Lettuce Cultivation Research Articles

Hydroponic Lettuce Cultivation with Organic Liquid Fertilizer: Examining Bacterial Inhibition and Phosphate Solubilization

This study explores organic hydroponic cultivation as a sustainable alternative to chemical fertilizers amid global supply challenges. With rising costs and the depletion of conventional nitrogen sources, organic liquid fertilizers are gaining attention for their microbial enrichment processes (MEP) that convert organic matter into plant-accessible nutrients. This experiment focuses on lettuce cultivation using two organic liquid fertilizers, Power Fish and POF vol. 2, in controlled environments. The results show that there are significant differences in plant growth parameters such as leaf number, fresh weight, chlorophyll content, and root length across different fertilizer treatments. Key findings include that effective management practices, including pH control and regular nutrient application, are crucial for maintaining microbial activity and optimizing nutrient uptake efficiency. Additionally, Bacillus sp. and Xanthomonas sp. were isolated from these fertilizers and dual-cultured with rot fungi, Pythium sp. and Fusarium sp. This dual cultivation demonstrated inhibitory activity against these pathogens, showcasing the potential of these microorganisms in promoting biofilm-mediated disease resistance in organic hydroponic systems. The study also emphasizes the phosphate solubilization capabilities of isolated bacteria, essential for sustainable nutrient cycling. Overall, organic hydroponic systems present a promising strategy for sustainable agriculture, reducing dependency on chemical inputs while enhancing crop productivity and resilience to environmental stressors.

Evaluation of the Quality of Organic Compost Produced From Fish Filleting Waste: Application and Use in Agriculture

Objective: This study aims to chemically characterize the compost resulting from fish filleting waste, identifying macro and micronutrients, and investigating the effects of different dosages of this compost on lettuce fertilization. Theoretical Framework: The research is based on concepts of sustainable management of urban solid waste, highlighting composting as an effective practice for recycling organic matter. Previous studies on composting animal waste and its application underpin the context of the research. Method: The methodology consisted of experiments with 28 plants, applying 7 treatments with 4 replications, ranging from 10% to 50% fish compost. Fresh and dry mass, root size and volume, and nutrients were analyzed. Results and Discussion: The results indicated that fish waste compost has significant potential as a source of nutrients, with medium to high levels of macro and micronutrients. In lettuce cultivation, the 10% dosage was the most cost-effective, although proportions of up to 30% promoted good development in all the indicators evaluated. Research Implications: The practical implications of this research suggest that fish waste compost could be a viable alternative for organic fertilization, promoting sustainable practices in waste management and agricultural production. Originality/Value: This study contributes to the literature by exploring the use of fish filleting waste compost as a fertilizer, demonstrating its effectiveness and potential as a source of nutrients for lettuce cultivation.

Differences in Biomass Accumulation in the Cultivation of Lettuce (Lactuca sativa L.) var. Batavia Under Two Greenhouses: Traditional and Heated

