Optimum Potassium Concentrations in Recirculating Subirrigation for Selected Greenhouse Crops

Two experiments were conducted to investigate the effect of K fertilizer rates on growth of New Guinea impatiens (Impatiens Hawkeri Bull.), vinca (Catharanthus roseus (L.) G. Don) and petunia (Petunia ×hybrida Hort. Vilm.-Andr.) in a recirculating subirrigation system. Based on a variety of growth parameters, a broad range of K concentrations allowed maximum growth, notably 1 to 6 mM for New Guinea impatiens `Ovation Salmon Pink Swirl', 2 mm for New Guinea impatiens `Cameo' and `Illusion', 2 to 8 mm for vinca `Pacifica Apricot', and 2 to 16 mm for petunia `Trailing Wave Misty Lilac'. Thus, the lowest concentration that allowed maximum growth was 1 to 2 mm K. A third experiment compared the optimum K concentration and K balance of vinca grown with recirculating subirrigation versus top-watering. Based on a variety of growth parameters of vinca `Pacifica Red', the lowest concentration that allowed maximum growth was 2 mm K with recirculating subirrigation and 4 mm K with top-watering. The K balance demonstrated that subirrigated plants were twice as efficient in K use compared to the top-watered plants. Leachate loss was the major contributor to inefficiency in top-watered plants. Electrical conductivity (EC) of the growing medium remained below the recommended level of 1.2 dS·m-1 in both irrigation methods at K concentrations of 16 mm and below in the bottom layer and 8 mm and below in the middle layer. In the top layer of the growing medium, EC was above the recommended level at all K concentrations tested in subirrigation at all concentrations, and in top-watering at 16 mm and above.

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Characterizing Salinity Limits of New Guinea Impatiens in Recirculating Subirrigation

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.123.1.156 ◽

1998 ◽

Vol 123 (1) ◽

pp. 156-160 ◽

Cited By ~ 9

Author(s):

Nancy Morgan Todd ◽

David Wm. Reed

Keyword(s):

Root Zone ◽

New Guinea ◽

Middle Layer ◽

Molar Ratio ◽

Salinity Treatment ◽

Root Mass ◽

Growing Medium ◽

Leaching Fraction ◽

Impatiens Hawkeri ◽

New Guinea Impatiens

New Guinea impatiens (Impatiens hawkeri Bull.) were grown in a recirculating ebb-and-flow subirrigation system under increasing levels of salinity stress from a mixture of NaCl and CaCl2 (1:1 equivalent ratio, 2:1 molar ratio) and recommended production levels of other nutrients. Growth and quality decreased as salinity level increased, with a 75% to 80% growth reduction at 18 mol·m-3 NaCl-CaCl2 compared to controls. Among controls, root mass distribution was 10%, 50%, and 40% in the top, middle, and bottom layers of the root zone, respectively. In the highest salinity treatment (18 mol·m-3 NaCl-CaCl2), most of the root mass was in the middle layer (80%), while the root mass in the top and bottom layers was reduced to 5% and 15%, respectively. The electrical conductivity (EC) of the growing medium was high in the top layer in all treatments, but only exceeded maximum recommended levels in the middle and bottom layers in the 4·mol·m-3 or higher treatments. Initial postproduction leaching caused the salts in the top layer to migrate to the middle and bottom layers, which in some experiments induced a rapid and transient wilting. Up to six leaching and drying cycles of a 0.20 leaching fraction were required to reduce EC in all layers to recommended levels. Overall, salable plants of good quality and size were produced with up to 2 mol·m-3 (total 152 mg·L-1) NaCl-CaCl2 in the recirculated nutrient solution.

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Nitrogen Nutrition of New Guinea Impatiens and Spathiphyllum in a Subirrigation System

HortScience ◽

10.21273/hortsci.30.4.859a ◽

1995 ◽

Vol 30 (4) ◽

pp. 859A-859

Author(s):

Matthew W. Kent ◽

David Wm. Reed

Keyword(s):

