Silicon Supplements Affect Horticultural Traits of Greenhouse-produced Ornamental Sunflowers

Abstract

<jats:p>In greenhouse production, most floricultural crops are cultivated in soilless substrates, which often supply limited amounts of plant-available silicon (Si). The goal of this study was to determine the effects of Si supplementation on greenhouse-produced ornamental sunflower (<jats:italic>Helianthus annuus</jats:italic> L. ‘Ring of Fire’). Potassium silicate (KSiO<jats:sub>3</jats:sub>) substrate incorporation or weekly substrate drenches, sodium silicate (NaSiO<jats:sub>3</jats:sub>) foliar applications, and rice husk ash substrate incorporation were used as Si supplements. Silicon content of Si-treated plants increased compared with untreated controls. Depending on the source and concentration of silicon supplied, several horticultural traits were improved as a result of Si supplementation. Thick, straight stems, increased flower and stem diameters, and increased height were observed in some of the treatments, upgrading sunflower quality compared with untreated controls. However, growth abnormalities were observed when concentrations of 100 and 200 mg·L<jats:sup>−1</jats:sup> Si were supplied as KSiO<jats:sub>3</jats:sub> substrate drenches. In these treatments, plants appeared stunted with deformed flowers and were delayed in flowering. Consequently, Si supplementation effects on greenhouse-produced sunflowers can vary from beneficial to detrimental depending on the applied source and concentration.</jats:p>

Biostimulant activity of silicon in horticulture

“…The excessively high Si concentration in the drenching solution was presumably responsible for the decreases in flower yield and other morphological traits that were recorded in some species. Indeed, as reported by Kamenidou et al (2008), growth abnormalities were observed in ornamental sunflowers when concentrations of 100 and 200 mg L −1 Si were supplied as KSiO 3 through substrate drenching. Based on these results as well as on the results from another relevant study (Kamenidou et al, 2009), these authors concluded that the form and concentration of applied Si significantly impacts stem height and anthesis in ornamental sunflower and zinnia.…”

“…As reported by Kamenidou et al (2008), application of Si through drenching at a concentration of 50 mg L −1 upgraded the quality of ornamental sunflower by increasing thickness and height of the flower stem, as well as the diameter of the flower head, compared with untreated controls. In Paeonia lactiflora, Si application through foliar sprays (500 mg L −1 of sodium silicate) increased resistance to lodging and the mechanical strength of the inflorescence stem (Zhao et al, 2013).…”

“…In ornamental crop plants, Si is applied not only through drenching or foliar applications, but also by blending with medium mixtures in the form of rice husk ash (Kamenidou et al, 2008(Kamenidou et al, , 2010. Mattson and Leatherwood (2010) applied silicon through drenching to 21 ornamental plant species at a concentration of 100 g L −1 (about 3.5 mM of Si) and recorded variable responses.…”

Silicon application enhances resistance to xanthomonas wilt disease in banana

“…Enhancement of these growth parameters was most notable for plants that had a continuous supply of Si. Although Si has not been recognized as an essential element for plant growth, the beneficial effects of Si have been observed in a wide variety of plant species, particularly graminaceous plants such as rice and sugarcane as well as some cyperaceous plants (Kamenidou et al, 2008). Si may be involved in cell elongation and/or cell division and this may explain the larger plant height and pseudostem diameter observed in Si-treated plants.…”

“…There have been several reports on the ability of Si to improve tolerance to abiotic stresses such as drought, salinity, freezing, heavy metal toxicity and biotic stresses such as disease and pests, especially in crops that actively accumulate the element (Epstein, 1999;Heine et al, 2006;Liang et al, 2008). In particular, several studies have shown that adequate uptake of Si may substantially increase tolerance to both abiotic and biotic stresses in rice, sugarcane, sunflower, tomato, wheat and other crops (Heine et al, 2006;Cai et al, 2008;Kamenidou et al, 2008;Liang et al, 2008). Plants with low Si accumulation are known to be more susceptible to fungal disease and insect feeding, as well as other biotic and abiotic stresses that adversely affect crop production.…”