Influence of irrigation conditions in the germination of plasma treated Nasturtium seeds

Abstract

Plasma treatments had emerged as a useful technique to improve seed germination. In this work we investigate the influence of different irrigation conditions and plasma treatments on the germination of nasturtium seeds. During plasma treatment, seeds experience a progressive weight loss as a function of treatment time that has been associated to water release, a process that is more pronounced after longer plasma treatment times. Seeds treated for short times (<30 s) are able to germinate more efficiently than untreated specimen under hydric stress (drought conditions), while plasma treatments for longer times (up to 300 s) impaired germination independently on irrigation conditions. Characterization analysis of plasma treated seeds by FTIR-ATR, SEM/EDX and XPS showed that plasma treatment affected the chemical state of pericarp while, simultaneously, induced a considerable increase in the seeds water uptake capacity. The decrease in germination efficiency found after plasma treatment for long times, or for short times under optimum irrigation conditions, has been attributed to that the excess of water accumulated in the pericarp hampers the diffusion up to the embryo of other agents like oxygen which are deemed essential for germination.

The Combination of Simultaneous Plasma Treatment with Mg Nanoparticles Deposition Technique for Better Mung Bean Seeds Germination

“…Moreover, they showed that the enlarged water absorption, compared to the initial seed, was directly related to a better seed germination. The similar germination tendencies were observed by other authors as well, when the plasma treatment encouraged the seeds surface hydrophilicity, which is directly related to a better germination process [10,43,44]. The water contact angle measurement is a simple technique which is used for a qualitative evaluation of surface wettability.…”

“…This means that only a very top layer of the seeds surface is altered during the plasma treatment and such a method does not make any changes on the seeds bulk. However, a majority of the researchers claimed that the plasma ion penetration depth into the various seeds is up to 10 nm [10,32,33]. This disparity between the calculated results and the ion penetration depth provided by other authors could be related to several approaches.…”

Physicochemical surface analysis and germination at different irrigation conditions of DBD plasma‐treated wheat seeds

“…Therefore, it is suggested that the previously observed more asymptomatic weight loss could be related to incomplete removal of the pericarp outer layer and to the cessation of water release after a certain plasma treatment time. [ 7 ] When taking a look at the SEM images of the cross‐sectioned seeds, one can clearly discern the noteworthy surface character of the etching processes, as evidenced by the similar microstructure of the inner part of seeds before and after plasma treatment (Figure 5).…”

“…In line with the ample evidence in literature about the positive effect of plasma treatments in improving seed germination, a similar effect can be noticed in this study for wheat seeds, with extra findings showing that (a) water scarcity (dry and medium environments) that drastically conditions the germination can be compensated by short plasma treatments, whereas (b) water abundance significantly accelerates the germination that becomes less affected by plasma treatment. [ 7 ]…”

“…The seeds were subjected to an atmospheric pressure plasma generated in a DBD made of very simple borosilicate glass containers and spacers (Figure 1). [ 7 ] In short, the reactor consisted of two parallel metal electrodes (45 mm in diameter), separated by a gap of 12 mm, and both covered by a glass, acting as dielectric plates. To avoid the arching or the microdischarges that might damage the seed coat, helium was used as primary plasma gas.…”