Edible Parts Of Lettuce Research Articles

Uptake, translocation and health risk assessment of nonylphenol in vegetables under reclaimed water irrigation

AbstractNonylphenol (NP) is one of the typical endocrine‐disrupting chemicals (EDCs), which can be harmful at very low concentrations. Municipal sewage and reclaimed water are its two main sources. EDCs can enter into the soil with reclaimed water irrigation and accumulate in plants, causing environmental and human health risks. The occurrence and migration of NP in soil‐crop systems were studied by pot experiments of lettuce and eggplants simulating long‐term irrigation with reclaimed water. The health risks were also evaluated. The experiments set treatments with different initial soil NP concentrations (0.28–6.42 mg/kg) and soil moisture (60%–90% field water capacity [FC]). After harvest, the NP in edible parts of lettuce and eggplants were 35.80–54.30 and 15.45–23.38 μg/kg, respectively. The residual amounts of NP in the soil‐lettuce system and soil‐eggplant system were limited with the residual rates of 0.9%–24.4% and 0.3%–14.5%, respectively. The results showed that the lettuce and eggplant tissues had the highest bioconcentration factors (BCFs) in 75% FC and the translocation factors (TFs) tended to decrease with the initial soil NP contents increased. The noncancer hazard quotients (HQ) for adults and children exposed to NP had the order of 10−5, which showed little health risk for reclaimed water irrigation.

Effect of increased soil available phosphorus from vermicompost application on the bioavailability, chemical form, and bioaccessibility of heavy metals.

Phosphorus (P) plays an important role in immobilizing heavy metals (HMs), thereby preventing their accumulation, especially in edible parts of crops. In this study, vermicompost (VM) and chemical fertilizers (CFs) were used as soil amendments to increase the available P concentration in soil contaminated with cadmium (Cd) and nickel (Ni), with the aim of reducing their bioavailability, uptake, and bioaccessibility. Using CF and VM as soil amendments substantially increased the available P and exchangeable potassium concentrations in the soil. Furthermore, VM addition led to an increase in OM content and in exchangeable calcium and magnesium, resulting in the improved growth of lettuce. It also reduced the uptake of Cd and Ni in the two lettuce cultivars tested in the study. However, CF addition boosted the accumulation of Cd and Ni by increasing the soil acidity. CF addition, and especially VM addition, altered the chemical forms of Cd and Ni from active to inactive. Overall, the results of this study underscore the positive impact of using VM as a soil amendment on lettuce growth and the prevention of HM accumulation in edible parts of lettuce. VM addition led to decreased bioavailability, uptake, and bioaccessibility of HMs in soil, which could improve food safety and reduce potential risks associated with HM contamination.

Biochar derived from tobacco waste significantly reduces the accumulations of cadmium and copper in edible parts of two vegetables: an in-situ field study.

Biochar, as a soil amendment, can be applied to remediate heavy metal (HM) contaminated farmland. However, there is little research on the effect of tobacco biochar (TB) derived from tobacco waste on HM controlling in edible parts of vegetables. In this study, the impact of two TB levels on the plant growth, copper (Cu) and cadmium (Cd) accumulation in the edible parts of lettuce and chrysanthemum, and on Cu and Cd bioavailability of rhizosphere soil was investigated through in-situ field experiments. The results showed that TB has rich oxygen containing functional groups, high porosity, high nitrogen adsorption capacity. The addition of 5 t ha-1 and 10 t ha-1 TB significantly increased the shoot biomass of chrysanthemum, but had no effect on the growth of lettuce. Two levels of TB significantly increased the pH value, but decreased the available Cu and Cd concentrations of rhizosphere soil, thereby reducing the Cu and Cd accumulations in the edible parts of lettuce and chrysanthemum. The findings provided effective evidences that TB derived from tobacco waste is an efficient strategy for controlling Cu and Cd accumulation in the edible parts of vegetables to ensureagri-product safety production in HM-polluted farmland.

