Journal articles on the topic 'Lettuce'
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1
Ma, Yidong, Yin Zhang, Xin Jin, Xinping Li, Huankun Wang, and Chong Qi. "A Visual Method of Hydroponic Lettuces Height and Leaves Expansion Size Measurement for Intelligent Harvesting." Agronomy 13, no. 8 (July 27, 2023): 1996. http://dx.doi.org/10.3390/agronomy13081996.
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Harvesting is an important procedure for hydroponic lettuces in plant factories. At present, hydroponic lettuces are mainly harvested manually, and the key difficulty in mechanical harvesting is reducing the occurrence of leaf injury. Measuring the size of hydroponic lettuces using the image processing method and intelligently adjusting the operating parameters of the harvesting device are the foundation of high-quality harvesting for lettuces. The overlapped leaves of adjacent hydroponic lettuces cause difficulties in measuring lettuce size, especially the leaves expansion size. Therefore, we proposed an image processing method for measuring lettuce height and leaves expansion size according to the upper contour feature of lettuces and an image included three lettuces. Firstly, the upper contours of the lettuces were extracted and segmented via image preprocessing. Secondly, lettuce height was measured according to the maximum ordinate of the contour. Lastly, the lettuce’s upper contour was fitted to a function to measure the leaves expansion size. The measurement results showed that the maximal relative error of the lettuce height measurements was 5.58%, and the average was 2.14%. The effect of the quadratic function in fitting the upper contour was the best compared with the cubic function and sine function. The maximal relative error of the leaves expansion size measurements was 8.59%, and the average was 4.03%. According to the results of the lettuce height and leaves expansion size measurements, the grabbing parameters of each lettuce were intelligently adjusted to verify the harvesting effect. The harvesting success rates of lettuces was above 90%, and the injured leaves areas of the left, middle, and right lettuces in each image were 192.6 mm2, 228.1 mm2, and 205.6 mm2, respectively. This paper provides a reference for the design and improvement of intelligent harvesters for hydroponic lettuces.
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Martínez-Ispizua, Eva, Ángeles Calatayud, José Ignacio Marsal, Claudio Cannata, Federico Basile, Abdelsattar Abdelkhalik, Salvador Soler, José Vicente Valcárcel, and Mary-Rus Martínez-Cuenca. "The Nutritional Quality Potential of Microgreens, Baby Leaves, and Adult Lettuce: An Underexploited Nutraceutical Source." Foods 11, no. 3 (January 31, 2022): 423. http://dx.doi.org/10.3390/foods11030423.
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Interest in the cultivation of lettuce landraces is increasing because native varieties, as high-quality products, are particularly attractive to consumers. Lettuce is a popular leafy vegetable worldwide, and interest in the consumption of first leaves (microgreens) and seedlings (baby leaves) has grown due to the general belief that young plants offer higher nutritional value. The content of some bioactive compounds and antioxidants (chlorophylls, carotenoids, anthocyanins, ascorbic acid, phenols, antioxidant activity) was monitored in six lettuce landraces and five commercial varieties, and compared across three development stages: microgreen, baby, and adult. Ascorbic acid and phenolic contents were 42% and 79% higher, respectively, in the early stages than in adult lettuces, and red-leaf varieties (CL4 and L11) stood out. This finding agrees with lettuce’s marked antioxidant capacity and correlates with its pigment contents, especially anthocyanins. The nutritional value of adult lettuce is conditioned by its size, shape, and head structure as phytochemical concentrations are regulated by light. The low content of ascorbic acid, phenolics, and anthocyanins in crisphead lettuce (CL5) is a clear example (49, 67%, and 27% lower, respectively, than the adult mean). Our results indicate the wide variability of lettuces’ nutritional characteristics and emphasize that traditional varieties are a helpful source of agricultural biodiversity.
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Gisbert, Enric, Sandra Molas, Esteban Hernández, Ricard Carbó, and Alberto Ruiz. "Production of Flathead Grey Mullet (Mugil cephalus) and Lettuce (Lactuca sativa) in a Coupled Aquaponic System under Suboptimal Water Temperatures." Fishes 9, no. 6 (May 21, 2024): 189. http://dx.doi.org/10.3390/fishes9060189.
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The combined production of three varieties of lettuce (romaine, iceberg, and red leaf) with flathead grey mullet (Mugil cephalus) was tested in triplicate in three independent coupled aquaponic units with no thermal control. For this purpose, a total of 114 fish (2.5 kg/m3) were stocked in each fish tank (2 m3), and 92 lettuces were planted in the hydroponic unit (6 m2). As no thermal control was included in the design of the aquaponic system, water temperatures declined from maximum values of 20.4 °C to minimum values of 5.0 °C, which directly affected fish growth. However, the conditions imposed by the aquaponic system were suitable for promoting lettuce’s growth and external appearance, as no pests or leaf discoloration were noticed. Lettuce survival was similar among the three tested varieties (98.5 ± 1.7%). The yields for the romaine and iceberg varieties were 384 ± 100 g/lettuce and 316 ± 70 g/lettuce, respectively, and that for the red leaf variety was lower, at 176 ± 75 g/lettuce. Yield values ranged between 3.6 and 4.4 kg/m2 depending on the replicate considered (4.0 ± 0.4 kg/m2). According to present results, each aquaponic unit required ca. 2.6–2.7 L of water per unit of lettuce produced.
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Choosakul, Nithiwatthn, and Piyanath Pagamas. "The Influence of Color Shading Net on the Growing of Lettuce." Applied Mechanics and Materials 866 (June 2017): 33–36. http://dx.doi.org/10.4028/www.scientific.net/amm.866.33.
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Nowadays, shading net is widely use in Thailand, especially for vegetable production. Many colors of shading net can be found in the market. In this experiment, we set up three net houses for lettuce by using three colors of 50% transparent shading net, black, red and green. Ten of 15 days after planting (DAP) lettuces were moved to each color net house and control (direct sun). Total 40 lettuces were used for 10 days experiment. The result showed that the leave length and width of lettuce under red shading net respectively were significantly bigger than those under green shading net and control treatment without significant difference with the black shading net. The lettuce under red shading net had a highest stem diameter, fresh weight and dry weight comparing with others color shading net. The spectra of the solar radiations that transmitted through the red shading net were suitable for the photosynthesis of the lettuce leaves that could promote lettuce growth and yield.
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Ahsan, Mostofa, Sulaymon Eshkabilov, Bilal Cemek, Erdem Küçüktopcu, Chiwon W. Lee, and Halis Simsek. "Deep Learning Models to Determine Nutrient Concentration in Hydroponically Grown Lettuce Cultivars (Lactuca sativa L.)." Sustainability 14, no. 1 (December 31, 2021): 416. http://dx.doi.org/10.3390/su14010416.
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Deep learning (DL) and computer vision applications in precision agriculture have great potential to identify and classify plant and vegetation species. This study presents the applicability of DL modeling with computer vision techniques to analyze the nutrient levels of hydroponically grown four lettuce cultivars (Lactuca sativa L.), namely Black Seed, Flandria, Rex, and Tacitus. Four different nutrient concentrations (0, 50, 200, 300 ppm nitrogen solutions) were prepared and utilized to grow these lettuce cultivars in the greenhouse. RGB images of lettuce leaves were captured. The results showed that the developed DL’s visual geometry group 16 (VGG16) and VGG19 architectures identified the nutrient levels of lettuces with 87.5 to 100% accuracy for four lettuce cultivars, respectively. Convolution neural network models were also implemented to identify the nutrient levels of the studied lettuces for comparison purposes. The developed modeling techniques can be applied not only to collect real-time nutrient data from other lettuce type cultivars grown in greenhouses but also in fields. Moreover, these modeling approaches can be applied for remote sensing purposes to various lettuce crops. To the best knowledge of the authors, this is a novel study applying the DL technique to determine the nutrient concentrations in lettuce cultivars.
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Makkaew, P., M. Miller, H. J. Fallowfield, and N. J. Cromar. "Microbial risk in wastewater irrigated lettuce: comparing Escherichia coli contamination from an experimental site with a laboratory approach." Water Science and Technology 74, no. 3 (June 6, 2016): 749–55. http://dx.doi.org/10.2166/wst.2016.237.
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This study assessed the contamination of Escherichia coli, in lettuce grown with treated domestic wastewater in four different irrigation configurations: open spray, spray under plastic sheet cover, open drip and drip under plastic sheet cover. Samples of lettuce from each irrigation configuration and irrigating wastewater were collected during the growing season. No E. coli was detected in lettuce from drip irrigated beds. All lettuce samples from spray beds were positive for E. coli, however, no statistical difference (p > 0.05) was detected between lettuces grown in open spray or covered spray beds. The results from the field experiment were also compared to a laboratory experiment which used submersion of lettuce in wastewater of known E. coli concentration as a surrogate method to assess contamination following irrigation. The microbial quality of spray bed lettuces was not significantly different from submersed lettuce when irrigated with wastewater containing 1,299.7 E. coli MPN/100 mL (p > 0.05). This study is significant since it is the first to validate that the microbial contamination of lettuce irrigated with wastewater in the field is comparable with a laboratory technique frequently applied in the quantitative microbial risk assessment of the consumption of wastewater irrigated salad crops.
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Lee, Jung-Soo, Dulal Chandra, and Jinkwan Son. "Growth, Physicochemical, Nutritional, and Postharvest Qualities of Leaf Lettuce (Lactuca sativa L.) as Affected by Cultivar and Amount of Applied Nutrient Solution." Horticulturae 8, no. 5 (May 13, 2022): 436. http://dx.doi.org/10.3390/horticulturae8050436.
