Response Of Lettuce Research Articles

Photons at the ultraviolet-visible interface: Effects on leaf expansion and photoinhibition

High energy ultraviolet-A (UV-A) and violet photons are at the edge of photosynthetically active radiation and may induce damage to sensitive metabolic pathways. The increasing use of light emitting diodes (LEDs) that provide these photons makes it important to better understand their effects on horticultural crops. We compared the effects of UV-A/violet photons to blue photons on short-term photosynthetic efficiency and long-term growth and morphological responses of lettuce ‘Rex’ and cucumber ‘Straight Eight’ under high and low photon flux densities (PFD). All plants received 67 % of the total PFD from white LEDs with the remaining 33 % of the photons from either blue (peak at 442 nm) or UV-A/violet LEDs (peak at 404 nm). Under a high PFD (500 μmol m−2 s−1; 16 hr photoperiod), the UV-A/violet photon treatment increased leaf area (by 24 %) and dry mass (by 17 %) in cucumber. In contrast, ‘Rex’ lettuce plants grown with UV-A/violet photons had significantly reduced chlorophyll content, leaf area, leaf photosynthetic rate, Fv/Fm ratio (indication of photoinhibition) and dry mass. The photoinhibition induced by UV-A/violet photons was reversible. Chlorophyll concentration of ‘Rex’ lettuce dramatically increased 2 days after being transferred from the UV-A/violet + white treatment to the blue + white light treatment, and plants regained full photosynthetic capacity after one week. The photoinhibition was also dose-dependent and did not occur when the photon flux density of UV-A/violet photons was reduced by 50 % at a lower daily light integral. We further evaluated the effects of UV-A/violet photons on three additional lettuce cultivars. Contrary to the detrimental effects in ‘Rex’ lettuce, UV-A/violet photons significantly increased leaf area and dry mass of ‘Marshall’ and tended to improve growth of ‘Parris Island’ and ‘Red Salad Bowl’ (although not statistically significant). Our analysis revealed that ‘Rex’ lettuce contained much lower levels of photoprotective pigments carotenoids and anthocyanins than other cultivars. We conclude that differences in photoprotective pigments are likely responsible for the contrasting responses to UV-A/violet photons.

Responses of lettuce (Lactuca sativa L.) growth and soil properties to conventional non-biodegradable and new biodegradable microplastics

Residual plastic films in soils are posing a potential threat to agricultural ecosystem. However, little is known about the impacts of microplastics (MPs) derived from biodegradable and non-biodegradable plastic films on plant-soil systems. Here, we carried out a pot experiment using soil-cultivated lettuce treated by two types of MPs, degradable poly(butylene adipate-co-terephthalate) (PBAT-MPs) and non-biodegradable polyethylene (PE-MPs). MPs resulted in different degrees of reduction in shoot biomass, chlorophyll content, photosynthetic parameters, and leaf contents of nitrogen (N), phosphorus (P), and potassium (K), accelerated accumulation of hydrogen peroxide and superoxide, and increased malondialdehyde content in lettuce leaves. Moreover, MPs obviously decreased contents of total N, nitrate, ammonium, and available K in soils, and increased available P, thus altering soil nutrient availability. MPs also significantly decreased proportions of macroaggregates, and decreased soil electrical conductivity and microbial activity. PBAT-MPs had significantly greater impacts on oxidative damage, photosynthetic rate, soil aggregation, microbial activity, and soil ammonium than those of PE-MPs. Our results suggested that MPs caused oxidative damages, nutrient uptake inhibition, soil properties alteration, ultimately leading to growth reduction, and PBAT-MPs exhibited stronger impacts. Therefore, it is urgent to further study the ecological effects of MPs, especially biodegradable MPs, on soil-plant systems.

