| Because of the high value of floricultural crops and the precise
manipulations required to produce flowers for specific markets and
holidays
production systems for floricultural crops are perhaps the most advanced
of all cultural systems used to produce field or horticultural crops.
Research at GCREC has led to many advances in cultural systems for cut
flower, bedding plant, and flowering pot plant production. While
individual components of different
production systems were studied, much of the research has focused on a
systems approach to production involving interdisciplinary efforts from
scientists in horticulture, plant pathology, entomology, nematology,
weed science, agricultural economics, and soil/water science.
Significant advances that have greatly enhanced the effectiveness of
production practices of floricultural crops include: manipulation of
photoperiod to control the blooming dates of Easter lilies,
chrysanthemums, poinsettias, episcia, fuschia, Rieger begonias and many
other crops; field production techniques for statice and gypsophila
involving fertilization practices, irrigation, mulch, variety
development, and insect and disease management; improved flowering in
statice (for flower production) and caladium (for breeding) utilizing
gibberellic acid; integrating the use of tissue culture stock (pathogen
free stock), fumigation types and rates, herbicides, fertilizer rates,
ratio of macronutrients, and optimizing seed size and spacing for
caladium tuber production; effective storage techniques for bulb and
tuberous crops; use of growth regulators to maintain optimum sized
potted plants; day length extension and variety selection to control
flowering and stem length in Trachelium
and
lisianthus; economic considerations of starting an ornamental enterprise
and cost analyses for various crops were presented; and, development of
conservative water management techniques to include capillary mat and
trickle irrigation systems for pot and cut flowers. A wide variety of
floral crops was evaluated for their tolerance to fluoride and sulfur
dioxide, the symptoms of injury from these pollutants identified, and
methods of avoidance or amelioration of damage were provided.
A
tissue culture program was initiated in the early 1970’s to develop,
through asexual propagation, "known pathogen-free" stocks of commercial
varieties of orchids, gladiolus, gypsophila, and caladium. Explants were
utilized for the production of disease-free corms and tubers for
commercial plantings and research studies with gladiolus and caladium,
respectively. This technique was also used for the rapid multiplication
of seedlings developed through the breeding program to quicken the
release of new varieties such as Jessie M.
Conner gladiolus, Autumn Lace dendrobium, Floriana Mist and Floriana
Cascade gypsophila,
Florida Cardinal, Florida Roselight, and
Florida Sunrise caladium.
Water, Soil and Plant
Nutrition
Early research focused on cut flowers with special emphasis on gladiolus
and chrysanthemums. Cut flowers are grown commercially in Florida
primarily on light sandy soils of low native fertility. High
annual rainfall rates further complicate fertilization practices by
leaching nutrients. Extensive nutritional research has been
conducted since 1960 to enable production under these subtropical
conditions. Significant discoveries have been made in the
following areas: fertilizer rates, formulations, and methods of
application; nutritional effects on yield and keeping quality of
harvested flowers; and use of resin coated fertilizers to reduce
nutrient leaching.
Additional cut flower research furnished information on the causes and
solutions for problems associated with macro- and micro-nutrient
imbalances. For example, the yellow strapleaf malady of chrysanthemum
induced by antimetabolites produced by soil organisms, physiological
leaf roll caused by excessive carbohydrate accumulation in the leaves,
and the specific effects of excessive nitrogen on keeping quality of
chrysanthemums were solved and corrected for practical purposes. It was
determined that calcium deficiency was the cause of bud rot and topple
of gladiolus, while soil, water, or atmospheric fluoride toxicity caused
marginal leaf necrosis of gladiolus and other floral crops.
As the cut flower industry declined and the bedding and potted plant
industry emerged in the mid to late 1960’s, research was focused on
potted crops as well as cut flowers with studies involving integrated
delivery of water and nutrients to floricultural crops. As competition
for valuable water resources among user groups (municipalities,
industry, and agriculture) increased with rapid population increases in
the 1970’s, it became apparent that research was needed to provide
information to help agriculture cope with less water. In 1973, a
research program was initiated to determine crop water requirements, to
develop irrigation scheduling techniques, and to improve other
management practices that would improve the conservation of water
resources. Production systems utilizing slow release fertilizers in
conjunction with trickle irrigation or capillary mat irrigation were
developed to conserve water and nutrients. Cost analyses were performed
on costs of new systems, or cost comparisons of switching from old
systems to new systems. The determination of water requirements for
several commercial crops and the methods to predict water needs were
developed. These water requirements were and continue to be useful in
planning irrigation system designs and capacities, and for developing
irrigation scheduling.
With the new emphasis on potted crops,
procedures and techniques were developed for evaluation of chemical,
physical, and salinity properties of growing media. Soil, water, and
nutrient requirements were defined for new pot crops introduced into the
floriculture industry (such as episcia, pentas, and lisianthus as well
as for traditional crops being produced in different container sizes
(such as bedding plants or mini-mums in 4-inch pots). Additional studies
defined the cause of nutritional disorders of potted crops and included
marginal leaf necrosis of Easter lilies (fluoride toxicity), bract
necrosis of poinsettia (transitory, localized, calcium deficiency),
stunting and leaf chlorosis and necrosis of lisianthus (zinc toxicity
induced by low soil pH), and lower leaf necrosis and abscision of pentas
(iron toxicity). The recommended soil amendments, fertilizer
adjustments, and pH correction, integrated with calcium sprays and
selected varieties, have resulted in prevention of these nutritional
disorders.
Nutrient deficiency symptoms were characterized for many floricultural
crops. Descriptive visual nutrient deficiency symptoms can be used as an
aid in the diagnosis of nutrient disorders and help distinguish nutrient
imbalances from other disorders caused by pathogens, chemical damage, or
other stresses. For example, visual symptoms of N, P, K, Ca, Mg, Mn, Fe,
and B deficiencies were induced in caladium. Characteristic symptoms
were photographed and described and a key summarizing these symptoms
developed as a diagnostic tool for the caladium industry. |
