Growth Of Lettuce Research Articles

Manure sterilization reduced antibiotic resistance genes in lettuce endophytes

Livestock manure is commonly utilized as a fertilizer in agricultural system, potentially resulting in the dissemination of antibiotic resistance genes (ARGs) to plants. This raises concerns about the efficiency of manure treatment methods in reducing ARGs. Although sterilization treatment is frequently applied to mitigate the microbial loads, its efficacy in reducing ARGs remains unclear. This study investigated the impact of sterilized vs. unsterilized manure on the profiles of ARGs and bacterial community in a hydroponic lettuce system. After the 20-day cultivation period, 68 ARGs and 18 mobile genetic elements (MGEs) were identified. Manure sterilization not only promoted lettuce growth but also resulted in a reduction of ARG and MGE subtypes by 50.00%–86.21% in lettuce endophytes. Proteobacteria, Bacteroidota, and Firmicute were the dominant phyla, with a notable reduction of 70.05%–99.01% in Firmicutes by sterilization in lettuce endophytes. The predominant human pathogenic bacteria genera were Pseudomonas, Sphingomonas, and Bacillus, and sterilization effectively reduced the presence of Bacillus. Moreover, the estimated intake of ARGs in leaf endophytes ranged from 2.88 × 105 to 9.16 × 108 copies per day, including 6 high-risk ARGs. Manure sterilization reduced the association between high-risk ARGs and human pathogenic bacteria. The interaction between bacterial community and MGEs shaped ARG patterns with a contribution of 81.87%. Overall, these findings highlighted the critical role of sterilization in reducing ARGs in the manure used for hydroponic agriculture, providing guidance in waste management, crop safety, and public health.

Effects of polyester microplastics and naproxen on lettuce growth and development and soil abiotic factors

Effects of polyester microplastics and naproxen on lettuce growth and development and soil abiotic factors

Research on Composting of Garden Waste and Its Application in Cultivation Substrates

To achieve the resource utilization of garden waste, in this study, we used garden waste as the main raw material and conducted static composting with high-temperature aerobic treatment and forced ventilation by adding appropriate external additives. Our results showed that during the composting process, the pH was weakly alkaline, and the electrical conductivity was between 1.42 and 1.50 mS/cm. The E4/E6 (an important indicator of the quality or degree of condensation and aromatization of humic acid) gradually decreased, and nitrogen, phosphorus, and potassium contents increased. The germination index gradually rose and ultimately exceeded 80%. Treatment (T2) with a final C/N ratio of 25:1 and the addition of 0.3% bacterial agent resulted in the highest nutrient content and the best degree of compost maturity. All indicators met the requirements of the Chinese “Technical Requirements for Urban Landscape Waste Resource Recycling and Deep Processing (GB/T 40199-2021)”. When using a composite substrate of garden waste and other horticultural substrates for planting, a membership function was executed for comprehensive evaluation. The V (T2):V (peat):V (vermiculite):V (vermiculite) = 135:135:30:00 substrate treatment resulted in optimal lettuce growth and quality. In summary, combining the compost products of garden waste with traditional cultivation substrates at a specific ratio shows favorable applicative prospects.

Optimal Light Intensity for Lettuce Growth, Quality, and Photosynthesis in Plant Factories.

In agriculture, one of the most crucial elements for sustained plant production is light. Artificial lighting can meet the specific light requirements of various plants. However, it is a challenge to find optimal lighting schemes that can facilitate a balance of plant growth and nutritional qualities. In this study, we experimented with the light intensity required for plant growth and nutrient elements. We designed three light intensity treatments, 180 μmol m-2 s-1 (L1), 210 μmol m-2 s-1 (L2), and 240 μmol m-2 s-1 (L3), to investigate the effect of light intensity on lettuce growth and quality. It can be clearly seen from the radar charts that L2 significantly affected the plant height, fresh weight, dry weight, and leaf area. L3 mainly affected the canopy diameter and root shoot ratio. The effect of L1 on lettuce phenotype was not significant compared with that of the others. The total soluble sugar, vitamin C, nitrate, and free amino acid in lettuce showed more significant increases under the L2 treatment than under the other treatments. In addition, the transpiration rate and stomatal conductance were opposite to each other. The comprehensive evaluation of the membership function value method and heatmap analysis showed that lettuce had the highest membership function value in L2 light intensity conditions, indicating that the lettuce grown under this light intensity could obtain higher yield and better quality. This study provides a new insight into finding the best environmental factors to balance plant nutrition and growth.