The Benefit of Mycorrhizal Fungi and Beneficial Soil Bacteria in Drought Exposed Lettuce (Lactuca sativa var. capitata) Is Genotype and Environment Dependent

Morphological and biochemical responses were assessed in an iceberg (GIL) and butterhead (GBL) lettuce (Lactuca sativa var. capitata) treated with commercially available soluble preparation of mycorrhizal fungi and beneficial soil bacteria (MT) grown in three irrigation treatments considered in greenhouse (continental Croatia, 2022): I100—control treatment (100% volumetric water content—VWC); I80—80% VWC, moderate drought and I60—60% VWC, severe drought), in two growing cycles. MT was applied during lettuce drought-sensitive stages, i.e., transplanting and heading. Study results show that MT improved lettuce growth-related traits, yet the results are genotype and growing-cycle dependent. The beneficial effect of MT was also noted for root length, weight, and diameter which confirms the mycorrhizal role in improving the plant water uptake. Both lettuce genotypes responded to water deficit by overproduction of MDA and proline content, whereby the response of tested variables was growing cycle and genotype-specific. Both genotypes in severe drought treatment (MT-I60) responded with higher MDA in the first growing cycle and lower MDA content in the second growing cycle. MT-I60 treatment reduced proline accumulation in GBH in both growing cycles, while increased accumulation in GIL during the second growing cycle. The responses of lettuce to MT are genotype-specific and shaped by environmental conditions.

Nitrogen supply effect on lettuce response to Botrytis cinerea and Sclerotinia minor

Background information: Cultural practices play an important role on the development of pathogens (Datnoff, et al. 2007). In this context, several authors have been interested in studying the effects of mineral nutrition on the resistance of vegetables and fruits to fungi during storage, especially nitrogen. The purpose of the study: In this work we tested the effects of three contrasted regimes of nitrogen supply, with nitrate concentrations in the nutrient solutions of 2 mM (low), 10 mM (normal) and 20 mM (high) on the susceptibility of Lactuca sativa L towards Botrytis cinerea (BC87) and Sclerotinia minor (SM) during storage. Once harvested, the outerleaves of the plants derived from the three nitrogen regimes were inoculated with either Botrytis cinerea (BC87) or Sclerotinia minor (SM). Data showed that the resistance to this two pathogens increase when plants were developed under low nitrogen concentration. This resistance observed is correlated with low values in oxidative stress indicators (MDA and H2O2) and high values in total phenols.

Vertical and horizontal electric fields stimulate growth and physiological responses in lettuce

Vertical and horizontal electric fields stimulate growth and physiological responses in lettuce

Internalization, physiological responses and molecular mechanisms of lettuce to polystyrene microplastics of different sizes: Validation of simulated soilless culture

Microplastics (MPs) exists widely in the environment, and the resulting pollution of MPs has become a global environmental problem. Plants can absorb MPs through their roots. However, studies on the mechanism of the effect of root exposure to different size MPs on vegetables are limited. Here, we use Polystyrene (PS) MPs with different particle sizes to investigate the internalization, physiological response and molecular mechanism of lettuce to MPs. MPs may accumulate in large amounts in lettuce roots and migrate to the aboveground part through the vascular bundle, while small particle size MPs (SMPs, 100 nm) have stronger translocation ability than large particle size MPs (LMPs, 500 nm). MPs can cause physiological and biochemical responses and transcriptome changes in lettuce. SMPs and LMPs resulted in reduced biomass (38.27 % and 48.22 % reduction in fresh weight); caused oxidative stress (59.33 % and 47.74 % upregulation of SOD activity in roots) and differential gene expression (605 and 907 DEGs). Signal transduction, membrane transport and alteration of synthetic and metabolic pathways may be the main causes of physiological toxicity of lettuce. Our study provides important information for understanding the behavior and fate of MPs in edible vegetables, especially the physiological toxicity of MPs to edible vegetables, in order to assess the potential threat of MPs to food safety and agricultural sustainable development.

Changes in the photosynthetic response of lettuce exposed to toxic element multicontamination under hydroponic conditions

Changes in the photosynthetic response of lettuce exposed to toxic element multicontamination under hydroponic conditions

Lettuce response to the application of two commercial leonardites and their effect on soil properties in a growing medium with nitrogen as the main limiting factor

