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D. Sean Moodv and Douglas A. Hopper

Four cut rose cultivars (`Royalty', `Samantha', `Sonia', and `Gabriella') were exposed to supplemental radiation for 2 years of production at the W.D. Holley Plant Environmental Research Center (PERC) at Colorado State Univ. and 1 year at Jordan's Greenhouse (cultivars Royalty and Kardinal). At PERC the house was divided into two treatments: l) natural light, and 2) supplemental radiation at ≈100 μmol·m–2·s–1 (750 fc) from 1000-W high-pressure sodium (HPS) lamps for 10 h each night. Jordan's had a third treatment of supplemental radiation at ≈50 μmol·m–2·s–1 (400 fc). Nutrient solution recirculation was tested with one bench in each of the treatments. Each rose was counted and measured for stem length and fresh weight. At PERC, all the cultivars showed no significant differences in the weekly number of flowers produced or the total flower fresh weight when grown under nonrecirculation vs. recirculation of nutrient solution. From 1993 results, grade A production for 60 `Royalty' plants increased from 455 flowers under natural conditions to 522 flowers under lighted conditions over 7 months, a 97-flower increase (21%) due to lighting.

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Yan Chen, Regina P. Bracy, Allen D. Owings, and Donald J. Merhaut

the end of a growing season to avoid releasing nutrients back into the water, and new growth will begin the next season to continue removing nutrients from the water. A hydroponic nutrient recirculation system (NRS) was used for this study. The water

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Kyung-Hwan Yeo*, Jung-Min Son, and Yong-Beom Lee

The plant factory to control growing system automatically is necessary to cultivate single-node cutting rose, which produce large numbers of uniform shoots per unit area in short cultivation. However, the recirculation of the nutrient solution in closed system leads to several problems. One of them is connected with the quality of nutrient solution and the supply of minerals. The uptake of specific nutrients depends on growth and development, or plant stage, which results in a shift in ionic ratio in the drainage water compared to the nutrient solution supplied. Consequently, the nutrient supply should be controlled to be equal to the demand of the plant to avoid disorder of nutrient solution, such as depletion or accumulation. Therefore this study was conducted to examine the effect of mineral nutritional control on nutrient uptake of single-node cutting rose `Red velvet' and `Vital' in a plant factory. The nutritional control of nutrient solution was conducted by five methods: the control of electrical conductivity (EC), N, P, and K elements (NPK), macro elements (M), macro and micro elements (MM) to target ranges in root zone, and the supplement of nutrient solution (S). In NPK, M, and MM control system, the input of nutrients was calculated as amounts of absorption by the plants compared to target values in root environment. The fertilizer supplement of N, P, and K was lower in EC control system than other control systems. In EC and S control system, the concentration of NO3 - -N and K in root zone exceed optimal range whereas P, Ca, and Mg decreased at the later stage of growth. The concentrations of each nutrient in root environment were kept at the target ranges in M and MM control system, which showed optimum yield and product quality.

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Jae-Woo Soh* and Yong-Beom Lee

Experiments were carried out to determine nutrient management system for butterhead lettuce `Omega' and leaf lettuce `Grand Rapids' in nutrient film technique (NFT), and to develop a rapid and reliable program for recirculation solution. The effects of controlling solutions with UOSL (Leaf Lettuce solution of the Univ. of Seoul, Korea; NO3 -N 10.55, NH4 -N 1.02, P 2.0, K 6.7, Ca 3.5, Mg 2.0, SO4 -S 2.0 me·L-1; Fe 2.0, Cu 0.1, B 0.5, Mn 0.3, Zn 0.3, Mo 0.05 ppm) were studied by greenhouse with managing by distilled water (DW), managing pH and EC (CM), managing by nutrient solution analysis (MN), managing by nutrient solution with leaf analysis (ML). The CO2 assimilation, transpiration rate, relative chlorophyll contents, leaf color, fresh weight and dry weight were highest in MN control in the butterhead `Omega' and in MN and ML control in the leaf lettuces `Grand Rapids'. The highest relative growth rate (RGR) was in MN ML in the butterhead `Omega' but those wasn't in the leaf lettuce `Grand Rapids'. Calculation program of adjustable solution was based on the main works by Visual Basic 5.0. The developed program could select an automatic and passive process considering the type of fertilizers, run-off rate, nutrient concentration, and water volume, for calculation. All of them were done successfully by the fast and precise calculation program.

