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Philipp von Bieberstein, Ya-ming Xu, A.A. Leslie Gunatilaka, and Raphael Gruener

; Nagella and Murthy, 2011 ). Our study compares these variables for Withania somnifera when grown under soilless hydroponic and aeroponic conditions. W. somnifera (L.) Dunal (Solanaceae) has been used for over 3000 years in the Ayurvedic medical

Open access

Jaime Barros da Silva Filho, Paulo Cezar Rezende Fontes, Paulo Roberto Cecon, Jorge F.S. Ferreira, Milton E. McGiffen Jr., and Jonathan F. Montgomery

As new challenges in crop production emerge, the enhancement and improvement of production systems, including aeroponics, must be dynamic and continual. Among these challenges is the maximization of minituber multiplication rate at a reduced cost

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Eric J. Biddinger, Chunming Liu, Robert J. Joly, and K.G. Raghothama

technical assistance of Daniel Hahn in measuring photosynthesis. Our sincere thanks to L.A. Peterson and Armond Krueger, Dept. of Horticulture, Univ. of Wisconsin, for technical help in building the aeroponic growth facility. We thank W.R. Woodson and C

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R.W. Zobel and Laura Matthews

Aeroponics, as a method of soilless culture, has been in intermittent use since the 1950's. Early Russian and Italian research suggested that productivity and use of space was optimized with this technique. Prior to the introduction of ultrasonic techniques, aeroponics utilized spray nozzles or spinning disks. In addition to the need for frequent cleaning, the first results in the formation of a boundary layer on the root surface, similar to that formed in hydroponics, which results in nutrient and aeration gradients. The second results in significant physical disturbance to the root system and, except under very controlled conditions, also develops a boundary layer. Ultrasonic fogs avoid these side effects and allow the use of carbon dioxide enrichment of the root zone as well as reduced nutrient concentrations. Initial results with commercially available equipment are very promising. Commercial implementations of ultrasonic aeroponics promise to be far less energy and manpower intensive than any other method of plant culture. Lettuce, corn, tomato, soybean, dry bean, and geraniums have all been cultured with this method.

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Eric J. Biddinger, Chunming Liu, and K.G. Raghothama

We are interested in understanding the molecular changes that occur in response to phosphate starvation in the roots of tomato plants. Aeroponics offers a unique way to study the changes that occur in the roots of plants. Tomato plants were grown in an aeroponic system developed by L.A. Peterson at the Univ. of Wisconsin. Aeroponically grown tomato plants were treated with various concentrations of phosphate (Pi) ranging from 0 to 250 μm. Plants were harvested at different times after the initiation of Pi deficiency treatments for nutrient analysis and gene expression studies. Several changes in essential nutrient content were observed. A differential accumulation of magnesium between the root and shoot tissue of phosphorus-starved plants was noticed. The expression of a recently cloned phosphate starvation induced gene (TPSI1) increased with decreasing concentration of Pi in the growth media. There is a strong correlation between the concentration of the Pi in the growth media and expression of the gene. The effect of Pi starvation on the gene expression in different parts of the plant, including old and young leaves, will be discussed.

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Anita L. Hayden

Hydroponic and aeroponic production of medicinal crops in controlled environments provides opportunities for improving quality, purity, consistency, bioactivity, and biomass production on a commercial scale. Ideally, the goal is to optimize the environment and systems to maximize all five characteristics. Examples of crop production systems using perlite hydroponics, nutrient film technique (NFT), ebb and flow, and aeroponics were studied for various root, rhizome, and herb leaf crops. Biomass data comparing aeroponic vs. soilless culture or field grown production of burdock root (Arctium lappa), stinging nettles herb and rhizome (Urtica dioica), and yerba mansa root and rhizome (Anemopsis californica) are presented, as well as smaller scale projects observing ginger rhizome (Zingiber officinale) and skullcap herb (Scutellaria lateriflora). Phytochemical concentration of marker compounds for burdock and yerba mansa in different growing systems are presented.

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Bryan J. Peterson, Stephanie E. Burnett, and Olivia Sanchez

-free environment. A potential alternative to overhead mist is submist aeroponics, which relies on the application of mist from below the cutting, to the base of the stem inserted into an enclosed chamber. Several systems are available on the consumer market for use

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Michael D. Berg and Preston K. Andrews

An aeroponic growth chamber is a system for growing plants in air with water and nutrients supplied by intermittent mist. This type of plant growth system is especially useful for experiments where root accessibility is desired. Tomatoes (Lycopersicon esculentum L. `Bonnie Best') were used to test the performance of an aeroponic growth chamber. A nutrient solution mist was applied through spray nozzles suspended below roots of supported seedlings. Mist application was regulated by electric timers, so that mist was applied for 50 sec. every 5 min. during the 16-hr light period, which was supplemented with a high-pressure sodium lamp. Root and stem lengths, leaf number and leaf lengths were measured weekly. Plastochron index (PI) was used to measure rate of leaf initiation. PI increased linearly, indicating uniform initiation of leaf primordia and absence of environmental stresses. Stem and root lengths increased consistently throughout the growing period. Each plant was harvested, separated into leaves, shoots and roots, oven dried, and dry weights measured.

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Eric J. Biddinger, Chunming Liu, and K.G. Raghothama

Phosphate starvation in plants results in altered biochemical and physiological responses. We are interested in understanding the changes that occur in response to phosphate starvation in the roots of tomato plants. Plants were grown in an aeroponic system developed by L.A. Peterson at the Univ. of Wisconsin. Aeroponically grown tomato plants were treated with various concentrations of phosphate, ranging from to 250 mM. Phosphate-starved plants exhibited significantly higher root to shoot ratios and a 40% decrease in the chlorophyll content of the leaves. Several changes in essential nutrient content were also observed. The phosphate concentration of both root and shoot tissues decreased as the Pi content of the nutrient solution decreased. Whereas the ratio of phosphate content in roots compared to the shoots did not change significantly in response to Pi starvation. Phosphate-starved plants accumulated significantly higher amount of magnesium in stem tissues. Furthermore, it also resulted in an increased accumulation of potassium in roots. Interestingly, the total extractable RNA from phosphate-starved roots was 1/5th of that of control roots. There was also a noticeable decrease (50%) in the total extractable RNA content of leaves from phosphate-starved plants.

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Jernej Demšar, Jože Osvald, and Dominik Vodnik

With a high nitrate supply, and most frequently under low-light conditions, lettuce accumulates relatively large amounts of NO3-as a result of an excess of uptake over reduction. Different approaches, which are used to reduce leaf nitrate, often result in a yield loss. A computerized aeroponic system, which supplies different nitrate concentrations in accordance with the changeable light conditions (dynamic light-dependent application of nitrate), was used to reduce nitrate accumulation in lettuce (Lactuca sativa L.) var. Capitata cv. Vanity. Under unfavorable light conditions nitrate was supplied at limited rates (slight, medium, and strong reduction) to the plants. In response to given light conditions the nitrate supply was reduced close to one-half or one-fourth of the full nutrient solution (8 mmol·L-1 NO3-). Controlled nutrition resulted in efficient reduction in leaf nitrate. In the early-spring experiment the average nitrate content in outer leaves was decreased by 9%, 63%, and 92% and in the late-spring experiment the decrease was 23%, 58%, and 76% compared to control. At the same time, the controlled, light-dependent nitrate deprivation did not result in a loss of a lettuce yield (except in the treatment with strong nitrate reduction) and had limited effects on photosynthesis (P N-C i measurements) and photosynthetic pigments.