• Journal of Environmental Science International
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• v.31 no.7
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• pp.569-577
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• 2022

This study aimed to evaluate the growth of Cichorium intybus, Brassica juncea, and Lactuca sativa at varying seed ratios, and to suggest an efficient management plan for sustainable indoor agriculture systems. It was treated with mixed sowing as follows: 30 chicory seeds (chicory alone: CC), 22 chicory seeds + 8 lettuce seeds (C₃L₁), 20 chicory seeds + 10 lettuce seeds (C₂L₁), 15 chicory seeds + 15 lettuce seeds (C₁L₁) as intraspecies, and 30 mustard seeds (mustard alone: MC), 22 mustard seeds + 8 lettuce seeds (M₃L₁), 20 mustard seeds + 10 lettuce seeds (M₂L₁), 15 mustard seeds + 15 lettuce seeds (M₁L₁) as interspecies. The study identified the competitive response in seed germination between Cichorium intybus and Lactuca sativa, and in the C₃L₁ experimental group, Lactuca sativa had the highest leaf length, root length, chlorophyll content, and fresh weight. Therefore, the higher the ratio of Cichorium intybus, the higher the growth and productivity of Lactuca sativa; however, higher the ratio of Lactuca sativa, the lower the growth of Cichorium intybus. Furthermore, the nitrogen and potassium content in the substrate was the highest in the C₃L₁ experimental grorp which had the highest seeding rate of the Cichorium intybus. Comparing the groups Brassica juncea and Lactuca sativa, the higher the seeding ratio of Lactuca sativa, the higher the growth and productivity of Brassica juncea. Therefore, a companion seeding of Brassica juncea and Lactuca sativa is beneficial; this could be effective in having a high seeding ratio of Lactuca sativa.

• Plant Resources
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• v.7 no.1
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• pp.69-76
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• 2004

Lettuce (Lactuca sativa L.) is known to contain water-soluble substances that are biologically active. Aqueous or methanol extracts and residues from leaves of lettuce plants were assayed to determine their allelopathic effects, and the causative allelochemicals from fractions were quantified by means of HPLC analysis and bioassayed. Extracts from oven-dried leaf samples were more phytotoxic than those from freeze-dried samples. Leaf extracts of 40 g L$^{-1}$ were completely inhibitory on root growth of alfalfa (Medicago sativa L.), while root growths of barley (Hordeum vulgare L.) and soybean (Glycine max L.) were less sensitive. Early seedling growth of both alfalfa and barnyard grass (Echinochloa crus-galli) was significantly reduced by methanol leaf extracts. The major allelopathic substances analyzed by HPLC were coumarin, trans-cinnamic acid, o-coumaric acid, p-coumaric acid and chlorogenic acid. Of them p-coumaric acid was found as the greatest amount (8.9 mg 100 g$^{-1}$ ) in the EtOAc fraction; only coumarin was found in all the fractions. Hexane and EtOAc fractions of L. sativa reduced alfalfa root growth more than did BuOH and water fractions. These results suggest that lettuce had potent herbicidal activity, and that its activity differed depending on type and amount of causative compounds by fraction.

• The Plant Pathology Journal
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• v.30 no.1
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• pp.90-95
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• 2014

This study was conducted to evaluate the resistance of 212 accessions of lettuce germplasm to gray mold disease caused by Botrytis cinerea. The lettuce germplasm were composed of five species: Lactuca sativa (193 accessions), L. sativa var. longifolia (2 accessions), L. sativa var. crispa (2 accessions), L. saligna (2 accessions), and L. serriola (1 accession); majority of these originated from Korea, Netherlands, USA, Russia, and Bulgaria. After 35 days of spray inoculation with conidial suspension ($3{\times}10^7$ conidia/ml) of B. cinerea on the surface of lettuce leaves, tested lettuce germplasm showed severe symptoms of gray mold disease. There were 208 susceptible accessions to B. cinerea counted with 100% of disease incidence and four resistant accessions, IT908801, K000598, K000599, and K021055. Two moderately resistant accessions of L. sativa, K021055 and IT908801, showed 20% of disease incidence of gray mold disease at 45 days after inoculation; and two accessions of L. saligna, K000598 and K000599, which are wild relatives of lettuce germplasm with loose-leaf type, showed complete resistance to B. cinerea. These four accessions are candidates for breeding lettuce cultivars resistant to gray mold disease.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2022.09a
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• pp.73-73
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• 2022