Lettuce (Lactuca sativa L.) cultivation shows optimal development in soils with clay-loam or sandy-loam textures, under cool and humid climatic conditions. However, crop yield and quality are negatively affected by the debilitating effect due to high temperatures on plant development. This research aimed to evaluate the performance of the lettuce variety var. Batavia in two types of greenhouses (air-conditioned and traditional), located in the Calpi parish, belonging to the Riobamba canton, province of Chimborazo. During all phenological stages of the crop, measurements and evaluations of morphological and climatic variables were carried out every 15 days. The results obtained were subjected to a 5% Student’s T test. The best results were obtained during cultivation in a climate-controlled greenhouse. Compared to traditional greenhouse cultivation, the plant cycle was completed in less time, specifically in 43 days with an average weight of 467 gr, while in the traditional greenhouse, it took 48 days with an average weight of 380 gr. The average height and number of leaves were also higher in the climate-controlled greenhouse, with values of 22.71 cm and a dry matter percentage of 29.87%. The data obtained were subjected to statistical analysis, and it was found that there was a highly significant difference between the means in the two conditions evaluated, with a p-value less than 0.00012. While no significant difference was observed in relation to biometric parameters of the crop versus climatic factors (p-value > 0.05 ns). The results showed a yield of 29.18 t/ha in the air-conditioned greenhouse, whereas in the traditional greenhouse it was 23.76 t/ha, increasing the production and yield of fresh lettuce cultivation by 22.79% in the heated greenhouse compared to the traditional greenhouse. Keywords: temperature, relative humidity, curly lettuce, agronomic behavior, yield. Resumen El cultivo de lechuga (Lactuca sativa L.), presenta un óptimo desarrollo en suelos con texturas franco-arcillosas o franco-arenosas, bajo condiciones climáticas frescas y húmedas. Sin embargo, el rendimiento y la calidad de la cosecha se ven afectados negativamente por el efecto debilitante que las altas temperaturas ejercen sobre el desarrollo de la planta. La investigación realizada tuvo como objetivo evaluar el rendimiento de la variedad de lechuga crespa var. Batavia, en dos tipos de invernaderos (climatizado y tradicional), ubicados en la parroquia Calpi, perteneciente al cantón Riobamba, provincia de Chimborazo. Durante todas las etapas fenológicas del cultivo, se llevaron a cabo mediciones y evaluaciones de las variables morfológicas y climáticas, cada 15 días. Los resultados obtenidos fueron sometidos a una prueba T de Student al 5%. Los mejores resultados se obtuvieron en el cultivo bajo invernadero climatizado. En comparación con el cultivo en invernadero tradicional, el ciclo de la planta se completó en un menor tiempo, específicamente en 43 días con un peso promedio de 467 g, mientras que, en el invernadero tradicional tardó 48 días con peso promedio de 380 g. La altura y el número de hojas promedio también fueron superiores en el invernadero climatizado, con valores de 22,71 cm y un porcentaje de materia seca del 29,87%. Los datos obtenidos fueron sometidos a análisis estadístico, y se encontró que existía diferencia altamente significativa entre las medias en las dos condiciones evaluadas, con un p-valor menor a 0,00012. Mientras que, en relación de parámetros biométricos del cultivo frente a los factores climáticos no presentaron diferencia significativa (p-valor > 0,05 ns). Los resultados arrojaron un rendimiento de 29,18 t/ha en el invernadero climatizado, mientras que el invernadero tradicional un rendimiento de 23,76 t/ha, aumentando en un 22,79% la producción y rendimiento del cultivo de lechuga fresca en el invernadero climatizado, en comparación al invernadero tradicional. Palabras Clave: Temperatura, Humedad relativa, Lechuga crespa, Comportamiento agronómico, Rendimiento.

Effect of the residual levofloxacin on hydroponic vegetables with sewage treatment plant tailwater: Microbial community, discharge risk and control strategy

Tailwater-based hydroponic vegetable is a promising strategy for domestic wastewater recycling. However, the effect of residual antibiotics on the hydroponic vegetable system and the relation between hydroponic culture parameters and the residual water quality are still unclear. Here, the typical antibiotic Levofloxacin (LVFX) was employed, and the effect of LVFX (5 mg/L) on the residual water quality, plant growth and microbial community of water spinach hydroponic culture system were investigated under different hydraulic residence times (HRT). Obvious toxic effects on water spinach were observed, and the highest removal rate of LVFX (about 6 %) and TN (25.67±1.43 %) was observed when HRT was 7 days. Hydroponic culture increased the microbial abundance, diversity, and microbial community stability. To optimize the hydroponic culture, actual sewage plant tailwater spiked with 20 μg/L LVFX, along with three common planting substrates (sponge, ceramsite, and activated carbon) were used for the hydroponic culture of lettuce (seasonal reasons). The inhibition effect of LVFX on the removal of NO3--N and TN was observed even as the LVFX concentration decreased significantly (from 14.62 ± 0.44 μg/L to 0.65 ± 0.07 μg/L). The best growth situation of lettuce and removal rates of NH4+-N, NO3--N, TN, especially LVFX (up to 95.65 ± 0.54 %) were observed in the activated carbon treated group. The overall results indicate the negative effect of residual antibiotics on the hydroponic vegetable systems, and adding activated carbon as substrate is an effective strategy for supporting plant growth and controlling discharged risk.

