scholarly journals 654 PB 034 EVALUATION OF CHLOROPHYLL METER READINGS FOR ASSESSING THE N STATUS OF LETTUCE

HortScience ◽  
1994 ◽  
Vol 29 (5) ◽  
pp. 526d-526
Author(s):  
M. Wilcox ◽  
C.A. Sanchez ◽  
T.M. Blackmer
Keyword(s):  
Growth Rate ◽  
Color Variation ◽  
Chlorophyll Meter ◽  
Color Changes ◽  
Nitrate N ◽  
Lettuce Growth ◽  
Lettuce Yield ◽  
N Fertility ◽  
N Management ◽  
N Status

Several studies in the midwestem United States have shown that chlorophyll meter readings (Minolta SPAD 502) are useful in determining the N status of corn (Zea Mays L.), and show promise as a tool for the efficient N management of corn. Studies were conducted to evaluate the potential of the `chlorophyll meter for evaluating N deficiencies in lettuce (Lactuca sativa L.). Data for chlorophyll meter readings, midrib nitrate-N, lettuce growth rate, and marketable lettuce yield were collected in five N fertility experiments in 1993 and 1994. Chlorophyll meter readings not only varied among lettuce types (butter, cos, leaf, crisphead), but also among cultivars of the crisphead type. Chlorophyll meter readings were generally poorly correlated to midrib nitrate-N levels and marketable lettuce yield. Lettuce leaves have more color variation than corn leaves, and perhaps this variation in relation to the small sensor size on the SPAD 502 confounded readings. The observation that subtle N deficiencies in lettuce are usually manifested in growth rate reduction rather than abrupt color changes may also limit the usefulness of the chlorophyll meter for lettuce.

scholarly journals Use of a Chlorophyll Meter for Nondestructive and Rapid Estimation of Leaf Tissue Nitrogen in Macadamia

2019 ◽  
Vol 29 (3) ◽  
pp. 308-313 ◽  
Author(s):  
Russell Galanti ◽  
Alyssa Cho ◽  
Amjad Ahmad ◽  
Javier Mollinedo
Keyword(s):  
Linear Regression ◽  
Leaf Tissue ◽  
Sampling Period ◽  
Concentration Data ◽  
Total N ◽  
Chlorophyll Meter ◽  
N Concentration ◽  
Important Concern ◽  
N Management ◽  
N Status

Nitrogen (N) management in macadamia (Macadamia integrifolia) orchards is an important concern for growers. Leaf tissue analysis is the accepted method for determining N status in macadamia; however, this process is expensive and time-consuming. The chlorophyll meter has been used in other crops to estimate N status in plants through estimation of the amount of chlorophyll in leaf tissue. The use of the chlorophyll meter in two macadamia cultivars (Kakea and Kau) at two locations in Hawai’i (Kapa’au and Pahala) and five time periods (12 Apr. 2017, 13 June 2017, 15 June 2017, 18 Dec. 2017, and 20 Feb. 2018) was assessed. Leaf samples were collected based on a tissue-sampling protocol, chlorophyll meter (SPAD) values were collected, and leaves were analyzed for total N concentration. Data were analyzed statistically using linear regression. Leaf tissue N concentration had a positive monotonic relationship to SPAD values for both macadamia cultivars, both locations, and all sampling periods. The sampling period of Apr. 2017 for ‘Kakea’ macadamia had the greatest R2 value for the linear regression at 0.85. The Feb. 2018 sampling period had an R2 value for the linear regression of 0.74. ‘Kau’ macadamia had the greatest R2 value for the linear regression of 0.24 in the Dec. 2017 sampling period. The slopes of the two macadamia cultivars for June 2017 were different from each other, suggesting that N recommendations need to be customized for specific macadamia cultivars if sampled in summer. The chlorophyll meter can be used for general estimation of tissue N in macadamia. Additional methods need to be considered and researched to refine procedures for direct estimation of total N concentration when using the chlorophyll meter.

scholarly journals Sweet Corn Crop Nitrogen Status Evaluation by Stalk Testing

HortScience ◽  
2002 ◽  
Vol 37 (5) ◽  
pp. 783-786 ◽  
Author(s):  
Joseph R. Heckman ◽  
Ray Samulis ◽  
Peter Nitzsche
Keyword(s):  
Zea Mays ◽  
Crop Yield ◽  
Sweet Corn ◽  
Soil Nitrate ◽  
Corn Stalk ◽  
Leaf Material ◽  
N Fertility ◽  
N Management ◽  
Time Of Harvest ◽  
N Status

