Selenium (Se) is an essential element for human and animal, although considered beneficial to higher plants. Selenium application at high concentration to plants can cause toxicity decreasing the physiological quality of seeds. This study aimed to characterize the Se toxicity on upland rice yield, seed physiology and the localization of Se in seeds using X-ray fluorescence microanalysis (μ-XRF). In the flowering stage, foliar application of Se (0, 250, 500, 1000, 1500, 2000 g ha-1) as sodium selenate was performed. A decrease in rice yield and an increase in seed Se concentrations were observed from 250 g Se ha-1. The storage proteins in the seeds showed different responses with Se application (decrease in albumin, increase in prolamin and glutelin). There was a reduction in the concentrations of total sugars and sucrose with the application of 250 and 500 g Se ha-1. The highest intensities Kα counts of Se were detected mainly in the endosperm and aleurone/pericarp. μ-XRF revealed the spatial distribution of sulfur, calcium, and potassium in the seed embryos. The seed germination decreased, and the electrical conductivity increased in response to high Se application rates showing clearly an abrupt decrease of physiological quality of rice seeds. This study provides information for a better understanding of the effects of Se toxicity on rice, revealing that in addition to the negative effects on yield, there are changes in the physiological and biochemical quality of seeds.

中文翻译：

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旱田水稻中的硒毒性：使用μ-XRF技术的种子生理反应和养分分布。

硒（Se）是人和动物必不可少的元素，尽管被认为对高等植物有益。将硒高浓度施于植物会引起毒性，从而降低种子的生理品质。本研究旨在通过X射线荧光显微分析（μ-XRF）表征硒对旱稻产量，种子生理和种子中硒定位的毒性。在开花期，叶面喷施硒（0、250、500、1000、1500、2000 g ha-1）作为硒酸钠。从250 g Se ha-1观察到水稻产量下降和种子Se浓度增加。种子中的贮藏蛋白在施硒后表现出不同的反应（白蛋白减少，谷醇溶蛋白和谷蛋白增加）。使用250和500 g Se ha-1可以降低总糖和蔗糖的浓度。硒的最高强度Kα计数主要在胚乳和糊粉/果皮中检测到。μ-XRF揭示了种子胚中硫，钙和钾的空间分布。硒的高施用量使种子发芽减少，电导率增加，明显表明水稻种子的生理品质突然下降。这项研究为更好地了解硒对水稻的毒性提供了信息，表明除对产量的负面影响外，种子的生理和生化质量也发生了变化。μ-XRF揭示了种子胚中硫，钙和钾的空间分布。硒的高施用量使种子发芽减少，电导率增加，明显表明水稻种子的生理品质突然下降。这项研究为更好地了解硒对水稻的毒性提供了信息，表明除对产量的负面影响外，种子的生理和生化质量也发生了变化。μ-XRF揭示了种子胚中硫，钙和钾的空间分布。硒的高施用量使种子发芽减少，电导率增加，明显表明水稻种子的生理品质急剧下降。这项研究为更好地了解硒对水稻的毒性提供了信息，表明除对产量的负面影响外，种子的生理和生化质量也发生了变化。