Automatic Nutrient Control System Base on Internet of Things for Hydroponics Crops

The objectives of this research are to examine the growth rate of plants, the yield, and the nutrient application rate. The research team has developed an automatic nutrient control system which consisted of an Arduino MEGA 2560 R3 as the main processor to receive data from the sensor, such as pH sensor as the sensor to measure the acidity, EC sensor as the sensor used to measure the internal current of a liquid. The Arduino MEGA 2560 R3 will transfer the signal to control the opening and closing of the pump of each nutrient to get the nutrient solution as determined; in addition, the data is send to the cloud via a NodeMCU ESP8266 board connected to the Arduino MEGA 2560 R3, which users can track the data through the application. In the experiment, the developed system was used to grow hydroponic lettuce in a greenhouse and compared to growing hydroponic lettuce by human care under the same environment. The result from experiments revealed that the proposed system can maintain the pH and EC values more stable than the cultivation of hydroponic lettuce by human care, and the growth rate was 99.04%, while the use of caregivers was 95.38%; its harvest of yields was more compared to the use of caregivers up to 7.35%, and the nutrient application rate was less than the care of caregivers at 22.05%.

Evaluation of different breeding waste compost applications on lettuce cultivation: growth, quality, mineral elements, and heavy metals accumulation

In China, increasing breeding waste has caused environmental problems. This study explored the possibility of using breeding waste compost (BWC) instead of chemical fertilizer in vegetable cultivation. The experiment included no fertilizer (CK), 100% chemical fertilizer (CF), 10, 20, and 30% substitution of cow dung compost (CDC), goose dung compost (GDC), and duck dung compost (DDC) with chemical fertilizer (C01, C02, C03, G01, G02, G03, D01, D02, D03). The results showed that BWC, particularly GDC, promoted lettuce growth and development. Compared to CK, the leaf fresh and dry weight of G03 were the highest, increasing significantly by 6.60 and 7.29 times, and the root fresh and dry weight of G02 were the highest, increasing significantly by 12.72 and 6.00 times. Different BWC improved soluble sugar, soluble protein, and Vitamin C to varying degrees, and the nitrate contents of some BWC treatments were lower than that of CK and CF. Conversely, CF had the highest nitrate accumulation and limited effects on certain growth and quality parameters. The mineral elements in lettuce were also affected by the type and dosage of fertilizers. The total nitrogen of CF, total phosphorus of G03, total potassium of G02, Ca and Mg of D01, Fe of CF, and Zn of G02 were at the peak. The rapid increase of biomass in GDC treatments led to reductions in Ca and Fe. Applying fertilizers would affect heavy metals in lettuce to unequal degrees, but all were within the food safety scope. The principal component analysis revealed the comprehensive effect of GDC treatments was recommended.

Toxic and non-toxic cyanobacterial biomass as a resource for sustainable agriculture: A lettuce cultivation experiment

Cyanobacteria represent a promising resource for sustainable agriculture, as they have demonstrated the ability to restore soil fertility even after death and decay. However, several cyanobacteria can also release secondary metabolites, such as cyanotoxins, which may compromise the quality of agricultural products and pose a potential risk to human health. Depending on the concentration of exposure, few studies reported deleterious effects on plant species when irrigated with cylindrospermopsin (CYN) contaminated water, impairing plant growth and leading to food product contamination, while other studies show promoting effects on plant yield. To evaluate the potential of cyanobacterial biomass (cyanotoxin-containing or not) as a sustainable resource for soil amendment, biostimulants or fertilizers for lettuce cultivation, a study was carried out that consisted of the culture of lettuce plants under controlled conditions, in soil: (1) with no extra nutrient addition (control) and supplemented with 0.6 g of freeze-dried Raphidiopsis raciborskii biomass of (2) a non-CYN-producing strain, (3) a CYN-producing strain, and (4) the same CYN-producing strain pasteurized. Results showed no significant differences in photosystem II efficiency with the amendment addition. On the contrary, shoot fresh weight significantly increased in lettuce plants grown with the cyanobacterial biomass addition, especially in condition (3). In addition, there were significant differences in mineral concentrations in lettuce leaves after the cyanobacterial biomass addition, such as K, Na, Ca, P, Mg, Mn, Zn, Cu, Mo, and Co. CYN accumulation was detected under conditions (3) and (4), with concentrations observed in descending order from roots > soil > shoot. Nevertheless, the CYN concentration in edible tissues did not exceed the WHO-proposed tolerable daily intake of 0.03 μg/kg/day. These findings suggest that incorporating cyanobacterial biomass as a soil amendment, biostimulant or fertilizer for lettuce cultivation, even with trace amounts of CYN (1–40 μg/g), may enhance plant yield without leading to cyanotoxin accumulation in edible tissues above the WHO-recommended tolerable daily intake.