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The effects of different nutrient solution quantities on growth, physicochemical, nutritional, and postharvest qualities of lettuce were investigated. Two differently pigmented Korean leaf lettuce cultivars “Geockchima” and “Cheongchima” were grown in soilless perlite culture supplied with 250, 500, 1000, and 2000 mL·d−1·plant−1 nutrient solutions. Several growth parameters (plant height, leaf number, fresh weight, dry matter) were evaluated. The highest lettuce growth was observed when plants were supplied with 1000 mL·d−1·plant−1. Cultivating lettuces in the lowest nutrient solution quantity showed higher dry matter, crude fiber, osmolality, chlorophyll, and anthocyanin contents. Upon increasing the nutrient solution, the crispiness, greenness, and levels of ascorbic acid, nitrogen, and potassium, increased, while phosphorus and magnesium were unaffected, and calcium content declined. Postharvest qualities were better maintained in lettuces irrigated with the least amount of nutrient solution, extending their shelf life. We conclude that lettuce can be grown with 1000 mL·d−1·plant−1 for higher yield, and short-term storage and/or transportation. However, when lettuces need to be stored for a certain period, such as long-distance shipment, they should be cultivated with a limited nutrient solution, which requires further detailed investigation. The results of this study can be applied for distributing, storing, transporting, and marketing lettuce.
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Jefferson de Sá, Jean, Carolina Medeiros Vicentini-Polette, Marta Regina Verruma-Bernardi, Marta Helena Fillet Spoto, and Fernando César Sala. "Agronomic and sensory evaluation of lettuce in hydroponic system." Bioscience Journal 37 (December 29, 2021): e37074. http://dx.doi.org/10.14393/bj-v37n0a2021-53765.
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Lettuce is the most important leafy vegetable in Brazil. Hydroponic lettuce cultivation has grown due to the viability of harvesting throughout the year. In this context, this study aimed to evaluate the agronomic characteristics, color, and preference of curly lettuce in the NFT hydroponic system. Six lineages (6601-1A, 6601-2L, 7016-6A, 7119-1B, 7223-1A, and 7224-4A) and two commercial cultivars (Brida and Vanda) of lettuce were used, in a completely randomized blocks design with four replications. Shoot length, root length, stem length, number of leaves, stem diameter, plant diameter, shoot fresh mass, root fresh mass, chlorophyll content, instrumental color, and sensory characteristics were evaluated. As for agronomic evaluation, the bolting of 6601-2L lettuce was relevant in different attributes. The Vanda lettuce and the lineage 7016-6A presented best performances for shoot fresh mass (399.44 and 378.63 g, respectively), while the lineages 7119-1B and 6601-2L present the worst performance (279.50 and 273.13 g, respectively). There was variation in chlorophyll content and luminosity, however, the evaluators did not notice differences between lettuces for brightness or green color, as well as for crunchy texture. Lettuces 6601-2L, 7224-4A, 6601-1A, Brida, 7223-1A, and 7119-1B were preferred. The variation among plants may be due to different situations, such as harvesting times and bolting, and a direct relationship between agronomic properties and preference among lettuces has not been established yet.
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Ezziddine, Maha, and Helge Liltved. "Quality and Yield of Lettuce in an Open-Air Rooftop Hydroponic System." Agronomy 11, no. 12 (December 19, 2021): 2586. http://dx.doi.org/10.3390/agronomy11122586.
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In this study, the yield and growth performance of lettuce in an open-air rooftop hydroponic system were investigated. Lettuce was grown in a closed recirculating nutrient film technique (NFT) unit using a standard nutrient solution (NS). Yield, fresh weight, and nutrient content in the leaf tissue of the harvested lettuce were measured. The results were compared with the results obtained in indoor hydroponic lettuce growth with artificial lightning. Despite strong winds during the growth period, 25% of the total lettuce heads weighed twice the marketable weight; however, 25% of the total lettuce heads were below the marketable weight. A more efficient nutrient uptake was indicated by the lettuces in the rooftop system compared with the uptake in the indoor system. Foliar analysis revealed a higher content of all nutrients in the leaves of rooftop hydroponic lettuce compared with indoor hydroponic lettuce. This study suggests that hydroponic rooftop-grown lettuce can be competitive with their indoor counterparts if the rooftop hydroponic system is protected from extreme weather conditions.
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Jung, Dae-Ho, and Jung-Eek Son. "CO2 Utilization Strategy for Sustainable Cultivation of Mushrooms and Lettuces." Sustainability 13, no. 10 (May 13, 2021): 5434. http://dx.doi.org/10.3390/su13105434.
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Mushroom cultivation generates a large amount of CO2 that can be used sustainably. The objective of this study was to use actual cultivation and simulation to find a sustainable cultivation method that uses the CO2 generated by king oyster mushrooms for the production of romaine lettuces. A closed cultivation system consisting of one mushroom chamber, three lettuce chambers, and one gas-mixing chamber was used. Two cultivation conditions, non-continuous and continuous, were analyzed. The non-continuous system cultivated 15 lettuces and 12 mushroom bottles at a time every 25 and 16 days, respectively. The continuous system cultivated three lettuces and mushroom bottles every five and four days, respectively, so that each chamber contained mushrooms or lettuces at each growth stage. The CO2 concentrations in the lettuce and mushroom chambers were stably maintained above 1000 μmol∙mol−1 and below 2000 μmol∙mol−1 in the continuous system. Mathematical models were developed to analyze the CO2 concentration in each chamber. The shoot dry weight of lettuces grown in the mixed cultivation were 48.0%, 21.9%, 19.7%, and 18.1% at 10, 15, 20, and 25 days after transplanting, respectively, higher than those in the lettuce-only cultivation. Compared to mushroom-only cultivation, mixed cultivation reduced the accumulated CO2 emissions into the air by 80.6%. Thus, using CO2 from mushrooms to cultivate lettuce in a continuous cultivation system could reduce CO2 emissions into the air and enable mixed cultivation of mushrooms and lettuces, achieving sustainable agriculture.
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Mou, Beiquan, and Yong-Biao Liu. "Host Plant Resistance to Leafminers in Lettuce." Journal of the American Society for Horticultural Science 129, no. 3 (May 2004): 383–88. http://dx.doi.org/10.21273/jashs.129.3.0383.
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Leafminer (Liriomyza spp.) is a major insect pest of many important agricultural crops including lettuce (Lactuca sativa L.). The goals of this study were to evaluate lettuce genotypes for resistance to leafminers and to estimate the heritabilities of leafminer-resistant traits in the field, to examine the association among different resistant traits, and to study the mechanism of leafminer resistance in lettuce. Seventy-eight lettuce accessions and 232 F2 plants of crosses were evaluated for leafminer stings and the production of pupae and flies in the field in 2001 and 2002, and resistant genotypes were subjected to no-choice test. Wild species (Lactuca serriola L., L. saligna L., and L. virosa L.) had significantly fewer stings than cultivated lettuces. Among cultivated lettuces, sting densities were lowest on leaf lettuce and highest on romaine types. The sting results from the field were highly correlated with the results from insect cages (r = 0.770 and 0.756 for 2001 and 2002 tests, respectively), suggesting that a cage test can be used to screen for resistance in the field. Broad-sense heritability estimates for stings per unit leaf area in the field were 81.6% and 67.4% for 2001 and 2002 tests, respectively. The number of pupae produced per plant or per leaf was moderately correlated with sting density but was not correlated with leaf weight. Results suggest that both antixenosis and antibiosis exist in lettuce germplasm and resistant genotypes from choice tests remain resistant under no-choice conditions. These findings suggest that genetic improvement of cultivated lettuce for leafminer resistance is feasible.
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Mou*, Beiquan, and Yong-Biao Liu. "Resistance to Leafminers in Lettuce." HortScience 39, no. 4 (July 2004): 766C—766. http://dx.doi.org/10.21273/hortsci.39.4.766c.
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Leafminer (Liriomyza spp.) is a major insect pest of many important agricultural crops including lettuce (Lactuca sativa L.). The goals of this study were to evaluate lettuce genotypes for resistance to leafminers and to estimate the heritabilities of leafminer-resistant traits in the field, to examine the association among different resistant traits, and to study the mechanism of leafminer resistance in lettuce. Seventy-eight lettuce accessions and 232 F2 plants of crosses were evaluated for leafminer stings and the production of pupae and flies in the field in 2001 and 2002, and resistant genotypes were subjected to no-choice test. Wild species (Lactuca serriola L., L. saligna L., and L. virosa L.) had significantly fewer stings than cultivated lettuces. Among cultivated lettuces, sting densities were lowest on leaf lettuce and highest on romaine types. The sting results from the field were highly correlated with the results from insect cages (r = 0.770 and 0.756 for 2001 and 2002 tests, respectively), suggesting that a cage test can be used to screen for resistance in the field. Broad-sense heritability estimates for stings per unit leaf area in the field were 81.6% and 67.4% for 2001 and 2002 tests, respectively. The number of pupae produced per plant or per leaf was moderately correlated with sting density but was not correlated with leaf weight. Results suggest that both antixenosis and antibiosis exist in lettuce germplasm and resistant genotypes from choice tests remain resistant under no-choice conditions. These findings suggest that genetic improvement of cultivated lettuce for leafminer resistance is feasible.
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Mou, Beiquan. "Genetic Variation of Beta-carotene and Lutein Contents in Lettuce." Journal of the American Society for Horticultural Science 130, no. 6 (November 2005): 870–76. http://dx.doi.org/10.21273/jashs.130.6.870.
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There is increasing medical evidence for the health benefits derived from dietary intake of carotenoid antioxidants, such as β-carotene and lutein. Enhancing the nutritional levels of vegetables would improve the nutrient intake without requiring an increase in consumption. A breeding program to improve the nutritional quality of lettuce (Lactuca sativa L.) must start with an assessment of the existing genetic variation. To assess the genetic variability in carotenoid contents, 52 genotypes including crisphead, leaf, romaine, butterhead, primitive, Latin, and stem lettuces, and wild species were planted in the field in Salinas, Calif., in the Summer and Fall of 2003 with four replications. Duplicate samples from each plot were analyzed for chlorophyll (a and b), β-carotene, and lutein concentrations by high-performance liquid chromatography (HPLC). Wild accessions (L. serriola L., L. saligna L., L. virosa L., and primitive form) had higher β-carotene and lutein concentrations than cultivated lettuces, mainly due to the lower moisture content of wild lettuces. Among major types of cultivated lettuce, carotenoid concentration followed the order of: green leaf or romaine > red leaf > butterhead > crisphead. There was significant genetic variation in carotenoid concentration within each of these lettuce types. Crisphead lettuce accumulated more lutein than β-carotene, while other lettuce types had more β-carotene than lutein. Carotenoid concentration was higher in summer than in the fall, but was not affected by the position of the plant on the raised bed. Beta-carotene and lutein concentrations were highly correlated, suggesting that their levels could be enhanced simultaneously. Beta-carotene and lutein concentrations were both highly correlated with chlorophyll a, chlorophyll b, and total chlorophyll concentrations, suggesting that carotenoid content could be selected indirectly through chlorophyll or color measurement. These results suggest that genetic improvement of carotenoid levels in lettuce is feasible.
