Characterizing the Phytotoxic Effects of Hydrogen Peroxide Root Dips on Hybrid Phalaenopsis Orchid Plants

Hydrogen peroxide (H2O2) is a well-known oxidizing agent often used as a remedy by consumers to treat algae and root decay from presumed root disease on interior plants, as well as to encourage root growth and health. To characterize the phytotoxic effects and define the safe concentration threshold for H2O2 use on ‘Vivaldi’ hybrid phalaenopsis orchid (hybrid Phalaenopsis), root systems were dipped for 3 minutes in 0%, 3%, 6%, or 12% H2O2 one time and observed in greenhouse conditions for the following 27 days. Root systems of each plant were assessed over time for percent visible root damage; ratings of root health on a scale of 1 to 5 points, with 5 points indicating “very healthy”; and final fresh and dry weights. To determine when symptoms manifested above the root zone, foliage and flower damage was evaluated over time by assessing percent visible foliage damage, ratings of foliage health, percent foliar wilt, flower/bud count, and final foliage and flower fresh and dry weights. Over the evaluation period, the root health rating of the ‘Vivaldi’ hybrid phalaenopsis orchids treated with 12% H2O2 decreased from 5 to 1.13, whereas those treated with 3% H2O2 only decreased from 5 to 4.13. H2O2 concentrations of 6% and 12% damaged root health permanently, whereas the 3% H2O2 concentration only caused minor damage to overall root health. However, algae were not killed at the 3% rate. Neither foliage nor flowers were seriously affected during the 3 weeks after application, but foliage wilt did result in the 6% and 12% treatments by week 4. As H2O2 concentration increased, fresh weights decreased in roots and leaves. Although a single 3% H2O2 root dip did not result in severe symptoms of phytotoxicity, the treatment’s long-term plant health effects are unknown. Because the 3% H2O2 root dip caused minor plant health setbacks and failed to subdue algae populations in the root zone, consumers should be wary of using H2O2 to improve orchid (Orchidaceae) root health and should instead focus on altering care and watering practices.

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Characterizing the Phytotoxic Effects of Hydrogen Peroxide on Common Microgreen Species and Lettuce Cultivars

HortTechnology ◽

10.21273/horttech04255-18 ◽

2019 ◽

Vol 29 (3) ◽

pp. 283-289

Author(s):

Mitchell Eicher-Sodo ◽

Robert Gordon ◽

Youbin Zheng

Keyword(s):

Hydrogen Peroxide ◽

Damage Index ◽

Dry Weight ◽

Leaf Damage ◽

Phytotoxic Effects ◽

Leaf Surfaces ◽

Black Oil ◽

Concentration Threshold ◽

Extent Of Damage ◽

Oil Sunflower

Hydrogen peroxide (H2O2) is an oxidizing agent used to disinfect recirculated irrigation water during the production of organic crops under controlled environmental systems (e.g., greenhouses). To characterize the phytotoxic effects and define a concentration threshold for H2O2, three microgreen species [arugula (Brassica eruca ssp. sativa), radish (Raphanus sativus), and sunflower (Helianthus annuus ‘Black Oil’)], and three lettuce (Lactuca sativa) cultivars, Othilie, Xandra, and Rouxai, were foliar sprayed once daily with water containing 0, 25, 50, 75, 100, 125, 150, or 200 mg·L−1 of H2O2 from seed to harvest under greenhouse conditions. Leaf damage was assessed at harvest using two distinct methods: 1) the percentage of damaged leaves per tray and 2) a damage index (DI). Applied H2O2 concentrations, starting from 25 mg·L−1, increased the percentage of damaged leaves in every species except ‘Black Oil’ sunflower, which remained unaffected by any applied concentration. Symptoms of leaf damage manifested in similar patterns on the surface of microgreen cotyledons and lettuce leaves, while mean DI values and extent of damage were unique to each crop. Fresh weight, dry weight, and leaf area of all crops were not significantly affected by daily H2O2 spray. Identifying how foliar H2O2 damage manifests throughout the crop, as well at individual cotyledon or leaf surfaces, is necessary to establish an upper concentration threshold for H2O2 use. On the basis of the aforementioned metrics, maximum recommended concentrations were 150 mg·L−1 (radish), 100 mg·L−1 (arugula) for microgreens and 125 mg·L−1 (‘Othilie’), 75 mg·L−1 (‘Rouxai’), and 125 mg·L−1 (‘Xandra’) lettuce.