Effect of foliar application of nanoparticles on growth, physiology, and antioxidant enzyme activities of lettuce (Lactuca sativa L.) plants under cadmium toxicity.

Nanotechnology has attracted the interest of scientists due to its wide range of application specifically in agriculture. Nanoparticles (NPs) may act as a promising materials to alleviate cadmium (Cd) stress in plants. This study aims to assess the impact of multiple nanoparticles including nSiO2 (50mg L-1:100mg L-1), nTiO2 (20mg L-1:60mg L-1), nZnO (50mg L-1:100mg L-1), nFe3O4 (100mg L-1:200mg L-1), nCuO (50mg L-1:100mg L-1), and nCeO2 (50mg L-1:100mg L-1) in combination with CdCl2 (5µM) to mitigate Cd toxicity in lettuce through foliar application in hydroponic solution. Current findings indicate that foliar application of nSiL + Cd (50mg L-1), nZnL + Cd (50mg L-1), and nTiL + Cd (20mg L-1) is more effective in improving growth, biomass, root architecture, and elevated photosynthetic efficiency, which might be attributed to the increasing uptake of essential micronutrient (K, Mg, Ca, Fe, Zn) under Cd stress. Similarly, treatment with nanoparticles leads to reduced accumulation of ROS and MDA in lettuce, while enhancing the SOD, POD, CAT, and APX activities. The results showed that nanoparticles have high tolerance against Cd as depicted by the inhibition in Cd accumulation by 3.2-58% and 10-72% in roots as well as edible parts of lettuce, respectively. In addition, Cd alone reduces the morphological traits, antioxidant enzyme activity, and photosynthetic activity, while increasing the ROS, MDA, and Cd accumulation in lettuce. This comprehensive study suggests the role of nanoparticles in reducing Cd toxicity in lettuce, signifying their importance as stress mitigation agents. However, long-term pot, priming, and field trials are needed to identify the optimal nanoparticle for the lettuce under variable environmental conditions.

Uptake and Enantiomeric Selectivity of β-Blockers in Lettuce (Lactuca sativa L.) and Tomato (Lycopersicon esculentum M.) in Soil-Pot Culture.

The uptake and translocation of β-blockers in lettuce (Lactuca sativa L.) and tomato (Lycopersicon esculentum M.) were investigated by carrying out a 70-day soil-pot cultivation. The root uptake parameters of β-blockers in lettuce decreased in the order of atenolol (ATE) > sotalol (SOT) > propranolol (PRO) with root bioconcentration factors (BCFsroot/soil) of 0.158, 0.136, and 0.096, respectively, which were positively correlated with their water solubility. The BCFroot/soil of β-blockers in tomato was higher than those in lettuce. ATE and PRO were prone to migrate to the aerial parts of tomato with translocation factors of 3.31 and 4.11, respectively. In tomato fruits, the enantiomeric profile of PRO and ATE shifted to that dominated by the more toxic enantiomer, i.e., (S)-PRO and (R)-ATE. The enantiomeric selectivity of β-blockers in the edible parts of lettuce and tomato indicated the potential ecotoxicity of these pharmaceuticals for plants and the human exposure risk via vegetable intake.

Comparative effects of mineral fertilizer and digestate on growth, antioxidant system, and physiology of lettuce under salt stress