Nitrogen Nutrition ◽

Chlorophyll Concentration ◽

New Guinea ◽

Dry Weight ◽

Maximum Growth ◽

Fertilization Rate ◽

Relative Distribution ◽

Soluble Salts ◽

New Guinea Impatiens ◽

Peace Lily

Greenhouse cultural methods must change rapidly to minimize runoff and to keep pace with environmental regulation aimed at protecting water resources. Two experiments were designed to investigate the effect of N fertilization rate on New Guinea impatiens (Impatiens ×hawkeri) and peace lily (Spathiphyllum Schott) in an ebb-and-flow subirrigation system. Maximum growth response for impatiens was centered around 8-mM N levels as measured by root and shoot fresh and dry weight, height, leaf number, leaf area, and chlorophyll concentration. For peace lily, growth peaked around 10 mM N. Growing medium was divided into three equal layers: top, middle, and bottom. Root distribution favored the middle and bottom layers, and the relative distribution of roots was consistent as N level increased. Soluble salts remained low in middle and bottom layers at N concentrations below 10 mM, but increased significantly for all soil layers at levels above 10 mM. The top layer contained two to five times higher soluble salt levels than in the middle or bottom layers at all N levels. Increased nitrate concentration mimicked increases in soluble salts, while pH decreased as N concentration increased for both impatiens and peace lily.

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Postproduction Leaching Affects the Growing Medium and Respiration of Subirrigated Poinsettias

HortScience ◽

10.21273/hortsci.35.2.250 ◽

2000 ◽

Vol 35 (2) ◽

pp. 250-253 ◽

Cited By ~ 4

Author(s):

Marc van Iersel

Keyword(s):

Dark Respiration ◽

Plant Stress ◽

Middle Layer ◽

Bottom Layer ◽

Euphorbia Pulcherrima ◽

Whole Plant ◽

Growing Medium ◽

Plant Photosynthesis ◽

Saturated Medium ◽

Fertilizer Solution

Poinsettias (Euphorbia pulcherrima Willd. ex Klotzsch) were grown in pots filled with 1.5 L of soilless growing medium and subirrigated daily with a fertilizer solution containing N at 210 mg·L-1 [electrical conductivity (EC) = 1.5 dS·m-1] for 128 days. After production, plants were placed in a whole-plant photosynthesis system and the effects of applying different volumes of water (0, 0.75, 1.5, and 3 L) to the top of the pots were quantified. Leaching with 0.75, 1.5, or 3 L of water reduced the EC in the top and middle layers of the growing medium. Applications of 0.75 or 1.5 L of water significantly increased the EC in the bottom third of the pots, where most of the root growth occurred. However, even in these treatments the EC in the bottom layer was only 2.6 dS·m-1 (saturated medium extraction method), which is well within the recommended range. The 0.75- and 1.5-L treatments also reduced the respiration rate of the plants by 20%, but none of the treatments had a significant effect on the photosynthesis of the plants. Regression analysis indicated a negative correlation between the EC of the bottom layer of the growing medium and dark respiration, while the EC of the top and middle layer had no significant effect on respiration. Although top watering can increase the EC in the bottom layer of the growing medium, this effect is unlikely to be large enough to cause significant plant stress and damage.

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Effects of Fertilizer Concentration and Minimum-leach Drip Irrigation on the Growth of New Guinea Impatiens

HortScience ◽

10.21273/hortsci.33.4.683 ◽

1998 ◽

Vol 33 (4) ◽

pp. 683-688 ◽

Cited By ~ 5

Author(s):

Harvey J. Lang ◽

Timothy R. Pannkuk

Keyword(s):

Drip Irrigation ◽

Root Zone ◽

Irrigation System ◽

Irrigation Treatment ◽

Growth Index ◽

New Guinea ◽

Maximum Growth ◽

Dry Mass ◽

Leaching Fraction ◽

New Guinea Impatiens

New Guinea impatiens `Barbados' (Impatiens ×hawkeri) were fertilized with solutions containing N at 6, 12, or 18 mmol·L-1 delivered from a drip irrigation system with either minimum leaching or standard leaching (0.3 to 0.4 leaching fraction). Irrigation was monitored and controlled by computers using microtensiometers placed in representative pots of each treatment. In two separate experiments, growth index, fresh mass, and dry mass were dependent upon both fertilizer concentration and irrigation treatment. Maximum growth overall was achieved at 12 mmol·L-1 N regardless of irrigation treatment; however, standard-leached plants receiving N at both 6 and 18 mmol·L-1 produced larger plants than did similarly fertilized minimum-leached plants. Leaf scorch, spotting, or marginal necrosis did not occur in any of the treatments. Leaf N, P, and K concentrations were highest in plants treated with N at 18 mmol·L-1, but Ca, Mg, and several micronutrients were highest in plants at 6 mmol·L-1 N. At the end of the cropping period for both experiments, growing medium electrical conductivity (EC) in the uppermost one-third layer of the pot was two to four times as high as that in the bottom two-thirds (root zone) layer. Root-zone EC ranged from 0.6 to 4.0 dS·m-1 and increased as fertilizer concentration increased. Standard leaching had little effect in reducing root-zone EC except in plants fertilized with N at 18 mmol·L-1. All plants continued to perform well and flower after 4 weeks in a simulated interior environment. Minimum-leach drip irrigation used ≈35% less solution than did standard irrigation with leaching, and eliminated N runoff.

