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Improving nitrogen utilization efficiency (NUtE) is one of the most important challenges in the agricultural sector. The NUtE index, which is the amount of dry biomass (g) produced per nitrogen absorbed (g) by the plant, is influenced by some factors such as climate and nitrogen nutrition status. Therefore, providing management strategies to increase NUtE should be performed by taking into account the nitrogen status of the plant. In this study, relationships between nitrogen nutrition index (NNI) and NUtE in lettuce were extracted based on the concept of critical nitrogen concentration. For this purpose, two experiments were conducted in the research greenhouse of the College of Agriculture and Natural Resources, University of Tehran, located in Karaj, Iran, with six N fertilizer treatments. Then, NUtE and NNI were calculated for all treatments. The results showed that the NNI varied from 0.70 to 1.22 and 0.60 to 1.23 for the first and second experiments, respectively. The NUtE decreased due to the increase in fertilizer application rate. Also, application of nitrogen fertilizer more than the plant uptake capacity led to a decrease in the nitrogen uptake efficiency (NUpE). The relationship between NUtE and NNI for different dry biomass values was investigated. The results showed that at constant NNI values, NUtE increased non-linearly with increasing dry biomass production. Also, the critical nitrogen utilization efficiency curve (NUtEc) discriminated well between different N treatments. Under the optimal nitrogen nutrition conditions (NNI = 1), the critical value of NUtE for lettuce was equal to 24 (g g-1 N). [ABSTRACT FROM AUTHOR]

Copyright of Agronomía Colombiana is the property of Universidad Nacional de Colombia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Green lettuce is a vegetable crop favored by the people of Indonesia, so the demand is increasing. Demand is increasing, so it must increase lettuce production. One way to increase production is by using appropriate planting media and chicken manure fertilizer to provide nutrients for lettuce. The purpose of the study was to obtain the right composition of the growing medium with manure for the growth and yield of green lettuce. Thel relselarch melthold Factolrial RAK, Factolr 1 was polltry manulrel, P1 = 5 tolns ha-1, P2 = 10 tolns ha-1, P3 = 15 tolns ha-1. Factolr 2 is thel colmpolsitioln olf thel planting,M1 = Solil 100%, M2 = Colcolpelat : Solil = 50% : 50%, M3 = Colcolpelat : Solil = 75% : 25% and M4 = Solil : Colcolpelat = 25% : 75% . Thel data olbtaineld frolm thel olbselrvatiolns welrel analyzeld ulsing thel F telst olf analysis with a lelvell olf 5%. If thel telst relsullts havel a significant elffelct, theln prolceleld with thel BNJ with a lelvell olf 5%. The results showed that the composition of the planting media, namely cocopeat soil: soil = 50%: 50% and dosing 15 tons ha-1 poultry manure fertilizer had the best results on plant height, number of leaves, root length and consumption weight of lettuce plants compared to other treatments. The conclusion that the use of the composition of the planting medium, namely cocopeat soil: soil = 50%: 50% and dosing 15 tons ha-1 poultry manure fertilizer obtained the best results to increase lettuce growth and weight. [ABSTRACT FROM AUTHOR]

It is predicted that the average world temperature will rise by 1.5 °C in the next few decades, which may adversely affect vegetable productivity and global food security. The present study aimed to identify lettuce genotype(s) that are tolerant of heat stress so that they may be good candidates for future breeding programs to develop heatstress-tolerant lettuce cultivars. While using a complete randomized design with three replicates, we evaluated the performance of eight lettuce genotypes using a hydroponic system under non-stress (controlled) and heat stress (high temperature) environmental treatments. The effects of environmental treatments on the morphophysiological and agronomic characteristics of the genotypes were assessed. Ten traits were recorded after harvest, i.e., the number of leaves, plant height, root length, yield, fresh root weight, plant weight, leaf area, leaf width, leaf length, and chlorophyll contents. In general, lettuce genotypes cultivated under heat stress exhibited decreased performance in most traits compared to the non-stress treatment group. The yield of SAL092, SAL093, SAL094, SAL095, SAL096, SAL097, and SAL099 decreased by 65.8%, 66.4%, 65%, 28.2%, 40.6%, 76.3%, and 73.1%, respectively, under heat stress. In contrast, SAL098 grown under non-stress conditions showed higher yield, leaf count, root length, plant weight, and plant height by 0.1%, 15.2%, 0.9%, 4%, and 27%, respectively, compared to non-stress conditions. In addition, during heat stress, every trait exhibited a positive correlation with yield, except leaf width, suggesting that productive attributes are crucial for enhancing yield under high-temperature conditions. SAL095 and SAL098 exhibited effective adaptive mechanisms and may be regarded as potential heat-tolerant genotypes for future breeding programs and developing heat-tolerant cultivars and high yields. [ABSTRACT FROM AUTHOR]

Lettuce (Lactuca sativa L.) is considered as the most cultivated and consumed leafy vegetable all over the world. In Erbil Governorate, most farmers used sewage water to irrigate lettuce, which caused health risks especially heavy metal pollutants including cadmium. This research was applied as a factorial experiment to investigate the effects of foliar spraying of salicylic acid (SA) (0,0.5,1, 1.5 or 2mM) followed by spraying cadmium chloride (Cd) (0, 1, 2, or 4mM) on the growth, and some physiological and biochemical characteristics of this plant. The results show that most vegetative growth characteristics responded inversely to increasing SA concentrations, whereas the response of root performance improved with using SA application. A low concentration of Cd (1mM) improved root and shoot performance, whereas increasing the concentration to 4 mM decreased these characteristics significantly compared to no Cd added plants, except for the percent of shoot dry matter. Most of photosynthetic pigments decreased significantly by foliar spraying with SA and Cd. Applications of SA increased catalase enzyme activity significantly compared to no SA treated plants. Cadmium foliar application increased peroxidase enzyme activity, ascorbic acid, proline, and the percent of total carbohydrate content and decreased catalase enzyme activity and the percent of infection with watery soft rot significantly compared to no Cd treated plants. It is concluded that lettuce tolerance to cadmium stress was increased by pretreatment foliar application of SA. [ABSTRACT FROM AUTHOR]

Copyright of Lucrari Stiintifice, Universitatea de Stiinte Agricole Si Medicina Veterinara Ion Ionescu de la Brad Iasi, Seria Horticultura is the property of University of Agricultural Sciences and Veterinary Medicine (Editura Ion Ionescu de la Brad) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Most soils close to urban centers are often degraded due to intensive cultivation, resulting in low organic matter content and low plant nutrients. Remnants of vegetable materials are frequently abandoned in urban markets in Nigeria and their disposal by local councils is expensive; these materials therefore constitute a nuisance to the environment. However, these materials can be composted and used as soil amendment. A field experiment was conducted at the Teaching and Research Farm of the University of Ilorin, Ilorin, Nigeria during the 2018 and 2019 cropping growing seasons to evaluate the effects of urban wastes as compost on the growth, yield and nutritional composition of lettuce. The experiment was laid out in a randomized complete block design replicated four times. The rates of compost application were as follows; 0, 5, 10, 15, 20 Mg/ha and NPK at the rate of 300 kg ha-1. Data were collected on vegetative parameters (plant height, number of leaves, leaf area index), yield parameters (yield per net plot, yield per hectare), and the vitamin composition (Vitamins A and C). The results showed that the application of compost manure improved the soil physical and chemical properties such as the water holding capacity, which was improved by 27.77% and 29.43% in the first and second growing seasons respectively. The application of 20 Mg ha-1 produced superior growth and yield (34.93 and 33.64 Mg ha-1) in the first and second growing seasons, respectively. Farmers are therefore encouraged to plant their lettuce crop using compost manure especially in urban areas. [ABSTRACT FROM AUTHOR]

