Assessment of heavy metal contamination in leafy vegetables: implications for public health and regulatory measures.

Heavy metal contamination in leafy vegetables poses significant health risks, highlighting the urgent need for stringent monitoring and intervention measures to ensure food safety and mitigate potential adverse effects on public health. This study investigates the levels of heavy metals, including cadmium (Cd), chromium (Cr), nickel (Ni), lead (Pb), zinc (Zn), and copper (Cu), in locally grown and commercially available leafy vegetables, comparing them to the safety limits established by WHO/FAO. The results revealed that levels of Cd, Cr, Ni, and Pb in the vegetables exceeded WHO/FAO limits, while Zn and Cu remained within permissible bounds. Marketed vegetables exhibited higher metal concentrations than those from nearby farms. For Cu (0.114-0.289 mg/kg) and Zn (0.005-0.574 mg/kg), the daily intake of metals (DIM) was below the dietary intake (DI) and upper limit (UL). Cd's DIM (0.031-0.062 mg/kg) remained below the UL but exceeded the DI. Marketed kale and mint surpassed both DI and UL limits for Ni, while local produce only exceeded the DI. All vegetables had DIM below the DI, except for mint and kale. For Pb, every vegetable exceeded DI limits, with market samples contributing significantly. Cr's DIM ranged from 0.028 to 1.335 mg/kg, for which no set maximum daily intake exists. The health risk index (HRI) values for Zn, Cd, Cu, Ni, and Pb suggested potential health risks associated with leafy greens, while Cr's HRI was below 1. The study underscores the need for stringent monitoring and intervention measures to mitigate the health risks posed by heavy metal contamination in leafy vegetables. These findings suggest that consuming these leafy greens may put consumers at considerable risk for health problems related to Cd, Cu, Ni, Pb, and Zn exposure.

Conservation tillage: a way to improve yield and soil properties and decrease global warming potential in spring wheat agroecosystems.

Climate change is one of the main challenges, and it poses a tough challenge to the agriculture industry globally. Additionally, greenhouse gas (GHG) emissions are the main contributor to climate change; however, croplands are a prominent source of GHG emissions. Yet this complex challenge can be mitigated through climate-smart agricultural practices. Conservation tillage is commonly known to preserve soil and mitigate environmental change by reducing GHG emissions. Nonetheless, there is still a paucity of information on the influences of conservation tillage on wheat yield, soil properties, and GHG flux, particularly in the semi-arid Dingxi belt. Hence, in order to fill this gap, different tillage systems, namely conventional tillage (CT) control, straw incorporation with conventional tillage (CTS), no-tillage (NT), and stubble return with no-tillage (NTS), were laid at Dingxi, Gansu province of China, under a randomized complete block design with three replications to examine their impacts on yield, soil properties, and GHG fluxes. Results depicted that different conservative tillage systems (CTS, NTS, and NT) significantly (p < 0.05) increased the plant height, number of spikes per plant, seed number per meter square, root yield, aboveground biomass yield, thousand-grain weight, grain yield, and dry matter yield compared with CT. Moreover, these conservation tillage systems notably improved the soil properties (soil gravimetric water content, water-filled pore space, water storage, porosity, aggregates, saturated hydraulic conductivity, organic carbon, light fraction organic carbon, carbon storage, microbial biomass carbon, total nitrogen, available nitrogen storage, microbial biomass nitrogen, total phosphorous, available phosphorous, total potassium, available potassium, microbial counts, urease, alkaline phosphatase, invertase, cellulase, and catalase) while decreasing the soil temperature and bulk density over CT. However, CTS, NTS, and NT had non-significant effects on ECe, pH, and stoichiometric properties (C:N ratio, C:P ratio, and N:P ratio). Additionally, conservation-based tillage regimes NTS, NT, and CTS significantly (p < 0.05) reduced the emission and net global warming potential of greenhouse gases (carbon dioxide, methane, and nitrous oxide) by 23.44, 19.57, and 16.54%, respectively, and decreased the greenhouse gas intensity by 23.20, 29.96, and 18.72%, respectively, over CT. We conclude that NTS is the best approach to increasing yield, soil and water conservation, resilience, and mitigation of agroecosystem capacity.

Effects of conservation tillage strategies on soil physicochemical indicators and N2O emission under spring wheat monocropping system conditions.