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The effect of irrigation frequency on growth, flowering and stomatal conductance of osteospermum 'Denebola' and New Guinea impatiens 'Timor' grown on ebb·and-flow benches

Acta Agrobotanica ◽

10.5586/aa.2001.023 ◽

2013 ◽

Vol 54 (2) ◽

pp. 59-68

Author(s):

Jadwiga Treder ◽

Joanna Nowak

Keyword(s):

Water Stress ◽

Stomatal Conductance ◽

Water Potential ◽

Growth Parameters ◽

Soil Water Potential ◽

New Guinea ◽

Growth Stages ◽

Irrigation Frequency ◽

Growing Period ◽

New Guinea Impatiens

The response of osteospermum 'Denebola' and New Guinea impatiens 'Timor' grown on ebb-and-flow benches to different water potential of growing medium applied during whole growing period was investigated by measuring plant growth parameters and stomatal conductance (g<sub>S</sub>). After cutting establishment, four different irrigation treatments based on soil water potential were applied to osteospermum: at -0,5 , -3,0 , -10,0 , -20 kPa. In the case of impatiens the last water treatment was omitted. Plants were evaluated when they reach one ofthe three growth stages: lateral shoots development, visible flower buds (osteospermum) or beginning of flowering (impatiens) and at flowering. All plants produced with a moderate water deficit (irrigation at -3 and -10 kPa) were more compact than plants irrigated at -0,5 kPa but their flowering were not affected. Strong decrease in pIant growth and flowering was observed when plants were irrigated at the lowest water potential (-20 kPa). However, for impatiens the highest irrigation frequency was also not favorable. As a result of water stress the decrease in stomatal conductance (g~) in both plants was observed. Osteospermum was more resistant to water stress than impatiens.

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Nitrogen Nutrition of New Guinea Impatiens `Barbados' and Spathiphyllum `Petite' in a Subirrigation System

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.121.5.816 ◽

1996 ◽

Vol 121 (5) ◽

pp. 816-819 ◽

Cited By ~ 26

Author(s):

Matthew W. Kent ◽

David Wm. Reed

Keyword(s):

Nitrogen Nutrition ◽

Chlorophyll Concentration ◽

New Guinea ◽

Dry Weight ◽

Maximum Growth ◽

Fertilization Rate ◽

N Fertilization ◽

Relative Distribution ◽

New Guinea Impatiens ◽

Peace Lily

Greenhouse cultural methods must minimize runoff to keep pace with environmental regulation aimed at protecting water resources. Two experiments were designed to investigate the effect of N fertilization rate on New Guinea impatiens (Impatiens ×hawkeri) and peace lily (Spathiphyllum Schott) in an ebb-and-flow subirrigation system. Maximum growth response for impatiens was centered around 8 mm N levels as measured by root and shoot fresh and dry weight, height, leaf number, leaf area, and chlorophyll concentration. For peace lily, growth peaked at about 10 mm N. Growing medium was divided into three equal layers: top, middle, and bottom. Root distribution favored the middle and bottom layers, and the relative distribution of roots was consistent as N level increased. EC remained low in middle and bottom layers at N concentrations below 10 mm, but increased significantly for all layers at levels above 10 mm. The EC for the top layer was 2 to 5 times higher than in the middle or bottom layers at all N levels. Increased nitrate concentration paralleled increased EC, while pH decreased as N concentration increased for impatiens and peace lily.

