THE USE OF A SMALL HYDROPONIC SYSTEM FOR PRODUCING MARIGOLDS M.A. Wilson', D. Rogers', VA. Khan 2, and C. Stevens' 'Department of Agriculture, Southeast Missouri State University, Cape Girardeau, MO 63701. 2 George Washington Carver Experiment Station, Tuskegee University, Tuskegee Institute, AL 36088. Abstract: The experiment was conducted in a research-dedicated greenhouse in southeast Missouri (Cape Girardeau, an area with a moderate climate. Styrofoam ice trays, containing four plants each lined with black polyethylene plastic, were used with two nutrient solutions. Length of stem, number of leaves and number of flowers were significantly greater when compared to nutriculture when grown in 's solution. Fresh and dry weights of roots, stems and flowers were significantly greater when grown in 's solution. Non-aerated treatments performed significantly better than aerated treatments for either hydroponic solution. Keywords: Hydroponic system, Nutriculture, 's solution, marigolds. Introduction Prior to the use of plastics, hydroponic systems generally were not competitive because of engineering inadequacies, cost, and the difficulty in maintaining uniformity in the root environment throughout the life of the plant. Although costs continue to remain high, only a few vegetable crops can be profitable and little research on floricultural crops have been conducted within hydroponic systems. In cities where population densities are great, and the land is scarce, a small hydroponic system can be utilized to grow certain vegetables in sufficient amounts to supply the needs of the household or produce floricultural crops for aesthetics. This type of system would lend itself well to elderly growers and other gardeners who live in the inner-city and have a "love to produce their own vegetables or flowers." An economical hydroponic system would justify a grower to produce fresh vegetables twice a year. Methods and Materials The experiment was conducted in a research-dedicated greenhouse in southeast Missouri (Cape Girardeau), an area with a moderate climate. A polyethylene-lined Styrofoam trough, 26 cm deep x 29.5 cm wide & 40 cm long was used to grow marigolds. The solution-filled trough will be covered with a Styrofoam lid 29.5 mm wide x 41.5 mm long. A fiberglass window screen was clamped into the Styrofoam trough to fit and it was rested 0.10 m below the cover. The screen encouraged fine root growth and also served as an anchor point to enable the roots to better support the plant. A typical circulating hydroponic system consists of a tank containing 0.1 to 0.4 M of a 144
complete nutrient solution consisting of nitrogen, potassium, sulfur calcium, magnesium; and a micronutrient package consisting of zinc, iron, boron, molybdenum, manganese, copper, cobalt, and chlorine. The level of nutrient solution is positioned 0.1 to 0.2 m below an opaque tank cover. A net or layer of window screen is placed 10 to 20 mm above the nutrient solution level. African marigold of "Discovery Yellow" were seeded in Pro mix and covered with vermiculite and placed in a germination box. After one week the seedlings were transplanted into 6-packs of Redi Earth. When seedlings were ten mm in height, sixteen marigold seedlings were started in the 's solution and sixteen marigold seedlings were started in the nutriculture solution (20-10- 20) Four marigold plants were used as a control and transplanted into 15.24 mm pots. Redi Earth was washed from the roots of plants that were grown in the 's and nutriculture solutions. "Discovery Yellow" marigold seedlings were grown in plastic pot (6.5 mm x 6.5 mm wide x 6.5 mm in depth), and each pot was suspended in a 5.5 mm hole that had been made into the lid cover. Four pots each of "Discovery Yellow" marigolds were grown in each Styrofoam trough. Each experiment was replicated two times. The trough was lined with polyethylene 1 mil thick to support the nutrient solution in each tank. Care was taken to ensure that the roots were extended into the nutrient solution. The solution level was allowed to recede through evaporation, absorption, and transpiration until it was at or slightly below the level of the screen (0.1 m below the cover). In Missouri's climate, several weeks will be required for this change. Thereafter, addition of