Sweet corn (Zea mays L.) growers evaluating new practices for N management, such as the presidedress soil nitrate test (PSNT), are interested in relating observations about crop performance at time of harvest to their N fertility program. For this purpose, the concentration of nitrogen (N) in the lower portion of sweet corn stalks was examined on the day of harvest as a basis for evaluating the crop N status. Sweet corn stalk tissue was collected from N-rate experiments by cutting a stalk section at 15 and 35 cm aboveground and removing leaf material from the resulting 20-cm segment. Samples were dried and analyzed for total Kjeldahl N. Relationships between crop yield and stalk N concentration indicated that concentrations <11 g·kg-1 are N deficient and underfertilized; N concentrations between 11 and 16.5 g·kg-1 are marginally deficient; and between 16.5 and 21 g·kg-1 the N status is optimum. Concentrations of N >21 g·kg-1 are above optimum and indicate that sweet corn was overfertilized with N. When soil nitrate concentrations (PSNT >25 mg NO3-N per kilogram) indicated sufficient N at time of sidedressing, stalk N concentrations generally indicated N sufficiency at harvest.

scholarly journals Lettuce Response and Nitrate-N Leaching to Water and Nitrogen on Sand

HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 445E-445
Author(s):  
C.A. Sanchez
Keyword(s):  
Irrigation System ◽  
N Leaching ◽  
Vegetable Production ◽  
Rooting Zone ◽  
Maximum Economic Yield ◽  
Nitrate N ◽  
Large N ◽  
Leaching Fraction ◽  
Lettuce Yield ◽  
N Management

The low desert region of Arizona is the major area of lettuce (Lactuca sativa L.) production during the winter. Most lettuce is grown on alluvial valley loam and clay loam soils. There is interest in moving some vegetable production onto sandy soils on the upper terraces (mesa) to partially relieve the intensive production pressure currently being placed on land in the valleys. Water and N management is a major concern in coarse-textured soils. Studies were conducted to evaluate the response of crisphead lettuce to sprinkler-applied water and N fertilizer on a coarse-textured soil (>95% sand). The experiments were irrigated using a modified lateral irrigation system that applied five levels of water and five levels of N in specified combinations. Nitrate-N concentrations were determined in samples collected in ceramic suction cups placed below the crop rooting zone. Leaching fraction was estimated by frequent neutron probe soil moisture measurements. Lettuce yield increased with water and N but rates required for maximum economic yield exceeded rates typically required on finer-textured valley soils. These data show the potential for large N leaching losses on this coarse-textured soil.

Effect of gamma radiation on the structural, thermal and optical properties of PMMA/Sn0.75Fe0.25S2 nanocomposite

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Ali A. Alhazime ◽  
Nesreen T. El-Shamy ◽  
Kaoutar Benthami ◽  
Mai ME. Barakat ◽  
Samir A. Nouh
Keyword(s):  
Thermal Stability ◽  
Optical Properties ◽  
Gamma Irradiation ◽  
Optical Band Gap ◽  
Color Variation ◽  
Nanocomposite Films ◽  
Color Changes ◽  
Gamma Irradiated ◽  
Intermolecular Crosslinking ◽  
Amorphous Part

AbstractNanocomposite films of polymethylmethacrylate PMMA with Sn0.75Fe0.25S2 nanoparticles (NPs) were fabricated by both thermolysis and casting techniques. Changes in PMMA/Sn0.75Fe0.25S2 nanocomposite (NCP) due to gamma irradiation have been measured. XRD results indicate that the gamma doses of 10–80 kGy cause intermolecular crosslinking that reduces the ordered portion in the NPs. Bonding between the NPs and the host PMMA was confirmed by FTIR. TGA results indicate an enhancement in thermal stability in the NCP films irradiated with doses 20–80 kGy. The optical band gap was reduced from 3.23 to 2.47 eV upon gamma irradiation up to 80 kGy due bonding between the NPs and PMMA which enhanced the amorphous part of the NPs. Finally, the color variation between the blank and irradiated films (ΔE) was determined. Color changes immensely when the PMMA/Sn0.75Fe0.25S2 NCP films are gamma irradiated. Values of ΔE were as much as 31.6 which is an acceptable match in commercial reproduction on printing presses.

scholarly journals Urban Organic Waste for Urban Farming: Growing Lettuce Using Vermicompost and Thermophilic Compost

