Stillwater, Oklahoma
May 8, 2008
Vibrant, showy sunflowers are
revered worldwide for their beauty and versatility. While many
varieties of sunflower are grown specifically for their
nutritional benefits, ornamental sunflowers have become
standards for commercial growers and everyday gardeners. As
sunflowers' popularity grows, scientists are looking for new
supplements and growing methods to enhance production and
quality of this celebrated annual.
Horticulturists have found ample evidence that plants depend on
"essential nutrients"; naturally occurring elements that are
found in normal plant tissue that are essential for the
completion of the life cycle of the plant. Although silicon, a
predominant element in mineral soil, is not considered to be an
essential nutrient for most plants, there has been limited
evidence that silicon supplements affect the aesthetic qualities
of ornamental flowers and crops.
Drs. Sophia Kamenidou and Todd J. Cavins, formerly of the
Department of Horticulture and Landscape Architecture at
Oklahoma State University,
published a research study in the February, 2008 issue of
HortScience in
which they examine the effects of silicon supplements on
sunflowers grown in greenhouse environments.
"In greenhouse production, most floricultural crops are
cultivated in soilless substrates, which often supply limited
amounts of plant-available silicon. The goal of this study was
to determine the effects of silicon supplementation on
greenhouse-produced ornamental sunflower (Helianthus annuus L.
‘Ring of Fire’).", explained Cavins. "This is one of the first
studies to highlight supplemental silicon impact on
horticultural traits. Most previous research on silicon has
focused on disease suppression in hydroponic vegetable
production. This is also one of the few examples of detrimental
effects seen from high silicon concentrations."
Depending on the source and concentration of silicon used,
several horticultural traits were improved as a result of
silicon supplementation. "We observed thick, straight stems,
increased flower and stem diameters, and increased height in
some of the treatments, upgrading sunflower quality compared
with untreated controls. However, growth abnormalities were
observed when concentrations of silicon at 100 and 200 mg per
liter were supplied as potassium silicate substrate drenches. In
these treatments, plants appeared stunted with deformed flowers
and were delayed in flowering. Consequently, the effects of
silicon supplementation on greenhouse-produced sunflowers can
vary from beneficial to detrimental depending on the applied
source and concentration.", stated Cavins.
Summarizing the study outcomes, Cavins said, "Silicon is a key
component in mineral soil, but it has been overlooked for years
since it is not considered an essential element for plant growth
and development. Sunflowers are capable of accumulating silicon
from multiple sources and we found major benefits to some
silicon supplements, such as increased stem diameter and
improved quality."
The complete study and abstract are available on the ASHS
HortScience electronic journal web site:
http://hortsci.ashspublications.org/cgi/content/abstract/43/1/236
Founded in 1903, the American
Society for Horticultural Science (ASHS) is the largest
organization dedicated to advancing all facets of horticultural
research, education, and application. |
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