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Effects of Hydrogen Peroxide on Hydroponic Lettuce Grown With Conventional and Organic Fertilizers [Cornell University]

Journal of Student Research ◽

10.47611/jsr.vi.615 ◽

2019 ◽

Author(s):

Vanessa M. Lau ◽

Neil S. Mattson

Keyword(s):

Hydrogen Peroxide ◽

Microbial Respiration ◽

Root Zone ◽

Organic Fertilizers ◽

Pathogenic Microorganisms ◽

Trial And Error ◽

Dissolved Oxygen Concentration ◽

Cornell University ◽

Lactuca Sativa L ◽

Lettuce Yield

H2O2, commonly referred to as hydrogen peroxide, is an unstable oxidizing agent often used by hydroponic growers to help clear unwanted biofilm and pathogenic microorganisms by releasing free radicals that interact with the microbes. Other byproducts produced by the decomposition of hydrogen peroxide are simply H2O and O2. The released O2 increases the dissolved oxygen concentration in the root zone and may also help reduce oxygen losses to biofilm and microbial respiration. However, the suggested concentration of hydrogen peroxide varies greatly among hobbyists and are typically determined on a trial and error basis and excess H2O2 can cause damage to roots. With little to no scientifically backed information available on the topic, the aim of this study is to determine the effect of H2O2 concentrations in deep water culture hydroponics by assessing how it affects biofilm caused by the use of organic fertilizers, root development, and consequently, yield in lettuce (Lactuca sativa L.) ‘Oak Leaf’. In this experiment, three different treatments consisting of a control, 1.25 mL/L, and 2.5 mL/L of hydrogen peroxide are added to aerated 4-L reservoirs that are fertilized with either organic (4-1-1) or inorganic nutrients (21-5-20), both applied at 150 mg·L-1 N. Three replicates for each treatment and each fertilizer are prepared resulting in a total of eighteen reservoirs with one head of lettuce in each. By the end of this study, it was found that when added to conventional fertilizers, doses of 1.25 mL/L and 2.5 mL/L of hydrogen peroxide stunted the growth of or killed the heads of lettuce. However, when applied to organic fertilizers, the lettuce yield nearly matched that of the conventionally fertilized control.

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Soil Physical Methods for Estimating Recharge - Part 3

10.1071/9780643105355 ◽

1998 ◽

Cited By ~ 2

Author(s):

W Bond

Keyword(s):

Soil Water ◽

Root Zone ◽

Plant Root ◽

Water Flux ◽

Soil Physics ◽

Plane Method ◽

Physical Methods ◽

Basic Concepts ◽

Zero Flux Plane ◽

Over Time

Measurements in and just below the plant root zone, using principles of soil physics, can be used to estimate recharge. This booklet describes the Zero Flux Plane Method, Methods Based on Darchy's law, and Lysimetry for making such estimates. The work presents the basic concepts of soil water physics that will be referred to in this and other booklets in the series. Another method, the Soil Water Flux Meter, is discussed briefly, but as this is not sufficiently well developed for routine use readers are referred elsewhere for full details. All these methods require that consideration be given to interpolation over time and spatial extrapolation or averaging. A brief discussion of this is given.

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Water drawdown by radish (Raphanus sativus L.) multiple-root systems evaluated using computed tomography

Soil Research ◽

10.1071/sr07116 ◽

2008 ◽

Vol 46 (3) ◽

pp. 228

Author(s):

M. A. Hamza ◽

S. H. Anderson ◽

L. A. G. Aylmore

Keyword(s):

