Foliar Silicon and Titanium Applications Influence Growth and Quality Characteristics of Annual Bedding Plants

This study investigated the effects of foliar Si and Ti applications on annual bedding plant growth and quality in soilless media. The five annual plant species selected were geranium (Pelargonium x hortorum 'Elite Cherry'), impa- tiens (Impatiens walleriana 'Accent White'), pansy (Viola x wittrockiana 'Delta Premium Marina'), petunia (Petunia x hybrid 'Celebrity White') and snapdragon (Antirrhinum majus 'Montego Purple'). Sodium silicate (NaSiO3) supplied fo- liar treatments of 0, 50, 100, 150 and 200 mg Si·L -1 and Ti-ascorbate (Tytanit ® ) supplied foliar treatments of 0, 25, 50, 75 and 100 mg Ti·L -1 . Silicon treatments affected plant height for all five species, while Ti treatments only affected plant height for geranium, petunia and snapdragon. Snapdragon plant height increased linearly in response to Si and Ti treat- ments. Plant height increased, then decreased quadratically for geranium with Ti treatments and pansy with Si treatments. The number of days to flower for petunias exhibited a linear decrease with Ti treatments while impatiens exhibited a lin- ear increase with Si and Ti treatments. Geranium responded with a quadratic decrease, then increase for the number of days to flower with increasing Ti treatments. The chlorophyll SPAD content of impatiens exhibited a linear decrease in response to Ti treatments, while geranium had the same response to Si treatments. Silicon and Ti supplementations were found to affect growth and quality characteristics of annual bedding plants. However, this response was species specific and further research is needed to assess the specific impacts of Si and Ti on additional annual crop species and varieties grown in soilless media.