Zakir Hossen

Intensive vegetable production can increase the transfer of persistent toxic trace elements from agricultural soils into the food chain, particularly where agrochemical use, irrigation inputs, and local geochemical conditions are insufficiently characterized. This study was undertaken to assess toxic trace-metal contamination levels in soils and vegetables from two renowned vegetable-producing subdistricts—Shibganj and Kahaloo—in the Bogra district, Bangladesh. The study also estimated potential human health risks by evaluating the dietary intake of these elements. It measured Pb, Ni, Cd, and Cr content in six vegetables and their respective farm soils using an atomic absorption spectrophotometer (AAS). The average concentrations of Pb, Ni, Cd, and Cr in farm soils of Shibganj and Kahaloo subdistricts were 158.3 ± 8.83, 31.5 ± 5.25, 0.43 ± 0.08, and 14.1 ± 2.16 µg g⁻¹ and 164.1 ± 4.60, 35.7 ± 6.91, 0.53 ± 0.14, and 9.37 ± 2.87 µg g⁻¹, respectively. Soils collected from all locations in both subdistricts of Bogra fall under ‘moderate’ ecological risk. Regarding the pollution load index (PLI), 66.7% of Shibganj and 75.0% of Kahaloo sampling sites had a PLI > 1.0, confirming that ‘metal pollution exists.’ Based on the calculated bioconcentration factors (BCFs), Cr and Cd show a high tendency to migrate from soil to various vegetables in the study area, though the mean Cd BCF for brinjal in Shibganj exceeded 1.0 due to a single high observation. The results demonstrated that the edible parts of potatoes, onions, and chilies accumulate significant amounts of toxic trace elements. The calculated mean daily intake of Pb and Cr in all vegetables ranged from 0.33 to 1.21 mg person⁻¹ day⁻¹ and from 0.10 to 0.64 mg person⁻¹ day⁻¹, respectively, exceeding the upper tolerable intake limits. Similarly, dietary intake of potatoes showed both non-carcinogenic and carcinogenic risks, while brinjal showed only carcinogenic risks for adults. Redundancy analysis (RDA) indicates that the measured soil parameters are strong predictors of the response variables (trace element content in various vegetables). Overall, the results identified Pb-dominated soil contamination and human exposure to Pb and Cr associated with vegetables as the principal concerns. To address these issues, priority actions should be given to source apportionment and testing of various agricultural inputs. Additionally, before implementing site-specific remediation or issuing consumption advisories, these risks should be validated through metal speciation and bioaccessibility analyses.

Chitosan is an eco-friendly polysaccharide, enhancing growth and managing disease infections in fruits and vegetables. This study examines the effects of preharvest application of chitosan and calcium (Ca) on yield and postharvest chitosan coating on tomato storage. There were nine preharvest treatments, viz., T0 = control, T1 = 50 ppm chitosan, T2 = 80 ppm chitosan, T3 = 0.50% Ca, T4 = 1.0% Ca, T5 = T1 and T3 (combined), T6 = T2 and T3 (combined), T7 = T1 and T4 (combined), and T8 = T2 and T4 (combined), and three postharvest treatments, viz., C0 = control, C1 = 0.10% chitosan, and C2 = 0.20% chitosan, to examine the yield parameters and major physical and biochemical qualities of tomatoes on different days after postharvest storage (DAPS). The results revealed that chitosan and Ca treatments had a significant influence on yield while showing an insignificant impact on the biochemical qualities of fresh-harvested tomatoes. Postharvest application of chitosan coatings effectively reduced weight loss and shrinkage (34–37%) compared to the control. At 20 DAPS, only the 0.20% solution met the marketable threshold of ≥5.0, while the control failed in 100% of the samples. As storage duration increased, titratable acid and vitamin C decreased, while lycopene and sugar content rose in tomatoes. This research indicates that foliar spraying with 80 ppm chitosan during fruit initiation significantly boosts tomato yield, and a 0.20% chitosan coating on postharvest tomatoes enhances longevity and preserves biochemical quality.

In Bangladesh, sweetpotato is the fourth most important source of carbohydrates behind rice, wheat, and potatoes. Potassium is vital for sweetpotato growth, boosting tuber size, sweetness, disease resistance, and yield quality, with deficiencies leading to poor tuber formation and increased stress susceptibility. The present study evaluated the effect of varying dosages of potassium fertilizer (Muriate of Potash, MoP) on the growth, yield, and biochemical qualities of sweetpotato. As a genetic material, BAU sweetpotato-5 was chosen as it is recognized for its high yield, short duration, and nutritional advantages. There were three treatments—full dosage of MoP (321.6 kg ha⁻¹, T₀), half dosage of MoP (160.8 kg ha⁻¹, T₁) and no MoP (T₂). Four replications of a randomized complete block design (RCBD) were used in the experiment. According to analysis of variance, the morphological and biochemical parameters, such as the fresh weight plant⁻¹, number of tuber plant⁻¹, chlorophyll content, total phenolic content, vitamin C, carotenoid, anthocyanin, Zn, and Fe content varied significantly among treatments. The application of the full recommended dosage of MoP resulted in the highest values for several traits, including the fresh weight plant⁻¹, number of tuber plant⁻¹, chlorophyll content, carotenoid, anthocyanin, and Fe content. Conversely, total phenolic content and vitamin C were highest without MoP application. Principal component analysis (PCA) differentiated treatment T₀ from T₁ and T₂ due to higher positive coefficients of the number of leaves at 115 days after transplantation, vine length at 115 days after transplantation, number of branches, stem diameter, fresh weight plant⁻¹, tuber length, tuber diameter, tuber weight, number of tuber plant⁻¹, SPAD, carotenoid, anthocyanin, Fe, and negative coefficients of total phenolic content, vitamin C, and Zn. The findings suggest that potassium is integral to maximizing both yield and key nutritional components in sweetpotato cultivation.

A study was conducted to determine the concentration of toxic heavy metals in various agrochemicals available in Bangladesh and to assess the burden of these metals on agricultural soils. An atomic absorption spectrophotometer (AAS) was used to measure the content of 4 toxic metals (Cd, Pb, Cr, and Ni) in the aqueous extract of various agrochemicals. There were significant differences in the amounts of Cd, Pb, Cr, and Ni in different brands of insecticides (mean < 0.01, 3.16, 17.32, and 47.33 µgg⁻¹), fungicides (mean 12.42, 10.19, 9.63, and 243.34 µgg⁻¹), phosphatic fertilizers (mean 25.43, < 0.01, 206.33, and 210.69 µgg⁻¹), micronutrient fertilizers (mean 0.68, < 0.01, 43.43, and 65.79 µgg⁻¹), and plant hormones (mean < 0.01, < 0.01, 9.90, and 43.08 µgg⁻¹). The concentrations of Cd and Ni were on an average higher in phosphatic fertilizers, which exceeded the maximum acceptable limit of fertilizers in Bangladesh by 2.5 and 4.2 times, respectively. The study also revealed that the burden of toxic heavy metals from agrochemicals on farm soils was in the following order: phosphatic fertilizers > fungicides > micronutrient fertilizers > plant hormones > insecticides. Among the toxic heavy metals, Ni posed the highest burden on Bangladeshi farm soils due to a single application of different agrochemicals in a year. The average total burden of each metal in the soils of Bangladesh showed a decreasing trend in the order of Ni > Cr > Cd > Pb, resulting in a total metal burden of 22.88 g year⁻¹ ha⁻¹. Finally, the study recommended that certification about the content of metals be made mandatory for agrochemical manufacturing firms to ensure that their products entering in Bangladeshi markets are free from toxic metals.