Search

This study was conducted to ascertain the negative effects of dietary low-density polyethylene microplastics (LDPE-MPs) exposure on growth, nutrient digestibility, body composition and gut histology of Nile tilapia (Oreochromis niloticus). Six sunflower meal-based diets (protein 30.95%; fat 8.04%) were prepared; one was the control (0%) and five were incorporated with LDPE-MPs at levels of 2, 4, 6, 8 and 10% in sunflower meal-based diets. A total of eighteen experimental tanks, each with 15 fingerlings, were used in triplicates. Fish were fed at the rate of 5% biomass twice a day for 60 days. Results revealed that best values of growth, nutrient digestibility, body composition and gut histology were observed by control diet, while 10% exposure to LDPE-MPs significantly (P < 0.05) reduced weight gain (WG%, 85.04%), specific growth rate (SGR%, 0.68%), and increased FCR (3.92%). The findings showed that higher level of LDPE-MPs (10%) exposure in the diet of O. niloticus negatively affects nutrient digestibility. Furthermore, the results revealed that the higher concentration of LDPE-MPs (10%) had a detrimental impact on crude protein (11.92%) and crude fat (8.04%). A high number of histological lesions were seen in gut of fingerlings exposed to LDPE-MPs. Hence, LDPE-MPs potentially harm the aquatic health. [ABSTRACT FROM AUTHOR]

To the Editor, Since March 2023, Canada has been grappling with an unprecedented succession of wildfires, which have notably intensified in June. Symptoms of carbon monoxide poisoning can range from mild to severe and may resemble flu-like symptoms without a fever. The repercussions of these wildfires extend far beyond the fire zones, impacting different areas hundreds of miles away, particularly cities like Toronto (Canada) and New York (United States). [Extracted from the article]

Key message: Varying stand density was the principal factor altering bacterial diversity compared to soil properties. Soil bacteria with a higher alpha diversity were present in low stand density. Absract: Different land-use patterns and silvicultural practices contribute to the shifting composition and assemblage of soil bacterial communities. Positive plant and soil responses to nutrient acquisition, promotion of sustainable growth, resistance to biotic and abiotic stress, and disease suppression depend on favorable interactions between plant roots and microbes. This study investigated the community assemblage of soil bacteria and its interaction with soil quality indicators and canopy growth parameters (e.g., mean tilt angle of the leaf (MTA), leaf area index (LAI), and canopy openness index (DIFN)) in low, intermediate and high density stands of Chinese fir plantation at two soil depths (0–20 and 20–40 cm). The results showed that the soils of the low-density stand had higher α-bacterial diversity than the soils of medium and high-density forests. Among all variables, Acidobacteria was the most dominant phylum with 24.72%, followed by Actinobacteria, Proteobacteria and Chloroflexi with 20.41%, 15.89%, 11.67%, respectively. Among different canopy parameters, low-density associated bacterial diversity was positively correlated with the canopy openness index. Among soil properties, potassium, nitrogen, and phosphorus were considerably influential factors to bacterial communities. Redundancy analysis (RDA) results showed that soil physiochemical properties accounted for 31.86% of the total migration of the soil bacterial communities. Although soil attributes were the significant contributing factors affecting bacterial communities, varying stand density was the main factor altering bacterial diversity. By revealing changes in soil bacterial relative abundance and richness patterns at different levels of stand density, this study would provide comprehensive proof of the complexity of belowground ecology. It will also serve as a foundation for developing sustainable management strategies in silty oxisol soil types and plantation crops. [ABSTRACT FROM AUTHOR]

Purpose: Our knowledge of biochar as a tool for soil carbon (C) sequestration and soil quality in semi-arid regions remains limited in recent years. Moreover, there is a lack of understanding on the comparison between effects of biochar rates on soil organic C (SOC) and nitrogen (N) mineralization in organic C poor soils. Materials and methods: Interactive effects of corncob-biochar (B), prepared at 450 °C pyrolysis temperature, and wheat straw (W) on soil native and fresh organic matter were investigated in sandy loam alkaline calcareous soil. The corncob-biochar was applied alone and in combination with wheat straw (WB) at rates equivalent to 0 t ha-1 (unamended control), 22.5 t ha-1 (B1, W1, W1B1), and 45 t ha-1 (B2, W2, W2B2). After treatment applications, soils were incubated under laboratory conditions for 61 days and periodic CO2 evolution rates were measured to calculate the cumulative CO2 efflux and priming effects. Results and discussion: The lowest CO2 efflux was found in B2 treatment, whereas CO2 efflux was lower in W1B1 than in W1 treatment. Biochar alone and with wheat straw significantly reduced net C mineralization (NCM) compared to wheat straw only treatments and the effects became stronger as biochar rate increased. This was reflected in data on the priming effect, which also showed that increased biochar rates induced a stronger negative priming (− 87 to − 67%) on SOC. Biochar with wheat straw at both rates enhanced microbial biomass C (MBC) compared to the control, W1, B1, and B2 treatments. However, the W1B1 and W2B2 treatments decreased water-extractable organic C (WEOC) contents compared to W1 and W2. Microbial metabolic quotient (qCO2) and MBC/TOC ratio increased with biochar rate, suggesting more efficient utilization of labile C by microorganisms at higher biochar rate. Biochar alone and with wheat straw reduced soil mineral nitrogen (N) contents than the control treatment and resulted in net negative N mineralization or net N immobilization. Conclusions: Our findings indicate that biochar can reduce decomposition of soil organic matter to facilitate C and N sequestration in low organic C soils. However, our study also suggests the co-application of biochar and organic amendments/residues as labile C source to induce co-metabolism to improve microbial functions and C utilization efficiency in soils that are deficient in organic C. [ABSTRACT FROM AUTHOR]