The use of biostimulants as a key to sustainable hydroponic lettuce farming under saline water stress

BackroundThe utilization of high-quality water in agriculture is increasingly constrained by climate change, affecting availability, quality, and distribution due to altered precipitation patterns, increased evaporation, extreme weather events, and rising salinity levels. Salinity significantly challenges salt-sensitive vegetables like lettuce, particularly in a greenhouse. Hydroponics water quality ensures nutrient solution stability, enhances nutrient uptake, prevents contamination, regulates pH and electrical conductivity, and maintains system components. This study aimed to mitigate salt-induced damage in lettuce grown via the floating culture method under 50 mM NaCl salinity by applying biostimulants.ResultsWe examined lettuce’s physiological, biochemical, and agronomical responses to salt stress after applying biostimulants such as amino acids, arbuscular mycorrhizal fungi, plant growth-promoting rhizobacteria (PGPR), fulvic acid, and chitosan. The experiment was conducted in a greenhouse with a randomized complete block design, and each treatment was replicated four times. Biostimulant applications alleviated salt’s detrimental effects on plant weight, height, leaf number, and leaf area. Yield increases under 50 mM NaCl were 75%, 51%, 31%, 34%, and 33% using vermicompost, PGPR, fulvic acid, amino acid, and chitosan, respectively. Biostimulants improved stomatal conductance (58–189%), chlorophyll content (4–10%), nutrient uptake (15–109%), and water status (9–107%). They also reduced MDA content by 26–42%. PGPR (1.0 ml L‒1), vermicompost (2 ml L‒1), and fulvic acid (40 mg L‒1) were particularly effective, enhancing growth, yield, phenol, and mineral content while reducing nitrate levels under saline conditions.ConclusionsBiostimulants activated antioxidative defense systems, offering a sustainable, cost-effective solution for mitigating salt stress in hydroponic lettuce cultivation.

Rapid Reduction of Phytotoxicity in Green Waste for Use as Peat Substitute: Optimization of Ammonium Incubation Process.

The rapid growth of the horticultural industry has increased demand for soilless cultivation substrates. Peat, valued for its physical and chemical properties, is widely used in soilless cultivation. However, peat is non-renewable, and over-extraction poses serious ecological risks. Therefore, sustainable alternatives are urgently needed. Ammonium incubation, a novel method to reduce phytotoxicity, offers the potential for green waste, a significant organic solid waste resource, to substitute peat. This study optimized the ammonium incubation process to reduce green waste phytotoxicity. It systematically examined different nitrogen salts (type and amount) and environmental conditions (temperature, aeration, duration) affecting detoxification efficiency. Results show a significant reduction in phytotoxicity with ammonium bicarbonate, carbonate, and sulfate, especially carbonate, at 1.5%. Optimal conditions were 30 °C for 5 days with regular aeration. Under these conditions, ammonium salt-treated green waste significantly reduced total phenolic content and stabilized germination index (GI) at a non-phytotoxic level (127%). Using treated green waste as a partial peat substitute in lettuce cultivation showed promising results. This low-cost, low-energy method effectively converts green waste into sustainable peat alternatives, promoting eco-friendly horticulture and environmental conservation.

Pengembangan Inovasi Smart Aeroponik sebagai Upaya Efisiensi Urban Farming Produktif Ramah Energi

This article explores the development and application of smart aeroponic innovation as an effort to improve efficiency in energy-friendly urban farming. Smart aeroponics, which utilizes sensor technology and automatic control systems, is designed to maximize plant growth while minimizing energy and water use. In this community service project, we implemented a smart aeroponic system in several urban locations and trained local communities in its operation and maintenance. Evaluation of the results showed that this system can increase energy efficiency by up to 70% when compared to hydroponics with the Deep Flow Technique (DFT) method or each can save 29.02 kWh for mustard greens cultivation. And 41.00 kWh for lettuce cultivation. The potential of this technology is an effort to improve the efficiency of urban agriculture, but also provides significant ecological and economic benefits for urban communities, so that it can be a sustainable model for future agricultural development.