Lettuce (Lactuca sativa L., Family Asteraceae) is highly ranked in production and economic value and is consumed either fresh or in salad mixes because of its important dietary source of bioactive phytochemicals. The world collection of Lactuca spp. leafy crops, maintained in NAC, includes 2,464 accessions from 71 countries around the world, of which 2,411 belong to L. sativa species, nineteen to L. saligna, and fifteen to L. serriolar. We aimed to investigate the lettuce germplasm with morphological and biochemical analyses and provide new material for breeding. The lettuce crop comprises seven main groups of cultivars (including oilseed lettuce) differing phenotypically. Agricultural characteristcs were investigated including time to bolting, time to flowering, seed color, flower color, leaf attitude, leaf color, leaf anthocyanin coloration, type of incision of margin, depth of incisions of margins, and leaf venation. Screening of the health beneficial metabolites like anthocyanin and bitter sesquiterpene lactones (lactucin and lactucopicrin) was also conducted. The range of anthocyanin and SLs were 0~563.78 mg/100g D.W. and 3.74~3311.66 ug/g D.W., respectively. The investigation of the degree of variation regarding phenotypic traits and biochemical revealed adaptive stable and highly variable use of trait collection.

• Plant Resources
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• v.2 no.1
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• pp.16-21
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• 1999

An efficient regeneration system was established by using in vitro plantlets of germinated seedlings from different cultivars of lettuce (Lactuca sativa cv. Chongchima, Chongchuckmyun, Jeokchima, Jeokchuckmyun). Shoot formation were observed from all cultivars on MS medium supplemented with 0.1 mg/L NAA and 0.5 mg/L BA. In all cultivars, when cotyledon was cultured, the number of shoot per explant was more greater than that hypocotyl and leaf disc were cultured. Shoot formation rate (91.7%) was high in a cotyledon culture of cultivar, Chongchukmyun. The growth of multiple shoots derived from the cultivar, Chongchukmyun, was most effective on medium containing 0.5 mg/L BA and 1.0 mg/L GA$_3$. When shoots were transferred on MS medium without plant growth regulators, roots were effectively differentiated. Rooted plantlets were acclimated on pots for further propagation.

• Journal of Bio-Environment Control
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• v.6 no.4
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• pp.270-276
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• 1997

This experiment was conducted to develop a practical method to growth in hydroponics conditions. For this purpose, leaf lettuce (Lactuca sativa L., cv. 'Cheongchima') was cultivated under different temperature and light conditions in experimental fields of Sahmyook university from March, 1991 to May, 1996. The visual quality score(VQS), a quantitative parameter to evaluate harvested leaf lettuce quality. The leaf lettuce cultivated at $25^{\circ}C$ solution temperature showed the highest fresh weight pe, plant (59.7g/plant), but lowest visual quality score (5.2), while leaf lettuce cultivated at 15$^{\circ}C$ solution temperature showed lower fresh weight per plant (25.2g/plant) but highest visual quality score (7.2). In general, growth of leaf lettuce was retarded by low solution temperature, but quality was higher than those of other solution temperature. Different day/night temperature of nutrient solutions 20/2$0^{\circ}C$ and 25/2$0^{\circ}C$ was highest in yield, but leaf type was grow longer, and visual quality are inferior to low temperature. Yield was decreased as 10 and 25% at 60 and 80% shading treatment, respectively. Chlorophyll content was decreased by shading. but plant height and root length were increased of leaf lettuce growth with hydroponics.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.4
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• pp.498-505
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• 2010

To evaluate the effectiveness of AMF on the growth of horticultural crops, we compared mycorrhizal and non-mycorrhizal plants, lettuce (Lactuca sativa L.), that were inoculated with AMF propagules. As compared to the AMF- seedlings, in AMF+ seedlings at 3 weeks after sowing, the number of leaves increased 9%, leaf fresh weight increased 59%, leaf area increased 58%, and leaf length and width increased 21-22%, and chlorophyll content increased 2%. Furthermore, at 9 weeks after sowing, compared to the AMF- plants, in lettuce plants inoculated with AMF at the sowing and transplanting stages, the number of leaves increased 21% and 18%, leaf fresh weight increased 51% and 41%, root fresh weight increased 56% and 47%, and chlorophyll content increased 18% and 19%, respectively. Further this experiment indicated that the growth responses of lettuce plants inoculated with AMF during transplanting were similar to those inoculated with AMF during sowing. The results imply that the AMF infection timepoint is not important. The P content in the leaves of lettuce plants inoculated with AMF during transplanting was significantly higher (217%) than that of leaves from lettuce plants not inoculated with AMF. In contrast, the P content of the leaves of lettuce plants inoculated with AMF during the sowing stage was similar to that of leaves of control lettuce plants. In this experiment, P and chlorophyll content in AMF+ lettuce plants were higher than in AMF- plants, indicating that the photosynthetic rate was improved with AMF inoculation.