Effect of artificial light sources on the growth of green oak lettuce (Lactuca sativa L.) grown in plant factories

Effect of artificial light sources on the growth of green oak lettuce (Lactuca sativa L.) grown in plant factories

The effects of humic substances application on the phytohormone profile in Lactuca sativa L.

AbstractHumic substances (HS) are commonly employed as plant biostimulants to enhance crop yields. However, the HS mechanisms of action, as well as the differences between radicular and foliar modes of application, remain unclear. Here, we explored the changes in phytohormonal balance as possible mechanism of HS to enhance lettuce (Lactuca sativa L.) growth, and the difference between both modes of application. For this purpose, BLACKJAK®, a HS‐based product was applied as radicular (R) and foliar (F) at the concentrations (mL/L): 0.20 (R1), 0.40 (R2), 0.60 (R3), 0.80 (R4), 5.00 (F1), 7.50 (F2), 10.00 (F3), and 12.50 (F4). The experiment was performed in pots filled with vermiculite:perlite (3:1) and HS were applied three times with a periodicity of 10 days. Shoot and root growth parameters were measured. In addition, the phythormones indole‐3‐acetic acid (IAA), gibberellins (GAs), trans‐zeatine (tZ), isopentenyl adenine (iP), 1‐aminocyclopropane‐1‐carboxylic acid (ACC), abscisic acid (ABA), jasmonic acid (JA), and salicylic acid (SA), were analysed by U‐HPLC‐MS. BLACKJAK® application resulted in higher shoot growth at doses R1, R2, R3, F2, and F3, whereas root biomass was increased at R2, R3, F2, F3, and F4, showing radicular better plant growth than foliar applications. Furthermore, HS changed phytohormonal balance in shoots and roots. However, it was with radicular applications, especially at R2, where phytohormonal profile was best associated with plant growth due to the increases observed in IAA, GAs, JA, SA, tZ, and decreased ABA. However, further research is needed to clarify the involvement of hormones in the growth‐promoting action of HS.

Zinc oxide nanoparticles reduce cadmium accumulation in hydroponic lettuce (Lactuca sativa L.) by increasing photosynthetic capacity and regulating phenylpropane metabolism

Due to the continuous production of industrial wastes and the excessive use of chemical fertilizers and pesticides, severe cadmium (Cd) pollution in soil has occurred globally. This study investigated the impacts of incorporating zinc oxide nanoparticles (ZnONPs) into hydroponically grown lettuce (Lactuca sativa) under cadmium stress conditions, to seek effective methods to minimize Cd buildup in green leafy vegetables. The results showed that 1 mg/L of Cd significantly inhibited lettuce growth, decreasing in leaves (29 %) and roots (33 %) biomass. However, when lettuce was exposed to 2.5 mg/L ZnONPs under cadmium stress, the growth, chlorophyll content, net photosynthetic rate (Pn), stomatal conductance (Gs), actual photochemical efficiency of PSII (φPSII), and activity of key enzymes in photosynthesis were all significantly enhanced. Furthermore, ZnONPs significantly decreased the accumulation of Cd in lettuce leaves (36 %) and roots (13 %). They altered the subcellular distribution and chemical morphology of Cd in lettuce by modifying the composition of cell walls (such as pectin content) and the levels of phenolic compounds, resulting in a reduction of 27 % in Cd translocation from roots to leaves. RNA sequencing yielded 45.9 × 107 and 53.4 × 107 clean reads from plant leaves and roots in control (T0), Cd (T1), Cd+ZnONPs (T2), and ZnONPs (T3) treatment groups respectively, and 3614 and 1873 differentially expressed genes (DEGs) were identified. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis identified photosynthesis, carbon fixation, and phenylpropanoid metabolism as the main causes of ZnONPs-mediated alleviation of Cd stress in lettuce. Specifically, the DEGs identified included 12 associated with photosystem I, 13 with photosystem II and 23 DEGs with the carbon fixation pathway of photosynthesis. Additionally, DEGs related to phenylalanine ammonia-lyase, caffeoyl CoA 3-O-methyltransferase, peroxidase, 4-coumarate-CoA ligase, hydroxycinnamoyl transferase, and cytochrome P450 proteins were also identified. Therefore, further research is recommended to elucidate the molecular mechanisms by which ZnONPs reduce Cd absorption in lettuce through phenolic acid components in the phenylpropanoid metabolism pathway. Overall, treatments with ZnONPs are recommended to effectively reduce Cd accumulation in the edible portion of lettuce.