As one of the important greenhouse gas, nitrous oxide (N2O) has attracted much attention globally under climate change context. Agricultural practices are the main sources of greenhouse gas emissions. Nevertheless, scarcity of literature is available on the effects of different tillage measures on soil N2O emission under spring wheat (Triticum aestivum L.) ecosystem in the semi-arid area of the Loess Plateau. The main objective of the experimental study was to explore the influence of conservation tillage techniques on soil physicochemical properties, nitrous oxide emission and yield in the Northern semi-arid Dingxi region of China. Four treatments viz., conventional tillage (CT), no tillage (NT), straw mulch with conventional tillage (TS) and stubble-return with no-till (NTS) were evaluated under randomized complete block design with three replications. Our results depicted that compared with conventional tillage, bulk density and water content of topsoil was increased and soil pH value was reduced under conservation tillage techniques. Conservation tillage NT, TS and NTS increased organic carbon, TN, MBN and NH4+-N and reduced the accumulation of NO3-N. Additionally, although the N2O emission under NT, TS and NTS was 8.95, 41.90 and 21.05% respectively higher than under T treatment, the corresponding wheat yield was 15.40, 31.97 and 63.21% higher than T treatment. Moreover, correlation analysis showed that soil moisture and temperature were the most significant factors affecting soil N2O emission. The NTS treatment pointedly increased crop yield without significantly increasing soil N2O emission. Consequently, based on economic and environmental benefits and considering N2O emission and crop yield, we suggest that NTS technique is the best conservation tillage strategy in the semi-arid environmental zone of the Loess Plateau of Dingxi China.

Isolation and characterization of plant growth-promoting rhizobacteria from wheat rhizosphere and their effect on plant growth promotion.

The present study was conducted to characterize the native plant growth promoting (PGP) bacteria from wheat rhizosphere and root-endosphere in the Himalayan region of Rawalakot, Azad Jammu and Kashmir (AJK), Pakistan. Nine bacterial isolates were purified, screened in vitro for PGP characteristics and evaluated for their beneficial effects on the early growth of wheat (Triticum aestivum L.). Among nine bacterial isolates, seven were able to produce indole-3- acetic acid in tryptophan-supplemented medium; seven were nitrogen fixer, and four were able to solubilize inorganic phosphate in vitro. Four different morphotypes were genotypically identified based on IGS-RFLP fingerprinting and representative of each morphotype was identified by 16S rRNA gene sequencing analysis except Gram-positive putative Bacillus sp. Based on 16S rRNA gene sequence analysis, bacterial isolates AJK-3 and AJK-9 showing multiple PGP-traits were identified as Stenotrophomonas spp. while AJK-7 showed equal homologies to Acetobacter pasteurianus and Stenotrophomonas specie. Plant inoculation studies indicated that these Plant growth-promoting rhizobacteria (PGPR) strains provided a significant increase in shoot and root length, and shoot and root biomass. A significant increase in shoot N contents (up to 76%) and root N contents (up to 32%) was observed over the un-inoculated control. The study indicates the potential of these PGPR for inoculums production or biofertilizers for enhancing growth and nutrient content of wheat and other crops under field conditions. The study is the first report of wheat associated bacterial diversity in the Himalayan region of Rawalakot, AJK.

Isolation and identification of indigenous plant growth promoting rhizobacteria from Himalayan region of Kashmir and their effect on improving growth and nutrient contents of maize (Zea mays L.).

Introduction and exploitation of plant growth promoting rhizobacteria (PGPR) in agro-ecosystems enhance plant-microbes interactions that may affect ecosystems sustainability, agricultural productivity, and environmental quality. The present study was conducted to isolate and identify PGPRs associated with maize (Zea mays L.) from twenty sites of Himalayan region of Hajira-Rawalakot, Azad Jammu and Kashmir (AJK), Pakistan. A total of 100 isolates were isolated from these sites, out of which eight (HJR1, HJR2, HJR3, HJR4, HJR5, MR6, HJR7, HJR8) were selected in vitro for their plant growth promoting ability (PGPA) including phosphorus solubilization, indole-3-acetic acid (IAA) production and N2 fixation. The 16S rRNA gene sequencing technique was used for molecular identity and authentication. Isolates were then further tested for their effects on growth and nutrient contents of maize (Z. mays L.) under pouch and pot conditions. The 16S rRNA gene sequencing and phylogenetic analysis identified these isolates belong to Pseudomonas and Bacillus genera. The isolates promoted plant growth by solubilizing soil P which ranged between 19.2 and 35.6 µg mL(-1). The isolates HJR1, HJR2, HJR3, and HJR5 showed positive activity in acetylene reduction assay showing their N2-fixation potential. All eight isolates showed the potential to produce IAA in the range of 0.9-5.39 µg mL(-1) and promote plant growth. Results from a subsequent pot experiment indicated PGPRs distinctly increased maize shoot and root length, shoot and root dry weight, root surface area, leaf surface area, shoot and root N and P contents. Among the eight isolates, HR3 showed a marked P-solubilizing activity, plant growth-promoting attributes, and the potential to be developed as a biofertilizers for integrated nutrient management strategies.