Strategies for applying selenium for biofortification of rice in tropical soils and their effect on element accumulation and distribution in grains

This study aimed to investigate the effects of the selenium (Se) application via soil (SeVI) and leaf (SeIV and SeVI) on agronomic attributes of rice and the spatial distribution of Se and other elements in biofortified rice grains. For this, a field trial was conducted using six Se rates (0, 5, 10, 20, 40, and 80 g ha⁻¹). Physiological evaluations in rice leaves, rice grain yield, and Se and other elements content were assessed. Spatial distributions of Se and other elements were visualized mapping the biofortified rice grains with μXRF. The results showed that the strategies and rates of Se applied to the plants were effective for producing Se-rich rice grains. Although Se application did not change the rice yield, it affected some enzyme activities, improving the antioxidant system of the plant. The spatial distribution of the different elements found in the biofortified rice grains varied substantially, with Se accumulations mainly in the endosperm, whereas P, K, Fe, and Zn accumulate in the embryo. Agronomic biofortification of rice with Se, via soil or leaf, is a promising strategy to be adopted in tropical soils in order to produce rice grains with adequate Se contents for human consumption.     

Biofortification of Se and induction of the antioxidant capacity in lettuce plants

The aim of the present work is to analyse the way in which Se fertilization in both Se forms applied at different rates can affect the production and accumulation of Se and the foliar antioxidant capacity in lettuce plants Lactuca sativa L. cv Philipus. After different rates of sodium selenate and selenite were applied (5, 10, 20, 40, 60, 80, 120 μmol L⁻¹), the foliar biomass, lipid peroxidation, Se accumulation, antioxidant compounds, and the antioxidant capacity were analysed. Our results indicate that the less toxic form was selenate, as it induced greater biomass, higher Se accumulation, and more antioxidant compounds than did selenite. The treatment of 40 μmol L⁻¹ proved the most suitable for lettuce plants, as the antioxidant capacity and Se accumulation augmented without diminishing biomass, and making the two these lettuce plants healthier than control plants for human consumption, in comparison to control. Finally, regarding the antioxidant capacity test used (the ferric reducing ability of plasma [FRAP], 2,2-diphenyl-1-picryl-hydrazyl [DPPH] and reducing power), only FRAP showed a significant relationship with the different antioxidant compounds, while ascorbate best reflected the effect of Se on the antioxidant capacity under our experimental conditions.     

硒酸钠施用对小麦的富硒效应及其残效

为明确外源硒酸盐对小麦各器官硒含量的影响以及硒酸盐的残效,通过两年连续盆栽试验,设置了0、0.02、0.04、0.08、0.16 mg·kg^-1五个施硒水平,第一年施硒,第二年不施硒且在原土中继续种小麦,测定和分析了两年小麦不同器官（叶、茎、籽粒和颖壳）和土壤硒含量及产量和生物量。结果表明,施硒当季能够增加小麦产量及地上部生物量,显著提高各器官硒含量,各器官硒含量与施硒量均呈显著的线性正相关。器官中叶片对硒的富集能力最强,其次为籽粒、茎和颖壳。小麦不同器官硒强化指数大小与富集系数表现一致,施硒量每增加1 mg·pot^-1,叶片、籽粒、茎、颖壳的硒含量分别增加8.9、6.2、4.6和3.6 mg·kg^-1。外源硒酸盐具有残效,尤其在硒施用量较高时,小麦对外源硒的利用率两年均随施硒量的增加而增加,当季硒的利用率最高值为33.7%,两年累积利用率最高值为34.7%。施硒在第二年对小麦各器官硒的含量、土壤硒含量仍有显著的增加效应,尤其在施硒量较高时,但其对小麦硒含量的影响大于对土壤有效硒、总硒含量的影响。在农业生产应用中应选择适宜的施硒用量,关注硒肥的后效,实现高效安全的小麦硒强化。     

不同形态硒对金针菇吸收和富集硒的影响

通过基质栽培试验,研究了硒酸钠、亚硒酸钠和硒代蛋氨酸(0～0.8 mg/kg)对金针菇(Flammulina velutipes)吸收和富集硒的影响。结果表明,外源硒的添加显著增加了金针菇原基和子实体的硒含量,且硒含量均随硒添加浓度的上升而显著增加。在相同硒浓度水平下,3种外源硒对金针菇子实体硒含量的增加效果为亚硒酸钠硒代蛋氨酸硒酸钠:施硒量为0.8 mg/kg时,3种硒处理下金针菇子实体的硒含量分别为0.24、0.12和0.08 mg/kg。此外,亚硒酸钠处理下金针菇子实体和原基的硒回收率大于硒代蛋氨酸和硒酸钠处理。且随着硒添加浓度的增加,硒代蛋氨酸和硒酸钠处理下子实体硒的回收率显著下降:分别从14.28%逐渐降低到6.33%和从13.67%减少到3.70%;而添加硒酸钠时,硒的回收率随添加浓度的增加无显著变化。