The aim of the study was to compare the effect of two leonardites (Humitec® and Humic Gold®) and an organic compost (Nutrimais®) with an untreated control on lettuce. The pot experiment was carried out in NE Portugal, in autumn 2019 and spring 2020. Humitec, Humic Gold and Nutrimais were applied alone or as a supplement to nitrogen (N), phosphorus (P) and potassium (K). The experiment was arranged as a three-factor experimental design (organic amendment, NPK addition and growing season). The growing season significantly influenced lettuce dry matter yield (DMY), the spring cycle being the highest yielding (10.6 to 6.5 g plant−1). NPK fertilization also significantly increased lettuce DMY (11.2 to 5.9 g plant−1). The organic amendment significantly influenced the concentration of some nutrients in plant tissues and some soil properties, but it did not influence lettuce DMY. In respect of growing season, Nutrimais increased lettuce DMY in the first one. In relation to the absence or otherwise of NPK fertilization, Nutrimais increased lettuce DMY in the pots not receiving NPK. Leonardites did not influence soil properties, tissue nutrient concentration or lettuce DMY. The positive effect on the lettuce DMY of organic compost was probably due to the supply of N, apparently the plants’ most significant limiting factor. The non-positive results of leonardites were due to the fact that they neither provided N, nor enhanced its bioavailability from the soil. Thus, NPK fertilizer and Nutrimais, a compost of low C/N ratio, providing some N had the greatest effect on lettuce DMY.

Effects of selenite on the responses of lettuce (Lactuca sativa L.) to polystyrene nano-plastic stress

Nowadays, nano-plastics are widespread in agricultural soils and could be uptaken by crops to cause an increased risk for food safety. As a beneficial element for plants, selenium (Se) can alleviate oxidative damages under various environmental stresses (eg. heavy metals, heat, cold). This study investigated the single and co-applications of nano-size polystyrene (PS) (80 nm and 200 nm) and selenite (0.8 ppm and 5 ppm) in lettuce (Lactuca sativa L.). Results showed nano-PS significantly decreased the root-shoot fresh biomass ratios, inhibited physiological functions in roots and leaves (e.g. root length, chlorophyll content and net photosynthetic rate), as well as stimulated the activities of the antioxidant enzymes in roots and shoots with greater toxicity at the smaller particle size (80 nm). However, both exogenous selenite applications significantly alleviated the above toxic effects of nano-PS in lettuces, especially at a high Se level of 5 ppm. Regression Path Analysis (RPA) revealed that regulation of chlorophyll levels by Se might be a key mechanism for counteracting PS stress in lettuces, which led to the increase in indigenous defense capacity. The present findings provide a novel but safer and cleaner agricultural strategy to alleviate or minimize nano-plastics toxicity in agricultural soils for staple crops and vegetables via application of Se.

Effect Of Light Spectrum LED Lettuce on IOT-Based Indoor Farming

Lettuce (Lactuca sativa L.) is an economically important crop worldwide and one of the most popular species grown in indoor farming. Lettuce's fast growth and growing cycle make lettuce a model plant to study the interaction between plants and light. The influence of light is one of the fundamental environmental factors for plant growth and development. Light-emitting diodes (LEDs) have higher light efficiency and higher wear efficacy, leading to a reduction in associated heating compared to other artificial lighting sources, such as fluorescent lamps or sodium vapor lamps. This research aimed to determine different responses of the morphological response of lettuce by giving LED light spectrum with a single color spectrum difference and IOT-based temperature and humidity monitoring. This research used a t-student test with a level of 5% on the mean value of the white light spectrum with a yellow light on lettuce plants. The addition of the LED light spectrum produces a different response to the morphological parameters. The addition of the LED spectrum gave a response to the plant height variable, where the provision of a yellow LED light spectrum resulted in plant height which affected lettuce plants

Transcriptomic response of lettuce (Lactuca sativa L.) leaves to a postharvest intermittent-light treatment during storage

Transcriptomic response of lettuce (<i>Lactuca sativa</i> L.) leaves to a postharvest intermittent-light treatment during storage

Response of green lettuce (Lactuca sativa L.) by granting of biochar types and dosage of NPK fertilizer