Global warming has been increasing manifold in recent times, and this may cause tremendous economic losses in the near future. Recently, heat stress is considered one of the major constraints affecting crop growth and yield at world level. Heat stress reduced the plant growth, photosynthesis, mineral nutrients, and yield attributes. Heat stress caused both ultrastructural alterations and oxidative stress in different parts of plants. Plants can tolerate certain levels of heat stress by maintaining membrane stability, adjusting antioxidants and compatible solutes, and scavenging reactive oxygen species. Heat tolerance in plants can be improved by selecting heat-tolerant cultivars, genetic engineering, and exogenous application of osmolytes, microbes, mineral nutrients, soil amendments, and proper agricultural practices. This review is devoted to discuss the plants' physiological and biochemical responses to heat stress and various integrated approaches to improve heat stress tolerance in plants. [ABSTRACT FROM AUTHOR]

Plants face different types of biotic and abiotic stresses during their life span. Heavy metal (HM) stress is considered as one of the most challenging and emerging threats to sustainable agricultural development and overall economic yield of various plant species. Increasing levels of HMs in arable soils is a main environmental issue due to their deleterious effects on plant growth and productivity. The exogenous application of different plant growth regulators is a well-known strategy to alleviate the adverse effects of HMs stress on plants. In the present review, the role of 5-aminolevulinic acid (ALA) in the alleviation of HM stress in different plants is elaborated. 5-Aminolevulinic acid is identified as a highly efficient ameliorating agent to sustainably neutralize the harmful effects of abiotic stresses in plants. In particular, the role of ALA has been increasingly recognized in improving plant HM stress-tolerance via ALA-mediated control of principal plant-metabolic processes. However, various underlying mechanisms that unravel ALA-induced plant HM stress-tolerance remain unexplored. The application of ALA on HM-stressed plants improves plant height, root length, chlorophyll pigments, antioxidant enzyme activities, nutrient uptake and soluble protein contents and minimizes ultra-structural damage, oxidative stress and HM uptake. Furthermore, it triggers modification of glutathione reductase, ascorbic acid and GSH contents in HM-stressed plants. The lower concentration of ALA proved to be more beneficial in stress amelioration. The cost-effectiveness and efficiency of ALA in improving growth and production of plants under varying growth conditions is still not clear. Nevertheless, over-accumulation of ALA through genetic manipulation can enhance stress-tolerance in plants which is the key area to be investigated. This review article elaborates the potential role of ALA in HM tolerance and highlights the future research dimensions in the related ambits. [ABSTRACT FROM AUTHOR]

Water shortage and soil qualitative degradation are significant environmental problems in arid and semi-arid regions of the world. The increasing demand for water in agriculture and industry has resulted in the emergence of wastewater use as an alternative in these areas. Textile wastewater is produced in surplus amounts which poses threat to the environment as well as associated flora and fauna. A 60-day incubation study was performed to assess the effects of untreated textile wastewater at 0, 25, 50, 75, and 100 % dilution levels on the physicochemical and some microbial and enzymatic properties of an aridisol soil. The addition of textile wastewater provoked a significant change in soil pH and electrical conductivity and soil dehydrogenase and urease activities compared to the distilled-water treated control soil. Moreover, compared to the control treatment, soil phosphomonoesterase activity was significantly increased from 25 to 75 % application rates, but decreased at 100 % textile wastewater application rate. Total and available soil N contents increased significantly in response to application of textile wastewater. Despite significant increases in the soil total P contents after the addition of textile wastewater, soil available P content decreased with increasing concentration of wastewater. Changes in soil nutrient contents and related enzymatic activities suggested a dynamic match between substrate availability and soil N and P contents. Aridisols have high fixation and low P availability, application of textile wastewater to such soils should be considered only after careful assessment. [ABSTRACT FROM AUTHOR]

Correction to: Trees https://doi.org/10.1007/s00468-022-02278-0 During the publication process, Table 2 was placed at the wrong position in the published version of the original article. This has now been corrected in the PDF and HTML version of the article. [Extracted from the article]