EFFECT OF BIOSTIMULANTS ON SOME BIOACTIVE COMPOUNDS AND NITRATE LEVEL IN LETTUCE (Lactuca sativa L.) GROWN UNDER UNHEATED PLASTIC TUNNEL

Based on the regulation (EU) No 2015/1107 in 8 July 2015, Willow (Salix alba) bark extract is a recent approved basic substance in Europe as a safe and effective environmentally friendly fungicide to be used in plant protection. Because of having indole butyric acid content, it is also used as a growth hormone to promote rooting in cutting propagation of wooden part in horticultural plants. This research aimed to evaluate the effect of willow extract and Ferbanat L (Bistep) on lettuce leaves. Bistep is an organic solution of nano fertilizer which is produced in Hungary and allowed as „Bistep plant conditioner”. Furthermore, the experiment evaluated their interaction on some bioactive compounds in different lettuce varieties, too. Three different lettuce varieties (King of May, Kobak and Great Lakes) were evaluated for total polyphenols, vitamin C and nitrate content in fresh leaves. The results indicate that the contents were significantly affected by the used biostimulants rather than varieties. Significantly difference of the total polyphenols was recorded in the plants treated with Willow + Bistep (80.64 mg GAE / 100g) in comparison to the control (55.85 mg GAE / 100g) in the mean of varieties. Similar result was recorded for the vitamin C. However, plants treated with Willow extract resulted in the highest level of nitrate content (692.00 mg/100g), while the lowest amount was measured in the control (488.00 mg/100g). According to our results, Willow bark extract can be a beneficial source of natural growth regulator or fungicide; however, when it is used alone for vegetables, the nutrient content (mainly nitrate level) must be checked before consuming and delivering to the market.

Investigation of Groundwater Contamination from Akanran Open Waste Dumpsite, Ibadan, South-Western Nigeria, using Geoelectrical and Geochemical Techniques

In recent times, large waste is produced especially in an urban area due to population with careless handling which calls for worries. Hence, the study determines the effect of Akanran dumpsite on the groundwater quality for drinking and domestic purposes. It employs the geophysical and geochemical methods. Wenner configuration was adopted with constant electrode separation ranging from 5 to 25 m to acquire five profiles within and outside the dumpsite and processed using DIPROWIN 4.01 software. Soil and water samples were collected and analysed. The 2-D pseudosection revealed a very low resistivity value which is less than 10 ohm-meter and is suspected to be leachate infiltration which migrates to a depth of 7 m. The results of soil analysis show that clay ranges between 9.61 - 18.8 %., silt between 9.27 – 19.7 % and an average bulk density of 1.48 (relatively high for a sandy loam) which suggests that infiltration of the leachate is minimal. The pH of the water sample analysis obtained is 6.9, suggesting acidic concentrates in the groundwater of the study area. However, this pH value for drinking water is within the permissible level of 6.5 – 8.5 indicating that the groundwater in the study area is suitable for drinking and also for other purposes. A Nitrate level of 2.56 mg/l in the water sample falls within 50.0 mg/l, and nitrite level of 0.09 mg/l which is moderate when compared to the permissible level limit of 0.20 mg/l. The concentration of heavy metals in hand-dug well sample from Akanran dumpsite are Zn (1.81 mg/l), Cu (0.38 mg/l), Cr (0.003 mg/l) which are within the permissible level limit and Pb (0.21 mg/l) which recorded high metal concentration which may suggest that the dumpsite contain waste metals which may leach down the soil. In conclusion, the groundwater in the area of the survey is safe and there is possible contamination with time.