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Kupčinskienė, Asta, Aušra Brazaitytė, Neringa Rasiukevičiūtė, Alma Valiuškaitė, Armina Morkeliūnė, and Viktorija Vaštakaitė-Kairienė. "Vegetation Indices for Early Grey Mould Detection in Lettuce Grown under Different Lighting Conditions." Plants 12, no. 23 (November 30, 2023): 4042. http://dx.doi.org/10.3390/plants12234042.
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Early detection of pathogenic fungi in controlled environment areas can prevent major food production losses. Grey mould caused by Botrytis cinerea is often detected as an infection on lettuce. This paper explores the use of vegetation indices for early detection and monitoring of grey mould on lettuce under different lighting conditions in controlled environment chambers. The aim was focused on the potential of using vegetation indices for the early detection of grey mould and on evaluating their changes during disease development in lettuce grown under different lighting conditions. The experiment took place in controlled environment chambers, where day/night temperatures were 21 ± 2/17 ± 2 °C, a 16 h photoperiod was established, and relative humidity was 70 ± 10% under different lighting conditions: high-pressure sodium (HPS) and light-emitting diode (LED) lamps. Lettuces were inoculated by 7-day-old fungus Botrytis cinerea isolate at the BBCH 21. As a control, non-inoculated lettuces were grown under HPS and LEDs (non-inoculated). Then, the following were evaluated: Anthocyanin Reflectance Index 2 (ARI2); Carotenoid Reflectance Index 2 (CRI2); Structure Intensive Pigment Index (SIPI); Flavanol Reflectance Index (FRI); Greenness (G); Greenness 2 (G2); Redness (R); Blue (B); Blue Green Index 2 (BGI2); Browning Index 2 (BRI2); Lichtenthaler Index 1 (LIC1); Pigment Specific Simple Ratio (PSSRa and PSSRb); Gitelson and Merzlyak (GM1 and GM2); Zarco Tejada–Miller Index (ZMI); Normalized Difference Vegetation Index (NDVI); Simple Ratio (SR); Red-Eye Vegetation Stress Index (RVSI); Photochemical Reflectance Index (PRI); Photochemical Reflectance Index 515 (PRI515); Water Band Index (WBI); specific disease index for individual study (fD); Healthy Index (HI); Plant Senescence Reflectance (PSRI); Vogelmann Red Edge Index (VREI1); Red Edge Normalized Difference Vegetation Index (RENDVI); and Modified Red Edge Simple Ratio (MRESRI). Our results showed that the PSRI and fD vegetation indices significantly detected grey mould on lettuce grown under both lighting systems (HPS and LEDs) the day after inoculation. The results conclusively affirmed that NDVI, PSRI, HI, fD, WBI, RVSI, PRI, PRI515, CRI2, SIPI, chlorophyll index PSSRb, and coloration index B were identified as the best indicators for Botrytis cinerea infection on green-leaf lettuce (Lactuca sativa L. cv Little Gem) at the early stage of inoculated lettuce’s antioxidative response against grey mould with a significant increase in chlorophyll indices.
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Pradhan, Surendra K., Olufunke Cofie, Josiane Nikiema, and Helvi Heinonen-Tanski. "Fecal Sludge Derived Products as Fertilizer for Lettuce Cultivation in Urban Agriculture." Sustainability 11, no. 24 (December 11, 2019): 7101. http://dx.doi.org/10.3390/su11247101.
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Fecal sludge (FS) contains a significant amount of plant nutrients. FS (treated/untreated) has been used as soil ameliorant in several countries. Use of FS-based compost on lettuce may meet reservations due to possible microbiological contamination. The objectives of this research are: (1) To determine the fertilizer value of different formulations of sawdust and fecal sludge compost (SDFS) pellets, and (2) to compare the effect of these SDFS formulations with poultry manure, commercial compost, mineral fertilizer, and non-fertilization on lettuce cultivation. The SDFS products were made by enriching, and pelletized with ammonium sulphate, mineral-NPK, or ammonium sulphate + muriate of potash + triple superphosphate. Lettuce was cultivated in a greenhouse and an open field. The result showed that the saleable fresh weight lettuce yield obtained from all SDFS pellets with/without enrichments were higher than those obtained from commercial compost, poultry manure, mineral fertilizer, or no fertilizer. Cultivation in the open field gave higher yields than those in the greenhouse. No helminth eggs were detected in composts or lettuces. Some fecal coliforms were detected in lettuces fertilized with almost all fertilizers tested, including NPK and non-fertilized control. A properly treated fecal sludge-based fertilizer can be a sustainable solution for lettuce production, which helps urban and peri-urban agriculture.
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Zapata-Vahos, Isabel Cristina, Felipe Rojas-Rodas, Dorely David, Jaime A. Gutierrez-Monsalve, and Dagoberto Castro-Restrepo. "Comparison of antioxidant contents of green and red leaf lettuce cultured in hydroponic systems under greenhouse, and conventional soil culture." Revista Facultad Nacional de Agronomía Medellín 73, no. 1 (January 1, 2020): 9077–88. http://dx.doi.org/10.15446/rfnam.v73n1.77279.
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Hydroponic technologies have increased the cultivated area under greenhouses covered with UV filter polyethylene film. However, there is a concern about the antioxidant contents of lettuces produced under these systems. In this study, it was compared to the antioxidant contents of green and red leaf lettuces produced in two hydroponic systems in a greenhouse, against the ones produced with the conventional cultivation system by Colombian farmers. The antioxidant analysis revealed significant statistical differences for DPPH and Anthocyanin analyses (P=0) versus all other culture systems. The best results were obtained in the conventional cultivation. Red lettuce obtained the highest value of FRAP (655.3±82.6 mgAAE 100g-1), ABTS (17.8±6.9 mmolTE 100g-1), total phenols (680.2±69.3 mgGAE 100g-1) and anthocyanin (126.2±6.9 mgC3G 100g-1). Green lettuce exhibited the most antioxidant activity of DPPH (20.7±5.6 mmolTE 100g-1). These results suggest a detrimental effect of the greenhouse covered with UV filter polyethylene film in the antioxidant production of lettuce. Finally, red leaf lettuce showed better antioxidant capacity independent of the cultivation system.
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Mayorga, Cindy, Satoru Tsukagoshi, and Anna Sasaki. "Effect on the Growth and Nutritional Components in Two Red Lettuces (Lactuca sativa L.) Cultivated Under UV Light in a Mini Plant Factory." Journal of Agriculture and Crops, no. 56 (June 1, 2019): 71–77. http://dx.doi.org/10.32861/jac.56.71.77.
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Lettuce is one of the most suitable plant species to grow indoor or in a Plant Factory with Artificial lighting (PFAL) system, due to its short height and the relatively low light saturation point. Red lettuces are highly cultivated in PFALs, highly appreciated for its unique pigmentation and antioxidant activity, especially, the anthocyanin content that gives it the red color. However, red lettuces cultivated with PFAL in controlled environments face the challenge of having low anthocyanin content due of the lack of ultraviolet (UV) light that is necessary for its production. In this study, two red-lettuce cultivars ‘Annapolis’ and ‘Salanova’ were grown in a plant factory with LEDs (light-emitting diode) and UV light treatments to compare their growth trajectory and nutritional characteristics. Other characteristics such as Fresh Weight (FW) and total leaf area were measured to evaluate the influence of UV light in the lettuce growth. The nutritional quality of lettuces was assessed by measuring anthocyanins and polyphenols contents using a microplate reader and their ascorbic acid content measured via a reflectometer. Fresh Weight (FW), leaf area and leaf thickness under the conditions of this study, showed no effect (p>0.05) on the plants growth with the incorporation of UV radiation. However, the incorporation of UV light increased the functional components in ‘Annapolis’ and ‘Salanova’ lettuces. The polyphenol and anthocyanins contents in both lettuce cultivars showed significant differences (p<0.05). For ascorbic acid content, a significant difference was found only for ‘Annapolis’ lettuce. The incorporation of UV light can increase the functional ingredients such as polyphenols and anthocyanins without growth suppression for ‘Salanova’ cultivar. UV light increased polyphenol and anthocyanins contents in both cultivars, making them suitable cultivars for PFAL under the growth conditions used in this experiment. These results taken together can be used to improve the accumulation of functional ingredients in red lettuces without growth suppression incorporating UV light and that could be suitable for production in PFALs.
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Kreutz, Gustavo F., Germán V. Sandoya, Gary K. England, and Wendy Mussoline. "Exploring the Potential of Lettuce (Lactuca sativa L.) as an Early Crop in Florida’s Sandy Soils." HortScience 56, no. 1 (January 2021): 59–70. http://dx.doi.org/10.21273/hortsci15420-20.
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Lettuce (Lactuca sativa L.) is planted in Florida starting late fall at the end of September and continuing through the last harvest in May. In recent years, the season has shortened because of warm temperatures and weather-related events, such as rainfall at the beginning and the end of the season. During the transition between summer production in the Western U.S. lettuce season and the beginning of Florida’s winter production, there may be shortages of lettuce and other leafy vegetables in U.S. East Coast markets. In this research, we evaluated a set of lettuce breeding lines and cultivars in both sand and muck soils and a subset of romaine lettuces to determine whether lettuce planted in Florida’s sandy soils could help meet the supply shortage in the delay between the Western and Eastern U.S. lettuce seasons. Significant genetic variation and genotype × environment (G×E) interactions were observed among lettuce genotypes when planted in both sand and muck soils, suggesting that lettuce cultivars should be adapted and bred specifically for sandy soils. Romaine and butterhead lettuce lines produced higher yield in sandy soils; a particular romaine breeding line (BG18-0588) had good yield and less heat-related disorders when planted in warmer temperatures. Producing lettuce in sandy soils may have a higher production cost because of additional specific practices such as transplant production, plastic mulch, and fertigation, but these costs may be offset by increased productivity due to better weed control and nutrient timing. However, a future analysis should be conducted to elucidate the economic feasibility of producing lettuce in sandy soils.