either water or nutrient solution was made as needed to maintain the nutrient solution within 20 mm of the desired depth of 0.30 m. Half of the containers were aerated and half were not aerated. Data collected were root, stem and bloom weight, fresh and dry weight, stem length, and the number of blooms and leaves. The experimental design was a split-plot but the analysis would be Analysis of Variance. Results and Discussion When 's and the nutriculture solutions were compared, stem length, number of leaves and number of flower were significantly different (Table 1). The number of leaves and flowers were significantly different with aerated verses non-aerated marigolds. Results were significantly different for dry weight of root, and dry weight of stem and flowers when verses nutriculture data compared to and for data compared with aerated verses non-aerated (Table 3). The results indicate that marigold fresh root, stem, and flower weights were higher for both 's solution and non-aerated treatments (Table 2). However, yields were about 25% lower than when the solution was mechanically aerated. The results indicated marigold fresh root, stems, and flower weights were higher for both 's solution and non aerated treatments (Table 2). Data was significantly different when comparisons were made between 's verses nutriculture solutions and when aerated solutions were compared between non-aerated solution for fresh root, stem, and flowers weights. Similar results were found for dry weights (Table 3). Conclusions Stem length, number of leaves, and number of blooms were significantly greater when grown in 's solution. Fresh and dry weight of roots, stems, and blooms were significantly greater
when grown in 's solution. Non-aerated treatments performed significantly better than aerated treatments for either hydroponic solution. In modem hydroponics systems, the nutrient solution is typically aerated or circulated with careful monitoring and automated corrections applied to temperature, ph, electrical conductivity and nutrient content (Kratky, 1988). Thus, this system was design to be a simple low-maintenance hydroponic system that did not require a lot of power or complex equipment and was relatively low in cost. Hydroponics systems have been classified as liquid (plants growing without a supporting medium) and aggregates (root anchored in an inert medium, generally gravel, sand, vermiculite, rockwood or other materials) or closed (where reused water and nutrients pass through a drainage re-circulation mechanism (Ware and McCollum), 1980. Arnold and, (1940) grew tomatoes successfully with a passive hydroponic technique whereby aeration was achieved by positioning the plant container 50 mm above the nutrient solution level. Literature Cited 1. Arnon, D.I. and D.R.. 1940. Crop production in artificial culture solutions and in soils with special reference to factors influencing yields and absorbing of inorganic nutrients. Soil Science (50);463-64. 2. Kratky, B.A., J.E. Bowen and H. Imai. 1988. Observation on a non-circulating hydroponic system for tomato production. HortScience (23): 906-907. 3. Ware, George W J.P. McCollum. 1980. Producing Vegetable Crops. Third ed. The Interstate Publishers, Inc., Danville, IL. 146
Table 1. solutions. Mean stem length, number of leaves, and blooms of 'Discovery Yellow' marigold grown in two different hydroponic Treatment Stem Length (inch) Number of Leaves Number of Blooms Aerated 27 85 18 Non-aerated 29 81 12 Aerated 21 36 12 Non-aerated 25 62 8 F Test From Analysis of Variance Aerated vs. Non-aerated Interaction Table 2. solutions. Mean fresh weight of roots, stems, and blooms of 'Discovery Yellow' marigold grown in two different hydroponic Treatment Root Fresh Weight (g) Stem Fresh Weight (g) Bloom Fresh Weight (g) Aerated 253 345 262 Non-aerated 337 401 267 Aerated 178 243 134 Non-aerated 329 268 200 F Test from Analysis of Variance * * Aerated vs. Non-aerated Interaction
Table 3. Mean dry weight of roots, stems, and blooms of 'Discovery Yellow' marigold grown in two different hydroponic solutions. Treatment Root Dry Weight (g) Stem Dry Weight (g) Bloom Dry Weight (g) Aerated 18 41 42 Non-aerated 22 47 28 Aerated 8 22 13 Non-aerated 21 31 33 F Test From Analysis of Variance * * Aerated vs. Non-aerated Interaction