Reduction of Nitrate Content in Baby-Leaf Lettuce and Cichorium endivia Through the Soilless Cultivation System, Electrical Conductivity and Management of Nutrient Solution

Soilless cultivation systems are efficient tools to control nitrates by managing nutrient solution (NS) salinity and nitrogen availability, however, these nitrate-lowering strategies require appropriate calibration based on species/genotype-specific responses interacting with climate and growing conditions. Three experiments were carried out on lettuce and Cichorium endivia grown in ebb-and-flow (EF) and floating (FL) systems at two levels of NS salinity (EC = 2.5 and 3.5 dS m−1) (EC2.5, EC3.5, respectively) under autumn and early-spring (lettuce) and winter and late-spring conditions (C. endivia). Nitrogen deprivation (NS withdrawal a few days before the harvest) was tested at EC2.5, in the autumn and winter cycles. The EF-system caused an increase in salinity in the substrate where roots mainly develop so it mimicked the effect of the EC3.5 treatment. In the winter-grown lettuce, the EF-system or EC3.5 treatment was effective in reducing the nitrate level without effects on yield, with the EF baby-leaf showing an improved quality (color, dry matter, chlorophylls, carotenoid, vitamin C, phenol). In both seasons, the EF/EC3.5 treatment resulted in a decline in productivity, despite a further reduction in nitrate content and a rise in product quality occurring. This response was strictly linked to the increasing salt-stress loaded by the EC3.5/EF as highlighted by the concurrent Cl− accumulation. In early-spring, the FL/EC3.5 combination may represent a trade-off between yield, nitrate content and product quality. In contrast, in winter-grown endive/escarole the EC3.5, EF and EC3.5/EF reduced the nitrate level with no effect on yield, product quality or Cl− uptake, thus proving them to be more salt-tolerant than lettuce. High temperatures during the late-spring cycle promoted nitrate and Cl− uptake, overcoming the nitrate-controlling effect of salinity charged by the EF system or EC3.5. The nitrate level decreased after 3 day-long (lettuce) or 6 day-long (C. endivia) NS withdrawal. In C. endivia and EF-grown lettuce, it provoked a decrease in yield, but a concurrent improvement in baby-leaf appearance and nutritional quality. More insights are needed to fine-tune the duration of the NS removal taking into account the soilless system used and species-specific characteristics.

EC Sensitivity of Hydroponically-Grown Lettuce (Lactuca sativa L.) Types in Terms of Nitrate Accumulation

The goal of this research was to investigate the effect of electrical conductivity (EC) levels of the nutrient solution on the fresh weight, chlorophyll, and nitrate content of hydroponic-system-grown lettuce. The selected cultivars are the most representative commercial varieties grown for European markets. Seven cultivars (‘Sintia,’ ‘Limeira,’ ‘Corentine,’ ‘Cencibel,’ ‘Kiber,’ ‘Attiraï,’ and ‘Rouxaï’) of three Lactuca sativa L. types’ (butterhead, loose leaf, and oak leaf) were grown in a phytotron in rockwool, meanwhile the EC level of the nutrient solutions were different: normal (<1.3 dS/m) and high (10 dS/m). The plants in the saline condition had a lower yield but elevated chlorophyll content and nitrate level, although the ‘Limeira’ and ‘Cencibel’ cultivars had reduced nitrate levels. The results and the special characteristic of the lollo-type cultivars showed that the nitrate level could be very different due to salinity (‘Limeira’ had the lowest (684 µg/g fresh weight (FW)) and ‘Cencibel’ had the highest (4396 µg/g FW)). There was a moderately strong negative correlation (−0.542) in the reverse ratio among the chlorophyll and nitrate contents in plants treated with a normal EC value, while this relationship was not shown in the saline condition. Under the saline condition, cultivars acted differently, and all examined cultivars stayed under the permitted total nitrate level (5000 µg/g FW).

