Exogenous nanosilica improves germination and growth of cucumber by maintaining K+/Na+ ratio under elevated Na+ stress

Abstract

The current work was aimed to elucidate the role of engineered nanosilica (SiNPs) particles to mitigate the damaging impacts of Na⁺-derived salinity on cucumber (Cucumis sativus) Beit Alpha variety by conducting in vitro experiments applying various Na⁺ concentrations i.e. 0, 1000, 2000, 3000, 4000 and 5000 mg L^-1. By treating seeds and seedlings, respectively, of cucumber with SiNPs (0, 100, 200 and 300 ppm) and subsequent determination some germination and vegetative parameters as well as chemical analysis of seedlings, we verified that SiNPs succeeded to alleviate the detrimental effects of high Na⁺ salinity by increasing germination parameters and vegetative growth of cucumber seedlings. Even as little as 100 ppm of N-Si results in considerable improvement of seed germination and seedlings growth of cucumber compared to the control, while 200 ppm was optimal among the doses tested. At 5000 mg Na⁺ L^-1, applying SiNPs with 200 ppm increased final germination percentage by 101% over control, vigor index by 101%, germination rate index by 116%, germination index by 110%, fresh mass by 13%, K⁺/Na⁺ ratio by 77%, shoot dry mass by 384%, root dry mass by 304% and plant height by 70%. The results mentioned in this paper obviously outline the large practical relevance of SiNPs and imply that applying of SiNPs for cucumber seeds and seedlings under high Na⁺-derived salinity enhances germination and growth as a result for decreasing Na⁺ uptake and sequentially improves high K⁺/Na⁺ ratio.

Keywords: Cucumber; Germination rate index; Na(+)-stress; Nanosilica; Seed germination; Seedlings development.