Lactuca sativa Growth and Yield as Affected by Cashew Nut Shells Biochar, Cattle Manure and Urea in Northern and Central Benin

Aims: This study aims to identify good combinations of cashew nut shell biochar, cattle manure, and urea for enhancing lettuce (Lactuca sativa L.) growth and yield in the North and Central regions of Benin. Place and Duration of Study: Two agronomic trials were conducted: one in Tchaourou, Borgou department (2022), and another in Dassa, Colline department (2023). Methodology: A Fisher experimental design with three replications was used at each site, focusing on fertilization with seven treatments, including four reference treatments (local practices) and three treatments based on the reference treatments with biochar incorporation. Results: The results demonstrated significant improvements in plant growth parameters and yield, with the application of biochar combined with cattle manure and urea or with cattle manure only. The plants leaves number, height and yields obtained from the application of 10 t ha⁻¹ biochar + 20 t ha-1 cattle manure and 10 t ha-1 biochar + 0.025 t ha-1 urea +10 t ha-1 cattle manure were respectively at least 165 and 318%; 25 and 50%; 42 and 91% higher than those obtained under the producer's mineral fertilization practice at both sites. Conclusion: The findings showed that integrating cashew nut shell biochar with organic and inorganic fertilizers can significantly enhanced lettuce production, and thus overall vegetable crop yields while reducing the need for mineral fertilizers and dependence of cattle manure. Additionally, studying the best application methods and rates for different soil types and crop systems can help in maximizing the benefits of biochar.

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.

Phyto-cytogenotoxic potential assessment of two medicinal plants: Davilla nitida (Vahl) Kubitzki and Davilla elliptica (A. St.-Hill) (Dilleniaceae)

ABSTRACT Humans have been using plants in the treatment of various diseases for millennia. Currently, even with allopathic medicines available, numerous populations globally still use plants for therapeutic purposes. Although plants constitute a safer alternative compared to synthetic agents, it is well established that medicinal plants might also exert adverse effects. Thus, the present investigation aimed to assess the phytotoxic, cytotoxic, and genotoxic potential of two plants from the Brazilian Cerrado used in popular medicine, Davilla nitida (Vahl) Kubitzki, and Davilla elliptica (A. St.-Hil.). To this end, germination, growth, and cell cycle analyses were conducted using the plant model Lactuca sativa. Seeds and roots were treated with 0.0625 to 1 g/L for 48 hr under controlled conditions. The germination test demonstrated significant phytotoxic effects for both species at the highest concentrations tested, while none of the extracts produced significant effects in the lettuce growth test. In the microscopic analyses, the aneugenic and cytotoxic action of D. elliptica was evident. In the case of D. nitida greater clastogenic action and induction of micronuclei, (MN) were noted suggesting that the damage initiated by exposure to these extracts was not repaired or led to apoptosis. These findings indicated that the observed plant damage was transmitted to the next generation of cells by way of MN. These differences in the action of the two species may not be attributed to qualitative variations in the composition of the extracts as both are similar, but to quantitative differences associated with synergistic and antagonistic interactions between the compounds present in these extracts.