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Kyung-Hwan Yeo*, Jung-Min Son, and Yong-Beom Lee

Plant factory is a new plant production system that enables high quality, year-round, and planned production by controlling the environment. However, the recirculation of the nutrient solution leads to several problems because of unstable condition by nutrient uptake. The concentrations of nutrients in the recirculating solution should be kept at the required levels, since an optimum nutrition is determined by the specific concentrations of an element and mutual ratio to other nutrients in the root zone. Consequently, the nutrient solution is required adjustments based on regular analysis of the drain water and relationships among nutrient uptake, growth stage, and environmental factors for plant quality. This study was conducted to examine the effect of mineral nutritional control by five different methods on growth and photosynthesis of single-stemmed rose `Red velvet' and `Vital' in a plant factory. The nutritional control of nutrient solution was as following: the control of electrical conductivity (EC), N, P, and K elements (NPK), macro elements (M), macro and micro elements (MM) to target ranges in root environment, and the supplement of nutrient solution (S). The growth of single-node cutting rose `Vital' and `Red velvet' was higher in the M and MM than that of other control systems. Although M and MM system showed no significant difference, the photosynthetic rate, stomatal conductance, and transpiration rate were higher than those with other systems. The maximal efficiency of photochemistry (Fv/Fm) was higher in the M and MM control system, which showed the highest root activity. These results could be attributable for modelling the mineral nutritional control system, which reduces the use of fertilizers and increases the productivity of single-stemmed rose.

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Michael D. Cahn and Husein A. Ajwa

Agricultural runoff is a source of nutrients and sediments in surface water on the central coast of California. Treating soils with high molecular weight anionic polyacrylamide (PAM) may reduce sediments and P lost from furrow and sprinkler irrigated fields by maintaining infiltration and stabilizing soil aggregates. We conducted column and field studies to quantify the effect of PAM on infiltration rate, run off, and sediment and nutrient (ortho and total P, NO3, K) loss from cool season vegetable fields. Column studies demonstrated a reduction in infiltration for 10 soil types when PAM was continuously applied in the irrigation water at 10 ppm. Recirculating infiltrometer studies showed that in furrow systems, PAM, applied only in the initial water at 10 ppm, had no significant effect on infiltration at four of six sites evaluated. Turbidity and total suspended solids were significantly reduced in the PAM treated water. Across all sites, treatment with PAM reduced suspended solids by 85% compared to the untreated control. Additionally, soluble and total P, and total N were reduced in the PAM treated water. PAM had no effect on nitrate or salt levels in the runoff. PAM applied through sprinklers at a 5 ppm concentration was able to significantly reduce the turbidity and the suspended solids in the tailwater. Similar to the results obtained with the recirculation infiltrometer trials, PAM reduced soluble and total P and total N in the runoff, but had no significant effect on NO3-N. Total sediment loss under sprinklers was reduced by as much as 95% using PAM.

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Youssef Rouphael, Giampaolo Raimondi, Rosanna Caputo, and Stefania De Pascale

; Steidle Neto et al., 2014 ). The adoption of this nutrient management strategy may give encouraging results in terms of productivity and sustainability by prolonging the use and recirculation of the nutrient solution, thus minimizing nitrate loss from

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Youssef Rouphael and Giuseppe Colla

subirrigation system, the nutrient solution was pumped at the elevated end of the benches and allowed to run slowly down the trough past the pots, and the excess was drained back to the tank for later recirculation. In the drip irrigation system, the nutrient

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Youbin Zheng, Diane Feliciano Cayanan, and Mike Dixon

The use of a recirculating subirrigation system is becoming increasingly popular in the greenhouse industry. In a survey on the status of nutrient solution recirculation in Ontario, Canada, Richard et al. (2006) found that almost half of the

Open access

Yu-Wei Liu and Chen-Kang Huang

-emitting diode (LED) or fluorescent lighting ( Ikeda et al., 1992 ). This type of facility enables for the precise control of a cultivation environment in terms of irradiance, temperature, humidity, carbon dioxide concentration, and composition of the nutrient