Effects of dynamised high dilutions and vegetal extract based on silicon on the growth and induction of resistance in tomato plants against <i>Rhizoctonia solani</i>

The objective of this study was to study the response of tomato (<i>Solanum</i> <i>lycopersicum</i>) against <i>Rhizoctonia solani</i> using dynamised high dilutions and plant extract based on silicon. The treatments were <i>Silicea terra</i> (ST), <i>Thuya occidentalis</i> (TO), and <i>Equisetum arvense </i>(EA) at 30CH (Centesimal Hahnemannian dilution order), <i>Equisetum arvense</i> leaf extract (LE), and non-dynamised water as the control. Seeds of tomato cv Marmande were treated overnight. The in vitro bioassays involved assessment of <i>R. solani</i> mycelial growth, seed germination, and seedling development. In the greenhouse experiment, the emergence, root and aerial part development, and disease development were evaluated. Leaves were harvested to analyse concentrations of flavonoids, phenolic compounds, chlorophyll, carotenoids, and chitinase activity. In the in vitro bioassay, LE reduced mycelial growth and TO increased the seedling vigour index, dry weight, and length of seedlings. In the greenhouse experiment, TO and ST increased plant emergence. Tomato plants treated with ST improved the fresh weight and the length of the roots. The disease severity was decreased by ST, LE, and TO. The flavonoid concentration was higher in plants treated with TO and LE. Overall, the treatments of TO, EA, and ST improved the content of phenolic compounds. Moreover, endochitinase and chitobiosidase were activated by LE.