Exploring native arsenic (As)-resistant bacteria: unveiling multifaceted mechanisms for plant growth promotion under As stress.

This study explores the plant growth-promoting effect (PGPE) and potential mechanisms of the arsenic (As)-resistant bacterium Flavobacterium sp. A9 (A9 hereafter). The influences of A9 on the growth of Arabidopsis thaliana, lettuce, and Brassica napus under As(V) stress were investigated. Additionally, a metabolome analysis was conducted to unravel the underlying mechanisms that facilitate PGPE. Results revealed that A9 significantly enhanced the fresh weight of Arabidopsis seedlings by 62.6%-135.4% under As(V) stress. A9 significantly increased root length (19.4%), phosphorus (25.28%), chlorophyll content (59%), pod number (24.42%), and weight (18.88%), while decreasing As content (48.33%, P≤.05) and oxidative stress of Arabidopsis. It also significantly promoted the growth of lettuce and B. napus under As(V) stress. A9 demonstrated the capability to produce≥31 beneficial substances contributing to plant growth promotion (e.g. gibberellic acid), stress tolerance (e.g. thiamine), and reduced As accumulation (e.g. siderophores). A9 significantly promoted the plant growth under As stress and decreased As accumulation by decreasing oxidative stress and releasing beneficial compounds.

An Overview on the Use of Artificial Lighting for Sustainable Lettuce and Microgreens Production in an Indoor Vertical Farming System

With the global population projected to reach 8.6 billion by 2050 and urbanization on the rise, sustainable food production in cities becomes imperative. Vertical farming presents a promising solution to meet this challenge by utilizing space-efficient, controlled-environment agriculture techniques. In a vertical farming system, high quality, high nutritional value products can be produced with minimum water consumption, using LEDs as energy-efficient light sources. Microgreens are a new market category of vegetables among sprouts and baby leaf greens. The most critical challenge in their cultivation is the choice of growing medium, lighting, and light spectrum, which affect photosynthesis, plant growth, and yield. This review explores various cultivation methods, including hydroponics, within the context of vertical farming. Using current research, it investigates the effect of LED lighting on the physiological properties and growth of microgreens and baby leaf lettuce, but further research is needed to determine the response of the varieties and the optimal light spectrum ratios to meet their needs.

Effects of LED treatments on the growth and nutritional content of lettuce (Lactuca sativa) in a hydroponic vertical farming system

Introduction: LED-integrated hydroponic vertical farming system (HVFS) may address food security challenges arising from urbanisation, while antioxidants in vegetables may prevent cardiovascular disease. This study aimed to explore the LED effects on yield, antioxidant properties, and vitamin C content in Butterhead lettuce (BL) and Italian lettuce (IL). Methods: Three LED combinations were used: 77% red, 14% green, and 9% blue lights (77R:14G:9B); 7% red, 41% green, and 52% blue lights (7R:41G:52B); and 25% red, 67% green, and 8% blue lights (25R:67G:8B). The concentration and pH of nutrient solution in HVFS ranged from 0.878-2.061ppm and 6.0-6.6, respectively, with a 12:12 light-dark cycle. Chlorophyll and anthocyanin contents were measured using chlorophyll and anthocyanin meters, respectively. Total phenolic and vitamin C content were measured using Folin-Ciocalteu colorimetric assay. Total flavonoid and antioxidant activity were determined through aluminium chloride colorimetric assay and 2,2-diphenyl-1-picrylhydrazyl (DPPH) colorimetric assay, respectively. Completely randomised design was adapted with three replications. Results: BL exhibited greater yield, anthocyanin and chlorophyll contents, while IL had higher vitamin C content. Significantly (p<0.001) higher yields were produced under 77R:14G:9B and 25R:67G:8B. Significantly higher phenolic (p<0.001) and flavonoid (p=0.003) contents were produced under 25R:67G:8B. Vitamin C was significantly (p=0.037) higher under 25R:67G:8B than 7R:41G:52B. Conclusion: LED treatment with higher proportion of red light generated greater yield, whereas higher proportion of green light gave higher phenolic, flavonoids, and vitamin C accumulation. This study provided preliminary data on boosting crop yield and phytochemical contents, which may improve food self-production and population health.

