousi

Comparison of Selenium Toxicity in Sunflower and Maize Seedlings Grown in Hydroponic Cultures.

Several studies have demonstrated that selenium (Se) at low concentrations is beneficial, whereas high Se concentrations can induce toxicity. Controlling Se uptake, metabolism, translocation and accumulation in plants is important to decrease potential health risks and helping to select proper biofortification methods to improve the nutritional content of plant-based foods. The uptake and distribution of Se, changes in Se content, and effects of various concentrations of Se in two forms (sodium selenite and sodium selenate) on sunflower and maize plants were measured in nutrient solution experiments. Results revealed the Se content in shoots and roots of both sunflower and maize plants significantly increased as the Se level increased. In this study, the highest exposure concentrations (30 and 90 mg/L, respectively) caused toxicity in both sunflower and maize. While both Se forms damaged and inhibited plant growth, each behaved differently, as toxicity due to selenite was observed more than in the selenate treatments. Sunflower demonstrated a high Se accumulation capacity, with higher translocation of selenate from roots to shoots compared with selenite. Since in seleniferous soils, a high change in plants’ capability exists to uptake Se from these soils and also most of the cultivated crop plants have a bit tolerance to high Se levels, distinction of plants with different Se tolerance is important. This study has tried to discuss about it.

Biological changes of green pea (Pisum sativum L.) by selenium enrichment

Supplement of common fertilizers with selenium (Se) for crop production will be an effective way to produce selenium-rich food and feed. The value of green pea seeds and forages as alternative protein source can be improved by using agronomic biofortification. Therefore, biological changes of green pea (Pisum sativum L.) and influences of inorganic forms of Se (sodium selenite and sodium selenate) at different concentrations on the accumulation of magnesium (Mg) and phosphorus (P) were investigated in greenhouse experiment. 3 mg kg-1 of selenite had positive effects to enhance photosynthetic attributes and decrease lipid peroxidation significantly. At the same time, Se accumulation increased in all parts of plant by increasing Se supply. Moreover, Mg and P accumulations were significantly increased at 3 mg kg-1 selenite and 1 mg kg-1 selenate treatments, respectively. By contrast higher selenite concentrations (≥30 mg kg-1) exerted toxic effects on plants. Relative chlorophyll content, actual photochemical efficiency of PSII (ФPSII) and Mg accumulation showed significant decrease while membrane lipid peroxidation increased. Thus, the present findings prove Se biofortification has positive effects on biological traits of green pea to provide it as a proper functional product.

Sunflower seedlings hyperaccumulate Selenium

Selenium (Se) is an essential element for animals and humans, but not plants. However, the capacity of some plants to accumulate and transform Se into bioactive compounds has important implications for human nutrition and health. In this study, sunflower (Helianthus annuus) and maize (Zea mays) seedlings were cultivated in soil to investigate the effect of different rates of sodium selenite (1-90 mg kg-1 soil) and sodium selenate (1-30 mg kg-1 soil) on absorption and translocation of Se and sulphur (S). Sodium selenate decreased growth of sunflower roots at all applied rates and of maize roots at the highest rate applied. In contrast, sodium selenite up to 30 mg kg-1 for sunflower and 3 mg kg-1 for maize resulted in increased shoot and root growth. An increase in Se concentration in soil resulted in an increase in Se and a decrease in S accumulation in roots and shoots of both maize and sunflower. Selenium translocation from roots to shoot was higher in sunflower than maize. Root-to-shoot translocation of Se was 5 to 30 times greater in sunflower and 0.4 to 3 times greater in maize in the sodium selenate than sodium selenite treatments. Sunflower, as a Se-hyperaccumulator with up to 1.8 g kg-1 in shoots (with no significant decrease in shoot biomass) can be a valuable plant in biofortification to improve animal/human nutrition, as well as in phytoremediation of contaminated sites to restore ecosystem services.

Non-destructive and destructive measurements' chlorophyll content in sunflower and maize plants uptaken different chemical forms of selenium

Selenium (Se) is an example of an essential element becoming more and more insufficient in food crops as a result of intensive plant production in many countries. Se is an essential biological trace element. Accordingly, controlling the Se uptake and metabolism in plants will be important to reaching to adequate methods for bio fortification. Furthermore, chlorophyll content (chl) is one of the most important physiological parameters which is related to plant photosynthesis and is usually used to predict plant potential. In this regard, during and end of the experiment in hydroponic culture, chlorophyll content of sunflower and maize plants’ leaves treated different concentrations of Se in two forms of sodium selenite (SeIV) and sodium selenate (SeVI) was measured in two methods of non-destructive and destructive ones to clarify the relationship between Se and chl. Both measurements were done on old and young leaves and results showed that Relative Chlorophyll Content (RCC) and Chl a and b were not impaired at the end of experiment from Se exposure up to 3 mg L-1 of both SeIV and SeVI in two plants. Although high doses of sodium selenite caused toxicity in sunflower treatments.