Soil Solarization Efficiently Reduces Fungal Soilborne Pathogen Populations, Promotes Lettuce Plant Growth, and Affects the Soil Bacterial Community.

Lettuce is the most cultivated leafy vegetable in Greece; however, due to the adopted intensive cropping system, its cultivation is susceptible to many soilborne pathogens that cause significant yield and quality losses. In the current study, the impact of various soil disinfestation methods such as solarization, chemical disinfestation, and application of a biofungicide were evaluated in a commercial field that has been repeatedly used for lettuce cultivation. The populations of soilborne pathogens Rhizoctonia solani, Pythium ultimum, Fusarium oxysporum, and Fusarium equiseti were measured via qPCR before and after the implementation of the specific disinfestation methods. Although all the tested methods significantly reduced the population of the four soilborne pathogens, soil solarization was the most effective one. In addition, solarization reduced the number of lettuce plants affected by the pathogens R. solani and F. equiseti, and at the same time, significantly influenced the growth of lettuce plants. Amplicon sequence analysis of 16S rRNA-encoding genes used to study the soil bacterial community structure showed that Firmicutes, Proteobacteria, and Actinobacteria were the predominant bacterial phyla in soil samples. In general, solarization had positive effects on Firmicutes and negative effects on Proteobacteria and Actinobacteria; soil fumigation with dazomet increased the relative abundance of Firmicutes and Proteobacteria and reduced the corresponding values of Actinobacteria; and biofungicide had no significant effects on the three predominant bacterial phyla. The bacterial community composition and structure varied after the application of the soil disinfestation treatments since they imposed changes in the α- and β-diversity levels. The results of this study are expected to contribute towards implementing the most effective control method against the most common soilborne pathogens in intensively cultivated fields, such as those cultivated with leafy vegetables.

Modeling Bibb Lettuce Nitrogen Uptake and Biomass Productivity in Vertical Hydroponic Agriculture

Global fertilizer production and mismanagement significantly contribute to many harmful environmental impacts, revealing the need for a greater understanding of crop growth and nutrient uptake, which can be used to optimize fertilizer management. This study experimentally adapts first-principles microbial modeling techniques to the hydroponic cultivation of Bibb lettuce (Lactuca sativa) under nitrogen-limited conditions. Monod and Michaelis–Menten’s approaches are applied to predict biomass productivity and nutrient uptake and to evaluate the feasibility of reclaimed wastewater as a nutrient source of nitrogen. Experimental and modeling results reveal significantly different kinetic saturation constants (Ks = 1.331 and Km = 17.887 mg L−1) and a corresponding cell yield strongly dependent on nutrient concentration, producing visually and compositionally distinct tissue between treatments receiving ≤26.2 and ≥41.7 mgN L−1. The resulting Monod model overestimates dry mass predictions during low nutrient conditions, and the collective results support the development of a dynamic Monod curve that is temporally dependent during the plants’ lifecycle. Despite this shortcoming, these results support the feasibility of reclaiming nitrogen from wastewater in hydroponic agriculture, expecting to produce lesser biomass lettuce exhibiting healthy tissue. Furthermore, this study provides a mathematical foundation for agricultural simulations and nutrient management.

Humic Substances for the Productio1n of Liquid Fertilizer

Objective: This study sought to determine the best stabilizers for the HS extract and to evaluate the resulting extract in the semi-hydroponic cultivation of lettuce. Method: Experiment I and II was conducted in a completely randomized design (CRD) with 6 treatments and 4 replications. The treatments were: T1: Humic substances extract (extract without additives); T2: Algae extract 5% + calcium lignosulfonate 5% + 0.3% guar gum; T3: Algae extract 5% + calcium lignosulfonate 5% + pyroligneous acid 5% + 0.3% guar gum; T4: Algae extract 3% + calcium lignosulfonate 3% + 0.3% guar gum; T5: Algae extract 3% + calcium lignosulfonate 3% + pyroligneous acid 3% + 0.3% guar gum; T6: Control salts. A slab was used with the dimensions of 0.30 m x 1.5 m and with 5 plants per slab, using 30 slabs. The treatments were: T1: Salts; T2: Salts 25% x liquid fertilizer; T3: Salts 50% x liquid fertilizer; T4: Salts 75% x liquid fertilizer; T5: Salts 100% x liquid fertilizer; T6: Dose x liquid fertilizer. Results and Discussion: The response variables were: spectroscopy in the visible ultraviolet region (UV/Vis); NDVI; SPAD; EC; green and dry mass of the shoot, and leaf tissue analysis. In the conditions in which the experiment was conducted, it can be concluded that in Experiment I, Treatment 5 (Algae extract 3% + calcium lignosulfonate 3% + pyroligneous acid 3% + 0.3% guar gum) has the most suitable stabilizers for the HS extract, and that in Experiment II, Treatment 1 (salts) provided the best results. Implications of the research: In line with the environmental theme, the study presents and discusses relevant initiatives in society associating agribusiness and sustainable development.