This study aims to determine the effect of giving the type of biochar, the effect of the dose of NPK fertilizer, and knowing the interaction of the type of biochar and the dose of NPK fertilizer on the growth and production of green lettuce. This research was conducted in May 2020 at the Screen House of the Jember State Polytechnic with an altitude of ±89 meters above sea level. The method used is a factorial Completely Randomized Design (CRD). The first factor is the type of biochar which consists of 3 levels, namely B0 (without biochar), B1 (rice husk charcoal biochar), B2 (coconut shell biochar). The second factor is the dose of NPK fertilizer which consists of N0 (NPK 0.501 g), N1 (NPK 1.02 g), N2 (NPK 2.04 g). Parameters observed were number of leaves (strands), plant height (cm), leaf area (cm2), canopy wet weight (gr), canopy dry weight (gr), root wet weight (gr), root dry weight (gr), and total chlorophyll content. Based on the results of the recapitulation analysis of the F test, the application of biochar fertilizer on the growth and production of green lettuce gave a very significant effect on the chlorophyll amount of treatment B2 (coconut shell biochar), the application of NPK fertilizer got significantly different results in the treatment of plant height 3 WAP, number of leaves 3 MST and leaf area with the highest yields were 29.33 cm (N3), 11.56 strands (N3) and 116.56 cm2 (N3). There was no interaction between biochar treatment and the position of NPK fertilizer.

Metabolomic Responses of Lettuce (Lactuca sativa) to Allelopathic Benzoquinones from Iris sanguinea Seeds.

Weed management is important in modern crop protection. Chemical weed control using synthetic herbicides, however, suffers from resistance and ecotoxicity. Metabolomic investigation of allelopathy (or allelochemicals) may provide novel alternatives to synthetic herbicides. This study aimed to investigate the detailed metabolomic responses of plants to allelochemicals in Iris seed extracts. The seed extracts of Iris sanguinea showed the strongest growth inhibitory activity against alfalfa, barnyard grass, lettuce, and mustard. 3-Hydroxyirisquinone (3-[10(Z)-heptadecenyl]-2-hydroxy-5-methoxy-1,4-benzoquinone) was isolated as a major allelochemical from I. sanguinea seeds through bioassay-guided fractionation. The compound inhibited the growth of shoots and roots by browning root tips. Discriminant analysis identified 33 differentially regulated lettuce metabolites after treatment with 3-hydroxyirisquinone (3HIQ). Metabolic pathway analysis revealed that several metabolic pathways, including aromatic amino acid biosynthesis and respiratory pathways, were affected by the compounds. Differential responses of membrane lipids (accumulation of unsaturated fatty acids) and extensive formation of reactive oxygen species were observed in root tissues following treatment with 3HIQ. Overall, alkylbenzoquinone from I. sanguinea induced extensive metabolic modulation, oxidative stress, and growth inhibition. The metabolomic responses to allelochemicals may provide fundamental information for the development of allelochemical-based herbicides.

Soilless urban gardening as a post covid-19 food security salvage technology: A study on the physiognomic response of lettuce to hydroponics in Uganda

This study was conducted to assess the performance of vegetables using a non-greenhouse hydroponic system as a sustainable urban farming technology to increase food security (in terms of vegetable production and availability). Leafy lettuce (red and green) was grown using non-circulating hydroponics under a complete randomized design. The effect of hydroponics on growth and yield of the vegetables was studied. Six parameters were studied: plant height, length of the root, number of leaves, weight of lettuce, moisture content and dry matter. Data was collected 20 and 40 Days after transplanting and analyzed using T-test at 5% significance level with Origin Pro software (version 9.0). Soil-based cultivation was used as the control experiment. A significant difference (P < 0.05) existed at yield for lettuce grown under soil and hydroponics for; dry matter content (0.02, 0.01), fresh weight (0.03, 0.02) and root length (0.01, 0.02) in that order. Based on number of leaves which is the key edible part of the vegetable, hydroponics has the potential to perform as equally well as conventional farming. Further research can be done to study the nutritional composition of the lettuce and performance of the other vegetables using the system.

Effect of Biostimulants on Leafy Vegetables (Baby Leaf Lettuce and Batavia Lettuce) Exposed to Abiotic or Biotic Stress under Two Different Growing Systems

Plant biostimulants are substances or microorganisms aimed at promoting plant growth by increasing the mineral nutrition efficiency, tolerance to environmental stress, and crop quality traits. This new category of crop inputs has been capturing the interest of both researchers and agriculture takeholders in light of the promising effects they could have on crop productivity and sustainability. This study investigated a variety of biostimulants for their effect on germination rates, plant health, chlorophyll fluorescence parameters, SPAD index, and growth of baby leaf lettuce and Batavia lettuce submitted to biotic (absence/presence of Pythium ultimum in the growing medium) or abiotic (0, 40, 80, and 120 mM NaCl L−1 concentrations and −0.5, −2, −4, and −6 kPa water potentials) stresses when grown in a greenhouse under conventional and organic cultivation. The results obtained show that lettuce response to biostimulants was influenced by the type or level of stress applied and the growing system used. The effects of the tested biostimulants varied from strongly detrimental to strongly beneficial.