Effects of planting densities on the growth of lettuce (Lactuca sativa) under continuous lighting by blue, red and far-red light emitting diodes

Effects of planting densities on the growth of lettuce (<i>Lactuca sativa</i>) under continuous lighting by blue, red and far-red light emitting diodes

Effect of substrates elaborated with waste of tires and cables in lettuce growth

Effect of substrates elaborated with waste of tires and cables in lettuce growth

Evaluation of the Effectiveness of a Humic Substances-Based Product for Lettuce Growth and Nitrogen Use Efficiency under Low Nitrogen Conditions

Increasing crop yield with low-N supplies has become one of the main aims of current agriculture to reduce the excessive use of chemical fertilizers. A sustainable strategy to improve crop productivity, N assimilation, and N Use Efficiency (NUE) under limit-N growth conditions is the application of biostimulants, such as humic substances (HS). Here, we evaluated the effectiveness of an HS-based biostimulant, BLACKJAK®, in improving lettuce growth and NUE under N-deficit conditions. Thus, BLACKJAK® was applied radicularly (R) and foliarly (F) at the following doses: R-HS 0.40 mL/L, R-HS 0.60 mL/L, F-HS 7.50 mL/L, and F-HS 10.00 mL/L. Three N levels were applied: optimal (7 mM) and N-deficit (3 mM and 1 mM). The results showed that shoot dry weight (DW) was reduced at 3 mM N (−32%) and 1 mM N (−42%). However, R and F BLACKJAK® enhanced plant growth at all three N levels, especially with F-HS at 10.00 mL/L, which showed an increase of 43% in shoot DW at 3 and 1 mM N, compared to plants not treated with HS. BLAKCJAK® also improved photosynthesis, NO3− and organic N accumulation, the activity of N assimilation enzymes, and the concentration of amino acids and proteins, regardless of the N level. In addition, HS enhanced NUE parameters under all N conditions, except for R-HS 0.60 mL/L at 1 mM N. Hence, our study suggests that the HS-based product BLACKJAK® could be a good candidate for reducing chemical fertilizer use and improving lettuce growth and NUE under low N conditions, although further research is required.

Mitigating acid rain stress and enhancing aquaponics lettuce quality through root protection

Aquaponics is a sustainable eco-agricultural technology that combines aquaculture with horticulture. However, there is still limited research on the effects and preventive measures of acid rain on aquaponics vegetables. Herein, we conducted an experiment to decipher the combined effect of acid rain (pH 5.0, 4.0, and 3.0) and the protecting treatments (AR and AG) on the lettuce, in which plant growth, photosynthetic system, antioxidant system, nutrition and mineral elements were investigated. The results indicated that acid rain was the main factor affecting the growth of lettuce. Without acid rain, the various indicators of lettuce did not alter under AR and AG treatments. As pH decreased, lettuce yield and quality gradually decreased. Acid rain stimulated the antioxidant system and reduced root vitality and nutrient absorption. AG treatment mitigated the harm of acid rain on lettuce root vitality, soluble sugars, nitrate, and ascorbic acid content. At pH 4.0, AG treatment had the greatest mitigating effect. While at pH 3.0, AG treatment had no effect on the SOD activity, total phenolic and soluble sugar content of lettuce. These findings indicated that protecting the roots can mitigate the impact of acid rain on the edible and nutritional value of aquaponics lettuce. As pH decreased, this mitigating effect gradually diminished. In summary, the detrimental effect of acid rain on aquaponics lettuce was inevitable, yet protective root treatments offered a viable strategy to mitigate this stress. This research established a foundation for the enhancement of aquaponics systems resilience to acid rain.

