Potassium silicate and/or silicate-solubilizing bacteria stimulate Cuscuta campestris germination but mitigate oxidative stress induced by it on Guizotia abyssinica

Abstract

Environmental and economic considerations have heightened interest in silicate-solubilizing bacteria (SSB) as an alternative to silicon nanoparticles in agricultural crop production. However, related research has not considered the response of weeds to silicon. This study, conducted at three levels: laboratory, greenhouse, and field, examines whether K₂SiO₃ and/or SSB affect the seed germination of dodder and niger, as well as their parasitic relationship. In the laboratory, a germination test was performed for each species with and without 1 mM K₂SiO₃ or 0.1 % v/v SSB. In the greenhouse and field studies, niger was grown with and without dodder, K₂SiO₃, or SSB. Combined use of K₂SiO₃+SSB synergistically increased seed germination for niger and dodder by 12.3 and 142.6 %, while accelerating the process by 39.5 and 43.6 %, respectively. The invasion of dodder, when paired with K₂SiO₃ and/or SSB, significantly increased the activity of superoxide dismutase and catalase in niger. Untreated niger contained 213.6 mg silicon kg⁻¹ dry weight. Dodder alone reduced it by 38.5 %, but when combined with K₂SiO₃+SSB, a 2.2-fold increase in the silicon content of niger occurred. Dodder-parasitized niger treated with K₂SiO₃+SSB exhibited over a 3-fold increase in lignin content and phenylalanine ammonia-lyase activity. The highest emergence of dodder was recorded when SSB was used alone or in combination with K₂SiO₃. Although dodder-parasitized niger treated with K₂SiO₃+SSB experienced more infestation due to the increased emergence of dodder, it yielded a higher seed than untreated niger, indicating a mitigated oxidative stress induced by dodder in niger through both physical and biochemical mechanisms.