Nitrate removal in potable groundwater by nano zerovalent iron under oxic conditions

Groundwater pollution by nitrate contamination has become a significant issue in some areas of Sri Lanka, giving rise to health concerns and a dearth in good quality potable water. In this study, the effectiveness of nano zerovalent iron (nZVI) for the removal of nitrate in potable groundwater under oxic conditions was investigated to meet the drinking water quality standards stipulated by World Health Organization (WHO) and Sri Lanka Standards Institution (SLSI) (nitrate level &lt;50 mg/L). Under oxic conditions, the nZVI was synthesized and batch experiments were conducted using an artificial nitrate (150 mg/L) contaminated water sample. Our results corroborated that with an optimum nZVI dose of 1 g/L and optimum contact time of 30 minutes, 80% nitrate removal could be achieved and the remaining nitrate level was ≈ 30 mg/L as nitrate (&lt;50 mg/L), which was equivalent to ≈ 7 mg/L as nitrate–N (≈21% of the total–N). Ammonium ions were the main product of nitrate reduction by nZVI and at 30 minutes contact time, ≈ 20 mg/L of ammonium as ammonium–N was detected (≈ 59% of the total–N). Ammonia stripping took place under the basic solution pH (pH &gt; 9.5). At 30 minutes of contact time, ≈7 mg/L of ammonia as ammonia–N was accounted for ammonia stripping, which is 20% of the total–N. Ammonia stripping resulted in a decrease in nitrogen-containing species in the aqueous phase. The spent nZVI particles were recovered (99.9%) from the treated water using an external magnetic field. In conclusion, nZVI particles synthesized under oxic conditions are viable to successfully treat the nitrate-contaminated groundwater under aerobic conditions to reduce the nitrate levels to meet the WHO/SLSI drinking water quality standards.

Nitrate in Groundwater and Health Risk Assessment: A Cross-Sectional Study in Three Villages in Tanah Merah District, Kelantan, Malaysia During Paddy Pre-Planting Season

ABSTRACT Introduction: Contamination of nitrate is one of the most common groundwater problems worldwide. Around 70% of residents in the state of Kelantan still rely on groundwater as their primary source of water supply. Extensive usage of fertilizer in agricultural areas may cause nitrate leaching into the groundwater. This study aimed to determine the level of nitrate in groundwater and health risk assessment at three villages in Tanah Merah District, Kelantan, Malaysia. Subjects and Method: This was a cross-sectional study conducted at Tanah Merah district, Kelantan, in January 2020. A total of 52 residents was selected by purposive sampling. The inclusion criteria for study subjects were long life residents, age ≥18 years old, and groundwater as a primary source of drinking supply. The study variables were (1) Level of nitrate in groundwater measured according to age (year), depth (meter), and distance (meter) of well from the agricultural area; and (2) Health risk assessment measured by hazard quotient (HQ). A set of questionnaires consisted of four sections to gather information related to socio-demographic, water usage, living environment, and health status. Groundwater samples were collected in duplicates and were analysed using a Hanna Instruments portable pH/ORP/ISE meter with an attached nitrate electrode. The data were reported descriptively. Results: Nitrate levels were found to be under the maximum acceptable value of 10 mg/L, as stated by the Drinking Water Quality Standard of Malaysia. Nitrate level ranged from 0.22 to 8.81 mg/L (Mean= 2.94; SD= 2.27). Spearman rho correlation showed that nitrate level was significantly and negatively correlated the age of wells (r= -0.31; p= 0.025). Nitrate level was not significantly correlated with the depth (r= 0.19; p= 0.183) and distance of wells (r= -0.05; p= 0.751). Hazard quotient (HQ) for all study subjects was <1, which means that exposure to nitrate contained drinking water in study subjects was not detrimental to health. Conclusion: Nitrate levels were below the maximum acceptable value, but continuous monitoring from health authorities is essential since other seasons of paddy planting may contribute higher deposition of nitrate into groundwater. Keywords: nitrate, groundwater, levels, hazard quotient, Tanah Merah Correspondence: Muhammad Syafiq N. Department of Environmental and Occupational Health, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia. UPM Serdang, Selangor, Malaysia. Email: [email protected]. Mobile: +601140731881. DOI: https://doi.org/10.26911/the7thicph.01.27