Salt stress in plants presents a major challenge to future agricultural production. Digestate has various effects on plant growth, but little information is available on its effects on the antioxidant system and physiological characteristics of lettuce under salt stress. In this study, the impacts of mineral fertilizer and digestate application on edible parts of lettuce were compared under three salinities. Experimental treatments comprised application of two types of fertilizer (mineral fertilizer and digestate) and three NaCl concentrations (0, 3, and 7.5 dS m− 1). High NaCl concentrations resulted in significantly lower photosynthesis, growth, and physiological indices compared with those under no NaCl addition. However, under the 7.5 dS m− 1 NaCl condition, digestate application (DA) increased the fresh weight (42%), dry weight (27%), photosynthetic pigment contents and photosynthesis (20%) of lettuce compared with that under mineral fertilizer application (MFA). Accumulation of reactive oxygen species was markedly lower, and the membrane stability index was therefore higher, under DA compared with under MFA within the same salinity level. Lipid peroxidation was lower under DA compared with under MFA in all salinity treatments. Salt stress up-regulated the antioxidant system and DA further increased the enzymatic and non-enzymatic antioxidant capability compared with that under MFA. In addition, the total water use was lower and water-related indices, such as water use efficiency of fresh weight, water use efficiency of dry weight and relative water content, were higher under DA compared with under MFA. The application of digestate instead of mineral fertilizer could be a promising practice to alleviate the negative impact of salt stress on the productivity and physiological characteristics of lettuce plants.

Risk assessment of heavy metals in soils and edible parts of vegetables grown on sites contaminated by an abandoned steel plant in Havana.

Food production in areas contaminated by industrial wastes poses a serious risk to farmers and consumers. Here, we evaluate Cd, Cr, Ni, and Pb concentrations in the soils and the edible parts of lettuce, chives, tomatoes, pepper, and cassava plants grown by small farmers in areas contaminated by slag from an abandoned steel plant in Havana, Cuba. The total, environmentally available, and bioavailable concentrations of metals in the soils and the metals bioconcentration factor in the plants were determined. The risks to human health from food and soil ingestion were estimated. The total and environmentally available concentrations of Cd, Cr, and Pb were above values considered safe by international standards, with likely adverse effect on human health. Cadmium was the most bioavailable metal, reflected in the highest accumulation in the crops' edible parts. Even with negligible DTPA-available Cr concentrations in soils, the Cr concentrations in edible parts of the crops exceeded regulatory levels, suggesting that rhizosphere mechanisms may increase Cr availability. The consumption of vegetables represented 70% of the daily intake dose for Cr, Cd, and Ni, while accidental ingestion of contaminated soil is the predominant human exposure route for Pb. Our results demonstrated the health risks associated with cultivating and consuming vegetables grown on metal contaminated soils in Havana and can assist public policies capable of guaranteeing the sustainability of urban agriculture and food security.

Photosynthetic Parameters and Growth of Rice, Lettuce, Sunflower and Tomato in an Entisol as Affected by Soil Acidity and Bioaccumulation of Ba, Cd, Cu, Ni, and Zn.

The bioaccumulation of trace elements (TEs) in crops consumed by humans can reduce food production as a consequence of photosynthetic damage in plants and cause several diseases in humans. Liming is a soil management strategy designed to alleviate soil acidity and mitigating these problems by reducing the TE bioavailability. In this study, we evaluated the effect of liming on photosynthesis, growth, and bioaccumulation of barium (Ba), cadmium (Cd), copper (Cu), nickel (Ni), or zinc (Zn) in lettuce (Lactuca sativa L.), rice (Oryza sativa L.), sunflower (Helianthus annuus L.), and tomato (Solanum lycopersicum L.) grown in a sandy Entisol. The crops were grown in either uncontaminated or contaminated Entisol, at two base saturation (BS%) ratios: 30% for all crops or 50% for rice and 70% for lettuce, sunflower, and tomato. The photosynthesis-related parameters varied depending on the metal and the crop, but in general, increasing BS% did not attenuate photosynthetic damage induced by Ba, Cd, Cu, Ni, and Zn in the crops. There was no strong correlation between the photosynthetic parameters and biomass production, which indicates that the suppression of biomass induced by Ba, Cd, Cu, Ni, or Zn is related to other metabolic disorders in addition to the impairment of CO2 assimilation or chlorophyll synthesis in the crops assayed, with the exception of Ni and Zn in lettuce. In conclusion, increasing BS% was not consistent in reducing Ba, Cd, Cu, Ni, and Zn accumulation in the edible parts of lettuce, rice, sunflower, and tomato grown in the sandy soil, which is probably related to the low capacity of this soil to control TE bioavailability.

