Graduation Term


Document Type


Degree Name

Master of Science (MS)


Department of Agriculture

Committee Chair

David E. Kopsell


The U.S. floriculture industry was estimated at $4.77 billion in 2018 with annual bedding plants representing the main segment valued at $1.46 billion dollars. Silicon (Si) and titanium (Ti) are beneficial nutrients which can improve growth and quality of greenhouse horticultural crops when applied exogenously. Information is lacking as to whether Si and Ti enhancement during greenhouse production increases bedding plant performance in the outdoor landscape. Therefore, this study examined landscape performance of four annual bedding plant species treated with foliar applications of Si and Ti during greenhouse production over two growing seasons. Plant species were selected based on U.S. consumer popularity and included ‘Black Velvet Rose F1’ geranium (Pelargonium zonale), ‘Mega Bloom Pink Halo F1’ vinca (Catharanthus roseus), ‘Double Hot Cherry’ zinnia (Zinnia hybrid) and ‘Accent White Hybrid’ impatiens (Impatiens walleriana). Silicon treatments were supplied as foliar sodium silicate (NaSiO3) treatments at rates of 0, 50, 150 and 250 mg Si·L-1 in a randomized block design. In a similar separate experiment, Ti treatments were supplied as foliar Ti-ascorbate (Tytanit®) at rates of 0, 50, 100 and 150 mg Ti·L-1. Each study was conducted during the 2018 and 2019 growing seasons. Treatment applications were applied weekly for 4 weeks for impatiens, vinca, and zinnias, and 7 weeks for geraniums. Once plants reached marketable size, they were transplanted into the field in a randomized block design, mulched, and irrigated as needed. Growth and quality trait (plant height, number of leaves and flowers/inflorescences, basal stem and flower/inflorescence diameter, SPAD chlorophyll content, and growth index) data were collected before and during treatment application under greenhouse culture and every 15 days in the field starting 30 days after transplanting up until frost. Silicon treatments had a significant impact on the landscape performance of zinnia for the number of inflorescences (P=0.016) and growth index (P=0.071) in 2019. The 50 mg Si·L-1 treatment produced the highest number of inflorescences (P=0.019) and highest growth index (P=0.056). Titanium treatments also had a significant effect over time for geranium for plant height (P=0.013) in 2019 and chlorophyll content (P=0.011) for impatiens in 2018. The 100 mg Ti·L-1 and 150 mg Ti·L-1 treatments had a significant effect on plant height (P=0.016) for geraniums. The 50 mg Ti·L-1 and 100 mg Ti·L-1 treatments had a significant effect for chlorophyll content (P=0.012) for impatiens. Overall, Si and Ti supplementation affected the quality and performance of annual bedding plants in the landscape. However, this response was species, concentration amount applied, and year specific.


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