Selenium (Se) can induce stress in plants. Our main purpose is to assess the effect of a biostimulant, based on hetero-polyoxometalates mixed with humic acids, on Se bio-fortified wheat plants. Secondly, to evaluate a possible modification of the Se species in the plant tissues and to investigate the response of phytohormones. Wheat plants were grown hydroponically and exposed to either selenite (Se(IV)), selenate (Se(VI)) or a mixture of both species (Se(MIX)) in the presence or absence of the biostimulant (foliar, FA; or root application, RA). Biomass, mineral nutrient concentration, phytohormones and Se speciation were investigated. The biostimulant FA did not modify the plant biomass but RA significantly increased the root biomass in all treatments as well as the shoot biomass of plants exposed to Se(VI) and Se(MIX) even when both modes of application caused a severe reduction of IAA levels in shoots. The biostimulant accelerated the translocation of Se from roots to shoots in the presence of Se(VI) and Se(MIX), and it only had a noticeable influence on the Se speciation in roots, but not significant in shoots. X-ray absorption spectroscopy allowed to identify organic Se as the main Se species formed in the shoots. The biostimulant has a mild effect on the Se speciation. The biostimulant has a remarkable influence on both the uptake and accumulation of certain mineral nutrients and the plant metabolism by increasing the biomass under Se exposure. This indicates the potential of this biostimulant that also will prevent the possible Se-induced plant stress.

中文翻译：

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植物生物刺激素对富硒小麦（Triticum aestivum L. cv. Pinzón）硒吸收、分布和形态形成的影响

硒 (Se) 可以诱导植物应激。我们的主要目的是评估基于杂多金属氧酸盐与腐殖酸混合的生物刺激剂对硒生物强化小麦植物的影响。其次，评估植物组织中硒种类的可能修饰并研究植物激素的反应。在存在或不存在生物刺激素（叶面、FA；或）的情况下，水培种植小麦植物并暴露于亚硒酸盐（Se（IV））、硒酸盐（Se（VI））或两种物种的混合物（Se（MIX））；或根应用程序，RA）。研究了生物量、矿物质营养浓度、植物激素和硒形态。生物刺激剂 FA 没有改变植物生物量，但 RA 显着增加了所有处理中的根生物量以及暴露于 Se(VI) 和 Se(MIX) 的植物的枝条生物量，即使两种施用方式都导致 IAA 的严重减少芽中的水平。在Se(VI)和Se(MIX)存在的情况下，生物刺激剂加速了Se从根向地上部的转运，并且仅对根中的Se形态形成有显着影响，而对地上部的影响不显着。X 射线吸收光谱允许将有机硒鉴定为芽中形成的主要硒种类。生物刺激素对硒形态的影响不大。通过增加硒暴露下的生物量，生物刺激素对某些矿质营养素的吸收和积累以及植物代谢都有显着影响。