Hydroponic production typically uses conventional fertilizers, but information is lacking on the use of organic hydroponic fertilizers. Development of microbial communities and biofilm that can reduce dissolved oxygen availability is a difficulty with organic hydroponics. One potential solution is the use of hydrogen peroxide (H2O2 ) which can reduce microbial populations and decompose to form oxygen. However, information is lacking on the impact of hydrogen peroxide on hydroponic crop performance. The aim of this study was to determine the effects of H2O2 concentrations in deep water culture hydroponics by assessing how it affects plant size and yield in lettuce (Lactuca sativa L.) “Rouxai”. In this experiment, three H2O2 treatments, namely the application of 0, 37.5 or 75 mg/L H2O2 to 4 L aerated hydroponic containers with either conventional or organic fertilizer, were compared. The containers had either fish-based organic fertilizer (4-4-1, N-P2O5 -K2O) or inorganic mineral based conventional nutrient solution (21-5-20, N-P2O5 -K2O), both applied at 150 mg/L N. Three replicates of each H2O2 treatment–fertilizer combination were prepared resulting in a total of eighteen mini hydroponic containers each with one head of lettuce. There were two growth cycles: fall 2018 and spring 2019. When added to conventional fertilizers, both 37.5 mg/L and 75 mg/L of H2O2 led to stunted growth or death of lettuce plants. However, when 37.5 mg/L of H2O2 was applied to organic fertilizers, the lettuce yield nearly matched that of the conventionally fertilized control, demonstrating that the application of H2O2 has the potential to make organic hydroponic fertilization a more viable method in the future. [ABSTRACT FROM AUTHOR]

Copyright of Egyptian Journal of Soil Science is the property of Egyptian National Agricultural Library (ENAL) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Blue light and ultra-violet (UV) light have been shown to influence plant growth, morphology, and quality. In this study, we investigated the effects of pre-harvest supplemental lighting using UV-A and blue (UV-A/Blue) light and red and blue (RB) light on growth and nutritional quality of lettuce grown hydroponically in two greenhouse experiments. The RB spectrum was applied pre-harvest for two days or nights, while the UV-A/Blue spectrum was applied pre-harvest for two or four days or nights. All pre-harvest supplemental lighting treatments had a same duration of 12 h with a photon flux density (PFD) of 171 µmol m−2 s −1 . Results of both experiments showed that preharvest supplemental lighting using UV A/Blue or RB light can increase the growth and nutritional quality of lettuce grown hydroponically. The enhancement of lettuce growth and nutritional quality by the pre-harvest supplemental lighting was more effective under low daily light integral (DLI) compared to a high DLI and tended to be more effective when applied during the night, regardless of spectrum. [ABSTRACT FROM AUTHOR]

Copyright of Revista IRRIGA - Brazilian Journal of Irrigation & Drainage is the property of Revista IRRIGA (Brazilian Journal of Irrigation & Drainage) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Light and nitrogen are the main factors commanding horticulture production. Therefore, this study aims at evaluating the effects of two different greenhouse cover films (clear-Film A and diffuse light-Film B) on yield and nutritive value of a ready-to-eat salad lamb's lettuce (Valerianella locusta L.), grown under several nitrogen regimes (no nitrogen [N0], sub-optimal [N25] and optimal N fertilization [N50] corresponding to 0, 25 and 50 kg ha-1, respectively). The combination N50 and Film B boosted SPAD index by 10.3% and yield by 91.9% compared to N0 × Film A. Concerning antioxidant activity and bioactive compounds, only total ascorbic acid was positively affected by Film B (9.4%), while there was no effect of this cover film on carotenoids and chlorophyllous pigments, which increased along the increment of nitrogen rates. Nitrate content in leaves was influenced by both factors and it showed increasing values, when nitrogen doses increased, reaching the highest value under N50-Film B conditions (3312.3 mg kg-1 fw). Our study showed that in the Mediterranean area, the use of greenhouse diffuse light film improved lamb's lettuce yield, but on the other hand incurred significant increase in nitrate level, nonetheless remaining constantly under the legal threshold imposed by the commission regulation (EU). Secondary metabolites, such as total phenols and carotenoids, showed similar values under both films, instead the diffuse light film improved total ascorbic acid content. [ABSTRACT FROM AUTHOR]

Highlights • Lettuce cultivation in closed hydroponics experiences autotoxicity. • Due to autotoxicity yield and quality decrease in non-renewed nutrient solution. • Yield gradually decrease in accordance to increase culture solution reuse times. • Electro-degradation of culture solution recovers lettuce yield and quality. Abstract In this study we investigated autotoxicity in lettuce under successive cultivation and applied alternating current electro-degradation (ED) to non-renewed nutrient solution to degrade the accumulated allelochemicals and consequently to improve the retarded yield and quality of lettuce. In our first experiment, lettuce was grown in renewed, non-renewed and non-renewed + ED solution. Every two weeks interval nutrient solution was changed in the renewed treatment while non-renewed solution was unchanged throughout the growing period but major minerals were adjusted bi-weekly. ED was also applied bi-weekly for 24 h. Compared to renewed solution, shoot fresh weight was decreased to 24% (301.8 g plant−1) in non-renewed solution. But when ED was applied, non-renewed + ED solution produced shoot fresh weight statistically similar to renewed solution plants. In the second experiment, lettuce was grown in renewed nutrient solution, one culture non-renewed (non-renewed 1C), two culture non-renewed (non-renewed 2C) and non-renewed 2C + ED solutions. In non-renewed 1C, the starting solution was fresh nutrient solution while in non-renewed 2C it was once used. Lettuce grown in non-renewed 2C solution produced shoot fresh yield (258.8 g plant−1), about 35% lower compared to renewed solution. When ED was applied to non-renewed 2C solution produced shoot fresh weight 383.3 g plant-1 which was statistically similar to renewed solution. Calcium and iron concentration in lettuce followed the similar trend. Therefore, it was evident that yield and quality of lettuce could be improved through ED in non-renewed solution in two successive cultivations using same nutrient solution. In the following study, we tried to determine the proper ED interval in the third experiment. Results showed that ED to non-renewed solution both weekly and bi-weekly equally improved growth, yield and mineral concentration in lettuce. Hence, ED at two weeks interval was sufficient. [ABSTRACT FROM AUTHOR]

