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Dynamics, Fate, and Toxicity of Pesticides in Soil and Groundwater and Remediation Strategies in Mainland China
Published in P.M. Huang, I.K. Iskandar, M. Chino, T.B. Goh, P.H. Hsu, D.W. Oscarson, L.M. Shuman, Soils and Groundwater Pollution and Remediation, 2020
In the entire crop rotation system, the leguminous plants play an important role in enhancing the soil fertility, the main contribution of which is the nitrogen fixation effect of root nodule bacteria. Researchers in Northeastern China Agricultural College (1989) studied the effect on the formation of soybean root nodules and the activity of nitrogenase when using trifluralin and metribuzim as weed killers. Potted planting experimental results showed that for the use rate of 48% trifluralin at 1.0 kg/ha and 1.5 kg/ha, the root nodules of soybean have been reduced 41.5% and 85.4%, respectively. Compared with that in the CK, the activity of nitrogenase in root nodules have been reduced 18.2% and 56.9%, respectively. The experimental results of applying 0.5 kg/ha, 1.0 kg/ha, and 1.5 kg/ha of metribuzim showed that the root nodules of soybean have been reduced 56.0%, 72.3%, and 85.7%, respectively, while the nitrogenase activity of root nodules have been reduced 14.4%, 32.2%, and 56.2%, respectively Trifluralin and metribuzim are the main herbicides used In soybean fields now In China; the above two group experiments indicated that their use in serious weed problem regions has obvious effects on increasing soybean production. Nevertheless, the harmful effects mentioned above cannot be neglected. Therefore, selecting a pesticide with good weeding effects and at the same time not affecting the growth of root nodules will achieve better ecological and economic benefits.
Ecological Principles for Vegetation Establishment and Maintenance
Published in R.P.C. Morgan, R.J. Rickson, Slope Stabilization and Erosion Control, 2003
Some species, notably those of the legume family, have root nodules containing bacteria which can fix nitrogen from the air, so that it is available within the ecosystem. The relationship between the plant and the bacteria is a ‘symbiotic’ one, and usually dependent on specific environmental conditions. However, legumes form a very useful group of plants for use on infertile soils, and can be a vital component in the long-term build-up of soil nitrogen and organic matter. Care needs to be taken with their establishment, in particular the need to inoculate the legume seeds with the correct strain of bacteria for effective nitrogen fixation. On infertile soils the legumes may not become inoculated naturally.
Insights in nodule-inhabiting plant growth promoting bacteria and their ability to stimulate Vicia faba growth
Published in Egyptian Journal of Basic and Applied Sciences, 2022
Amr M. Mowafy, Mona S. Agha, Samia A. Haroun, Mohamed A. Abbas, Mohamed Elbalkini
Symbiotic nitrogen fixation, which is positioned as a major part of biological nitrogen fixation, is an important alternative source of chemical nitrogen fertilizers not only for leguminous but also for non-leguminous plants. The interaction between legumes and rhizobia leads to root nodule organogenesis, an organ that is produced in response to bacterial nod factors and plant developmental signals leading to the formation of a plant stem cell niche [1]. Recently, rhizobia have been shown to improve the nutrition of non-leguminous crops, such as barley, wheat and canola [2]. It has been established that the legume nodule is exclusively inhabited by the rhizobium. Meanwhile, in 2001, this concept has changed dramatically when non-rhizobial strains were regarded for their ability to nodulate legumes, such as Methylobacterium and Burkholderia that have been isolated from Crotalaria [3] and Mimosa [4], respectively. In addition to nodule-inducing bacteria, several bacterial strains have been isolated from nodules as co-inhabitants with rhizobium, such as Klebsiella, Pseudomonas [5], Bacillus [6] and Streptomyces [7]. Interestingly, a review titled ‘the nodule microbiome: N2-fixing rhizobia do not live alone’ has been published in 2017 to conclude that some of these non-rhizobial bacteria might be nitrogen fixer or participate in nodule genesis and the others, more striking, might neither participate in nodulation nor fix nitrogen [8].
Study of formation of valuable organic products from bioremediation of chlorpyrifos by bacteria catalyzed by molybdenum and zinc salt
Published in Bioremediation Journal, 2019
Sangita Saha, Achintya Mondal, Tanusri Mandal
Zinc and molybdenum are two most essential micronutrients for plant-growth. Both these micronutrients play major role in many complex metabolic reactions and photosynthesis (El-Quesni et al. 2014). They help non-leguminous plants to collect nitrate from soil and also help leguminous plants to fix atmospheric nitrogen with the means of root-nodules (Farooq, Wahid, and Siddique 2012). Zinc is required for several biochemical processes, such as enzyme activities, DNA transcription, nucleotide and cytochrome synthesis, auxin metabolism, and chlorophyll and carbohydrate formation (Khalid, Fiaz, and Sarwar 2013; Singh et al. 2012). Again, phosphorous is one of the macronutrients for plant-growth but it is scarcely available in soil. Hence, synthetic phosphate-fertilizers are being used for meeting the high demand for crop production. However, the synthetic-fertilizers are not beneficial for lithospheric habitats (Sharma, Rakhra, and Singh 2012). Hence, it is necessary to minimize the use of chemical-fertilizers, pesticides, and insecticides.