Agronomy ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1175
Author(s):  
Corinna Schröder ◽  
Franziska Häfner ◽  
Oliver Christopher Larsen ◽  
Ariane Krause
Keyword(s):  
Organic Waste ◽  
Nutrient Management ◽  
Nutrient Recycling ◽  
Mineral Fertilization ◽  
Urban Waste ◽  
Sustainable Food ◽  
Fertilizer Value ◽  
Sand Control ◽  
Lettuce Growth ◽  
Lettuce Yield

A transformation towards sustainable food production requires improved circular nutrient management. Urban organic waste contains relevant nutrients and organic matter, yet only 4% of global urban nitrogen (N) and phosphorus (P) sources are presently recycled. One recycling approach is the composting of urban wastes for urban horticulture. We characterized compost from various urban waste fractions and assessed their fertilizer value in a pot trial with lettuce plants. Seven treatments were investigated: food waste vermicompost with coir and paperboard bedding material, thermophilic compost from green waste and human feces, two references with mineral fertilization and a sand control. The lettuce yield and total uptake of P, potassium (K), calcium (Ca), and magnesium (Mg) were highest in plants grown in coir-based vermicompost. The fecal compost led to the highest shoot P and K content, but the shoot uptake of Ca and Mg were lower than in the other treatments. All composts required additional N for lettuce growth. In conclusion, urban waste-derived vermicompost and fecal compost demonstrate a high delivery rate of plant-available Ca, Mg, P, and K. Research is needed on macronutrient availability and alternative N sources for the substitution of synthetic fertilization. These findings support the production of urban waste composts, furthering efforts in nutrient recycling.

scholarly journals Evaluation of color change in acrylic and bisacrylic resin resins in different solutions

2018 ◽  
Vol 5 (4) ◽  
pp. 76
Author(s):  
Mone Laiz Bortoli ◽  
Cristina Von Appen ◽  
Camila Longoni ◽  
Carmen Beatriz Borges Fortes ◽  
Jefferson Tomio Sanada
Keyword(s):  
Color Change ◽  
Color Stability ◽  
Acrylic Resin ◽  
Color Variation ◽  
Color Reading ◽  
Control Group ◽  
Color Changes ◽  
Significant Difference ◽  
Prosthesis Material ◽  
Chlorhexidine Solution

Aim: This work aimed to evaluate the color stability of an acrylic resin chemically activated (ARCA) using different handling techniques, and a bisacrylic resin when exposed to different pigmentation solutions.Material and Methods: Silicon matrixes were confectioned (10x10x3mm) to be used as specimens. The groups were designed as follows: Group Pot, Group Brush, Group Manufacturer and Group Bisacrylic (n=18). Each group was exposed to three different pigmentation solutions: distilled water, coke and chlorhexidine digluconate 0.12%. Three readings were performed for each specimen using a spectrophotometer, and the evaluations were carried out in three different time. After the color reading, three averages and the standard deviation of variation were performed after 24 hours (T1), 7 days (T2) and 14 days (T3). Data were submitted to the ANOVA and 2 criteria and Tukey (P<0.05) in the statistical software SSPS 18 for Macintosh (SPSS Inc., Chicago, USA).Results: When compared the solutions in each group of material, there was no statistically significant difference, except for T3, where the group Dencor Brush and Bisacrylic demonstrated higher color variation in all the solutions, even in the control group, and the values in Chlorhexidine higher than the other, showing greater instability after 14 days.Conclusions: With the results, bisacrylic resin used as provisory prosthesis material presents greater color instability than the ARCA, when submitted to different solutions. Bisacrylic resin and Dencor Brush present significantly visible color changes in chlorhexidine solution after 14 days. All the materials in coke solution present homogeneity in the color change after 7 days exposition to the solution, with no visible color change.

scholarly journals LEAF TOTAL NITROGEN CONCENTRATION AS AN INDICATOR OF NITROGEN STATUS FOR PLANTLETS AND YOUNG PLANTS OF EUCALYPTUS CLONES

2015 ◽  
Vol 39 (4) ◽  
pp. 1127-1140 ◽  
Author(s):  
Eric Victor de Oliveira Ferreira ◽  
Roberto Ferreira Novais ◽  
Bruna Maximiano Médice ◽  
Nairam Félix de Barros ◽  
Ivo Ribeiro Silva
Keyword(s):  
Total Nitrogen ◽  
Block Design ◽  
Nitrogen Concentration ◽  
Soil N ◽  
Total N ◽  
Chlorophyll Meter ◽  
N Concentration ◽  
Total Nitrogen Concentration ◽  
N Status ◽  
Leaf N