Highlights • Supplemental light increased lettuce growth and yield, regardless of light quality. • Providing red and far-red light at the end of day did not influence lettuce growth. • There was little effect of the quality of supplemental lighting on leaf coloration. • Consumers preferred lettuce grown without supplemental light. Abstract Supplemental lighting (SL) is often used in greenhouse lettuce production to increase yield when the solar daily light integral is low. High-pressure sodium (HPS) fixtures are traditionally used to deliver SL, but light-emitting diodes (LEDs) have become a feasible, more energy-efficient replacement. Red light (R; 600–700 nm) and blue light (B; 400–500 nm) are especially effective in promoting photosynthesis and increasing crop growth, whereas far-red (FR; 700–800 nm) radiation has the potential to increase yield by promoting leaf expansion. We performed three greenhouse experiments with HPS or LED fixtures to determine the effects of SL on lettuce growth, coloration, and sensory attributes. We grew lettuce at 20 °C without or with SL from HPS or R + B LEDs with a 16-h photoperiod (Expts. 1 and 2). In Expt. 3, we grew plants without or with HPS SL without or with R + FR photoperiodic lighting at the end of the day during the growing (first) stage, SL from R + B or B LEDs during the finishing (second) stage, or both. SL enhanced lettuce growth and yield by 32%–104% regardless of light quality. Four hours of end-of-day R + FR lighting at 2 to 5 μmol m−2·s−1 had few effects on lettuce growth or quality attributes. Compared with lettuce with no SL, lettuce provided with R + B LED SL for 7 d before harvest was 27% darker, 76%–82% redder, and 39%–55% less yellowish. Consumers tended to prefer lettuce grown under natural daylight more than plants grown with SL, and judged it to be less bitter, to be sweeter, and to have a more likable aftertaste. We conclude that providing different types of greenhouse SL at different growing stages can improve lettuce growth and coloration but that consumers could prefer taste attributes less. [ABSTRACT FROM AUTHOR]

Highlights • Omeprazole application rate effect on lettuce at 1 or 30 mM NaCl was explored. • Application of omeprazole at 10 or 50 μM mitigated yield reduction. • Omeprazole at 10 μM under saline conditions decreased Na+ and Cl− and improved NO 3 −. • Under nonsaline conditions, omeprazole enhanced root biomass, nutrient and water uptake. Abstract Natural or synthetic small molecules (<500 Da), bioactive at very low concentrations, can potentially increase plant tolerance and resilience to abiotic stresses and improve the resources use efficiency (RUE) of a wide range of crops. Hence, they represent a promising tool in coping with the increasing global food demand imposed by climate change. In this study, the responses of butterhead lettuce (cv. Trocadero) treated with omeprazole (OMP), a benzimidazole inhibitor of animal proton pumps, were studied. OMP was applied as substrate drench at five rates (0, 10, 50, 100 or 200 μM) on lettuce plants grown under nonsaline or saline conditions of 1 or 30 mM NaCl. Increasing NaCl concentration decreased lettuce fresh and dry biomass by 37% and 25% in the 0 μM OMP treatment, respectively; whereas these reductions were mitigated by the 10 μM (12% and 19%, respectively) and 50 μM (15% and 14%, respectively) OMP application. Though OMP was not directly involved in ion homeostasis and K+/Na+ ratio regulation, treatment with 10 μM OMP under saline conditions decreased Na+ in leaves and Cl− in leaves and roots while increasing NO 3 − concentration in both organs. The synthesis of nitrogenous osmolytes may be implicated in increasing salt tolerance and the sustenance of transpiration and photosynthesis. Under nonsaline conditions, OMP increased root biomass, improving nutrient and water uptake, and therefore RUE. [ABSTRACT FROM AUTHOR]

Highlights • Lighting environment at seedling stage influenced mature lettuce yield. • Nitrate content of lettuce was not affected by light treatment at seedling stage. • Broad spectrum LED with red to blue ratio of 2.2 was suitable for seedling growth. • Daily light integral of 11.5 mol m−2 d−1 was appropriate for seedling growth. Abstract In order to obtain high-quality lettuce seedlings, effects of photosynthetic photon flux density (PPFD), photoperiod and light quality at seedling stage on growth and quality of hydroponic lettuce were investigated at different growth stages. Hydroponic lettuce (Lactuca sativa L. cv. Frill ice) seedlings were grown under 12 combinations of two levels of PPFD (200 and 250 μmol m−2 s-1) and two photoperiods (14 and 16 h d-1) under three light quality: light-emitting diodes (LEDs) with red to blue ratio (R:B ratio) of 1.2 and 2.2, and fluorescent lamps with R:B ratio of 1.8 as control. After the 20-day treatment during seedling stage, lettuce seedlings were transplanted to a homogeneous lighting environment for another 20 days before harvest. Results showed that leaf length and ratio of leaf length to leaf width at 20 days after sowing decreased in a logarithmic way with increasing daily light integral and fluorescent lamps resulted in larger seedlings with bigger leaves and higher leaf and root dry weights compared to LEDs. Leaf and root fresh weights of harvested lettuces were higher in the seedlings grown under PPFD at 200 μmol m−2 s-1 with a 16 h d-1 photoperiod, regardless of light quality at seedling stage. Generally, vitamin C content of mature lettuce was lower in seedlings grown under LEDs with R:B ratio of 1.2 and no significant differences were observed in nitrate content among the three lighting sources. In consideration of mature yield and quality, lighting efficiency and electrical consumption of lighting sources, PPFD of 200 μmol m−2 s-1 with a photoperiod of 16 h d-1 provided by LEDs with R:B ratio of 2.2 was suitable for hydroponic lettuce (cv. Frill ice) seedling production. [ABSTRACT FROM AUTHOR]

Highlights • Pyroglutamic acid increased lettuce yield by 31% under water deficit stress. • Pyroglutamic acid enhances photosynthesis parameters and plant stress defences. • Pyroglutamic acid treatment did not affect soil microbiology. Abstract Water scarcity is one of the main challenges faced by modern agriculture, leading to a substantial drop in crop productivity and a threat to food security. Thus, novel agricultural approaches are necessary and urgent to face this problem. Some natural compounds such as amino acids have been shown to increase yield and mitigate the effects of drought stress. In this study, we demonstrate that the application of pyroglutamic acid (PG) is capable of increasing lettuce yield, under field conditions with 30% less than optimal irrigation. PG treatment showed a clearly protective effect in stressed plants, enhancing their fresh weight by 37% and yield by 31%, in comparison to untreated plants. PG appears to promote drought tolerance effects in deficit irrigated lettuce plants, with several advantages. It acts by enhancing photosynthesis rate and antioxidant defences, while maintaining osmotic and water balance, without toxicity to soil microorganisms. This illustrates the potential use of PG to combat productivity losses due to water scarcity. [ABSTRACT FROM AUTHOR]

It is known that the magnetic field works to change the chemical and physical properties of water and this is reflected in the properties of soil and plant. An experiment was conducted during 2017 and 2018 seasons at a farm in MitKenana village, Qalyobia, Egypt. The aim was to study the effect of water re-magnetization on the properties of water, soil and Lettuce growth. The experiment was divided into four treatments with three replicates. Normal water treatment and other magnetized water treatments were irrigated with water passed through the magnetic device one, two and three times. EC, pH, anions and cations for both water and soil as well as yield and yield components for Lettuce were measured. Results indicated that, irrigation with magnetized water induced positive significant effect on all studied treatments on water, soil and plant where it improved water and soil properties with increasing plant productivity. The one-time passing magnetic treatment of irrigation water significantly decreased electrical conductivity of the soil, but the effect on pH was moderatein addition to increasing lettuce productivity by 29.1% more than non-magnetic treatment. With multiple magnetic treatments, did not show big differences between treated and untreated treatments. [ABSTRACT FROM AUTHOR]