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Faza, Qintar Layallia, Diana Chusna Mufida, Muhammad Ali Shodikin, Bagus Hermansyah, and Elvia Rahmi Marga Putri. "The Correlation between Personal Hygiene of Greengrocer and Coliform Bacteria Contamination in Lettuce in Jember Traditional Markets." Journal of Agromedicine and Medical Sciences 8, no. 2 (June 24, 2022): 91. http://dx.doi.org/10.19184/ams.v8i2.30237.
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Lettuce is a vegetable that is usually consumed in raw condition or unprocessed by people. Unprocessed vegetables can cause food-borne diseases. Lettuce that is not processed and being consumed directly can cause contamination by Coliform bacteria. The purpose of this study is to know the correlation between Greengrocer’s personal hygiene and Coliform bacteria contamination in lettuce in Jembertraditional markets. This research used a descriptive observational design with the cross-sectional approach. It took place in eight traditional markets in Jember Regency and Microbiology Laboratory, Faculty of Medicine, University of Jember. The samples used were 41 lettuces purchased from 41 traditional market sellers. The microbiological examination was performed in the laboratory using the most probable number method. The results showed that lettuce sellers had bad personal hygiene (92,7%) and the data from the most probable number test found 97,6% contaminated by Coliform bacteria. The bivariate analysis was used to know the relationship between personal hygiene vegetable seller and contamination Coliform bacteria in lettuce. Thep-value was 0,072, which means there was no relationship between personal hygiene vegetable seller and contamination Coliform bacteria in lettuce.
Keywords: lettuce, Coliform, contamination, personal hygiene
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Makkaew, P., M. Miller, N. J. Cromar, and H. J. Fallowfield. "The influence of the microbial quality of wastewater, lettuce cultivars and enumeration technique when estimating the microbial contamination of wastewater-irrigated lettuce." Journal of Water and Health 15, no. 2 (December 9, 2016): 228–38. http://dx.doi.org/10.2166/wh.2016.145.
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This study investigated the volume of wastewater retained on the surface of three different varieties of lettuce, Iceberg, Cos, and Oak leaf, following submersion in wastewater of different microbial qualities (10, 102, 103, and 104E. coli MPN/100 mL) as a surrogate method for estimation of contamination of spray-irrigated lettuce. Uniquely, Escherichiacoli was enumerated, after submersion, on both the outer and inner leaves and in a composite sample of lettuce. E. coli were enumerated using two techniques. Firstly, from samples of leaves – the direct method. Secondly, using an indirect method, where the E. coli concentrations were estimated from the volume of wastewater retained by the lettuce and the E. coli concentration of the wastewater. The results showed that different varieties of lettuce retained significantly different volumes of wastewater (p < 0.01). No statistical differences (p > 0.01) were detected between E. coli counts obtained from different parts of lettuce, nor between the direct and indirect enumeration methods. Statistically significant linear relationships were derived relating the E. coli concentration of the wastewater in which the lettuces were submerged to the subsequent E. coli count on each variety the lettuce.
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Bojilov, Dimitar, Soleya Dagnon, Kostadin Kostadinov, and Stoyan Filipov. "Polyphenol composition of lettuce cultivars affected by mineral and bio-organic fertilisation." Czech Journal of Food Sciences 38, No. 6 (December 23, 2020): 359–66. http://dx.doi.org/10.17221/97/2020-cjfs.
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Three types of Lactuca sativa L. plants (green lettuces Batavia cv. Maritima and cv. Winter Butterhead, red lettuce Lolo rosa cv. Tuska) were investigated for their polyphenol composition. The lettuce plants were grown in polyethylene greenhouses and treated with different fertilisers. The qualitative and quantitative polyphenol composition was evaluated according to the use of mineral, organic (Italpollina and Arkobaleno) and bio (Lombricompost and EKOprop NX) fertilisers. The individual polyphenol components (caffeoyl derivatives and quercetin glycosides) were determined by high-performance liquid chromatography and the sample differences were estimated. The differences in the polyphenol content in the green lettuce cultivars in dependence on fertilisation were much higher than those in the red cultivar. In general, the red lettuce Lolo rosa cv. Tuska was characterised by the highest content of polyphenols. The highest content of all components was determined in the samples of red lettuce with the use of organic fertiliser Arkobaleno. In. the red lettuce and the green lettuce cv. Winter Butterhead organic fertilisation resulted in the higher content of polyphenols in comparison with mineral fertilisation and unfertilised samples. An exception was observed in cv. Maritima, where the unfertilised samples showed higher content of polyphenols compared to the fertilised samples
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Gustave, Kouassi Adingra, Kouassi Kouassi Clément, Ouina Toualy Serge Thibaut, and Konate Ibrahim. "Risks of Salmonellosis Linked to the Consumption of Lettuce Grown on the Outskirts and in Unexploited Intra-Urban Areas of the City of Bouaké, Central-Côte d’Ivoire." Journal of Advances in Microbiology 24, no. 1 (January 13, 2024): 30–38. http://dx.doi.org/10.9734/jamb/2024/v24i1783.
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Lettuce is one of the most popular and consumed vegetables in the world. It could be contaminated with Salmonella spp. which would lead to food poisoning. The objective of this study was to quantitatively assess the risk of salmonellosis linked to the consumption of lettuce produced in Bouaké (Central-Côte d’Ivoire). A survey of 138 urban lettuce producers and 384 salad lettuce consumers was first conducted. Then, microbiological analyzes were carried out on forty-five lettuce samples collected in the city of Bouaké. A probabilistic approach was followed to quantitatively assess the risks associated with the consumption of lettuce. Finally, the risk of ingestion of the infectious dose which is 105 cells of Salmonella spp. was estimated by a Monte Carlo type simulation. Microbiological analyzes showed that Salmonella spp. loads ranged from 0 ± 0 CFU/g to 7.73.102 ± 2.33.101 CFU/g. Furthermore, the prevalence of Salmonella spp. in lettuce was 77.78%. The risk of salmonellosis exists and is 6.36% to 6.56%; i.e. 6,360 to 6,560 cases per 100,000 inhabitants. This study showed that lettuces were contaminated with Salmonella spp. There is a risk of developing typhoid or paratyphoid salmonellosis following their consumption.
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Afonso, Alexandra, Mariana Regato, Mariana Patanita, Silvana Luz, Maria João Carvalho, Annabel Fernandes, Ana Lopes, Adelaide Almeida, Idália Costa, and Fátima Carvalho. "Reuse of Pretreated Agro-Industrial Wastewaters for Hydroponic Production of Lettuce." Water 15, no. 10 (May 13, 2023): 1856. http://dx.doi.org/10.3390/w15101856.
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The utilization of agro-industrial wastewaters (AIWWs), pretreated by immediate one-step lime precipitation + natural carbonation, as a nutritive solution for the hydroponic production of lettuce was evaluated. The AIWWs studied were olive mill wastewater (OMW), winery wastewater (WW), and cheese whey wastewater (CWW). Lettuces (Lactuca sativa L. var. crispa) were grown in a closed nutrient film technique hydroponic system, using the pretreated AIWWs (OMW-T, WW-T, and CWW-T) and a control nutrient solution (CNS). The growth and sensory analysis of lettuces and the environmental parameters of effluents after hydroponics were evaluated. The average number of lettuce leaves obtained with nutrient solutions prepared with AIWW-T was lower than that from CNS, but the highest lettuce chlorophyll content was attained with CWW-T, which also presented the best grow results. In general, sensory analysis did not show significant differences from the lettuces grown in the different pretreated AIWWs and CNS. As for the environmental parameters of the effluents from hydroponics, according to the Portuguese legislation, only the chemical oxygen demand of the OMW-T and WW-T presented slightly higher values than that of the environmental limit values for discharge in surface waters, showing the feasibility of using pretreated agro-industrial effluents in hydroponic lettuce cultivation, while obtaining a treated effluent, in a circular economy perspective.
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Stufkens, M. A. W., and A. R. Wallace. "Effectiveness and persistence of six insecticides for control of lettuce aphid on field lettuce in Canterbury New Zealand." New Zealand Plant Protection 57 (August 1, 2004): 233–38. http://dx.doi.org/10.30843/nzpp.2004.57.6916.
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Since its arrival in March 2002 lettuce growers in New Zealand have been struggling to control the lettuce aphid (Nasonovia ribisnigri) using topically applied insecticides Potter tower tests have shown there is some level of resistance in New Zealand to two insecticides (acephate and methomyl) at the recommended field rate A field trial was set up to examine the effectiveness and persistence of six insecticides on autumn sown seedling lettuces for control of the lettuce aphid Acephate and methomyl failed to give complete kill of lettuce aphids unlike the other four insecticides tested The synthetic pyrethroid lambdacyhalothrin gave a higher level of protection having both a longer persistence period than the other insecticides tested and a significantly lower rate of increase in aphid numbers
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Lucas, J. Raul, Daphne Ramos, S. Sonia Balcázar, and Carlos Santos. "The Presence of Potentially Pathogenic Protozoa in Lettuce (Lactuca sativa) Sold in Markets in the Central Peruvian Andes." International Journal of Environmental Research and Public Health 20, no. 2 (January 4, 2023): 943. http://dx.doi.org/10.3390/ijerph20020943.