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Phosphorus Concentration Affects New Guinea Impatiens and Vinca in Recirculating Subirrigation

HortScience ◽

10.21273/hortsci.40.7.2047 ◽

2005 ◽

Vol 40 (7) ◽

pp. 2047-2051 ◽

Cited By ~ 6

Author(s):

Carrie L. Whitcher ◽

Matthew W. Kent ◽

David Wm. Reed

Keyword(s):

Linear Models ◽

Growth Parameters ◽

Growth Parameter ◽

New Guinea ◽

Dry Weight ◽

Water Soluble ◽

Phosphorus Concentration ◽

Flower Number ◽

P Rate ◽

New Guinea Impatiens

The objective of this study was to quantify the optimum rates of water-soluble phosphorus (P) under constant nitrogen and potassium on the growth of new guinea impatiens (Impatiens hawkeri Bull.) `Paradise Violet' and vinca Catharanthus roseus `Pacifica Red' in soilless media in a recirculating subirrigation system. The experiment was designed so that only phosphate varied between treatments while all other nutrients remained constant. The ammoniacal N to nitrate N ratio was varied to counter balance increases in phosphate. Sodium was used as a counter ion to phosphate at higher concentrations of phosphate; sodium proved to be toxic at concentrations above 6 mm. In the new guinea impatiens experiment, there was a small increase in K due to the use of dibasic K phosphate to buffer pH. All growth parameters measured (height, leaf number, flower number, and shoot fresh and dry weight) showed significant differences with increasing P rate. Depending on the growth parameter measured, quadratic–linear models revealed an optimum P rate of 0.1 to 0.96 mm for new guinea impatiens `Paradise Violet' and 0.45 to 1.25 mm P for vinca `Pacifica Red'. For dry shoot weight, a common measure of optimum plant growth, the optimum P rate was 0.75 mm P for new guinea impatiens `Paradise Violet' and 0.67 mm P for vinca `Pacifica Red'. For flower number, a common measure of floral quality, the optimal P rate was 0.96 mm P for new guinea impatiens `Paradise Violet' and 1.25 mm P for vinca `Pacifica Red'. Electrical conductivity (EC) of the growing media increased significantly with increasing rate of P. At all rates, EC was significantly greater in the top layer than in the bottom and middle layers. The pH of the growing medium did not vary in relation to P concentration.

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The Growth of New Guinea Impatiens with Controlled-release Fertilizer in a Recirculating Subirrigation System

HortScience ◽

10.21273/hortsci.33.3.557b ◽

1998 ◽

Vol 33 (3) ◽

pp. 557b-557

Author(s):

Daphne Richards ◽

David Wm. Reed

Keyword(s):

Controlled Release ◽

New Guinea ◽

Release Rates ◽

High Quality ◽

Fertilizer Rate ◽

Growing Medium ◽

Excellent Growth ◽

Slight Growth ◽

Complete Fertilizer ◽

New Guinea Impatiens

New Guinea impatiens `Illusion' were grown in a recirculating subirrigation system using a controlled-release complete fertilizer (Osmocote 14–14–14). In a preliminary experiment, plants were grown under varying label rates (0, 0.5x, 1x, 2x, 4x) incorporated throughout the growing medium. Excellent growth and high-quality plants were produced at the 0.5x and 1x rates. Higher rates caused reduced growth and quality. The next study was a factorial experiment of rate (0.25x, 0.5x, 0.75x, and 1x) times placement (incorporated, top dress, bottom placement, and dibble). Slight growth increases and dramatic leaf area increases were observed with increasing fertilizer rate, regardless of placement. Slightly higher fresh and dry weights were observed in the incorporated treatment compared to the top dress treatment. Both the incorporated and top dress treatments yielded better growth than bottom placement or dibble treatments. Other parameters measured (height, chlorophyll content) did not appear to be affected by placement. EC (dS/m) of the growing medium was highest in the top 1/3 of the container in all placement treatments. EC increased with increasing rate. EC was higher in the incorporated than in the top-dress treatment, which may be due to different release rates or may be an artifact of extraction (prill removal). No rates or placements showed damaging EC levels.

