The role of silicon (Si) in alleviating the effects of biotic and abiotic stresses, including defence against insect herbivores, in plants is widely reported. Si defence against insect herbivores is overwhelmingly studied in grasses (especially the cereals), many of which are hyper-accumulators of Si. Despite being neglected, legumes such as soybean (Glycine max) have the capacity to control Si accumulation and benefit from increased Si supply. We tested how Si supplementation via potassium, sodium or calcium silicate affected a soybean pest, the native budworm Helicoverpa punctigera Wallengren (Lepidoptera: Noctuidae). Herbivory reduced leaf biomass similarly in Si-supplemented (+Si) and non-supplemented (–Si) plants (c. 29 and 23%, respectively) relative to herbivore-free plants. Both Si supplementation and herbivory increased leaf Si concentrations. In relative terms, herbivores induced Si uptake by c. 19% in both +Si and –Si plants. All Si treatments reduced H. punctigera relative growth rates (RGR) to a similar extent for potassium (−41%), sodium (−49%) and calcium (−48%) silicate. Moreover, there was a strong negative correlation between Si accumulation in leaves and herbivore RGR. To our knowledge, this is only the second report of Si-based herbivore defence in soybean; the rapid increase in leaf Si following herbivory being indicative of an induced defence. Taken together with the other benefits of Si supplementation of legumes, Si could prove an effective herbivore defence in legumes as well as grasses.

中文翻译：

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硅是大豆中针对 Helicoverpa punctigera（鳞翅目：Noctuidae）的可诱导且有效的草食动物防御


硅 (Si) 在减轻植物中生物和非生物胁迫影响（包括防御食草昆虫）方面的作用已被广泛报道。对食草昆虫的硅防御作用在草类（尤其是谷物）中进行了大量研究，其中许多是硅的超积累者。尽管被忽视，大豆等豆类（大豆）有能力控制硅积累并受益于硅供应的增加。我们测试了通过硅酸钾、硅酸钠或硅酸钙补充硅如何影响大豆害虫（本土芽虫）黑夜蛾Wallengren（鳞翅目：夜蛾科）。相对于无食草动物的植物，食草动物在补充硅 (+Si) 和未补充硅 (–Si) 的植物中类似地减少了叶片生物量（分别约为 29% 和 23%）。补充硅和食草都会增加叶片硅浓度。相对而言，食草动物通过c诱导Si的吸收。 +Si 和 –Si 工厂均为 19%。所有硅处理均减少红点花硅酸钾 (-41%)、钠 (-49%) 和钙 (-48%) 的相对增长率 (RGR) 相似。此外，叶片中Si积累量与草食动物RGR之间存在很强的负相关关系。据我们所知，这只是大豆中硅基食草动物防御的第二篇报道；食草后叶子 Si 的快速增加表明诱导防御。与豆科植物中补充硅的其他好处相结合，硅可以证明是豆科植物和禾本科植物中有效的食草动物防御。