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Peru is currently one of the world’s leading culinary destinations, whose world-renowned cuisine uses vegetables, mainly lettuce, as frequent ingredients. Vegetable consumption is promoted worldwide as a part of a healthy diet. However, vegetables, more frequently lettuce, have been implicated as a vehicle of infection for several foodborne parasites. This study aimed to determine the presence of potentially pathogenic parasites in lettuce marketed in the Central Andes of Peru. A total of 75 lettuce samples were collected from the two largest wholesale markets and the main open-air market in Jauja province, in the central Peruvian Andes. The province of provenance (coast vs. highlands), lettuce variety (“curly-leaf”, “iceberg”, and “butter”), and type of market were recorded. The samples were microscopically examined for detection of parasitic life forms using standard parasitological methods including direct slide smear, Lugol’s iodine staining, and Modified Ziehl–Neelsen staining. The overall positivity of parasitic contamination in lettuces was 45.3% (CI 95%: 34–56.6%). Cryptosporidium spp., Isospora belli, Giardia lamblia, Balantidium coli, and Entamoeba spp. were detected in twenty-six (34.7%), six (8%), four (5.3%), two (2.7%), and two (2.7%) lettuces, respectively. I. belli was found in a significantly (p < 0.01) lower proportion in the “butter” variety, and significantly (p < 0.05) higher contamination with G. lamblia was found in lettuce sold at the open-air market. B. coli, G. lamblia, and E. histolytica/E. dispar/E. moshkovskii were detected only in lettuce from the highlands (Tarma province). This study provides important data for health authorities to develop food safety programs. This information is also of interest to the international community because of the increased visibility that Peru has gained as a tourist destination.
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Mou, Beiquan, and Yong-Biao Liu. "Leafminer Resistance in Lettuce." HortScience 38, no. 4 (July 2003): 570–72. http://dx.doi.org/10.21273/hortsci.38.4.570.
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Leafminer (Liriomyza langei Frick) is a major insect pest of many important agricultural crops including lettuce (Lactuca sativa L.). The goals of this study were to evaluate lettuce genotypes for resistance to leafminer and to estimate heritabilities of three leafminer-resistant traits. Forty-six lettuce genotypes were evaluated in two tests in insect cages. Wild species (Lactuca serriola L., Lactuca saligna L., and Lactuca virosa L.) had significantly fewer leafminer stings than cultivated lettuce (L. sativa) in both tests. PI 509525 (L. saligna) had few leafminer stings and no flies emerged. Leaf (leaf and romaine) lettuce also showed significantly less stings than head (crisphead and butterhead) types, while differences between leaf and romaine lettuces, and between crisphead and butterhead types were nonsignificant. Broad-sense heritability for number of stings per unit leaf area was relatively high, averaging 65% over the two tests. Heritabilities for egg-hatching period and flies per plant were 10% and 15%, respectively. Stings per unit leaf area from the two tests were highly correlated (r = 0.828), suggesting that resistance was stable over different plant ages and against different pressures of leafminer. These results suggest that genetic improvement of cultivated lettuce for leafminer resistance is feasible.
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LEE, JONG WHAN. "MACHINE VISION MONITORING SYSTEM OF LETTUCE GROWTH IN A STATE-OF-THE-ART GREENHOUSE." Modern Physics Letters B 22, no. 11 (May 10, 2008): 953–58. http://dx.doi.org/10.1142/s0217984908015668.
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Farmers want a monitoring system to support decisions for plant cultivation and to obtain information for plant health conditions. This study established the remote monitoring system in a greenhouse and provided the machine vision system with remote control camera to extract plant images, to analyze a trend of lettuce growth, and to predict fresh weights of lettuce plants. The calibration bars with color patches were used for the geometric calibration and the extraction of lettuce regions from the image captured under sunlight conditions. The fresh weight prediction model was developed by the image analysis of lettuces growing in a greenhouse.
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de Aquino, Nathanyelle Soraya Martins, Susana de Oliveira Elias, and Eduardo Cesar Tondo. "Evaluation of PhageDX Salmonella Assay for Salmonella Detection in Hydroponic Curly Lettuce." Foods 10, no. 8 (August 3, 2021): 1795. http://dx.doi.org/10.3390/foods10081795.
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Lettuce is one of the most consumed leafy vegetables worldwide and has been involved in multiple foodborne outbreaks. Salmonella is one of the most prevalent etiological agents of foodborne disease (FBD) in lettuces, and its detection may take several days depending on the chosen method. This study evaluates a new rapid method that uses recombinant bacteriophages to detect Salmonella in hydroponic curly lettuce. First, the ability of the assay to detect six Salmonella serovars at three different concentrations (1, 10, and 100 CFU/well) was tested. Second, the detection of Salmonella was tested in lettuces using a cocktail of the same Salmonella serovars and concentrations after a 7 h enrichment. The results of these experiments showed that the detection limit was dependent on the serovar tested. Most serovars were detected in only 2 h when the concentration was 100 CFU/well. Salmonella was detected in 9 h (7 h enrichment + 2 h bioluminescence assay) in all lettuce samples with 10 CFU/25 g or more. Salmonella detection was not influenced by natural microbiota of lettuces. This study demonstrated that the phage assay was sensitive and faster than other detection methods, indicating that it is a better alternative for Salmonella detection on lettuces.
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Erwanto, Danang, and Yudo Bismo Utomo. "Image Extraction of Lettuce Leaves using Fast Fourier Transform Method and Color Moments." JEEMECS (Journal of Electrical Engineering, Mechatronic and Computer Science) 5, no. 2 (September 26, 2022): 55–62. http://dx.doi.org/10.26905/jeemecs.v5i2.5275.
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Lettuce (Lactuca sativa L.) is a seasonal leaf vegetable with high nutritional content which is usually fresh for consumption. Typical harvest age for lettuce is 45 days. Lettuce which is harvested more than 45 days will affect the taste of the lettuce. In addition to the lettuce’s age, there are several things that can affect taste of the lettuce, including room temperature, harvest time, and thickness of the leaf color. In this study, Fast Fourier transform (FFT) was used as feature extraction by changing the spatial domain in frequency domain image of the lettuce leaves, while the color moment method was used as the extraction of lettuce leaves. With this digital image processing, it can automatically identify maturity level of lettuce leaves. The classification process uses the Naïve Bayes method with the Weka application. The obtained results of texture and color extraction using FFT method and the color moment using Naïve Bayes classification method in the Weka application work well. From the results of the age classification of lettuce based on its leaf color, the average percentage of total accuracy was 94.4%. The correlation of color and taste using the correlation test which performed by SPSS, and it was found that there are positive relationship between color and taste with sig. (1-tailed) 0.05.
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Malarz, Janusz, Klaudia Michalska, and Anna Stojakowska. "Stem Lettuce and Its Metabolites: Does the Variety Make Any Difference?" Foods 10, no. 1 (December 29, 2020): 59. http://dx.doi.org/10.3390/foods10010059.
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The objective of the present study was to characterize chemical composition of hitherto unexamined aerial parts of Lactuca sativa var. angustana cv. Grüner Stern. In contrast to leafy and head varieties of the lettuces, asparagus lettuce grown in Europe is much less studied. Fractionation of a methanolic extract from leaves of L. sativa cv. Grüner Stern, supported with HPLC/DAD and 1H NMR analysis, led to the isolation and/or identification of numerous terpenoid and phenolic compounds, including five apocarotenoids—(-)-loliolide, (+)-dehydrovomifoliol, blumenol A, (6S,9S)-vomifoliol, and corchoionoside C; three sesquiterpene lactones; two lignans—((+)-syringaresinol and its 4-O-β-glucoside); five caffeic acid derivatives; and three flavonoids. Some of the compounds, to the best of our knowledge, have never been isolated from L. sativa before. Moreover, monolignols, phenolic acids and a tryptophan-derived alkaloid were found in the analyzed plant material. Stems, leaves and shoot tips of the asparagus lettuce were examined to assess their phenolics and sesquiterpene lactone content as well as DPPH scavenging activity. Another stem lettuce—L. sativa var. angustana cv. Karola, two cultivars of leafy lettuces and one species of wild lettuce—L. serriola, were also examined as a reference material using HPLC/DAD. The results have been discussed regarding our previous studies and the literature data available.
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Eshkabilov, Sulaymon, John Stenger, Elizabeth N. Knutson, Erdem Küçüktopcu, Halis Simsek, and Chiwon W. Lee. "Hyperspectral Image Data and Waveband Indexing Methods to Estimate Nutrient Concentration on Lettuce (Lactuca sativa L.) Cultivars." Sensors 22, no. 21 (October 25, 2022): 8158. http://dx.doi.org/10.3390/s22218158.
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Lettuce is an important vegetable in the human diet and is commonly consumed for salad. It is a source of vitamin A, which plays a vital role in human health. Improvements in lettuce production will be needed to ensure a stable and economically available supply in the future. The influence of nitrogen (N), phosphorus (P), and potassium (K) compounds on the growth dynamics of four hydroponically grown lettuce (Lactuca sativa L.) cultivars (Black Seeded Simpson, Parris Island, Rex RZ, and Tacitus) in tubs and in a nutrient film technique (NFT) system were studied. Hyperspectral images (HSI) were captured at plant harvest. Models developed from the HSI data were used to estimate nutrient levels of leaf tissues by employing principal component analysis (PCA), partial least squares regression (PLSR), multivariate regression, and variable importance projection (VIP) methods. The optimal wavebands were found in six regions, including 390.57–438.02, 497–550, 551–600, 681.34–774, 802–821, and 822–838 nm for tub-grown lettuces and four regions, namely 390.57–438.02, 497–550, 551–600, and 681.34–774 nm for NFT-system-grown lettuces. These fitted models’ levels showed high accuracy (R2=0.85−0.99) in estimating the growth dynamics of the studied lettuce cultivars in terms of nutrient content. HSI data of the lettuce leaves and applied N solutions demonstrated a direct positive correlation with an accuracy of 0.82–0.99 for blue and green regions in 400–575 nm wavebands. The results proved that, in most of the tested multivariate regression models, HSI data of freshly cut leaves correlated well with laboratory-measured data.
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Hayes, Ryan J., Bo Ming Wu, Barry M. Pryor, Periasamy Chitrampalam, and Krishna V. Subbarao. "Assessment of Resistance in Lettuce (Lactuca sativa L.) to Mycelial and Ascospore Infection by Sclerotinia minor Jagger and S. sclerotiorum (Lib.) de Bary." HortScience 45, no. 3 (March 2010): 333–41. http://dx.doi.org/10.21273/hortsci.45.3.333.