Biological Effect of Tetracycline Antibiotics on a Soil-Lettuce System and Its Migration Degradation Characteristics

Residual tetracycline antibiotics (TCs) in farmland soils with the application of livestock manure cause risks to the growth of vegetables and soil ecology. Here, pot experiments are carried out using through exogenous addition of different levels of oxytetracycline (OTC), tetracycline (TC), and chlortetracycline (CTC), to study the physiological toxicity, uptake, and transportation of TCs in lettuce. The subsequent degradation of TCs in soil was also evaluated along with analyses of soil enzyme activity and microbial population dynamics. The results showed that the biomass of lettuce decreased with application of TCs as well as the chlorophyll-a, chlorophyll-b, and carotenoid content. Consequently, net photosynthetic rates were inhibited, and SOD, POD, and CAT increased under the stress imposed by the TCs. With an increase in the level of TC application, uptake by lettuce plants increased while the bioconcentration and translocation factors decreased. When OTC, TC, and CTC in the soil were below 150 mg·kg-1, the health risk from the edible parts of lettuce was low (HQ<0.1). The TC degradation rate in different soils was ranked in the order of control soil > rhizosphere soil > bulk soil. The OTC degradation rates in the soils were significantly lower than for TC and CTC. TCs (150-1350 mg·kg-1) significantly inhibited urease and rhizosphere catalase activity in soil and reduced the number of soil culturable bacteria and fungi.

The effect of fertilizing soils degraded by the metallurgical industry on the content of elements in Lactuca sativa L.

The aim of the study was to determine the content of macroelements (Ca, K, P, S, Mg) and microelements (Fe, Cr, Ni, Mn, Zn, Pb, Zn, Ti) in the leaves of Lactuca sativa grown in soils contaminated by the mining and metallurgical industry. The plants were cultivated using four fertilization variants: (a) unfertilized soil, (b) mix of straight fertilizers, (c) multinutrient fertilizer and (d) organic fertilizer, namely granular cattle manure. The study also involved an analysis of metal accumulation degree in the edible parts of lettuce by means of calculating a bioaccumulation index—transfer factor (TF). The analysis of the impact of fertilization on the content of the elements in the edible parts of fertilized versus unfertilized lettuce demonstrated that phytoavailability of the metals was most effectively limited by the multinutrient fertilizer and the mix of straight fertilizers. The organic fertilizer proved to be the least effective. The highest TF values (> 0.1) were recorded for macroelements, which denotes their intense and moderate accumulation. Poor bioaccumulation was observed for Cr, Mn, Ni and Zn (0.01 ≤ TF < 0.1), whereas in the case of Fe, Pb and Ti—trace bioaccumulation or no bioaccumulation was found (TF ≤ 0.01).

Red soil amelioration and heavy metal immobilization by a multi-element mineral amendment: Performance and mechanisms

This field study aims to identify the performance and mechanisms of red soil amelioration and heavy metal immobilization by a multi-element mineral amendment (MMA) mainly containing a mixture of zeolites (laumontite and gismondine), montmorillonite, gehlenite, grossular and calcium silicate powder. The results indicated that the acidity of red soil was neutralized, and the soil EC, CEC, and content of montmorillonite and illite were increased after application of MMA, improving the soil fertility as well as the ability of heavy metals immobilization. The high amounts and reactivity of dissolved and colloidal Fe provided by the ferralsol (red soil) combined with the abundant available Si, Ca, Mg, Na and K supplied by MMA, readily destabilizes kaolinite and facilitates the formation of 2:1 type clay minerals. Meanwhile, the application of MMA was effective in reducing the bioavailability of soil heavy metals due to the activated mineralogical compositions of MMA as well as the increase of pH and 2:1 type clay minerals in the soil, which significantly decreased the up-taking and accumulation of Cd, Pb, Cr and Hg in lettuce tissues (p < 0.05). Compared with the untreated soil, the plant height, the total yield and content of vitamin C in the edible parts of lettuce in MMA-treated soil was increased by 7.6%, 23.6%, and 12.8%, respectively. These results showed that MMA could be a promising amendment for red soil amelioration and heavy metal immobilization.