Computed Tomography ◽

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Water Uptake ◽

Root Zone ◽

Multiple Root ◽

Root Systems ◽

Bulk Soil ◽

Water Drawdown

Although measurements of water drawdown by single radish root systems have been previously published by the authors, further research is needed to evaluate water drawdown patterns in multiple-root systems. The objective of this study was to compare water transpiration patterns estimated using X-ray computed tomography (CT) with the traditional gravimetric method and to evaluate the effects of variably spaced multiple root systems on soil water content and corresponding water content gradients. Water drawdown showed a dual pattern in which it increased rapidly when soil water content was high at the beginning of transpiration, then slowed down to an almost constant level with time as water content decreased. These results contrast with the single-root system wherein transpiration rates initially increased rapidly and then slowly increased with time. Water uptake estimated using the CT method was observed to be 27–38% lower than the gravimetrically estimated water uptake; this difference was attributed to lower water uptake for the upper 30 mm layer (CT measured) than lower layers due to differences in root density. However, good correlation (r = 0.97) was found between both measurement methods. The drawdown patterns for multiple root systems showed a convex shape from the root surface to the bulk soil, compared with a nearly linear shape for single roots. The water content drawdown areas and the drawdown distances for multiple root systems were found to be much larger than those corresponding to single radish roots. Differential water content gradients were observed for roots spaced at 15-mm distances compared with 3–4-mm distances. These differential gradients from the bulk soil towards the root-zone occurred probably creating localised water potential gradients within the root-zone, which moved water from between roots to root surfaces. The lowest water content values were located in the inter-root areas. The CT-scanned layer probably acted as one drawdown area with particularly higher water drawdown from the inter-root areas.

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Effects of Weed Control Methods on Sweet Corn

Weed Science ◽

10.1017/s0043174500034597 ◽

1970 ◽

Vol 18 (6) ◽

pp. 707-711 ◽

Cited By ~ 1

Author(s):

L. L. Danielson

Keyword(s):

Sweet Corn ◽

Root Zone ◽

Soil Surface ◽

Root Systems ◽

Severe Drought ◽

Silt Loam ◽

Control Methods ◽

Herbicide Treatments ◽

Drought Conditions ◽

Corn Plants

Three tractor cultivations that severely pruned the root systems of hand-weeded plots of sweet corn [Zea mays L. var. rugosa Bonaf., Iochief] grown on a Codorus-Elkton silt loam under extreme drought conditions did not reduce the yield of marketable ears when irrigation totalling 2 acre-inches was applied during pollination and ear-filling. Pre-emergence application of 2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine [atrazine] to the soil surface without cultivation reduced brace root growth and yields significantly in the year of most severe drought. These effects of atrazine were avoided when the herbicide treatments were supplemented with tractor cultivations that covered the brace root zone of the corn plants with soil.

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Effects of Nutrient and Growth Regulator Treatments on the Growth and Development of Marigolds

HortScience ◽

10.21273/hortsci.31.4.679d ◽

1996 ◽

Vol 31 (4) ◽

pp. 679d-679

Author(s):

Arvazena E. Clardy ◽

Stephen Garton

Keyword(s):

Growth Regulator ◽

Growth And Development ◽

Block Design ◽

Root Systems ◽

Tagetes Erecta ◽

Flower Bud ◽

Bud Formation ◽

Randomized Complete Block Design ◽

Flower Bud Formation ◽

Nutrient Solutions

Two cultivars of Tagetes erecta Marigolds—Hero Yellow and Safari Tangerine—were grown hydroponically in two different nutrient solutions. The experiment was implemented in the greenhouses on the campus of Alabama A&M Univ., from March to May 1995. The experiment was to assess the effects of growth and development of Marigolds. Heights of seedlings, germinated in grodan (rockwool) cubes were measured and placed randomly in the hydroponic units. Plants were drenched with five rates of either Paclobutrazol (Bonzi) and Uniconazole (Sumagic). The experiment was laid out as a randomized complete block design with either three or four replications of the treatment, which were factorial combinations of variables. After 75 days measurements were made of plants heights, flower bud numbers and dry weights of shoot and root systems. Shoot dry weights were affected by growth regulator treatments, variety, nutrient treatments and a combination of variety and nutrient treatments. Root dry weights were affected by nutrient treatments. Flower bud formation and numbers were affected by the combination of nutrient and variety. Heights were affected by growth regulator treatments, variety and nutrient treatments.

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Effects of general medical health on Alzheimer's progression: the Cache County Dementia Progression Study

International Psychogeriatrics ◽

10.1017/s104161021200049x ◽

2012 ◽

Vol 24 (10) ◽

pp. 1561-1570 ◽

Cited By ~ 31

Author(s):

Jeannie-Marie S. Leoutsakos ◽

Dingfen Han ◽

Michelle M. Mielke ◽

Sarah N. Forrester ◽

JoAnn T. Tschanz ◽

...