The use of leaf total nitrogen concentration as an indicator for nutritional diagnosis has some limitations. The objective of this study was to determine the reliability of total N concentration as an indicator of N status for eucalyptus clones, and to compare it with alternative indicators. A greenhouse experiment was carried out in a randomized complete block design in a 2 × 6 factorial arrangement with plantlets of two eucalyptus clones (140 days old) and six levels of N in the nutrient solution. In addition, a field experiment was carried out in a completely randomized design in a 2 × 2 × 2 × 3 factorial arrangement, consisting of two seasons, two regions, two young clones (approximately two years old), and three positions of crown leaf sampling. The field areas (regions) had contrasting soil physical and chemical properties, and their soil contents for total N, NH+4-N, and NO−3-N were determined in five soil layers, up to a depth of 1.0 m. We evaluated the following indicators of plant N status in roots and leaves: contents of total N, NH+4-N, NO−3-N, and chlorophyll; N/P ratio; and chlorophyll meter readings on the leaves. Ammonium (root) and NO−3-N (root and leaf) efficiently predicted N requirements for eucalyptus plantlets in the greenhouse. Similarly, leaf N/P, chlorophyll values, and chlorophyll meter readings provided good results in the greenhouse. However, leaf N/P did not reflect the soil N status, and the use of the chlorophyll meter could not be generalized for different genotypes. Leaf total N concentration is not an ideal indicator, but it and the chlorophyll levels best represent the soil N status for young eucalyptus clones under field conditions.

scholarly journals Spectrophotometric Evaluation of Enamel Color Variation Using Infiltration Resin Treatment of White Spot Lesions at One Year Follow-Up

2020 ◽  
Vol 8 (2) ◽  
pp. 35 ◽  
Author(s):  
Roberto Lo Giudice ◽  
Frank Lipari ◽  
Francesco Puleio ◽  
Angela Alibrandi ◽  
Fabrizio Lo Giudice ◽  
...  
Keyword(s):  
Color Change ◽  
Statistical Significance ◽  
Color Variation ◽  
White Spot ◽  
White Spot Lesions ◽  
Color Changes ◽  
The Difference ◽  
One Year ◽  
The Stability

The aim of this study is to evaluate the color changes and the stability at a 1-year follow-up of white spot lesions (WSLs) treated with an infiltrating technique by using etching and TEGDMA resin. The color of 22 white spot lesions and the sound adjacent enamel (SAE) were assessed with a spectrophotometer at T0 (baseline), T1 (after treatment), and T2 (1 year after). The color change ΔE (WSLs-SAE) at T0 vs. T1 were compared to evaluate the camouflage effect efficiency, and at T1 vs. T2 to assess the stability of outcomes. To evaluate the effect on the treatment outcome of gender, the presence or not of previous orthodontic treatment, WSLs onset more/less than 10 years, the age of the patient, and the ΔE WSL (T0 vs. T1) was analyzed. The difference between ΔE (WSLs-SAE) at T0 and T1 resulted in statistical significance (p < 0.01). No statistical difference was found between ΔE (WSLs-SAE) at T1 vs. T2. The variables considered showed no statistical differences in treatment outcomes. The results of our investigation show that the technique used is immediately effective and the camouflage effect keeps up and steady one year after treatment. Such results do not appear to be influenced by analyzed clinical variables.

Chlorophyll Meter for the Evaluation of Potato N Status

2013 ◽  
Vol 90 (4) ◽  
pp. 313-323 ◽  
Author(s):  
Claudia M. Giletto ◽  
Hernán E. Echeverría
Keyword(s):  
Chlorophyll Meter ◽  
N Status

scholarly journals Mechanoresponsive liquid crystals exhibiting reversible luminescent color changes at ambient temperature

2016 ◽  
Vol 4 (14) ◽  
pp. 2752-2760 ◽  
Author(s):  
Masato Mitani ◽  
Shuhei Ogata ◽  
Shogo Yamane ◽  
Masafumi Yoshio ◽  
Miki Hasegawa ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Ambient Temperature ◽  
Color Variation ◽  
Subsequent Aging ◽  
Color Changes ◽  
Mechanical Shearing

Oligothiophene-based liquid crystals having a wide luminescent color variation exhibit reversible luminescent color changes induced by mechanical shearing and subsequent aging at ambient temperature.

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