Effects of exogenous abscisic acid on the growth and cadmium accumulation of lettuce under cadmium-stress conditions

ABSTRACTAbscisic acid (ABA) is an important hormone that can regulate the heavy-metal uptake of plants. In this study, exogenous ABA was applied to lettuce (Lactuca sativa) grown under cadmium (Cd)-stress conditions, and the effects of exogenous ABA on the growth and Cd accumulation of lettuce were evaluated. The results showed that treatment of Cd significantly decreased biomass and increased Cd content of lettuce compared with the control. The shoot biomass increased after spraying 1, 5 and 10 μmol/L ABA, and the root biomass increased after spraying 1–20 μmol/L ABA compared with the treatment of Cd. The Cd content in shoots significantly decreased when exposed to different ABA concentrations. The lowest Cd content in shoots of lettuce was produced by the ABA concentration of 5 μmol/L, with decreased by 23.60% compared with the treatment of Cd. Therefore, spraying ABA effectively alleviated Cd toxicity and reduced Cd uptake in the edible parts of lettuce, and 5 μmol/L ABA was the optimal dose.

Study of the contamination rate and change in growth features of lettuce (Lactuca sativa Linn.) in response to cadmium and a survey of its phytochelatin synthase gene

Crops can become contaminated when grown in soils containing heavy metals. Cadmium is a heavy metal that poses a significant health risk to humans. The purpose of this study was to evaluate the effect of cadmium on lettuce (Lactuca sativa Linn) and the contamination risk of lettuce grown in cadmium environments. The results showed that photosynthesis and growth parameters were significantly affected by cadmium. Lettuce has the ability to absorb large amounts of cadmium from the contaminated environment and so is a cadmium hyperaccumulator plant. The study showed that approximately 35% of the total absorbed cadmium is transmitted to aerial and edible parts of lettuce. This study was undertaken as lettuce has the ability to absorb and accumulate high levels of cadmium. There are however are no reports on the PCS gene and the potential for high cadmium accumulation in lettuce. The bioinformatics study revealed that lettuce has two phytochelatin synthase genes that produce 6 PCSs through splicing leading to the ability of lettuce to store high levels of cadmium. These six sequences although different in length have high similarity. Sequence structure, cellular location, three-dimensional structure, phylogeny and a comparison of their catalytic power were evaluated. The high accumulation of cadmium in lettuce and the presence of several PCSs contribute to the accumulation of cadmium in aerial tissues. The cultivation of lettuce in contaminated environments led us to evaluate suspected farms for the presence of cadmium in produce. Lettuce grown in industrial environments contaminated with cadmium can pose a serious threat to human health.

Occurrence and human health implications of chemical contaminants in vegetables grown in peri-urban agriculture

Recent studies have proven that vegetables cultivated in peri-urban areas are exposed to a greater concentration of organic microcontaminants (OMCs) and trace elements (TEs) than those grown in rural areas. In this study, the occurrence and human health risk of chemical contaminants (16 TEs and 33 OMCs) in edible parts of lettuce, tomato, cauliflower, and broad beans from two farm fields in the peri-urban area of the city of Barcelona and one rural site outside the peri-urban area were assessed. The concentration of TEs and OMCs (on fresh weight basis) ranged from non-detectable to 17.4 mg/kg and from non-detectable to 256 μg/kg, respectively. Tomato fruits showed the highest concentration of TEs and OMCs. Principal component analysis indicated that the occurrence of chemical contaminants in vegetables depended on the commodity rather than the location (peri-urban vs rural). Risk assessment using hazardous quotient (HQ) and threshold of toxicological concern (TTC) approaches showed that the risk for the consumption of target vegetables in the peri-urban area was low and similar to that observed for the rural site. Total HQ values for TEs were always below 1, and a minimum consumption of 150 g/day for children and 380 g/day for adults is required to reach the TTC due to the presence of pesticides. Further studies are needed to estimate the combined effect of TEs and OMCs on human health.