Zinc (Zn) mitigates copper (Cu) toxicity and retrieves yield and quality of lettuce irrigated with Cu and Zn-contaminated simulated wastewater.

Owing to a competitive interaction, zinc (Zn) contained in highly Cu-contained wastewater was hypothesized to mitigate Cu toxicity-induced negative effects on the growth and quality of lettuce. Thus, growth, metal accumulation and biochemical responses of lettuce irrigated with simulated wastewater (SW, control), Cu-contaminated SW (CuSW, 20mg Cu L-1), Zn-contaminated SW (ZnSW, 100mg Zn L-1) and both Cu- and Zn-contaminated SW (CuZnSW, 20mg Cu and 100mg Zn L-1) were evaluated. Results revealed that irrigation with CuSW negatively affected growth (dry matters, root length and plant height) and quality (low mineral concentrations) of lettuce, which were associated with higher Cu uptake. Irrigation with Zn + Cu-contaminated SW retrieved Cu toxicity and improved root and shoot dry matters and root length by 13.5%, 46% and 19%, respectively compared to that with alone Cu-contaminated SW. Moreover, CuZnSW improved lettuce leaf quality compared to CuSW and increased concentrations of Mg (30%), P (15%), Ca (41%), Mn (24%) and Fe (23%). Moreover, compared to CuSW, CuZnSW improved flavonoids (54%), total polyphenolic compounds (1.8-fold), polyphenolic acids (77%) and antiradical activities (16.6%). Most importantly, Zn addition boosted up lettuce Cu tolerance index by 18% under Cu-contaminated SW treatment. Pearson's correlation analysis among various growth and mineral parameters demonstrated that shoot Zn concentration was positively related to elemental concentrations, phytochemical contents and antioxidant activity under Cu-contaminated environment. Thus, it is concluded that Zn supplementation retrieves negative effects of Cu toxicity to lettuce grown with Cu-contaminated wastewater.

Ameliorative role of salicylic acid in the growth, nutrient content, and antioxidative responses of salt-stressed lettuce

Plant responses to biotic and abiotic stresses are regulated by salicylic acid (SA), a signaling molecule. The goal of this study was to determine the efficacy of foliar SA treatments (0.25, 0.50, or 1.00 mM) in reducing salt stress in lettuce exposed to 100 mM NaCl. Salt-stressed plants given a foliar application of SA showed alleviation of the negative effects of salinity, resulting in higher growth performance (increases of 6%–198%). The positive impacts of SA were especially noticeable as an increase in the content of photosynthetic pigments, such as total chlorophyll (31–72%) and total carotenoids (49–141%). Application of SA also helped to reduce membrane damage, as seen by significantly lower levels of MDA (31–70%) in the leaves of salt-stressed lettuce plants. Moreover, the use of SA enhanced overall flavonoid and phenolic content, as well as nutrient absorption. SA treatment also increased the activities of antioxidant enzymes, such as ascorbate peroxidase, catalase, glutathione reductase, and superoxide dismutase, resulting in a considerable reduction in salt-induced oxidative damage. The most efficient SA application concentration was 0.50 mM. Overall, the use of SA as a foliar spray could be recommended as a long-term strategy for improving the defense systems of salt-stressed lettuce.