Suitability of coconut bran and biochar as a composite substrate for lettuce cultivation in aquaponic systems

Growth substrates are essential for aquaponic systems and play an important role in vegetable growth and water quality. In this study, we explored an innovative combination of coconut bran and coconut shell biochar (CSB) as a composite growth substrate for lettuce cultivation in aquaponic systems. The study included the control (100 % coconut bran as the growth substrate) and treatment groups (T1–T5; containing 10 %, 20 %, 30 %, 40 %, and 50 % CSB as the growth substrate, respectively). The substrate properties; lettuce growth performance; and soil enzyme activity, nitrogen content, and abundance of microbial communities in the substrate were analyzed to determine the optimal substrate. Our findings indicated that CSB incorporation significantly altered the properties of the substrate, resulting in increased dry and bulk densities, pH, and water-holding capacity, and decreased electrical conductivity, water-absorption capacity, and porosity. Furthermore, the fresh weight of lettuce was notably increased in the treatment groups. The activities of fluorescein diacetate hydrolase, urease, nitrate reductase, and hydroxylamine reductase initially increased and further decreased, reaching the maximum in the T3 group. Conversely, the activity of nitrite reductase and contents of available nitrogen, nitrate-nitrogen, and ammonium-nitrogen in the substrates initially decreased and further increased, with the minimum values observed in the T3 group. The microbial sequencing results indicated that CSB incorporation significantly increased the microbial diversity and relative abundance of microorganisms associated with nitrogen transformation. Moreover, 30 % CSB incorporation exhibited the greatest effect on lettuce growth, with a 34.5 % and 31.6 % increase in fresh weight compared to the control during the growth and harvest periods, respectively. This study indicated the enormous potential of biochar in the research and development of green technologies for substrate amendment in aquaponic systems.

Life cycle assessment of a high-tech vertical decoupled aquaponic system for sustainable greenhouse production

IntroductionAquaponics provide multiple benefits due to the simultaneous yield of vegetables and fish, however they are characterized by increased greenhouse gas emissions owing to intensive production system. The most appropriate method for quantifying the environmental effects of these systems is Life Cycle Assessment with which the identification of hotspots and the suggestion of improved production plans can be achieved. The purpose of the present study was to evaluate the environmental impact of a pilot high-tech aquaponic system utilized for the simultaneous production of baby lettuce and rocket as well as rainbow trout, in indicators such as Global Warming Potential.Materials and methodsTo achieve this goal, data on inputs and outputs were collected from 12 case studies that were implemented, combining different fertilizer treatments, substrate choices, plant species cultivated and water source provision. Life Cycle Assessment was performed using SimaPro v.9.4.0.2 software.ResultsThe results showcase that the optimal case studies include the cultivation of baby lettuce and rocket in perlite substrate using wastewater from fish and partial use of synthetic fertilizers. Indicatively, Global Warming Potential of these cases was calculated at 21.18 and 40.59 kg CO2-eq/kg of vegetable respectively. The parameter with the greatest impact on most of the environmental indicators was electricity consumption for the operation of the oxygen supply pump for the fish tanks, while greenhouse infrastructure had the greatest impact in Abiotic Depletion and Human Toxicity impact categories. In an alternative production scenario tested where renewable energy sources were used, system impacts were reduced by up to 50% for Global Warming Potential and 86% for Eutrophication impact. The results of this study aspire to constitute a significant milestone in environmental impact assessments of aquaponic production systems and the adoption of more sustainable farming practices.