Abstract Toxic chromium [(Cr(VI)] in food chain has created an alarming situation for human life and ecosystems. The present study through a greenhouse pot experiment aims to (a) investigate the ability of organic matter in reducing Cr uptake by lettuce (Lactuca sativa L.) from a sandy loam soil irrigating with Cr(VI)-water, (b) to provide a way for the restriction of Cr transfer from contaminated soils and irrigation water to plants/crops and (c) to contribute to the better management of soil (land) and water use, without reduction of the agricultural production. Since soil and groundwater contamination by Cr is a potential risk in a worldwide scale, due to industrial activities and/or natural processes, organic carbon may play a key role in the mobility of added Cr(VI) to soil via irrigation water, in a significant way. The cultivation of lettuce, using organic matter in the form of leonardite (10 and 30 wt%) and Cr(VI)-irrigation water (100, 200 and 300 mgL−1), showed that the uptake of Cr in both shoots and roots increased with increasing concentration of Cr in the irrigation water. The highest Cr values in shoots (average = 10 mg/kg) and in roots (average = 28 mg/kg) were recorded in those plants cultivated in soil after the addition of Cr(VI)- water without organic matter, whereas the lowest Cr values in shoots (average = 0.44 mg/kg) and in roots (average = 0.7 mg/kg) were recorded in those plants cultivated in soil with addition of 30 wt% organic matter. The used leonardite as organic matter that is an oxidized form of lignite, due to its high content of humic acid is considered to be a useful organic fertilizer that provides possibilities for combining food production with soil protection. Therefore, the application of the natural organic material leonardite, as a land management technique, seems to be a cost-effective method consistent to related protocols for the protection of the soil quality. Graphical abstract Image 1 Highlights • Cr uptake by lettuce from a sandy loam soil irrigated with Cr(VI)-water. • Added leonardite reduced significantly Cr accumulation in roots and shoots. • Negative correlation between pH and Eh (mV) of the cultivated soil. • Negative correlation between organic carbon and Cr accumulation. • Restriction of Cr transfer from contaminated soils and waters to food chain. [ABSTRACT FROM AUTHOR]

Highlights • A novel segmentation method for lettuce in 3D coloured point clouds is proposed. • Points are clustered into leafs, which are assigned to plants based on orientation. • Physical features are extracted from the segmented plant point clouds. • Fresh weight and extracted features show strong correlations. Abstract Monitoring the health and yield of crops during production is an important, but labour intensive component of commercial agriculture, especially in high value crop such as lettuce. This article proposes a novel method for segmenting lettuce in coloured 3D point clouds and estimating the fresh weight. The proposed segmentation method operates by clustering points into leaves and then evaluating their affiliation to a lettuce of interest. From the segmented lettuce point clouds, the volume, surface area, leaf cover area and height predictors are extracted and correlated to the fresh weight. The proposed segmentation and yield estimation methods are evaluated on Cos and Iceberg lettuce point clouds generated from images collected by an agricultural robot in an outdoor field experiment. The results demonstrate that the proposed segmentation method is able to successfully isolate lettuce (F 1 -score = 0.88–0.91). Analysis of the segmented lettuce models show that the calculated surface areas correlate strongly with measured fresh weight (R2 = 0.84–0.94). Not only does this validate the segmentation method, it allows an accurate estimate of the lettuce fresh weight (RMSE = 27–50 g) to be produced non-destructively. [ABSTRACT FROM AUTHOR]

Highlights • A novel HBV antigen combining S and L-derived epitopes was produced in lettuce. • The chimeric antigen induces humoral immune responses in orally-vaccinated mice. • Antibodies elicited by the chimeric antigen are strong inhibitors of HBV infection. Abstract Hepatitis B Virus (HBV) infection can be prevented by vaccination. Vaccines containing the small (S) envelope protein are currently used in universal vaccination programs and achieve protective immune response in more than 90% of recipients. However, new vaccination strategies are necessary for successful immunization of the remaining non- or low-responders. We have previously characterized a novel HBV chimeric antigen, which combines neutralization epitopes of the S and the preS1 domain of the large (L) envelope protein (genotype D). The S/preS121–47 chimera produced in mammalian cells and Nicotiana benthamiana plants, induced a significantly stronger immune response in parenterally vaccinated mice than the S protein. Here we describe the transient expression of the S/preS121–47 antigen in an edible plant, Lactuca sativa, for potential development of an oral HBV vaccine. Our study shows that oral administration of adjuvant-free Lactuca sativa expressing the S/preS121–47 antigen, three times, at 1 μg/dose, was sufficient to trigger a humoral immune response in mice. Importantly, the elicited antibodies were able to neutralize HBV infection in an NTCP-expressing infection system (HepG2-NTCP cell line) more efficiently than those induced by mice fed on Lactuca sativa expressing the S protein. These results support the S/preS121–47 antigen as a promising candidate for future development as an edible HBV vaccine. [ABSTRACT FROM AUTHOR]

Microcystins and copper commonly co-exist in the natural environment, but their combined toxicity remains unclear, especially in terrestrial plants. The present study investigated the toxicity effects of microcystin-LR (0, 5, 50, 500, 1000 μg L −1 ) and copper (0, 50, 500, 1000, 2000 μg L −1 ), both individually and in mixture, on the germination, growth and oxidative response of lettuce. The bioaccumulation of microcystin-LR and copper was also evaluated. Results showed that the decrease in lettuce germination induced by copper alone was not significantly different from that induced by the mixture, and the combined toxicity assessment showed a simple additive effect. Lettuce growth was not significantly reduced by microcystin-LR alone, whereas it was significantly reduced by copper alone and the mixture when copper concentration was higher than 500 μg L −1 . High concentrations of microcystin-LR (1000 μg L −1 ) and copper (≥50 μg L −1 ),as well as their mixture (≥50 + 500 μg L −1 ), induced oxidative stress in lettuce. A synergistic effect on the growth and antioxidative system of lettuce was observed when exposed to low concentrations of the mixture (≤50 + 500 μg L −1 ), whereas an antagonistic effect was observed at high concentrations (≥1000 + 2000 μg L −1 ). Moreover, the interaction of microcystin-LR and copper can increase their accumulation in lettuce. Our results suggest that the toxicity effects of microcystin-LR and copper are exacerbated when they co-exist in the natural environment at low concentrations, which not only negatively affects plant growth but also poses a potential risk to human health via the food chain. [ABSTRACT FROM AUTHOR]

The main aim of this study was to evaluate the effect of saline water, chemicals and organic fertilizers on lettuce (Lactuca sativa L.) growth, its yield and their antioxidant and soil properties. There were two experiments, one was soil, and another was lettuce growth parameters with anti-oxidant enzyme activities by using split-plot design method. Study findings showed the soil properties, the effect of saline water and rice wastes on some soil characters in the first experiment. And the second experiment findings revealed that the higher effect of overall yield, chlorophyll, NPK content, antioxidant enzymes and proline, higher POX level, increased activity of CAT, SOD level, maximum accumulation of proline and dry weight of head were observed in rice wastes and DAP 400 kg/ha treatment than control. [ABSTRACT FROM AUTHOR]