Effects of exogenous indole-3-acetic acid on the growth and cadmium accumulation of lettuce under cadmium stress

Indole-3-acetic acid (IAA) plays crucial roles in plant growth and stress tolerance. In present study, the effects of spraying different concentrations (0, 25, 50, 100 and 200 μmol/L) of IAA on the growth and cadmium (Cd) accumulation in lettuce (Lactuca sativa) were investigated. The lettuce exposed to Cd exhibited a substantial decline in growth, and the Cd content of them significantly increased. Spraying exogenous IAA resulted in alleviating the inhibitory of Cd toxicity to lettuce. The dry weight in shoots of lettuce increased by spraying with IAA compared with the Cd treatment alone, but the dry weight of roots had no significantly differences. Although exogenous IAA increased the root Cd content, it significantly reduced shoot Cd content, indicating its role in Cd transport. Therefore, spraying IAA effectively alleviated Cd toxicity and reduced Cd uptake in the edible parts of lettuce, and the 100 μmol/L IAA was the optimal dose.

EFFECT OF HUMIC ACID APPLICATION ON CADMIUM ACCUMULATION BY LETTUCE LEAVES

Humic acid (HA) is a plant growth stimulator compound that may also reduce cadmium (Cd) concentration in plant tissues. The aim of the present study was to investigate the effect of adding humic acid (HA) to the growth medium on Cd concentration in lettuce leaves. In a soilless experiment, seedlings of lettuce (Lactuca sativa L.) were exposed to three levels of Cd [0, 2 and 4 mg L−1 in the form of cadmium chloride (CdCl2)] and three levels of HA (0, 100 and 1000 mg L−1). Application of HA increased significantly the shoot fresh weight of lettuce while it had no effect on the photosynthetic rate and concentrations of chlorophyll, proline, and phosphorus (P) in lettuce leaves. In contrast, increasing Cd concentration was associated with decreases in the photosynthetic rate, shoot fresh weight, and leaf chlorophyll concentration. A significant reduction in leaf Cd concentration was found by addition of HA to the growth media. It seems that application of HA could be successful for improving plant growth and reducing accumulation of Cd in edible parts of lettuce.

Spatiotemporal changes of nitrate and Vc contents in hydroponic lettuce treated with various nitrogen-free solutions

Nowadays, off-season leafy vegetables are generally characterized by low vitamin C (Vc) content and high nitrate accumulation due to low light intensity inner protected systems and high-level nitrogen supply. A glasshouse experiment was conducted to investigate the effects of three kinds of nitrogen-free solution treatments before harvest on Vc and nitrate contents in expanded leaf blades, expanded leaf petioles and old leaves of hydroponic lettuce. The results showed that using nitrogen-free solutions could decrease nitrate contents of expanded leaf blades, expanded leaf petioles and old leaves, also nitrate contents in above parts reduced increasingly with treatment time extending. In addition, three nitrogen-free solution treatments increased the Vc content of expanded leaf blades instead of expanded leaf petioles and old leaves. There were instead of significant positive correlations between nitrate contents but Vc contents of expanded leaf blades, expanded leaf petioles and old leaves. To conclude, nitrogen disruption treatment before harvest could effectively reduce nitrate contents in edible parts of lettuce, and also improve Vc content in expanded leaf blade.

THE EFFECT OF ORGANIC MATTER IN SOIL ON THE LEAD LEVEL IN EDIBLE PARTS OF LETTUCE AND CARROT

ISHS International Symposium on Quality of Fruit and Vegetables: Influence of Pre- and Post- Harvest Factors and Technology THE EFFECT OF ORGANIC MATTER IN SOIL ON THE LEAD LEVEL IN EDIBLE PARTS OF LETTUCE AND CARROT