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Lettuce drop caused by Sclerotinia spp. is an economically important disease of lettuce (Lactuca sativa L.), and cultivars with resistance to mycelial infection by Sclerotinia sclerotiorum (Lib.) de Bary and S. minor Jagger as well as to S. sclerotiorum ascospores are needed. Assessing resistance in field experiments can be complicated by fast bolting or small stature lettuce lines that may escape rather than resist the pathogens. Therefore, methods to select resistant lines from morphologically variable populations are needed. We used S. sclerotiorum and S. minor-infested field experiments, regression analysis, field experiments with artificially high plant densities, and S. sclerotiorum ascospore inoculations to identify lettuce lines with resistance to both pathogens. Three replicated experiments in S. sclerotiorum-infested fields were conducted in Yuma, AZ, and three replicated experiments in a S. minor-infested field were conducted in Salinas, CA, using diverse populations of iceberg, romaine, leaf, butterhead, Latin, oilseed lettuce, and wild relatives of lettuces; and genetic variation for the incidence of lettuce drop from mycelial infections was identified. In two S. minor field experiments, a quadratic regression model was developed that related rapid bolting with reduced lettuce drop. Regression residuals were calculated, and eight cultivars or PIs had negative residuals in two independent field experiments, indicating higher resistance than predicted by their rate of bolting. Eruption, a small-statured Latin cultivar, had significantly lower disease levels than susceptible cultivars in experiments with high plant densities, indicating that its small size did not facilitate disease escape. Ascospore inoculations confirmed resistance in ‘Eruption’ and L. virosa SAL012, whereas the oilseed lettuce PI 251246 may have partial resistance to infection. These lines will likely be useful for development of Sclerotinia spp.-resistant lettuce cultivars.
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Lee, Ah-Chiou, Fang-Shin Liao, and Hsiao-Feng Lo. "Temperature, Daylength, and Cultivar Interact to Affect the Growth and Yield of Lettuce Grown in High Tunnels in Subtropical Regions." HortScience 50, no. 10 (October 2015): 1412–18. http://dx.doi.org/10.21273/hortsci.50.10.1412.
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The production of lettuce, a cool-season leafy vegetable, in high tunnels the year around is a challenge for growers in subtropical regions. The aims of this research were to characterize the growth of locally grown lettuce cultivars, develop a new high-yielding cultivar by crossing romaine-type lettuce ‘Jhih Li Wo’ and Batavia type lettuce ‘Fu San’, and determine the relationships between climatic variables, temperature, and daylength, and days to harvest for maximum marketable yield (DMMY) in individual cultivars in high tunnels. Nine cultivars were grown in high tunnels in the spring and winter of 2008 and summer of 2009 to evaluate growth and maximum marketable yield (MMY), the latter being defined as the aboveground fresh weight of 5 ± 0.7 cm of plant stem. Romaine lettuce ‘Jhih Li Wo’ had a higher growth rate during the initiation of plant growth in the spring of 2008. ‘Jhih Li Wo’ and Batavia lettuce ‘Fu San’ also showed higher growth rate before harvest for the MMY (GRBHD) and exhibited higher MMY and DMMY than butterhead lettuce and leaf lettuce cultivars under summer and winter regimes. However, landraces of leaf lettuce are the main lettuces grown in high tunnels in summer rather than ‘Fu San’ and ‘Jhih Li Wo’ due to their needing fewer DMMY and having a more upright growth form. Among nine cultivars studied, Batavia lettuce ‘Fu San’, romaine lettuce ‘Jhih Li Wo’, and landrace ‘Bai Yeh Wo’ were found to be more adaptable to summer weather. Genotypes with superior growth and yield traits are essential for not only production but also breeding. A new cultivar, Taoyuan No.3, was developed by introducing the high growth rate trait during the initial period of plant growth from romaine lettuce ‘Jhih Li Wo’ into high-yielding Batavia lettuce ‘Fu San’. Another experiment was performed over eight successive seasons to analyze the correlation of temperature and daylength on DMMY for each cultivar using multiple regression analysis from 2008 to 2009. This showed that the proposed models expressed as coefficients of multiple determinants (R2) accounted for 72% to 91% of the total variation in DMMY in each cultivar. Temperature affected DMMY the most and the relative contributions of temperature and daylength to DMMY differed with cultivar. These results provide information about production practices for growers in subtropical regions to use in choosing suitable lettuce cultivars.
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Matysiak, Bożena, Stanisław Kaniszewski, and Monika Mieszczakowska-Frąc. "Growth and Quality of Leaf and Romaine Lettuce Grown on a Vertical Farm in an Aquaponics System: Results of Farm Research." Agriculture 13, no. 4 (April 19, 2023): 897. http://dx.doi.org/10.3390/agriculture13040897.
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The integration of indoor vertical cultivation with a recirculating aquaculture system into an aquaponic system has the potential to become one of the most effective sustainable production systems for fish and leafy vegetables. In this study, lettuce was produced on rafts in a coupled recirculation aquaponic system in the plant factory under controlled environmental conditions. The aims of this study were to evaluate the yield, mineral status, and health-promoting bioactive compounds of leaf and romaine lettuce cultivars grown in a recirculating aquaponic system. The yield and biometric parameters and quality parameters of lettuce leaves (nitrate, mineral, L-ascorbic acid, carotenoid, phenolic compound, and total polyphenolic contents) were examined. Monitoring of the water in the aquaponic system showed a low concentration of nitrates, phosphorus (P), potassium (K), and magnesium (Mg), but the proportion of mineral nutrients as well as pH were stable throughout the lettuce cultivation period. The heads of romaine lettuce ‘Yakina’, ‘Pivotal’, and ‘Waygo’ reached a fresh weight of 86 g, on average, 23% higher than the leaf lettuce ‘Nordice’ over a three-week cultivation period. Despite the low nutrient concentration in the aquaponic solution, the nutrient status of the romaine lettuces ‘Yakina’ and ‘Pivotal’ was within the optimal range. The concentrations of chlorophyll a and carotenoids in ‘Yakina’ and ‘Pivotal’ were higher than those in ‘Nordice’ and ‘Waygo’. The nitrate, phosphorus, and potassium contents in the leaves of ‘Nordice’ and ‘Waygo’ were below the optimal range; however, their polyphenol concentrations were the highest. Our results indicate that the effectiveness of aquaponic cultivation of lettuce in terms of biomass production and the nutritional and health-promoting value of lettuce depends on the plant genotype.
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White, Katherine, Julie Northcutt, Lance Beecher, and Paul Dawson. "Shelf Life of Aquaponically-grown Finstar Lettuce in Different Oxygen Transmission Rate Films." Journal of Food Research 12, no. 2 (February 14, 2023): 1. http://dx.doi.org/10.5539/jfr.v12n2p1.
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The effects of oxygen transmission rate of packaging material on the shelf life of aquaponically-grown Finstar lettuce was studied. Parameters of packaging headspace gas composition (oxygen and carbon dioxide concentrations), lettuce pH, percentage weight loss, total aerobic microorganisms, and color were analyzed every ten days for sixty days. Finstar lettuce was stored at 4○C in four different types of packages (treatments), including a clamshell package and three film bags with oxygen transmission rates (OTR) of 3.0-6.0 cc/(m2/24 hr/1 atm), 80-90 cc/(m2/24 hr/1 atm), and >225 cc/(m2/24 hr/1 atm). The percentage weight loss of the 3.0-6.0 OTR package (-0.76-1.05%) was lowest while the percentage weight loss of the clamshell package was highest (0.81-7.72%) among packaging treatments. Nearly ½ of the panelists rated lettuce as fresh enough to eat as is after 50 days of storage in 80-90 cc/(m2/24 hr/1 atm) films while lettuce packaged in the other treatments had less that 1/3 of the panelists judging the lettuce fresh enogh to eat as is. The long shelf-life may be attributed to Finstar having resilient genetic properties along with being greenhouse-grown which lessens the possibility of contamination compared to field-grown lettuces.
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Tang, Yulu, Bifeng Zhong, Bing Qu, Shujin Feng, Sanglan Ding, Shijun Su, Zhi Li, and Zhiwei Gan. "Occurrence of perchlorate in groundwater, paired farmland soil, lettuce, and rhizosphere soil from Chengdu, China." Environmental Science: Processes & Impacts 19, no. 5 (2017): 752–57. http://dx.doi.org/10.1039/c7em00114b.
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Regarding perchlorate levels in lettuce and its rhizosphere soil at field sites simultaneously” into “Simultaneously investigated the perchlorate levels in lettuces and their rhizosphere soil at field sites.
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Xu, Hong-jia, Masafumi Johkan, Toru Maruo, Natsuko Kagawa, and Satoru Tsukagoshi. "New Insight on Low-K Lettuce: From Photosynthesis to Primary and Secondary Metabolites." HortScience 56, no. 4 (April 2021): 407–13. http://dx.doi.org/10.21273/hortsci15130-20.
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With the increase in dialysis patients worldwide, the demand for low-K vegetables is growing. Thus, a type of lettuce with a low-K content has been marketed in Japan. To learn more about low-K vegetables, information is needed on the physiological differences between these vegetables and those with typical levels of potassium (K). In this study, lettuces (Lactuca sativa L.) were cultivated using two low-K management methods in an environment-controlled system. One method was based on electrical conductivity (EC) management, and the K was replaced by sodium (Na) at the end of cultivation. The other method was based on quantitative nutrient management, and the nutrients required for low-K lettuce were quantitatively supplied, but no extra Na was added. Meanwhile, lettuce with normal K concentration was cultivated with EC management as the control. Plant growth indices, leaf photosynthesis traits, chlorophyll fluorescence characteristics, concentrations of secondary metabolites (SMs), and antioxidant activity were examined to investigate the physiological effects of low-K and high-Na concentrations during low-K lettuce cultivation. Both low-K treatments significantly restrained the growth of lettuce and increased the concentration of soluble sugar. However, photosynthesis and fluorescence characteristics remained unchanged. This indicates that the biomass reduction of low-K lettuce was due to the wasteful accumulation of carbohydrates rather than the decline in photosynthesis. Concentrations of SMs were increased in the low-K lettuce. In addition, higher concentrations of Na influenced the concentration of SMs, indicating that SMs were more sensitive to environmental stress.