Key message: The nonhost resistance of wild lettuce to lettuce downy mildew seems explained by four components of a putative set of epistatic genes.Abstract: The commonplace observation that plants are immune to most potential pathogens is known as nonhost resistance (NHR). The genetic basis of NHR is poorly understood. Inheritance studies of NHR require crosses of nonhost species with a host, but these crosses are usually unsuccessful. The plant-pathosystem of lettuce and downy mildew, Bremia lactucae, provides a rare opportunity to study the inheritance of NHR, because the nonhost wild lettuce species Lactuca saligna is sufficiently cross-compatible with the cultivated host Lactuca sativa. Our previous studies on NHR in one L. saligna accession led to the hypothesis that multi-locus epistatic interactions might explain NHR. Here, we studied NHR at the species level in nine accessions. Besides the commonly used approach of studying a target trait from a wild donor species in a cultivar genetic background, we also explored the opposite, complementary approach of cultivar introgression in a wild species background. This bidirectional approach encompassed (1) nonhost into host introgression: identification of L. saligna derived chromosome regions that were overrepresented in highly resistant BC1 plants (F1 × L. sativa), (2) host into nonhost introgression: identification of L. sativa derived chromosome regions that were overrepresented in BC1 inbred lines (F1 × L. saligna) with relatively high infection levels. We demonstrated that NHR is based on resistance factors from L. saligna and the genetic dose for NHR differs between accessions. NHR seemed explained by combinations of epistatic genes on three or four chromosome segments, of which one chromosome segment was validated by the host into nonhost approach. [ABSTRACT FROM AUTHOR]

Municipal waste management has been of major concern to many developing countries and is presently one of the subjects under discussion due to rapid industrialization and population growth. Most of these municipal wastes have the potential of being recycled and use in crop production. They are gradually becoming a problem in Ghana instead of being used for purposes to benefit human kind. In this study, dried faecal sludge and municipal waste co-compost was used as an organic fertilizer to cultivate cabbage and lettuce to assess its effects on their microbial load and yield. The yields of vegetables increased significantly with the application of recommended doses of the co-compost. The analysis of microbial load on the vegetables also showed significantly low microbial load on vegetables cultivated on co-compost plots followed by the chemical fertilizer and control. The presences of faecal coliforms such as Salmonella spp., Shigella spp., Escherichia coli, and Klebsiella spp. were confirmed in all. The performance of vegetable cultivated on plots treated with the co-compost makes it a good source of plant nutrients to be recommended to farmers. This could also serve as prudent strategy for managing municipal waste and faecal sludge to avoid impact of unscientific disposal on public health and quality of life. [ABSTRACT FROM AUTHOR]

The aim of the study was to identify the abiotic factors that influence the onset of diseases in a salad (Lactuca sativa L.) var. romana and var. capitata, grown under polyethylene film in Sofia field. Based on the objective, we set plots experienced in duplicate salads with foil, and two plots without foil. In order to obtain comparable results we carried out soil sampling in advance to check the availability of nitrogen, phosphorus and potassium. The first inspection was conducted in February 2017 with an analysis of the presence of soil pathogens in the experimental plots. So far we have identified soil fungi of the genus Alternaria, Fusarium, Rhizoctonia, Botritis, Aspergillus, Penicillium and Mucor. The second inspection will be conducted before the active growing season, with a sampling of plants with disease symptoms and comparison of the microbiological parameters after the end of the salad growing season. Currently the results show a significantly better development of plants grown under the plastic film without the occurrence of pathogens threatening collapse of salad plants. After the final results, we sincerely hope to recommend to salad producers to implement the use of foil against the collapse of lettuce under the influence of low temperatures and pathogens. [ABSTRACT FROM AUTHOR]

The lettuce (Lactuca sativa L.) is one of the oldest vegetable crops. Due to its valuable nutritional, dietetic and healing properties, it was grown in the Middle Ages. Salad as a vegetable culture is found in almost all countries. The largest areas occupy in Europe, North America and New Zealand and attacked by a large number of phytopathogens causing economically significant diseases and their degree of manifestation and assault are greatly influenced by climatic growing conditions. The aim of the current study was to detect diseases in lettuce induced by abiotic stress factors. Studies were conducted on 19 lettuce varieties in the Educational experimental field of the University of Forestry, located in the region of Sofia field. The plants were planted at three different conditions with three repetitions without treatments (three types of greenhouses - two unheated greenhouses and low tunnel covered with a polymer foil). The observations were conducted in the fall of 2015 and twice at the beginning and at the end of spring 2016 and funded under Project 17/2016 of the Forestry University. All plants with symptoms of the disease were examined in the laboratory and the losses were reported statistically. Samples of plants with suspected viral infection were subjected to a serological analysis and fungal pathogens were isolated on nutrient media and a morphology (microscopic) identification was carried. Up to datе, the results of the studies indicate that the viral infection has not been established yet. The fungal pathogens as Verticilium, Botritis and Septoria spp., causaing plant diseases were established and identified. The largest attack and manifestation of gray mould was found in three varieties Fuzila, Funfix and Sumetie and the degree of looses reached more than 90%. Explaining the impact of stress factors will improve the quality and quantity of crops grown from different varieties in the particular climate area. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the influence of the spacing of lettuce rows on the production of a lettuce-rocket intercropping system over two growing seasons (11 August to 25 September 2011 and 12 January to 24 February 2012) in Jaboticabal, São Paulo, Brazil. We evaluated 11 treatments in each season: lettuce-rocket intercrops with five row spacings for the lettuce (0.20, 0.25, 0.30, 0.35 and 0.40 m) and the rocket planted midway between the lettuce rows, sole crops of lettuce at the same five row spacings and a sole crop of rocket. Fresh and dry masses of the lettuce and rocket and number of lettuce leaves per plant were highest with a lettuce row spacing of 0.40 m, but the productivities of the lettuce and rocket were higher with a lettuce row spacing of 0.20 m. The productivities and fresh and dry weights of the lettuce and rocket and the number of lettuce leaves per plant were highest in the sole crops, but the fresh and dry weights of the rocket were higher with intercropping. The land equivalent ratios were >1.0 in both seasons in all intercrops and were highest for the densest crop (1.41). Intercropping was therefore 41% more efficient than sole cropping for the production of lettuce and rocket. [ABSTRACT FROM AUTHOR]

Greenhouse crops are often affected by salinity due to water quality decay associated with crop fertilization and irrigation managements as well as the fact that greenhouse environment may become even hotter during summer time. Thus, combined effects of salt, heat and light stresses can affect plants grown in greenhouse. This research work addressed the combined effect of white greenhouse covering film and foliar proline spray application to reduce the detrimental effects of salinity on two cultivars of lettuce ( Lactuca sativa cv. Teide and cv. Impulsion ) grown on a floating system. Five different experiments were conducted in two twin greenhouses covered with plastic films characterized by different light permeability. The experiments aimed at identifying the most suitable nutrient solution (exp. #1), and assessing how the effects of mild salinity (0–15 mM NaCl) would be alleviated by the greenhouse covering film (exp. #2, #3, #4 and #5) and foliar proline spray application (0–15 μM) (exp. #4 and #5). Results showed that the white covering film changed the spectral light intensity and decreased the Photosynthetically Active Radiation (PAR) of the light transmitted causing a delay in the plant growth and leaf chlorophyll content. Although salinity negatively affected plant growth and leaf photosynthesis of both cultivars, using the white film partially mitigated the influence of salt stress. The beneficial effects of the white film on salt stress mitigation were more evident during summer and in the heat sensitive genotype (cv. Teide ) in terms of greater total and marketable yield as compared to control conditions. Exogenous application of foliar proline (up to 5 μM) increased the yield under control condition and enhanced the plant response to salinity. Overall, for summer cultivation of cv. Teide , in presence of saline water (15 mM NaCl), the combination of both white covering film and proline application enabled to preserve efficiently the plant growth and final yield. [ABSTRACT FROM AUTHOR]