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New Guinea Impatiens Growth Response and Nutrient Release from Controlled-release Fertilizer in a Recirculating Subirrigation and Top-watering System

HortScience ◽

10.21273/hortsci.39.2.280 ◽

2004 ◽

Vol 39 (2) ◽

pp. 280-286 ◽

Cited By ~ 13

Author(s):

Daphne L. Richards ◽

David Wm. Reed

Keyword(s):

Controlled Release ◽

Lower Bound ◽

Growth Response ◽

Growth Parameters ◽

Dry Weight ◽

Maximum Growth ◽

Controlled Release Fertilizer ◽

Shoot Dry Weight ◽

Quadratic Response ◽

New Guinea Impatiens

New Guinea impatiens (Impatiens hawkeri Bull.) `Illusion' were grown in a recirculating subirrigation system under various rates and placements of 14N-6.1P-11.6K (Osmocote; Scotts-Sierra, Marysville, Ohio) resin-coated, controlled-release fertilizer (CRF). Four CRF placements (incorporated, top-dressed, bottom, and dibble) were tested. Incorporated placement yielded slightly greater dry weights than the other placements. A rate experiment tested incorporating from 0.5 to 2 times the fertilizer manufacturer's recommended rate of 7.11 kg·m-3. All shoot growth parameters (height, leaf number, shoot, and root fresh and dry weight) exhibited a significant quadratic response, as exemplified by shoot dry weight, where shoot dry weight increased up to the 1.5× rate, after which shoot dry weight decreased. A quadratic response surface model revealed that the optimum rate response ranged from 1.16× rate for height to 1.47× rate for shoot dry weight. The lower bound of the 95% confidence interval (CI) would be the lowest rate at which one could expect maximum growth response. The lower bound of the 95% CI varied from 0.56× rate for height to 1.30× rate for shoot dry weight. Thus, the lowest rate that would be within the 95% CI for all growth parameters, and thus yield maximum growth response, would be the 1.30× rate. Electrical conductivity (EC) of the growing media increased significantly with increasing CRF rate. At all rates, EC was significantly greater in the top layer than in the middle and bottom layers. Only in the 1.75× and 2× rates did EC exceed the recommended EC levels in the middle and bottom layer. All rates >0.75× exceeded recommended EC in the top layer. Release characteristics and total nutrient balance of the CRF was compared in subirrigated and top-watered systems. There was no significant difference between top-watered and subirrigated treatments for the amount of K recovered in plant tops and released from prills. By day 84, in subirrigation, 46% of the K was still in the prills, 41% was recovered in the plant tops, and 22% was recovered in the medium. Similar results were obtained in the top-watering treatment, except that a lesser amount was recovered in the medium (9%) and a small amount (4%) was recovered in the leachate. The uptake of K by plants and release of K by the CRF were inversely proportional and linear with respect to time. Of the K released from the prills, 77% and 83% were recovered in the plant tops for subirrigation and top-watering, respectively, indicating very high fertilizer use efficiency.

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Corn Stover Removal Responses on Soil Test P and K Levels in Coastal Plain Ultisols

Sustainability ◽

10.3390/su13084401 ◽

2021 ◽

Vol 13 (8) ◽

pp. 4401

Author(s):

Jeffrey M. Novak ◽

James R. Frederick ◽

Don W. Watts ◽

Thomas F. Ducey ◽

Douglas L. Karlen

Keyword(s):

Coastal Plain ◽

Nutrient Removal ◽

Fertilizer Application ◽

First Year ◽

Soil Test ◽

Concentration Data ◽

Extractable P ◽

K Fertilizer ◽

Soil Test P ◽

K Concentration

Corn (Zea mays L.) stover is used as a biofuel feedstock in the U.S. Selection of stover harvest rates for soils is problematic, however, because excessive stover removal may have consequences on plant available P and K concentrations. Our objective was to quantify stover harvest impacts on topsoil P and K contents in the southeastern U.S. Coastal Plain Ultisols. Five stover harvest rates (0, 25, 50, 75 and 100% by wt) were removed for five years from replicated plots. Grain and stover mass with P and K concentration data were used to calculate nutrient removal. Mehlich 1 (M1)-extractable P and K concentrations were used to monitor changes within the soils. Grain alone removed 13–15 kg ha−1 P and 15–18 kg ha−1 K each year, resulting in a cumulative removal of 70 and 85 kg ha−1 or 77 and 37% of the P and K fertilizer application, respectively. Harvesting stover increased nutrient removal such that when combined with grain removed, a cumulative total of 95% of the applied P and 126% of fertilizer K were taken away. This caused M1 P and K levels to decline significantly in the first year and even with annual fertilization to remain relatively static thereafter. For these Ultisols, we conclude that P and K fertilizer recommendations should be fine-tuned for P and K removed with grain and stover harvesting and that stover harvest of >50% by weight will significantly decrease soil test M1 P and K contents.

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