Phycoremediation of Potato Industry Wastewater for Nutrient Recovery, Pollution Reduction, and Biofertilizer Production for Greenhouse Cultivation of Lettuce and Celery in Sandy Soils

Microalgae-based wastewater treatment offers an eco-friendly opportunity for simultaneous nutrient recovery and biomass generation, aligning with the circular bioeconomy concept. This approach aims to utilize the nutrients of potato industry wastewater (PIW) for algal growth while mitigating the environmental impact of this industrial byproduct. This study focused on cultivating three cyanobacterial strains, Anabaena oryzae, Nostoc muscorum, and Spirulina platensis, in PIW and synthetic media for 30 days to assess feasibility. Growth performance was monitored by measuring chlorophyll content, dry weight (DW), optical density (OD), and pH at 3-day intervals. The high-performing cyanobacterial biomass from the laboratory findings was formulated into a biofertilizer, which was then evaluated in a controlled greenhouse experiment on celery and lettuce plants. The biofertilizer replaced conventional NPK mineral fertilizers at different levels (25%, 50%, and 75%), while a control group received 100% chemical fertilizer. The results showed favourable growth of all three cyanobacteria strains and their mixture in PIW throughout the experiment. The mixed cyanobacteria followed by Spirulina platensis exhibited the highest growth rates, achieving chlorophyll contents of 3.75 and 2.30 µg·mL−1, DWs of 1.79 g·L−1 and 1.63 g·L−1, and ODs of 0.41 and 0.38, respectively, surpassing the other treatments. The formulated biofertilizers, Spi-PIW (Spirulina platensis + potato industry wastewater) and Cyano-PIW (mixed culture+ potato industry wastewater), significantly enhanced plant height, root and stem lengths, and the number of leaves per plant in celery and lettuce compared to the control group. These biofertilizer treatments also improved chlorophyll contents, as well as macro- and micronutrient levels, in the two crops. Additionally, the application of these biofertilizers improved certain sandy soil properties, i.e., pH, total organic matter, total nitrogen, phosphorus, and potassium. In conclusion, utilizing PIW as a substrate for cultivating cyanobacteria strains and producing high-quality liquid bio-organic fertilizers holds potential for reducing recommended NPK fertilizer doses by 25–50% in celery and lettuce growth, providing an environmentally friendly approach.

Genome-wide analysis of ABF gene family in lettuce (Lactuca sativa L.) reveals the negative roles of LsABF1 in thermally induced bolting

ABSTRACT High-temperature-induced early bolting poses a pressing challenge in annual leaf lettuce cultivation. ABF transcription factors, or ABA-responsive element binding factors, are crucial components of the ABA signalling pathway. In this study, we identified 8 members of the ABF gene family in leaf lettuce, categorising them into groups A, B, and C through phylogenetic analysis. All LsABFs exhibited a conserved domain, RMIKNRESAARSRARKQAY (Bzip_plant_BZIP46), as revealed by multiple sequence alignment. A total of 1242 cis-acting elements were detected, with 323 elements screened. Predictive analysis indicated 304 phosphorylation sites. Expression patterns of LsABFs were similar, peaking on the 8th day, implicating their role in bolting. Silencing LsABF1 positively impacted lettuce bolting, signifying its regulatory potential. This study establishes a theoretical foundation for comprehending the molecular mechanisms governing ABF genes in high-temperature-induced bolting in leaf lettuce.

Reducing nitrate accumulation through the management of nutrient solution in a floating system lettuce (Lactuca sativa, L.)

Lettuce is a leading greenhouse-grown vegetable highly appreciated by consumers for its nutritional properties texture and flavor. However, leafy vegetables are known to accumulate an excessive amount of nitrate and this constitutes a strong health concern in Europe. Among the factors that most affect the yield and quality of hydroponic crops, the composition and management of the nutrient solution stand out. In this work, different strategies have been studied in the management of the nutrient solution for hydroponic lettuce cultivation. Production nutritional status, and quality parameters were evaluated. The concentrations of nutrients in the nutrient solution significantly influence the harvested product, 100 to 50 % H treatment resulted in highest yields with significant increase of 14 % compared to 50 % H at 34 DAT, from the point of view of both biomass production and quality, regarding the contents of anthocyanins, chlorophylls, and calcium, constituents that add value to the product due to their importance in the human diet. A significant reduction of nitrates in lettucewas observed one (14 %) and two (22 %) weeks after modifying the nutrient solution (100 to 50 % H). After one week there was no reduction in lettuce growth. In addition, no significant reduction in the concentration of most macro- and micronutrients was observed.

