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Charlene M. Grahn, Barbara Hellier, Chris Benedict, and Carol Miles

field HortTechnology. 1 78 81 Penaloza, P. Ramirez-Rosales, G. McDonald, M.B. Bennett, M.A. 2005 Lettuce ( Lactuca sativa , L.) seed quality evaluation using seed physical attributes, saturated salt accelerated aging, and the seed vigor imaging system

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Geoffrey Weaver and Marc W. van Iersel

cultivars of lettuce ( Lactuca sativa ) ( Koontz and Prince, 1986 ; Soffe et al., 1977 ), as well as for other vegetable species ( Soffe et al., 1977 ) and strawberry ( Fragaria × ananassa) ( Tsuruyama and Shibuya, 2018 ). Plant growth generally increases

Open access

Gustavo F. Kreutz, Germán V. Sandoya, Gary K. England, and Wendy Mussoline

Lettuce ( Lactuca sativa L.) is one of the most valuable vegetables in the world. The United States ranks as the second largest lettuce producer after China, harvesting ≈105,000 ha worth $3.5 billion in 2019 [ Food and Agriculture Organization of

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Geoffrey Weaver and Marc W. van Iersel

photochemical performance of a greenhouse-grown crop of a romaine-type lettuce cultivar ( Lactuca sativa L. ‘Green Towers’) under growing conditions comparable to a commercial production environment. Specific hypotheses tested were whether the current ETR is

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Marie Abbey, Neil O. Anderson, Chengyan Yue, Michele Schermann, Nicholas Phelps, Paul Venturelli, and Zata Vickers

year-round ( Abbey et al., 2019 ). However, there were several production issues that needed careful management to have yields comparable to hydroponic greenhouse or field-grown types. Lettuce, Lactuca sativa , is the most commonly grown leafy green in

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Ryan J. Hayes, Bo Ming Wu, Barry M. Pryor, Periasamy Chitrampalam, and Krishna V. Subbarao

. Ryder, E.J. 2004 Identification of lettuce ( Lactuca sativa L.) germplasm with genetic resistance to drop caused by Sclerotinia minor J. Amer. Soc. Hort. Sci. 129 70 76 Koopman, W.J.M. Guetta, E. van de

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Furn-Wei Lin, Kuan-Hung Lin, Chun-Wei Wu, Yu-Sen Chang, Kuan-Hung Lin, and Chun-Wei Wu

's ability to cope with water stress in specific/localized environments will lead to better-informed decisions on the suitability of irrigation management practices. Lettuce ( Lactuca sativa L. var. capitata), a member of the Asteraceae family, is cultivated

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Melek Ekinci, Ertan Yildirim, Atilla Dursun, and Metin Turan

The objective of this study was to determine the effect of 24-epibrassinolide (24-EBL) applications on growth, chlorophyll, and mineral content of lettuce (Lactuca sativa L. var. Crispa) grown under salt stress. The study was conducted in pot experiments under greenhouse conditions. Lettuce seedlings were treated with seed and foliar 24-EBL applications at different concentrations (0, 1, 2, and 3 μM). Salinity treatments were established by adding 0, 50, and 100 mm of sodium chloride (NaCl) to a base complete nutrient solution. Results showed that salt stress negatively affected the growth and mineral content of lettuce plants. However, seed and foliar applications of 24-EBL resulted in greater shoot fresh weight, shoot dry weight, root fresh weight, and root dry weight as well as higher stem diameter than the control under salt stress. Salinity treatments induced significant increases in electrolyte leakage of plant, but foliar 24-EBL application reduced leaf electrolyte leakage and has determined lower values of leaf electrolyte leakage than non-treated ones. In regard to nutrient content, it can be inferred that 24-EBL applications increased almost all nutrient content in leaves and roots of lettuce plants under salt stress. Generally, the greatest values were obtained from 3 μM 24-EBL application. Treatments of 24-EBL alleviated the negative effect of salinity on the growth of lettuce.

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J.D. Chung, B.J. Lee, H.S. Lee, and C.K. Kim

Lettuce (Lactuca sativa L.) were transformed using microparticle bombardment with two different genes, alpha-glucuronidase (GUS) gene and Chinese cabbage Glutathione Reductase (GR) gene. The adventitious shoots of cotyledonary explant from 4-day-old seedlings were formed (46.7%) in MS basal media supplemented with 5.0 μm IAA and 1.0 μm 2ip. When 1100 psi helium pressure, 9 target distance, and coating with tungsten 10 microparticles were used and explants were treated with osmoticum-conditioning medium (0.6M sorbitol/mannitol), 4 h prior to and 16 h after bombardment, it was identified by GUS assay that these conditions were the most efficient for transformation of foreign genes into cotyledon tissue of lettuce with particle bombardment. PCR confirmed that the band observed in the transgenic plants were originated from T-DNA tranfer with strong hybridization. The genomic Southern analysis showed that the 1.5-kbp fragment was hybridized with radiolabeled 1.5-kbp GR probe. To know whether the expression of the GR gene can be stably maintained in the next generation, when T2 selfing seeds that were obtained from the transformed mother plants were sowed on MS medium supplemented with 200 μm kanamycin, 70% of seedlings were revealed resistance to kanamycin.

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Jernej Demšar, Jože Osvald, and Dominik Vodnik

With a high nitrate supply, and most frequently under low-light conditions, lettuce accumulates relatively large amounts of NO3-as a result of an excess of uptake over reduction. Different approaches, which are used to reduce leaf nitrate, often result in a yield loss. A computerized aeroponic system, which supplies different nitrate concentrations in accordance with the changeable light conditions (dynamic light-dependent application of nitrate), was used to reduce nitrate accumulation in lettuce (Lactuca sativa L.) var. Capitata cv. Vanity. Under unfavorable light conditions nitrate was supplied at limited rates (slight, medium, and strong reduction) to the plants. In response to given light conditions the nitrate supply was reduced close to one-half or one-fourth of the full nutrient solution (8 mmol·L-1 NO3-). Controlled nutrition resulted in efficient reduction in leaf nitrate. In the early-spring experiment the average nitrate content in outer leaves was decreased by 9%, 63%, and 92% and in the late-spring experiment the decrease was 23%, 58%, and 76% compared to control. At the same time, the controlled, light-dependent nitrate deprivation did not result in a loss of a lettuce yield (except in the treatment with strong nitrate reduction) and had limited effects on photosynthesis (P N-C i measurements) and photosynthetic pigments.