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Gong, Binbin, Xiaowei Ren, Wenyu Hao, Jingrui Li, Shenglin Hou, Kun Yang, Xiaolei Wu, and Hongbo Gao. "Response Surface Methodology for Development of Nutrient Solution Formula for Hydroponic Lettuce Based on the Micro-Elements Fertilizer Requirements at Different Growth Stages." Agronomy 14, no. 6 (May 29, 2024): 1160. http://dx.doi.org/10.3390/agronomy14061160.
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In order to precisely obtain the impact of nutritional elements on lettuce yield and quality, in the present study, a nutrient solution formula suitable for lettuce hydroponic production was development using response surface methodology based on the determination for micro-elements in three growth stages and taking the interaction between elements into account. Then, the formula was optimized and validated, aiming for the goal of improving lettuce yield and quality. The results showed that 200 healthy lettuce leaves contained similar amounts of macro-elements, and there was no significant difference in the unit content of micro-elements among the seedling, rosette, and harvest stages. Quadratic regression models between shoot fresh weight, SPAD value, soluble sugar content, Vc content, and nutrient content were established (R2 = 0.91, 0.95, 0.98, and 0.81, respectively). The optimal concentrations of P, K, Ca, and Mg obtained by multi-objective optimization of the quadratic regression models for fresh weight, SPAD value, soluble sugar content, and Vc content were 2.71 mmol·L−1, 6.42 mmol·L−1, 5.58 mmol·L−1, and 7.11 mmol·L−1, respectively. The nutrient solution formula (T1) was found to be the optimal nutrient solution formula for improving lettuce growth and quality. Overall, we developed a specific and targeted nutrient solution formulation for lettuce; this formulation not only meets lettuce’s demand for nutrients, but also improves lettuce yield and quality, providing more choices for lettuce production in a region with high salts and high pH in the irrigation water.
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Fernandes Colombari, Lidiane, Vitor Massami Imaizumi, Luiz Felipe Guedes Baldini, Prínscilla Pâmela Nunes Chaves, and Rumy Goto. "WINTER COVER CROPS SOWING SYSTEMS FOR PLANTING LETTUCE." COLLOQUIUM AGRARIAE 14, no. 3 (September 1, 2018): 169–78. http://dx.doi.org/10.5747/ca.2018.v14.n3.a239.
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The sowing system, as well as the species used as covercrops, may interfere with the production of straw and the development of further crops. The objective of this research was to evaluate sowing systems for black oat (Avena strigosaSchreb) and white lupine (Lupinus albus) as cover crops, the dry matter production of these plants and their influence on Americana and Curly lettuces yield. Two experiments were performed, one for each lettuce cultivar. The experimental design was composed of 8 treatments (factorial 4x2), evaluated in randomized blocks, with five replications. The first factor is related to four soil coverages (black oat, white lupine, black oat + white lupine and weed) and the second one is the sowing system (handand mechanized in line). The cover plants drying was performed 47 days after planting and the amount of dry matter produced in the area (straw) was then measured. After 30 days from drying, varieties of Curly and Americana lettuce were planted under straw. The lettuce cultivars were evaluated for fresh mass, shoot height and head diameter. For both lettuces, the benefit ofgreen manure was higher using black oat only or combinedwith white lupine, either handor mechanized sowed.
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Kim, Moo Jung, Youyoun Moon, Dean A. Kopsell, Suejin Park, Janet C. Tou, and Nicole L. Waterland. "Nutritional Value of Crisphead ‘Iceberg’ and Romaine Lettuces (Lactuca sativa L.)." Journal of Agricultural Science 8, no. 11 (October 11, 2016): 1. http://dx.doi.org/10.5539/jas.v8n11p1.
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<p>Lettuce (<em>Lactuca sativa</em> L.) is one of the most popular vegetables worldwide, but is often viewed as low in nutritional value. However, lettuce contains health-promoting nutrients and biosynthesis of such phytochemicals varies depending on cultivar, leaf color and growing conditions. Studies of such parameters on the nutritional value have not been conclusive because the lettuce samples were collected from heterogeneous growing conditions and/or various developmental stages. In our study nutritional composition was evaluated in the two most popular lettuce types in Western diets, romaine and crisphead ‘Iceberg’, with red or green leaves grown under uniform cultivating conditions and harvested at the same developmental stage. In the investigated lettuce cultivars, insoluble fiber content was higher (<em>P </em>≤ 0.05) in romaine than crisphead lettuces. Alpha-linolenic acid (omega-3 polyunsaturated fatty acid) was the predominant fatty acid and was higher in romaine than crisphead. Iron and bone health-promoting minerals (Ca, Mg and Mn) were significantly higher (<em>P</em> ≤ 0.001) in romaine. The content of Beta-carotene and lutein in romaine (668.3 ug g<sup>-1</sup> dry weight) was ~45% higher than in crisphead (457.3 ug g<sup>-1</sup>dry weight). For leaf color comparison, red cultivars provided higher amount of minerals (Ca, P, Mn and K), total carotenoids, total anthocyanins and phenolics than green cultivars. Based on our study results, romaine was generally higher in nutrients analyzed, especially red romaine contained significantly higher amount of total carotenoids, total anthocyanins and phenolics. Therefore, romaine type lettuces with red rather than green leaves may offer a better nutritional choice.</p>
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Fontana, Larissa, Claudia A. Rossi, Silviane Z. Hubinger, Marcos D. Ferreira, Marta H. F. Spoto, Fernando C. Sala, and Marta R. Verruma-Bernardi. "Physicochemical characterization and sensory evaluation of lettuce cultivated in three growing systems." Horticultura Brasileira 36, no. 1 (March 2018): 20–26. http://dx.doi.org/10.1590/s0102-053620180104.
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ABSTRACT There exists a growing demand and promising market for new lettuce varieties in Brazil. Cv. Brunella is an innovative lettuce variety which mixes crisp lettuce and head lettuce characteristics besides being adapted to the Brazilian growing conditions. The physicochemical and sensory quality of this lettuce, cultivated under different growing systems, was evaluated. The conventional planting and the hydroponic systems were carried out in the experimental area of the Universidade Federal de São Carlos, São Paulo State, Brazil and the organic system was done by certified organic producer in the municipality of Cordeirópolis. After harvesting, leaf area, leaf size, unit leaf area, fresh mass, mass loss, turgor pressure, instrumental color, pH, total titratable acidity (TTA), total soluble solids (TSS), total phenolic compounds (TPC), and sensory characterization were evaluated. We verified that the growing system influenced on physicochemical traits producing lettuces of different sizes, weights and stability. For pH, TSS and TPC, difference among the three growing systems was not observed. For TTA, the hydroponic sample showed higher acidity. About sensory evaluation, the testers noticed difference for green color, thickness, size and leaf crispness, grass aroma and bitter taste. The samples cultivated in conventional and hydroponic systems showed greater preference and purchase intention.
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Humaida, Nida, Krisdianto Krisdianto, and Setia Budi Peran. "ESTIMATION OF CARBON STORAGE IN WATER LETTUCE (Pistia stratiotes) AT FRESHWATER SWAMPS." TROPICAL WETLAND JOURNAL 2, no. 2 (July 13, 2016): 38–46. http://dx.doi.org/10.20527/twj.v2i2.30.
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This study was conducted in Banjar Regency, in the areas of Keraton, Keramat Baru, Tungkaran, Akar Baru and Sungai Tabuk villages, South Kalimantan, from April-July 2009. The purpose of the study was to estimate the amount of carbon storage in water lettuce (Pistia stratiotes) at freshwater swamps. The information obtained through this study is expected to provide benefits for the swampland management. The swamplands observed were the ones with water lettuce growing in the swamps. The sampling was carried out using purposive sampling technique with the consideration of grouping water lettuce’s distribution. The carbon storage measurement was performed by measuring biomass, organic carbon percentage in water lettuce, and total carbon storage in m2. The organic carbon was analyzed using Walkey & Black's Method. There were also analyses of crude fiber and ash in water lettuce. Data were then analyzed using descriptive statistics and hierarchical clusters. The carbon storage in water lettuce at freshwater swamps in Banjar Regency ranged between 64.07 – 237.75 g/m2. The average crude fiber ranged between 19.89 - 24.94 % and ash between 20.91 - 28.69%.
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Assefa, Awraris Derbie, On-Sook Hur, Bum-Soo Hahn, Bichsaem Kim, Na-Young Ro, and Ju-Hee Rhee. "Nutritional Metabolites of Red Pigmented Lettuce (Lactuca sativa) Germplasm and Correlations with Selected Phenotypic Characters." Foods 10, no. 10 (October 19, 2021): 2504. http://dx.doi.org/10.3390/foods10102504.
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Lettuce is an important dietary source of bioactive phytochemicals. Screening and identification of the health beneficial metabolites and evaluating the relationships with phenotypic characters can help consumers adjust their preferences for lettuce plant types. Thus, we explored the major health-beneficial individual metabolites and antioxidant potential of 113 red pigmented lettuce leaf samples. A UV–Vis spectrophotometer and UPLC-DAD-QTOF/MS (TQ/MS) instruments were used for the identification and quantification of metabolites and antioxidant activity accordingly. The metabolites were quantified against their corresponding external standards. The contents of metabolites varied significantly among lettuce samples. Cyanidin 3-O-(6″-O-malonyl)glucoside (4.7~5013.6 μg/g DW), 2,3-di-O-caffeoyltartaric acid (337.1~19,957.2 μg/g DW), and quercetin 3-O-(6″-O-malonyl)glucoside (45.4~31,121.0 μg/g DW) were the most dominant in red pigmented lettuce samples among anthocyanins, hydroxycinnamoyl derivatives, and flavonols, respectively. Lettuces with dark and very dark red pigmented leaves, circular leaf shape, a strong degree of leaf undulation, and highly dense leaf incisions were found to have high levels of flavonoids and hydroxycinnamoyl derivatives. Principal component analysis was used to investigate similarities and/or differences between samples, and the partial least square discriminant analysis classified them into known groups. The key variables that contributed highly were determined. Our report provides critical data on the bioactive constituents of red pigmented lettuce to breeders developing varieties with enhanced bioactive compounds and to nutraceutical companies developing nutrient dense foods and pharmaceutical formulations.
