The increasing demand for agricultural products can be met by maximizing production potential and reducing crop losses caused by common plant-parasitic nematodes. Chemical-based nematode management is a successful technique for mitigating damage and yield losses caused by nematode pests; however, inappropriate and irresponsible application of synthetic pesticides has negative impacts on fauna, bioflora, and natural enemies such as predators and parasites. The use of biocontrol agents is the most appreciated method for nematode control among farmers because it’s safe and reduces environmental pollution. There is increasing focus on the biological control of plant-parasitic nematodes using plant growth-promoting rhizobacteria (PGPR) as a biopesticide. Moreover, PGPR strains can promote plant growth by producing various secondary metabolites of these PGPRs. This review focuses on the direct (Nitrogen fixation, phytohormone formation, phosphate solubilization, Potassium solubilization, siderophores and ammonia production) and indirect mechanisms (Hyperparasitism, antibiosis, lytic enzyme production, induced systemic resistance) of action of PGPR in plant-parasitic nematodes management, and the future prospects of PGPR-based plant-parasitic nematodes biocontrol agents.
Plastic particles have the ability to transfer harmful chemical pollutants due to their high adsorption capacity. Therefore, this study aimed to investigate the effects of combined exposure to polyethylene microplastics (PE-MPs) and 4-nonylphenol (4-NP) on juvenile common carp (Cyprinus carpio) using histopathological and histochemical biomarkers. Fish were separated into a control group and three treatment groups (10 mg/L PE-MPs; 10 mg/L PE-MPs + 200 µg/L 4-NP; 200 µg/L 4-NP) for a two-week continuous exposure experiment followed by two weeks of recovery. The three treatment groups showed histopathological changes compared to the control. These alterations included severe edema, lifting of the outer epithelium, interlamellar fusion and vacuolation, secondary lamellar shortening and complete fusion, increased mucous cell numbers in the gill tissue, enlargement of inner layer stratum periventricular, cell degeneration with pyknotic nuclei, increased blood capillaries, spongiosis in the brain tissue (optic tectum), central vein hemorrhage, shrunken and fatty degeneration of hepatocytes, rosette shapes around small congested blood sinusoids, vacuoles, necrosis, and severe glycogen reduction in the liver tissue. Some tissue changes improved during the two-week recovery period but did not return to normal. In conclusion, the mixture exposure of the PE-MPs and 4-NP on fish carp induced some histological alterations in most studied tissues and post-exposure made improvement in cellular and tissue structure.
This study aims to answer the following questions: 1-what are the crop diversity and distribution in Nile Delta and its outskirts?, 2-what are their annual cyclic distribution? and 3-what are the economic goods and environmental services which they offer?. One hundred field trips were conducted to many districts in Nile Delta including Greater Cairo and Alexandria during summer 2012 to spring 2014. One hundred and seventy three crop species belonging to 99 genera and 44 families were recorded. Poaceae was the most represented family, where Cucumis was the most represented genus. Herbaceous plants were the most represented, followed by trees and shrubs. The period from March to May was characterized by the highest flowering activity. Most of the species were propagated by seeds (86.9%), followed by cutting (13.2%). Twenty two groups of crops were resulted after the application of TWINSPAN and DCA: 6 groups occurred in only one district, 3 in 2 districts, and another 3 in > 10 districts. Group 10 that included 13 districts had the highest species richness (67.9 species region -1 ), while G 11 that included 20 districts had the highest species turnover (3.7). Of the 173 crop species recognized in Nile Delta, 82.1 % had at least one potential or actual economic good. Food plants were the most common crops, while grazing plants were the least. In addition, 64.2 % of the crop species had at least one environmental service; cold-tolerant plants were the most represented, while the sand accumulators were the least. This study is the first attempt to evaluate the agro-diversity in Nile Delta and introduces for the scientific community a baseline data for evaluating the agro-biodiversity in Egypt as a whole.
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