Influence of nitrogen stress on nitrate accumulation and yield of lettuce varieties

Relevance. Many authors note the existence of significant genotypic differences in the assimilation of nitrogen and the accumulation of nitrates by lettuce, point to the additive-dominant nature of the inheritance of the trait. The aim of the work was to evaluate the response of lettuce of various cultivars to mineral nutrition stress created against a nitrogen-deficient background (N0) and with an increased dose of nitrogen (N200).Material and Methods. In a microfield experiment on well-cultivated soddy-podzolic soil, a collection of lettuce varieties belonging to the main cultivated variety types was studied. The varieties differed in geographical origin, early maturity and morphological characteristics.Results. Differences in yield between varieties against the background of N200 were 4.5 times, and against the background of N0 – 5.7 times. Against an increased background of nitrogen nutrition, the highest yield – 2.22-2.64 kg/m2 was formed by the following varieties: All the Year, Quedlinburger Dickkopf, Berlin Yellow, Great lakes. Against a nitrogen-deficient background, Azart and Odessa Kucheryavets varieties stood out in terms of yield, which absorbed soil nitrogen better than others. The content of nitrates in lettuce plants of different varieties varied more strongly when grown on the background of N200 and ranged from 10.7 to 13.6 times (on average over 2 years – 11,2 times), on the control of N0 – 33 times. Varieties accumulating maximum NO3 under conditions of excess nitrogen nutrition were revealed. Lettuce Romaine (Lactuca romana) – 353 mg/kg and White paris cus (198 mg/kg) had a low content of NO3. The period of the maximum increase in biomass also corresponded to the maximum decrease in NO3 in plants. Power function equations were calculated to estimate the rate of change in biomass and NO3 content. The results indicate that there may be some scope for NO3 reduction in lettuce through cultivar selection or breeding.

Evaluation of Growth Responses of Lettuce and Energy Efficiency of the Substrate and Smart Hydroponics Cropping System.

Smart sensing devices enabled hydroponics, a concept of vertical farming that involves soilless technology that increases green area. Although the cultivation medium is water, hydroponic cultivation uses 13 ± 10 times less water and gives 10 ± 5 times better quality products compared with those obtained through the substrate cultivation medium. The use of smart sensing devices helps in continuous real-time monitoring of the nutrient requirements and the environmental conditions required by the crop selected for cultivation. This, in turn, helps in enhanced year-round agricultural production. In this study, lettuce, a leafy crop, is cultivated with the Nutrient Film Technique (NFT) setup of hydroponics, and the growth results are compared with cultivation in a substrate medium. The leaf growth was analyzed in terms of cultivation cycle, leaf length, leaf perimeter, and leaf count in both cultivation methods, where hydroponics outperformed substrate cultivation. The results of the 'AquaCrop simulator also showed similar results, not only qualitatively and quantitatively, but also in terms of sustainable growth and year-round production. The energy consumption of both the cultivation methods is compared, and it is found that hydroponics consumes 70 ± 11 times more energy compared to substrate cultivation. Finally, it is concluded that smart sensing devices form the backbone of precision agriculture, thereby multiplying crop yield by real-time monitoring of the agronomical variables.

Agronomic and physio-biochemical responses of lettuce to exogenous sodium nitroprusside (SNP) applied under different irrigation regimes

Drought adversely affects crop production in areas with water shortages. In such areas, various methods need to be implemented to alleviate the effect of water stress on plants. Nitric oxide (NO) is an important plant growth regulator that affects various physiological processes. In this study, we determined ways to increase water-stress tolerance of lettuce by applying exogenous sodium nitroprusside (SNP, a donor of NO). In total, 12 treatments were administered, including three SNP doses (0, 50, and 100 µM) and four levels of irrigation (I100, I80, I60, and I40). An increase in the doses of NO partially increased the water consumption of lettuce under full and deficit irrigation conditions. The highest water consumption (125.1 mm) and the highest yield (39.1 t/ha) were recorded for lettuce plants that were administered the I100 treatment with 100 µM SNP. SNP significantly increased the lettuce yield and irrigation water productivity (IWP) under deficit irrigation and full irrigation. SNP promoted chlorophyll synthesis by increasing photosynthesis. The application of 100 µM SNP increased catalase (CAT) activity approximately three times compared to CAT activity in the control group, and it also significantly increased peroxidase (POD) activity. Additionally, high doses of SNP reduced membrane damage in lettuce leaves. These results indicated that under water stress, exogenous NO improves photosynthesis by increasing chlorophyll synthesis, activates antioxidant enzymes, such as CAT and POD, protects lettuce against oxidative damage, and increases irrigation water productivity, thus increasing the yield.