• Korean Journal of Plant Tissue Culture
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• v.26 no.3
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• pp.219-222
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• 1999

To induce adventitious buds, hypocotyl and cotyledonary explants from 7 to 10 day-old seedlings of lettuce (Lactuca sativa L.: two Japanese cultivars of crisphead lettuce and four Korean cultivars of leaf lettuce) were cultured or Murashige and Skoog (MS) and Schenk and Hildebrandt (SH) media supplemented with BA and NAA in the light for five weeks. Cotyledonary explants produced adventitious shoots at greater frequencies than hypocotyl explants. MS medium was more favorable to adventitious shoot formation than HS medium. Combination of 0.5 mg/L BA and 0.1 to 1 mg/L HPh in MS medium led to the greatest frequency (86%) in adventitious shoot formation. Creator than 95% of shoots excised from explants were rooted when cultured on MS basal medium.

• Journal of Environmental Science International
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• v.20 no.12
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• pp.1509-1519
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• 2011

The protective effect of nitric oxide (NO) on the antioxidant system under paraquat(PQ) stress was investigated in leaves of 8-week-old lettuce (Lactuca sativa L.) plants. PQ stress caused a decrease of leaf growth including leaf length, width and weight. Application of NO donor, sodium nitroprusside (SNP), significantly alleviated PQ stress induced growth suppression. SNP permitted the survival of more green leaf tissue preventing chlorophyll content reduction and of higher quantum yield for photosystem II than in non-treated controls under PQ exposure, suggesting that NO has protective effect on chloroplast membrane in lettuce leaves. Flavonoids and anthocyanin were significantly accumulated in the leaves upon PQ exposure. However, the rapid increase of these compounds was alleviated in the SNP treated leaves. PQ treatment resulted in lipid peroxidation and induced accumulation of hydrogen peroxide ($H_2O_2$) in the leaves, while SNP prevented PQ induced increase in malondialdehyde (MDA) and $H_2O_2$. These results demonstrate that SNP serves as an antioxidant agent able to scavenge $H_2O_2$ to protect plant cells from oxidative damage. The activities of two antioxidant enzymes that scavenge reactive oxygen species, superoxide dismutase (SOD) and catalase (CAT) in lettuce leaves in the presence of NO donor under PQ stress were higher than those under PQ stress alone. Application of 2-(4-carboxyphenyl)-4, 4, 5, 5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO), a specific NO scavenger, to the lettuce leaves arrested SNP mediated protective effect on leaf growth, photosynthetic pigment and antioxidant systems. However, PTIO had little effect on lettuce leaves under PQ stress compared with that of PQ stress alone. The obtained data suggest that the damage caused by PQ stress is in part due to increased generation of active oxygen by maintaining increased antioxidant enzyme activities and SNP protects plants from oxidative stress. From these results it is suggested that NO might act as a signal in activating active oxygen scavenging system that protects plants from oxidative damage induced by PQ stress and thus confer PQ tolerance.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.5
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• pp.621-626
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• 2016

The present study evaluated the variations in soil microbial population of controlled horticultural land used for lettuce (Lactuca sativa) cultivation by their fatty acid methyl ester and chemical properties. We utilized four treatment groups, no treatment (NT), culture medium (CM), Bacillus subtilis S37-2 (KACC 91281P) ${\times}10^6CFU\;mL^{-1}$ (BS1), and Bacillus subtilis $S37-2{\times}10^7CFU\;mL^{-1}$ (BS2) and analyzed these variations throughout the before treatment and harvesting stage. The chemical properties such as pH, organic matter, available phosphate, and electrical conductivity in soils before treatment and harvesting stage showed no significant difference among the treatments. Total numbers of bacteria and microbial biomass C in soil treated with BS1 were larger than those of NT, CM, and BS2, whereas total number of fungi at the harvesting stage was significantly lower in the BS1 soil than in the NT and CM soils (P < 0.05). On basis of leaf length, leaf width, leaf number and leaf weight, the growth characteristics lettuce on the soil treated with BS1 and BS2 was faster than those of NT and CM soils. Yield of lettuce with treated BS1 and BS2 were 35% and 29% more than that of NT, respectively.