Keyword(s):

Health Status ◽

Apoe Genotype ◽

Population Based ◽

Clinical Dementia Rating ◽

Dynamic Relationship ◽

Cache County ◽

Medical Health ◽

Rate Of Decline ◽

Health Rating ◽

Over Time

ABSTRACTBackground: Several observational studies have suggested a link between health status and rate of decline among individuals with Alzheimer's disease (AD). We sought to quantify the relationship in a population-based study of incident AD, and to compare global comorbidity ratings to counts of comorbid conditions and medications as predictors of AD progression.Methods: This was a case-only cohort study arising from a population-based longitudinal study of memory and aging, in Cache County, Utah. Participants comprised 335 individuals with incident AD followed for up to 11 years. Patient descriptors included sex, age, education, dementia duration at baseline, and APOE genotype. Measures of health status made at each visit included the General Medical Health Rating (GMHR), number of comorbid medical conditions, and number of non-psychiatric medications. Dementia outcomes included the Mini-Mental State Examination (MMSE), Clinical Dementia Rating – sum of boxes (CDR-sb), and the Neuropsychiatric Inventory (NPI).Results: Health status tended to fluctuate over time within individuals. None of the baseline medical variables (GMHR, comorbidities, and non-psychiatric medications) was associated with differences in rates of decline in longitudinal linear mixed effects models. Over time, low GMHR ratings, but not comorbidities or medications, were associated with poorer outcomes (MMSE: β = –1.07 p = 0.01; CDR-sb: β = 1.79 p < 0.001; NPI: β = 4.57 p = 0.01).Conclusions: Given that time-varying GMHR, but not baseline GMHR, was associated with the outcomes, it seems likely that there is a dynamic relationship between medical and cognitive health. GMHR is a more sensitive measure of health than simple counts of comorbidities or medications. Since health status is a potentially modifiable risk factor, further study is warranted.

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In vitro tooth whitening effectiveness of whitening mouth rinses

Brazilian Journal of Oral Sciences ◽

10.20396/bjos.v19i0.8656779 ◽

2020 ◽

Vol 19 ◽

pp. e206779

Author(s):

Ana Paula Morona Rodrigues ◽

Mariele Cristina Klein ◽

Mauro Antonio Dall Agnol ◽

Sinval Adalberto Rodrigues-Junior

Keyword(s):

Hydrogen Peroxide ◽

Color Change ◽

Artificial Saliva ◽

Acrylic Resin ◽

Mouth Rinse ◽

Tooth Whitening ◽

Mouth Rinses ◽

Immersion Period ◽

Over Time

Regardless of the extensive availability of mouth rinses that claim to whiten teeth, evidence of achievement of such effect is still missing. Aim: Therefore, this study assessed in vitro the whitening effectiveness of whitening mouth rinses. Methods: Sixty intact bovine incisors were embedded in acrylic resin and had their buccal surface flattened and polished. Then, the specimens were randomly allocated to three conventional (Colgate Plax, Cepacol and Listerine Cool Mint) and three whitening mouth rinse groups (Colgate Luminous White, Cepacol Whitening and Listerine Whitening Extreme) (n=10). Following, the specimens were immersed twice a day in the mouth rinses for one minute for 28 days. In between each immersion period, the specimens remained in artificial saliva at 37oC. Color was measured at baseline, 7, 14, 21, and 28 days using a portable spectrophotometer (Easyshade, Vita Zahnfabrik, Germany) with a 6 mm of diameter probe. Color change was analyzed considering the parameters of ∆L*, ∆a*, ∆b* and, ultimately, ∆E*. The whitening efficacy of the mouth rinses was analyzed using the Whiteness Index for Dentistry (WID). Data of ∆s was analyzed using two-way ANOVA and Tukey’s test (α=0.05). Results: The type of mouth rinse affected significantly all the ∆ parameters (p<0.05). A non-whitening (conventional) mouth rinse produced the highest ΔE*, followed by the three whitening mouth rinses. The application time also affected ΔE* (p<0.05), with emphasis on the third week of treatment. Only the hydrogen peroxide-containing mouth rinse (Listerine Whitening Extreme) presented a whitening effect, with an increasing trend over time. Conclusion: Although the overall color change was not different when comparing conventional and whitening mouth rinses, the hydrogen peroxide-containing whitening mouth rinse produces an increasing whitening trend over time. Not every mouth rinse that claims to whiten teeth produces the desired effect.