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Gaucin-Delgado, Jazmín M., Adriel Ortiz-Campos, Luis G. Hernandez-Montiel, Manuel Fortis-Hernandez, Juan J. Reyes-Pérez, José A. Gonzáles-Fuentes, and Pablo Preciado-Rangel. "CuO-NPs Improve Biosynthesis of Bioactive Compounds in Lettuce." Plants 11, no. 7 (March 29, 2022): 912. http://dx.doi.org/10.3390/plants11070912.
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The application of metallic nanoparticles improves the yield and content of bioactive compounds in plants. The aim of the present study was to determine the effects of the foliar application of copper nanoparticles (CuO-NPs) in the yield and content of bioactive compounds in lettuce. Different concentrations of CuO-NPs (0, 0.5, 1, 2, 4, and 6 mg mL−1) were applied in lettuce. The yield, nutraceutical quality, and enzymatic activity were determined. Foliar spraying of CuO-NPs induced an increase in the biosynthesis of bioactive compounds. In addition to an increase in the activity of the enzymes superoxide dismutase (SOD) and catalase (CAT) in lettuce plants, there were no negative effects on yield. Therefore, with the application of CuO-NPs, better quality lettuces are produced for the human diet due to the higher production of bioactive compounds.
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Kabay, Turgay. "Effects of Different Salt Applications on Ion and Physiological Analysis in Lettuce." Turkish Journal of Agriculture - Food Science and Technology 10, no. 8 (August 26, 2022): 1455–58. http://dx.doi.org/10.24925/turjaf.v10i8.1455-1458.5242.
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The increase in salinization in agricultural lands adversely affects crop production. In particular, yield and quality losses occur in many vegetables such as lettuce, which are grown and consumed in every season. Realizing these losses in crop production, more careful fertilization and agricultural practices should be done. Yedikule lettuce seeds were used in the study to draw attention to these negative aspects. The study, which was carried out for two years, was designed with 0, 50, 100 and 150 mmol doses of salt according to a randomized parcel design with three replications and four pots in each replicate. Each 2-liter pot was filled with a 2:1 ratio of peat: perlite mixture and the study was carried out with 2 lettuces in each pot. As a result of the study, when the plant weight data of the first year and the second year are examined, it is seen that the weight loss of lettuce plants and damage to the plants increase when the salt doses increase. It was observed that the highest plant weight loss occurred at 150 mmol salt dose. Membrane damage index in lettuce leaves was observed to increase as the salt dose increased. It was observed that the leaf water rate decreased with increasing salt doses. Membrane damage index and leaf water content of lettuce plants were more negatively affected at 150 mmol of salt in both years. Potassium, calcium and magnesium contents in lettuce leaves were statistically decreased due to increasing salt doses in both years, while sodium content increased with increasing salt doses and the highest sodium content was observed at 150 mmol dose in both years. As seen in these results, increasing salt doses reduce the nutrient content and plant weight in lettuce plants and cause physiological damage to the plant, resulting in yield and quality loss.
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Imron S Jaya, Moh Haris, Septafiansyah Dwi Putra, and Imam Sofi'i. "Effect Of Light Spectrum LED Lettuce on IOT-Based Indoor Farming." Biotropika: Journal of Tropical Biology 11, no. 1 (May 23, 2023): 38–43. http://dx.doi.org/10.21776/ub.biotropika.2023.011.01.05.
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Lettuce (Lactuca sativa L.) is an economically important crop worldwide and one of the most popular species grown in indoor farming. Lettuce's fast growth and growing cycle make lettuce a model plant to study the interaction between plants and light. The influence of light is one of the fundamental environmental factors for plant growth and development. Light-emitting diodes (LEDs) have higher light efficiency and higher wear efficacy, leading to a reduction in associated heating compared to other artificial lighting sources, such as fluorescent lamps or sodium vapor lamps. This research aimed to determine different responses of the morphological response of lettuce by giving LED light spectrum with a single color spectrum difference and IOT-based temperature and humidity monitoring. This research used a t-student test with a level of 5% on the mean value of the white light spectrum with a yellow light on lettuce plants. The addition of the LED light spectrum produces a different response to the morphological parameters. The addition of the LED spectrum gave a response to the plant height variable, where the provision of a yellow LED light spectrum resulted in plant height which affected lettuce plants
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Riga, Patrick, and Leyre Benedicto. "Effects of light-diffusing plastic film on lettuce production and quality attributes." Spanish Journal of Agricultural Research 15, no. 1 (April 20, 2017): e0801. http://dx.doi.org/10.5424/sjar/2017151-10315.
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In general, plants grown under diffuse light yield higher biomass than those grown under direct light as a result of a more uniform distribution of the light across the plant canopy. We compared the effects of a light-diffusing plastic film and a clear plastic film on growth of Batavia lettuce (Lactuca sativa L.) in two greenhouses during five growth periods. Lettuce grown under the light-diffusing film were smaller (up to 36%) than control plants grown under the clear film, due to the fewer leaves per plant (up to 22%) and lower mean values of individual leaf area (up to 29%). The photosynthetically active radiations use efficiency was sometimes lower (up to 23%) in lettuces grown under the light-diffusing film. The pigment contents tended to be lower in plants grown under the light-diffusing plastic. The total macroelement contents of the lettuces grown under the light-diffusing plastic were up to 10% higher than in the lettuces grown under clear plastic, mainly as a result of higher leaf K contents (up to 19% higher). In addition, use of the light-diffusing plastic tended to increase leaf nitrate contents (by up to 23%). The leaf solid soluble content and acidity values were higher in the lettuces grown under the light-diffusing plastic, while leaf pH values were lower than in the control plants. The findings showed that the light-diffusing plastic was detrimental to production of compact heads of lettuce, and to some quality parameters such as nitrate and pigment contents. Nevertheless, open-leaf cultivars would likely show a different response to the diffuse light.
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Volpe, Melisa Lanza, Verónica C. Soto Vargas, Anabel Morón, and Roxana E. González. "Bioactive Compounds, Antioxidant Activity and Growth Behavior in Lettuce Cultivars Grown under Field and Greenhouse Conditions." Proceedings 70, no. 1 (November 10, 2020): 52. http://dx.doi.org/10.3390/foods_2020-07709.
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Lettuce (Lactuca sativa L.) is one of the most important leafy greens worldwide. The nutritional value of its edible leaf depends on different factors including type and growing conditions. The aim was to determine the bioactive compounds content, antioxidant activity and growth behavior of twenty-two lettuce genotypes, cultivated under field and greenhouse conditions. Total phenolic compound, chlorophylls, carotenoids, anthocyanin contents and antioxidant activities were analyzed by spectrophotometric methods. Data were analyzed by analysis of variance (ANOVA). Significant differences between bioactive compounds, antioxidant activity and growth behavior were found among cultivars and morphological types, for both growth conditions. Carotenoid and chlorophyll content was higher in greenhouse conditions for all genotypes. In field production, butterhead and iceberg lettuces showed lower content of these bioactive compounds. The red-pigmented Falbala cultivar from field production showed the highest level of polyphenols and anthocyanin. Meanwhile, in greenhouse conditions, the oak leaf cultivar Grenadine displayed the highest concentration of these phenolic compounds. The iceberg type lettuce showed the lowest percentages of antioxidant activity in both environments. The results showed the effect of growing conditions and the high variability in lettuce bioactive compounds content and antioxidant activity among the different types.
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Tomás-Barberdán, F. A., J. Loaiza-Velarde, and M. E. Saltveit. "Early Changes in Wound-induced and Ethylene-induced Phenylpropanoid Metabolism in Lettuce." HortScience 31, no. 4 (August 1996): 599f—599. http://dx.doi.org/10.21273/hortsci.31.4.599f.
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Mechanical wounding and exposure to ethylene induces an increase in phenylpropanoid metabolism in lettuce and an increase in the concentration of several soluble phenolic compounds that are easily oxidized to brown substances by polyphenol oxidase. To study the early response of lettuce to wounding and ethylene, leaves of iceberg, butter leaf, and Romaine lettuces were either wounded or exposed to ethylene at 10 μL·L–1 in flows of humidified air at 5 or 10°C. Soluble phenolic compounds were extracted at intervals up to 72 hours and were analyzed by HPLC. After 72 hours, wounded leaves of all three lettuce types showed elevated levels of caffeoyl tartaric acid, Chlorogenic acid, dicaffeoyl tartanc acid, and 3,5-dicaffcoyl quinic acid at both temperatures. In contrast, there were no significant increases in soluble phenolic compounds in iceberg lettuce exposed to ethylene at 10°C. At 5°C for iceberg, and at both temperatures for the other two types, there was the same pattern for ethylene treated and wounded leaf tissue. The kinetics of wound and ethylene-induced phenolic metabolism are different and will be discussed in relation to phenolics produced and browning susceptibility.
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Han, Yi, Joan King, and Marlene E. Janes. "Detection of antibiotic resistance toxigenic Clostridium difficile in processed retail lettuce." Food Quality and Safety 2, no. 1 (January 24, 2018): 37–41. http://dx.doi.org/10.1093/fqsafe/fyx032.
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Abstract Objectives: Clostridium difficile is the major cause of infectious diarrhoea in humans after antimicrobial treatment. Clostridium difficile has been isolated from food animals and meat. The main purpose of this study was to characterize C. difficile isolated from retail lettuce and determine the antibiotic resistance using five common clinical-selected antibiotics (metronidazole, vancomycin, clindamycin, erythromycin, and cefotaxime). Materials and Methods: Lettuce samples (grown in California, Arkansas, and Louisiana) were purchased from retail stores. Results: Toxigenic C. difficile was isolated from 13.8 per cent (41/297) of the lettuce samples. Among the toxigenic isolates, only 82.9 per cent (34/41) produced toxin B, 17.1 per cent (7/41) produced both toxin A and toxin B, and two of the Louisiana C. difficile isolates were identified as ribotype 027. Under the treatment of the five antibiotics, the virulence C. difficile isolates were identified as having antibiotic resistance to metronidazole, vancomycin, and erythromycin. Conclusion: The present study reports the highest prevalence of toxigenic C. difficile in US retail lettuce. The antibiotic resistance to metronidazole, vancomycin, and erythromycin of the isolated C. difficile from retail lettuces could lead to public health concerns.