This research was conducted for the purpose of determining the effects of bat guano on plant nutrient contents in the soil and in lettuce (Lactuca sativa L.) during the spring of both 2014 and 2015 with three replications according to randomized blocks experiment design. Bat guano was applied to the soil in two different forms; According to the results organic matter, P, Cu and Mn amounts in the soil were found to be statistically significant and increased compared to the control. Likewise, in the application of bat guano dust, organic matter, P and Mn amounts in the soil were found to be statistically significant and increased compared to the control. In lettuce, N, K, Mg, Fe, Cu, Zn and Mn amounts in the application of bat guano powder and K, Ca, Mg, Fe, Zn and Mn amounts in the application of bat guano dust were found to be statistically significant. [ABSTRACT FROM AUTHOR]

In sub-Saharan Africa, manure and loam soil are popular growing media substrates. However, their poor physiochemical properties limit their use in growing media. Following a survey of farmers, single species sawdust, mixed species sawdust, and rice husk (RH) were selected and composted with poultry manure. Additionally, the RH was charred for use in soilless media. Objectives were to produce feedstock-specific composts and determine appropriate proportion for using them in containerized systems. Three composts produced were amended with soil in ratios of 1:1, 1:2, and 1:3 (v/v) in an initial experiment. In a second experiment (soilless), the single sawdust and RH compost were each amended with RH biochar in ratios of 1:0, 1:1, 1:2 (v/v) and subjected to half or full pot irrigation. RH compost amended soils gave the highest lettuce yield. In the soilless media, 2:1 ratio (v/v) of biochar to sawdust compost gave the highest yield. [ABSTRACT FROM AUTHOR]

Soil solarization is a non-chemical method used to destroy soil borne pathogenic, harmful, and weed seeds in agricultural field and greenhouses. Solarization is generally applied in regions with high summer air temperatures and high solar radiation. Organic materials obtained as a result of the pyrolysis process in an anaerobic environment is called biochar. It can be produced from a wide range of plant and animal origin biomass sources. Lettuce plants are an important vegetable species grown after the application of solarization because of their high value and compatibility with autumn growing. Researchers reported that lettuce yields increased following soil solarization. The aims of this work were to examine different mulch materials and addition of biochar (a new approach in soil solarization) of soil temperature change, and determine which month is more effective according to temperature difference, and also effect of solarization application on yield, quality, and leaf nutrient content characteristics of lettuce plant. The experimental site was located at the University of Suleyman Demirel University in Isparta and the study was conducted during summer and autumn of 2016. Two different polyethylene (PE) mulch materials have been tested. Four different treatments and non-solarization were performed in this research. There were PE mulch, bubble PE mulch, PE + biochar, bubble PE+ biochar and non-solarization treatments. In the parcels where biochar application is used, it was applied 150 g m −2 of the soil surface as a thin mulch. Biochar added bubble solarization mulching film was determined to be more effective with regard to temperature increase and heat conservation in comparison with the traditional mulch material. Solar radiation played an important role in rising soil temperature with mulch material. With the fall of solar radiation in August, temperatures under mulching films decreased. But, temperature inside the greenhouse and the temperature of the bare soil did not change or it was affected less. Yield increase of 100% was attained for lettuce yield increase with biochar added bubble solarization mulch in comparison with the control. Thus, the study reached the determined objective and it has been determined that biochar use plays an important role in the effectiveness of solarization applications. [ABSTRACT FROM AUTHOR]

Lettuce ( Lactuca sativa ) is one of the most popular leafy vegetables in the world, characterized by a diverse composition of phytochemical compounds but at low levels. However, their content may be increased with abiotic stresses. Accordingly, phytochemical enhancement and related microbiological and organoleptic quality and peroxidase (POD) and polyphenol oxidase (PPO) activities of Butterhead lettuce elicited during preharvest with natural compounds (chitosan 10 g L −1 and tea tree essential oil 2.7 mL L −1 ) were studied. Quality indices were evaluated at harvest and during 21 days of refrigerated storage (0–2 °C). Treatments with chitosan and tea tree increased the total phenolic content of freshly lettuces by 30.5 and 21.1%, respectively, and the total flavonoids concentration by 43.3 and 36.4%, respectively, compared with control samples. The antioxidant capacity at harvest of the elicited plants, measured with DPPH and TEAC assays, was also higher. Notably, these improvements were maintained during refrigerated storage. Conversely, although a higher concentration of ascorbic acid was initially detected in treated plants with chitosan and tea tree, these differences were not observed at later storage times. No differences were detected in the organoleptic quality of elicited and control plants, meanwhile the microbiological quality and enzymatic activity were affected by the preharvest treatments. In particular, the application of chitosan exerted a fungistatic effect reducing yeast and molds population counts by 1.6 log throughout the storage, compared with control samples. Furthermore, chitosan also reduced the activities of PPO and POD, enzymes related with browning processes. Preharvest treatments with chitosan and tea tree enhanced the content of health-promoting phytochemicals in lettuce, without affecting its organoleptic quality. Moreover, chitosan treatment appears as a promising method to improve the safety and reduce the enzymatic activity of lettuce. [ABSTRACT FROM AUTHOR]

BACKGROUND Lettuce is a significant source of antioxidants and bioactive compounds. Nitrate is a cardinal fertilizer in horticulture and influences vegetable yield and quality; however, the negative effects of nitrate on the biosynthesis of flavonoids require further study. It is expected that using fertilizers containing organic nitrogen (N) could promote the synthesis of health-promoting compounds. RESULTS Lettuces were hydroponically cultured in media containing 9 mmol L−1 nitrate or 9 mmol L−1 glycine for 4 weeks. Primary and secondary metabolites were analyzed using gas chromatography/mass spectrometry (GC/MS) and ultra-performance liquid chromatography/ion mobility spectrometry/quadrupole time-of-flight mass spectrometry (UPLC/IMS/QTOF-MS). Data analysis revealed that 29 metabolites were significantly altered between nitrate and glycine treatments. Metabolites were tentatively identified by comparison with online databases, literature and standards and using collision cross-section values. Significant differences in flavonoid biosynthesis, phenolic biosynthesis and the tricarboxylic acid (TCA) cycle response were observed between N sources. Compared with nitrate, glycine promoted accumulation of glycosylated flavonoids (quercetin 3-glucoside, quercetin 3-(6″-malonyl-glucoside), luteolin 7-glucuronide, luteolin 7-glucoside), ascorbic acid and amino acids ( l-valine, l-leucine, l-glutamine, asparagine, l-serine, l-ornithine, 4-aminobutanoic acid, l-phenylalanine) but reduced phenolic acids (dihydroxybenzoic acid hexose isomers 1 and 2, chicoric acid, chicoric acid isomer 1) and TCA intermediates (fumaric, malic, citric and succinic acids). CONCLUSION The novel methodology applied in this study can be used to characterize metabolites in lettuce. Accumulation of glycosylated flavonoids, amino acids and ascorbic acid in response to glycine supply provides strong evidence supporting the idea that using amino acids as an N source alters the nutritional value of vegetable crops. © 2017 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