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Differential Tolerance of Eleven Prunus Taxa to Root Zone Flooding

Journal of Environmental Horticulture ◽

10.24266/0738-2898-12.3.138 ◽

1994 ◽

Vol 12 (3) ◽

pp. 138-141 ◽

Cited By ~ 6

Author(s):

Thomas G. Ranney

Keyword(s):

Root Zone ◽

Survival Rates ◽

Net Photosynthesis ◽

Root Systems ◽

High Survival ◽

Japanese Apricot ◽

Subsequent Recovery ◽

Flooding Stress ◽

Relative Tolerance ◽

Chilling Period

Abstract Eleven taxa of own-rooted Prunus L. were subjected to incremental flooding for 7 weeks to assess relative tolerance to root zone flooding. Rates of net photosynthesis (Pn) decreased gradually as the flooding stress intensified. However, ‘Newport’ plum maintained higher Pn than any other taxa when root systems were completely submerged. Defoliation of flooded plants ranged from a low of 15% for ‘Newport’ plum to a high of 100% for ‘Canada Red’ chokecherry. Following a chilling period, survival of flooded plants ranged from a low of 0% for Carolina cherrylaurel to a high of 100% for ‘Newport’ plum and ‘F-12/1’ mazzard cherry. Of the 11 taxa evaluated, ‘F-12/1’ mazzard cherry and ‘Newport’ plum had the greatest tolerance to root zone flooding as indicated by high survival rates (100%) and low defoliation (≤27%). ‘Newport’ plum further demonstrated superior tolerance to flooding compared to other taxa as indicated by a greater capacity to maintain Pn during flooding and subsequent recovery. Carolina cherrylaurel, ‘Canada Red’ chokecherry, and ‘Peggy Clark’ Japanese apricot were relatively sensitive to flooding as indicated by low survival rates (≤50%) and considerable defoliation (≥82%). The remaining taxa, including Japanese bushcherry, Sargent, Yoshino, ‘Okame’, ‘Autumnalis’ and ‘Kwanzan’ cherries, were found to be intermediate in tolerance to flooding.

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(346) Effect of Rhizosphere pH on Root Growth of Two Landscape Species

HortScience ◽

10.21273/hortsci.40.4.1060b ◽

2005 ◽

Vol 40 (4) ◽

pp. 1060B-1060

Author(s):

Amy N. Wright ◽

Robert D. Wright ◽

Brian E. Jackson ◽

Jake A. Browder

Keyword(s):

Root Growth ◽

Soil Ph ◽

Root Zone ◽

Design Feature ◽

Pine Bark ◽

Rhizosphere Ph ◽

Alkaline Soil ◽

Dolomitic Limestone ◽

Mountain Laurel ◽

Over Time

Rhizosphere pH preferences vary for species and can dramatically influence root growth rates. Research was conducted to determine the effect of root zone pH on the root growth of BuxusmicrophyllaSieb. & Zucc. `Green Beauty' (boxwood) and KalmialatifoliaL. `Olympic Wedding' (mountain laurel). Boxwood plants removed from 3.8-L containers and mountain laurel plants removed from 19-L containers were situated in the center of separate Horhizotrons™. The key design feature of the Horhizotron is four wedge-shaped quadrants (filled with substrate) that extend away from the root ball. Each quadrant is constructed from glass panes that allow the measurement of roots along the glass as they grow out from the root ball into the substrate. For this experiment, each quadrant surrounding a plant was filled with a pine bark substrate amended per m3 (yd3) with 0.9 kg Micromax (Scotts-Sierra, Marysville, Ohio) and 0, 1.2, 2.4, or 3.6 kg dolomitic limestone. All plants received 50 g of 15N–3.9P–9.8K Osmocote Plus (Scotts-Sierra), distributed evenly over the surface of the root ball and all quadrants. Plants were grown from May to Aug. 2003 in a greenhouse. Root lengths were measured about once per week throughout the experiment. Root length increased linearly over time for all species in all substrates. Rate of root growth of boxwood was highest in pine bark amended with 3.6 kg·m3 lime and lowest in unamended pine bark. Rate of root growth of mountain laurel was lowest in pine bark amended with 3.6 kg·m3 lime. Results support the preference of mountain laurel and boxwood for acidic and alkaline soil pH environments, respectively.

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