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Carbon Nanotubes in the Agricultural Sector
Published in Soney C. George, Jacob Philip, Ann Rose Abraham, A. K. Haghi, Carbon Nanotubes for Energy and Environmental Applications, 2023
CNTs were also found to be effective against both plant bacterial88 and fungal pathogens.89,90 For example, the fungal pathogen Fusarium graminearum is known worldwide to affect wheat, corn, and other crops causing the plant disease Fusarium head blight (FHB). Currently, very few effective methods exist for the control of the same and so the disease is of great concern in the agricultural sector. However, it was demonstrated that both pristine and functionalized MWCNTs have an effective and durable inhibitory effect against the pathogen. The MWCNTs functionalized with –COOH, -NH2, and –OH were found to show enhanced inhibition of spore germination during the growth cycle preventing the formation of mature fungal mycelium, thus interrupting the pathogen reproduction and terminating infection cycle.89 Bacterial wilt is another plant disease caused by the bacterial pathogen Ralstonia solanacearum and is found to affect a large number of crops during the growing season and also during the post-harvest storage period. Though numerous chemical measures against the pathogen exist, with use, most of the pathogens have developed defense mechanisms against such antimicrobial agents and have built resistant strains. The current integrated management strategies, such as pathogen-free transplants, and crop rotation using nonhost cover crops have failed to control R. solanacearum. SWCNTs dispersion was found to destroy the cellular membrane of R. solanacearum and release the cytoplasm content, thereby showing strong antibacterial activity. Since they exhibit multipoint antibacterial mechanisms, it is less susceptible for the bacteria to develop resistance to CNT-based antimicrobial agents.88 Despite the exceptional antimicrobial properties of CNTs, very few studies have documented the antibacterial and antifungal properties of CNTs against different plant pathogens, which have turned resistant to conventional management practices. Thus, future studies may focus on other agricultural pathogenic microbes to extend the spectrum of CNTs’ antimicrobial activities thereby helping eliminate severe agricultural problems caused by them.
Effect of Different Concentrations of Ozone on in Vitro Plant Pathogens Development, Tomato Yield and Quality, Photosynthetic Activity and Enzymatic Activities
Published in Ozone: Science & Engineering, 2019
Zhenghong Guo, Zuoming Wang, Yingdong Li, Quanxi Wang
Tomato is a widely economically consumed crop worldwide due to its abundant nutrition, regarded as the “relative contribution to human nutrition”. However, warm and humid environments are ideal to cause tomato plants to become susceptible to pathogen infection and insect occurrence. Insect nets act only against pest invasions and cannot prevent pathogen infection. The quality and yield of tomato are easily affected by infection by pathogenic fungi and bacteria, especially during the growing season. Ralstonia solanacearum (R. solanacearum) has a wide host range and is a gram-negative plant pathogenic bacterium that causes a lethal wilt disease in more than 450 species of plants (Genin 2010). Currently, this pathogenic bacterium is considered an attractive model to investigate plant-pathogenic bacterial interactions (Coll and Valls 2013; Ferreira et al. 2017). R. solanacearum attaches to the xylem of the host plant and results in plant wilting and death. It was ranked the second most devastating bacterial phytopathogen in the world (Mansfield et al. 2012). In addition, humid, warm and closed greenhouse conditions are ideal for fungal growth. A. solani is listed as a ubiquitous fungal species and causes early tomato blight, resulting in agricultural yield losses of 35 to 78% in many tomato production areas worldwide (Datar and Mayee 1981; Jones et al. 1991; Rotem 1994). The fungi infect tomato leaves, causing two forms of plant damage: inhibition in the growth ring and a reduction in harvest because of fruit brown stain. Although scientific farming management and biological control methods have been utilized, some specific cultivars and the narrow usage range have restrained their application. In addition, alternaric acid, a metabolite produced by Alternaria solani (A. solani) fungi, is a contaminant in Solanaceous vegetables. During the cultivation of tomato, the fungicide chlorothalonil is used to control early blight (A. solani). However, chlorothalonil can cause severe eye, skin and gastrointestinal problems in humans (Draper et al. 2003). The ability to utilize a pesticide substitute that contributes to the reduction of plant diseases and pests while being less harmful to humans and the environment is highly needed.