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Aims: Distribution of selenium (Se) in soils around the world is not identical and many soils are classified as Se-poor soils. Therefore, Se fortification of crops grown on these soils is crucial, where increasing Se intake by human - below toxic threshold - is vital for better health. The recent work aims to investigate the possible use of Se to alleviate the detrimental effects of soil salinity on lettuce and enhance its growth, yield quality and Se enrichment. Methods: Field experiments were conducted during two successive seasons (2016 and 2017) in salt-affected soil (EC 4.49 dS m, pH 8.65) using four concentrations of Se (0, 50, 75 and 100 ppm) by three different application methods. Antioxidant capacity, ion leakage, Se content in plant and soil, yield and vegetative parameters of lettuce were measured. Results: The results showed that Se addition mitigated the detrimental effect of salinity on lettuce growth and its development. Se application (100 ppm) increased also the head weight, leaf area, leaves dry weight and chlorophyll content by 46.4, 66.4, 61.8 and 31.5%, respectively, compared to control plants. Likewise, catalase (CAT) and ascorbate peroxidase (APX) activities increased by 108.8 and 123.6%, respectively, as a result for using 100 ppm of Se. Otherwise, Se (100 ppm) reduced the electrolyte leakage from lettuce leaves by 68.4% against control. The positive effect of Se (100 ppm) on lettuce under salinity was fully verified with data of total yield which increased by 42.1% over control. Foliar application increased Se content in lettuce without exceeding the toxic level and residual Se in soil was the lowest among other treatments. Conclusion: The present work reports that in salt-affected soils spraying lettuce with Se (100 ppm) improves its growth, antioxidant capacity, Se fortification and yield quality. [ABSTRACT FROM AUTHOR]

The effect of suboptimal supply of nitrogen (N) and of replacing nitrate in the nutrient solution with ammonia on growth, yield, and nitrate concentration in green and red leaf lettuce was evaluated over two seasons (autumn and spring) using multiple regression analysis. The plants were grown in a greenhouse on a Nutrient Film Technique (NFT) system. Nitrogen concentrations in the nutrient solution were either 3 mM or 12 mM, and the form of N was varied as follows: 100% NO3, 50% NO3 + 50% NH4, and 100% NH4. In both seasons, the biomass (fresh weight) of lettuce heads increased with increasing NO3concentrations and in autumn, NO3even at 1.5 mM was sufficient for high yield. However, head dry weight was affected neither by the season nor by changes in the composition of the nutrient solution. The concentration of NO3had no effect on root dry weight, but it decreased at higher concentrations of NH4. The number of leaves increased as the ratio of NO3to NH4in the nutrient solution increased and was higher in autumn because of the longer growth period. Increasing the concentration of NO3in nutrient solution increased both total N and nitrate concentration in lettuce heads (dry weight) but decreased the concentration of total C. Also, leaf nitrate concentration was lower in spring than in autumn and decreased with increasing NH4concentration. Nitrogen utilization efficiency was maximum when NH4levels in the nutrient solution were either 0% or 50% irrespective of the season. Our results thus show that suboptimal N supply in autumn will not affect lettuce yield, and that nitrate concentration in leaves is lower when NH4concentrations in nutrient solution are higher and also much lower in red lettuce than in green lettuce. [ABSTRACT FROM AUTHOR]

High tunnels may help mitigate unfavorable climate and weather on lettuce (Lactuca sativa L.) production leading to greater yields and quality, yet information for using these systems in the Southeast region is lacking. This study evaluated the effect of high tunnels and three planting dates (PDs) (early March, late-March, and mid-April) on spring organic lettuce production. A 25% to 36% increase in marketable fresh weight for butterhead and romaine lettuce, respectively, was observed under high tunnels compared with the field in 2016, but there was no difference among the two growing systems in 2015. High tunnel lettuce was harvested ≈2 to 7 days earlier than in the field in 2015 and 2016, respectively. Pest and disease pressure (e.g., Sclerotinia sclerotiorum) as well as the incidence of physiological disorders (i.e., bolting, tip burn, and undersized heads) were similar between the two systems indicating that our high tunnel system did not provide a benefit for these issues. High tunnel air temperatures were ≈3 to 5 °C greater on the coldest mornings and only 1 °C greater on the warmest days compared with the field. Average relative humidity (RH), leaf wetness, and light levels were all lower under the high tunnels. Our results indicate that high tunnels can help increase the production of spring organic lettuce in Georgia, but that the advantage may depend on yearly weather conditions. [ABSTRACT FROM AUTHOR]

The study involved investigating the effect of ion exchange substrate (IES) addition to a nutrient solution (2% or 5% v/v) on the yield and root parameters of butterhead lettuce (Lactuca sativaL. cv. “Justyna”) under the conditions of basic (1.5-times concentrated Hoagland solution, electrical conductivity, EC 2.41–2.47 dS m−1), and intensive (3-times concentrated Hoagland solution, EC 6.85–7.30 dS m−1) mineral nutrition level. Regardless of the mineral nutrition level, both experimental additions of IES significantly increased the yield and elevated the volume, as well as the whole (WRA) and the active (ARA) adsorptive surface area of roots. It was confirmed that the substrate did not cause salt stress. Additionally, it was revealed that the substrate constitutes a beneficial component of lettuce in non-salinized (basic) or salinized (intensive mineral nutrition level) environment and that the 2% dose was more favorable than 5% dose. [ABSTRACT FROM AUTHOR]

The objective of this work was to evaluate the production of lettuce manured with roostertree (Calotropis procera) under different amounts and times of its incorporation to the soil. The experimental design was of randomized complete blocks with treatments arranged in a 4 x 4 factorial scheme, with four replications, where the first factor was composed of four quantities of roostertree (5.4, 8.8, 12.2 and 15.6 t ha-1 on a dry basis), and the second factor by the incorporation times (0, 10, 20 and 30 days before lettuce transplanting - BLT). The lettuce cultivar planted was Tainá. The best productive performance of the lettuce was obtained in the amount of 15.6 t ha-1 of roostertree incorporated into the soil, in the time of 0 days before lettuce transplanting. The cultivation of the lettuce is agro-economically viable with the use of roostertree. [ABSTRACT FROM AUTHOR]

Lettuce (Lactuca sativaL.) is an important vegetable crop that can be grown in hydroponic and aquaponic systems. A comparative study to evaluate the efficacy of a cold water flow-through aquaponic system (FTS) to a hydroponic system is lacking. Twenty-seven lettuce cultivars with green or red leaves, in seven subtypes, belonging to four popular types in the Western diet, were grown in spring water or aquaponic or hydroponic treatments. Spring and aquaponic water flowed directly from a spring and a raceway growing rainbow trout, respectively. The hydroponic treatment had nutrients added to a recirculated system. Stand establishment, average yield, and productivity (yield/week) were determined for each subtype or cultivar and compared among water treatments. No comparison among lettuce types, subtypes, or cultivars was made due to inherent differences among genotypes. Total yield and productivity (402.5 g·m−2and 4.9 kg/tray/week, respectively) in the FTS were lower than those in the hydroponic system (468.9 g·m−2and 6.7 kg/tray/week, respectively). Average yields of butterhead and bibb subtypes in aquaponics were higher than in the hydroponic treatment. Bibb subtype lettuces performed better in the aquaponic treatment, and average yields of butterhead and romaine, one of the most popular and nutritious lettuce types, were similar to those in the hydroponic treatment. The cvs. Outredgeous in romaine, Winter Density in bibb, Red Sails in leaf, and Red Saladbowl in oakleaf subtypes were recommended for an FTS. Average yields of green lettuces were higher than red lettuces in the bibb subtype in all treatments. Lettuce yield, depending on cultivar, could be comparable to hydroponic or field production based upon yield per area. [ABSTRACT FROM AUTHOR]