Bioponic Cultivation Using Chicken Droppings to Produce Lettuce Plants (Lactuca sativa rz) Uncontaminated by Trace Metals

Anthropogenic activities have denatured aquatic, terrestrial, and aerial environments throughout the world in general, and in Lubumbashi in particular, where market garden soils have become uncultivable for many plants. Thus, bioponics could be an effective means of producing uncontaminated vegetables in soilless cultivation, not only reducing the amount of fertilizer used and limiting contamination of agricultural produce but also achieving higher yields than in open-ground cultivation. The overall objective of this study was to implement a new bioponic technique for producing liquid fertilizer from chicken manure and utilize it in the organic hydroponic cultivation of lettuce (Lactuca sativa var. Lucrecia) installed on floating raft systems. To achieve this, two types of trials were conducted. The first was aimed at determining the quantities of organic matter to be used in the formulation of nutrient solutions. The second trial aimed to determine the optimal nitrogen concentration to be provided for hydroponic plant growth. Mineralization and/or anaerobic digestion of chicken manure were conducted for 7 days in 200 L barrels. For the first trial, nutrient solutions were created from three different concentrations of chicken manure (0.35%, 3.5%, and 7% dry matter—D.M.). These solutions were then used in bioponic rafts where total ammonia nitrogen (TAN) concentrations were fixed at 150 mg/L. For the second trial, D.M. was fixed at 2.5% for each tested modality, but TAN concentrations varied among them (i.e., 60, 90, and 120 mg/L TAN concentration). Modalities with low D.M. concentration (0.35%) and those with low TAN concentration (60 mg/L) resulted in higher yields than bioponic modalities receiving high concentrations of dry matter or TAN, respectively, for trials 1 and 2. Although the reference chemical solutions generate the greatest yields, bioponic systems operating with chicken manure present a good alternative for the cultivation of vegetables in developing countries with heavily contaminated soils. Indeed, bioponics allows for the production of vegetables in large quantities from animal waste, which does not pose health risks for human consumption. Local vegetable species commonly grown in Lubumbashi should be tested under hydroponic conditions.

Dynamics of micro and macronutrients in a hydroponic nutrient film technique system under lettuce cultivation

While hydroponics is considered an efficient vegetable production system, there is a compelling need to investigate the efficiency of the current generic nutrient dosing recommendation primarily based on electrical conductivity (EC) measurements. Such information is critical to fine-tune and optimize the current hydroponic management practices for improved nutrient uptake efficiency. This study investigated the dynamics of some micro and macronutrients (N, P, Ca, Mg, K, Fe, and Mn) in a recirculating nutrient film technique (NFT) hydroponic system under lettuce cultivation. The research was conducted in an indoor controlled environment growth chamber with lettuce grown in different EC levels (1.2 and 1.6 dS m−1). Each treatment had four hydroponic cultivation units, each one with 24 plants. Nutrient solution and tissue samples were collected two to three times per week. Nutrient dynamics, including nutrient uptake efficiencies and environmental losses, were calculated using a mass balance approach. The effects of EC level on fresh and dry lettuce biomass and nutrient uptake were insignificant. Observed variations in nutrient solution composition during lettuce cultivation included the almost complete removal of ammonia nitrogen, nitrate decreases towards the end of the experiment, consistent increases in aqueous Ca concentration, and corresponding decreases in K and Mn. Average N losses ranged between 27 and 40 %, presumably through denitrification, while 10–14 % of N was assimilated into the plant biomass. The remaining N in the recirculating nutrient solution was estimated to be between 50 and 59 %. The average P loss was 11–35 %, likely due to precipitation, while 52–77 % remained in the nutrient solution. Nutrient uptake efficiencies averaged 19–31 % K, 12–21 % P, 9–16 % Mn, 4–6 % Ca, 3–4 % Mg, and 2–4 % Fe. These results suggest that elevated nutrient concentrations in recirculating nutrient solutions led to losses and underutilization. Findings from this study provide a comprehensive dataset critical to improving hydroponic nutrient management beyond N and P. Hydroponic nutrient management should target providing essential nutrients needed by plants at the correct proportions considering the plant growth stage.