Horticulture Digest #102
A CAPILLARY, NON-CIRCULATING HYDROPONIC SYSTEM FOR GROWING ANTHURIUMS

Tomatoes and lettuce have been grown successfully in non-circulating hydroponic systems, with yields equal to that of soil bed cultures (2,3,4,5,6). Non-circulating systems are simple and relatively inexpensive compared to conventional hydroponic methods. Mechanical aeration and/or circulation are not required for non-circulating systems and thus, electrical power is not needed. The lower portion of the plant roots are immersed in nutrient solution, and these roots specialize in nutrient and water uptake. The upper portion of the plant roots are suspended in the humid air above the nutrient solution and these roots specialize in oxygen uptake.

Anthuriums have been grown successfully without media in an aeroponics system (1), but this system is fairly complex and costly to set up. In their natural habitat, anthuriums are epiphytes growing on other plants for support and have numerous aerial root s for absorption of water and nutrients. Morphologically, anthuriums appear to be suited for culture in a non-circulating hydroponic system. The purpose of this study was to test a capillary, non-circulating hydroponic system (3,4) for growing anthuriums.

Results.
At six months after transplanting, the nutrient solution had an EC of 0.5 mS, indicating that about half of the initial nutrients had been used. After another 5 months, the electrical conductivity was 0.06 mS, and an analysis of the nutrient solution indi cated a very low level of available nutrients. The buckets were then replenished with the original concentration of nutrients.

The plants have been growing in this system for one year and continue to grow well, although the tubes appear too small at this time. Root growth is prolific and healthy and fills the bucket. In the past year, plants averaged over four flowers each and me dium to large flowers are now produced regularly.

The capillary non-circulating hydroponic system provides an alternative growing method for anthurium growers with the following advantages:

• it allows the development of healthy root systems in a nematode-free environment
• it provides a means for controlling water and nutrient delivery to plants and maximizes efficient usage of these resources
• it minimizes fertilizer leachate into the environment, and
• diseases are reduced because the foliage remains dry.

Further studies need to be carried out to determine whether this system can be adapted on a larger scale for anthurium cut flower production.

Experiment.
A non-circulating hydroponic kit (4) was tested for growing anthuriums at the University of Hawaii, Waiakea Agricultural Experiment Station in Hilo, Hawaii. Tissue cultured six-inch 'Kalapana' plants were transplanted from individual pots into plastic 8.2 5" x 1.5" forestry "cone-tainer" cells (Stuewe & Sons, Inc.) filled with cinder medium (screened with 1/4² screen to remove fine particles). Ten additional 3/16"-diameter holes were drilled in the tubes to supplement aeration of the roots. Four cells were suspended from holes drilled in a five-gallon plastic bucket lid and partially immersed (1 to 2") in the nutrient solution in the bucket.

The nutrient solution consisted of a commercial hydroponic fertilizer (Chem-Gro Universal Sump Tank Formula 10N-8P2 05 -22K2 0) containing the following nutrients (in ppm):

• N, 80
• P, 28
• K, 146
• Ca, 40
• Mg, 8
• Mn, 0.8
• Fe, 1.6
• Cu, 0.08
• Zn, 0.08
• B, 0.16 and
• Mo, 0.04.

Containers were initially filled with four gallons of nutrient solution. The bucket and lid were covered with black polyethylene to discourage algae growth. One bucket was placed under 80% shade saran in a fiberglass greenhouse, and a second was placed un der a polyethylene cover in an 80% shade saran house. No additional nutrients were added, but water was replenished by adding about 0.3 gallons per month.

1. Higaki, T., J. S. Imamura, and D. Moniz. 1992. Anthurium aeroponics. University of Hawaii Horticulture Digest. 97:1-4.

2. Kratky, B. A. 1990. Design of a capillary, subirrigation hydroponic lettuce cultivation system for a remote area. Proc. Nat. Agr. Plastics Cong. 22:141-146.

3. Kratky, B. A. 1993. A capillary, non-circulating hydroponic method for leaf and semi-head lettuce. HortTechnology. 3(2):206-207.

4. Kratky, B. A. 1993. A non-circulating hydroponic kit for leaf and semi-head lettuce. Proc. 24th Cong. of the Amer. Soc. for Plasticulture Cong. 24:8-11.

5. Kratky, B. A., J. E. Bowen, and H. Imai. 1988. Observations on a non-circulating hydroponic system for tomato production. HortScience 23(5): 906-907.

6. Kratky, B. A., H. Imai, and J. S. Tsay. 1989. Non-circulating hydroponic systems for vegetable production. Proc. 21st Nat. Agr. Plastics Congress. 21:22-25.

J. Lichty, lichty@hawaii.edu
B. A. Kratky, kratky@hawaii.edu
T. Higaki, N. Nakamura, and D. Moniz

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