Enhancing Head Lettuce Growth and Quality under Water Stress with Proline, Melatonin and Vermicompost Applications

Enhancing Head Lettuce Growth and Quality under Water Stress with Proline, Melatonin and Vermicompost Applications

Varying Light Intensities Affect Lettuce Growth and Physiology in Controlled Indoor Environments

Agriculture in controlled environments has gained popularity over time. Compared to traditional agriculture, controlled environments emerge as an alternative to mitigate the negative impacts of conventional farming methods. However, controlled environment agriculture, particularly plant factories with artificial lighting, incurs higher electricity costs, primarily for supplemental lighting and dehumidification of the cultivation area. Given these high costs, it is crucial to understand how efficiently plants utilize available light to convert it into biomass. This understanding can be used to design lighting strategies to reduce electricity usage. In this study, we cultivated ‘Rex’ lettuce (Lactuca sativa) plants on a soilless substrate and used an ebb-and-flow system for irrigation and fertilization. Plants grew in varying photosynthetic photon flux density (PPFD) levels ranging from 125 to 375 µmol·m−2·s−1 and were assessed for various physiological responses. Our findings revealed that plants exposed to higher light levels exhibited greater final dry weight, increased photosynthetic activity, higher water use efficiency, and accelerated growth compared to those under lower light conditions. Notably, plants subjected to higher light intensities did not show a significant increase in transpiration, suggesting a potential trade-off between energy expenditure on supplemental lighting and dehumidification. This finding opens the possibility of reducing energy consumption for dehumidification and achieving economic savings by subjecting plants to optimal growing conditions for shorter durations. This depends on whether higher savings on dehumidification are achieved compared to the energy required to maintain high PPFD levels.

Reduced Effect of Commercial Leonardite and Seaweed Extract on Lettuce Growth under Mineral, Organic, and No Fertilization Regimes

In this study, two commercial products based on the main groups of contemporary biostimulants—a commercial leonardite and a seaweed extract—were tested with the objective of assessing the conditions under which they can enhance lettuce (Lactuca sativa L.) performance, particularly to determine if synergies with conventional fertilization methods can be observed. The experimental protocol was arranged as a factorial design with two factors: organic or mineral fertilization × plant biostimulant. The organic or mineral fertilization factor included five levels: two rates of a nitrogen (N) fertilizer (40 (Nmin40) and 80 (Nmin80) kg ha−1 of N), the same N rates applied as an organic amendment (Norg40 and Norg80), and an unfertilized control (N0). The plant biostimulants used were a commercial leonardite (leonardite) for soil application before planting, a commercial seaweed extract (algae) for foliar application during the growing season, and a control without plant biostimulant. Leonardite significantly increased lettuce dry matter yield (DMY) compared to the control only in the first growing cycle (11.5 and 13.5 g plant−1) and showed no significant interaction with conventional fertilization. It also consistently increased phosphorus (P) levels in the plant tissues. The seaweed extract did not show any effect on the plant, nor did it have any interactions with conventional fertilization regarding DMY. In contrast, with mineral fertilization, lettuce DMY increased from 8.0 and 4.0 g plant−1 (N0) to 22.2 and 12.0 g plant−1 (Nmin80) in the first and second growing cycles, respectively. The response to organic fertilization was lower, yet DMY still increased from 4.0 to 8.1 g plant−1 in the second growing cycle. Generally, this type of plant biostimulant is tested under some form of environmental stress, where it often yields positive results. In this study, the optimal cultivation conditions maintained for the lettuce in the pots likely explain the limited response to the biostimulants. This study suggests that the product labels should more clearly indicate whether they are recommended for general cultivation conditions or specifically for situations where a particular environmental stress can be anticipated.