Departamento Departamento de Biologia Vegetal, Universidade Federal de Viçosa, 36570-900, Viçosa, MG, Brazil; Departamento de Ciências Biológicas, Universidade Estadual de Santa Cruz, Rodovia Jorge Amado Km, 16, Ilhéus, BA, Brazil.
Departamento Departamento de Biologia Vegetal, Universidade Federal de Viçosa, 36570-900, Viçosa, MG, Brazil; Australian Research Council Centre of Excellence in Plant Energy Biology, University of Western Australia, Crawley, WA, 6009, Australia.
Ecotoxicol Environ Saf. 2020 Feb;189:110008. doi: 10.1016/j.ecoenv.2019.110008. Epub 2019 Nov 30.
Excess iron (Fe) is commonly observed in wetland rice (Oryza sativa L.) plants, impairing crop growth and productivity. Some information suggests that silicon (Si) can reduce Fe content in leaves and roots of rice (vegetative phase), but nothing is known if Si could mitigate the effects of Fe toxicity on rice production and photosynthesis. Here, we assessed the role of Si in alleviating the well-known effects of Fe toxicity on nutritional imbalances, biomass accumulation, photosynthesis and grain yield using two rice cultivars having differential abilities to tolerate excess Fe. Plants were hydroponically grown under two Fe levels (25 μM or 5 mM) and the nutrient solutions were amended with Si (0 or 2 mM). Under excess Fe were detected (i) nutritional deficiencies, especially of calcium and magnesium in leaves; (ii) negligible changes in grain nutritional composition, independently of Si application; (iii) decreases in net photosynthetic rates, stomatal conductance and electron transport rate, in parallel to decreased grain yield components (total grain biomass, 1000-grain mass, percentage of filled grains, number of grains per plant and harvest index), especially in the Fe-sensitive cultivar. These impairments were partially reversed by the application of Si. Results also suggest that Si alleviated the negative impacts of Fe on spikelet sterility. In summary, we conclude that the use of Si can be recommended as an effective management strategy to reduce the negative impacts of Fe toxicity on rice photosynthetic performance and crop yield.
过量的铁（Fe）通常在湿地水稻（Oryza sativa L.）植株中被观察到，损害作物的生长和生产力。一些信息表明，硅（Si）可以减少水稻（营养生长阶段）叶片和根系中的铁含量，但目前尚不清楚硅是否可以减轻铁毒性对水稻生产和光合作用的影响。在这里，我们使用两种具有不同耐铁能力的水稻品种，评估了硅在缓解铁毒性对营养失衡、生物量积累、光合作用和籽粒产量的已知影响中的作用。在两种铁水平（25 μM 或 5 mM）下，采用水培法种植植物，并在营养液中添加硅（0 或 2 mM）。在过量铁存在的情况下，我们检测到：（i）营养缺乏，尤其是叶片中的钙和镁；（ii）无论是否施用硅，籽粒营养成分的变化可以忽略不计；（iii）净光合速率、气孔导度和电子传递速率下降，与籽粒产量成分（总籽粒生物量、千粒重、饱满籽粒百分比、每株籽粒数和收获指数）下降平行，尤其是在对铁敏感的品种中。硅的应用部分逆转了这些损伤。结果还表明，硅缓解了铁对小穗不育的负面影响。总之，我们得出结论，硅的应用可以作为一种有效的管理策略，以减轻铁毒性对水稻光合作用性能和作物产量的负面影响。