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Between factors which may influence on plant growth are light conditions and chemical composition of atmosphere. The objective of this study was to investigate the effect of ozone treatment (at the stage of seeds and seeds + seedlings, described as O 3 -I and O 3 -II) and light colour (white, blue, and white + blue 50:50) on photosynthesis and yield of lettuce ( Lactuca sativa L. ‘Subyana F 1 ’) grown in a hydroponic system. During the experiments the following conditions were maintained: photoperiod 12 h; temperature 22 °C; relative humidity (RH) 65–70%. LED lamps emitted the following light colours: white, blue and white + blue (50:50) (described as W, B and W + B). For all colours, quantum irradiance was 70 μmol m −2 s −1 . Plants were fertigated with a standard nutrient solution with the following chemical composition (mg dm −3 ): N-NH 4 < 10, N-NO 3 150, P-PO 4 50, K 150, Ca 150, Mg 50, Fe 3.00, Mn 0.5, Zn 0.44, Cu 0.03, B 0.01; pH 5.50, EC 1.8 mS cm −1 . The analysed factors significantly modified photosynthetic activity, growth, yield, chlorophyll content (SPAD measurements) and chemical composition of plants. The highest net photosynthesis rate (P N ) was recorded in plants cultivated with O 3 -I under W + B light, while the lowest was observed for O 3 -II under B light. In the case of O 3 -II a highly significant increase of mean N content in leaves was observed, together with decreases of P, Ca, Mg, Na, Fe and Mn contents in comparison to control plants. An improvement of yield (although not statistically significant) was found in O 3 -I plants, while O 3 -II application caused a decrease of the yield, for B light by about −27.87%, for W −53.74% and for W + B −46.51%. Similar observations were noted for the number of leaves. Moreover, a significant effect of O 3 -I on chlorophyll content was noted, excluding plants cultivated under W light. It seems that ozonization of seeds improves their germination and some other growth and physiological processes, while a second ozonization impairs the condition of plants and has a similar effect as tropospheric ozone in outside conditions. From the practical point of view, it would be interesting to investigate the effect of ozonization and other light colours on different crop species. [ABSTRACT FROM AUTHOR]

This study investigated whether intensive nutrition with sulfur–sulfate (S-SO4) (2, 6, or 9 mM S) of nickel-stressed (0, 0.0004, 0.04, or 0.08 mM Ni) butterhead lettuce cv. Justyna may improve macronutrient balance and reduce Ni bioaccumulation. Nickel exposure resulted in various unfavorable changes in the macronutrient content together with increase of Ni accumulation in the biomass. Intensive S nutrition of Ni-treated lettuce seems to have no beneficial effect on macronutrient balance. In general, it significantly reduced the root and foliar phosphorus (P), potassium (K), calcium (Ca), and S content and simultaneously did not affect the magnesium (Mg) content in the biomass. At the same time, the nitrogen (N) content was reduced in roots and elevated in shoots. Supplementation of Ni-exposed lettuce with high S doses raised in roots and reduced foliar Ni accumulation; however, Ni content in useable parts exceeded the acceptable limits established for consumption. [ABSTRACT FROM PUBLISHER]

Peat is the main component of growing media in horticulture. Increasing demand, environmental concerns and rising costs for peat make the search for alternative materials imperative. Much research has been performed aiming to find high quality and low cost substrates from different organic wastes such as compost and thus decrease peat consumption. Biochar is a carbon-rich material that has attracted important research as a soil amendment. However, its potential utilization as a peat substitute for growing media formulation remains less well explored. The aim of this study was to evaluate the effects of sewage sludge and sewage sludge biochar on peat properties as growing media and on lettuce (Lactuca sativa) growth. Sewage sludge transformation into biochar proved to be a sustainable waste management approach in order to promote their future use as growing media components. Addition of biochar from sewage sludge increased the N, P and K content of growing media. The biochar addition to peat at a 10%vol rate increased lettuce biomass production by 184–270% and the shoot length by 137–147% despite hydrophysical properties not being improved. Also, biochar addition had a positive effect on growing media microbial biomass which increased more than 966%. In spite of the higher metal concentration in biochar than in sewage sludge, their transfer to plants seems to be reduced when compared with direct sewage sludge use. [ABSTRACT FROM PUBLISHER]

Background: Faecal matter biochar offers an interesting value proposition where the pyrolysis process guaranties a 100% pathogen elimination, as well as significant reduction in transport and storage weight and volume. Therefore, to evaluate the effect of (1) biochar produced from dried faecal matter from household based septic tanks, and (2) N fertilizer, as well as their interaction on yield and nutrient status of lettuce ( Lactuca sativa), lettuce was grown over two growing cycles under glasshouse on two contrasting soils amended once at the start with factorial combination of faecal matter biochar at four rates (0, 10, 20 and 30 t ha) with 0, 25 and 50 kg N ha in randomized complete block design. Results: For both soils, maximum fresh yields were recorded with biochar and combined application of biochar with N treatments. However, the greatest biochar addition effects (with or without N) with regard to relative yield were seen in less fertile sandy loam soil. We have also observed that faecal matter biochar application resulted in noticeable positive residual effects on lettuce yield and tissue nutrient concentrations in the 2nd growing cycle. For both soils, most nutrients analyzed (N, P, K, Mg, Cu and Zn) were within or marginally above optimum ranges for lettuce under biochar amendment. Conclusions: The application of faecal matter biochar enhances yield and tissue nutrient concentrations of lettuce in two contrasting soils, suggesting that faecal matter biochar could be used as an effective fertilizer for lettuce production at least for two growing cycles. Moreover, the conversion of the faecal matter feedstock into charred product may offer additional waste management benefit as it offers an additional (microbiologically safe) product compared to the more common co-composting. [ABSTRACT FROM AUTHOR]

A 2-yr field study was conducted to evaluate the effects of calcium cyanamide as an alternative nitrogen (N) fertilizer source on N use efficiency (NUE), yield, and quality of two types of lettuce (Lactuca sativa L.), romaine (var. longifolia, cv. Manavert) and red oak-leaf (var. crispa, cv. Aruba), grown on clay soil under a Mediterranean environment. Pretransplanting application of 120 kg ha-1 of N as calcium cyanamide (120CC) was compared with a traditional split application of 120 kg ha-1 of soluble N (120SN) consisting of 50% ammonium sulfate applied before transplanting and 50% as ammonium nitrate applied after transplanting. An unfertilized control (0-N) was included to calculate NUE indices. At harvest leaf area index, dry weight, fresh yield, dry matter concentration, and NUE indices were not affected by the N source. Leaf nitrate (NO3-) content was on average 55 and 41% higher in Aruba than in Manavert in the first (Exp-1) and second (Exp-2) season, respectively. Plants fertilized with 120CC had lower leaf NO3- content (41 and 18% in Aruba and 70 and 21% in Manavert in Exp-1 and Exp-2, respectively) compared with those fertilized with 120SN. These results suggest calcium cyanamide may be used as an effective tool to reduce leaf NO3- accumulation and to produce high-quality lettuce in compliance with European Regulation No. 1258/2011 while assuring competitive yields. [ABSTRACT FROM AUTHOR]