Academic literature on the topic 'Tea rhizosphere'
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Journal articles on the topic "Tea rhizosphere"
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Wang, H. B., Q. X. Zhang, X. T. Chen, Y. H. Wang, L. W. Lin, J. H. Ye, Q. Zhang, X. L. Jia, and H. B. He. "Analysis of microbial diversity of tea tree (Camellia sinensis (L.) O. Ktze.) sick rhizospheric soil using soil metaproteomic technology." Allelopathy Journal 51, no. 2 (November 2020): 147–56. http://dx.doi.org/10.26651/allelo.j/2020-51-2-1296.
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Soil metaproteomics technology was used to analyse and undertand the changes in microbial diversity in rhizospheric soil of Tieguanyin tea trees (Camellia sinensis (L.) O. Ktze.) of different ages. The results showed We identified 2911 protein spots in the rhizosphere soil of tea tree. These were derived from 388 species of microorganisms [331 species of bacteria (85.31 %) and 57 species of fungi (14.69 %)]. According to the analysis of microbial species in tea tree rhizospheric soil with different ages, the number of microbial species in 0, 4, 9 and 30-years old rhizospheric soils were 346, 350, 345 and 354, respectively. Among them, 310 microbial species co-existed in the rhizospheric soil with different ages tea trees. The analysis of results of microbial species and function showed that, as the tea tree age increased, the pathogenic microorganisms in its rhizospheric soil increased, while the microorganisms, for decomposing harmful substances, probiotics and microorganisms related to carbon cycle and nitrogen cycle decreased. The microbial structure and functions of tea tree rhizospheric soil changed significantly with increase in tea tree age.
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Yang, Haoyu, Lingfei Ji, Lizhi Long, Kang Ni, Xiangde Yang, Lifeng Ma, Shiwei Guo, and Jianyun Ruan. "Effect of Short-Term Phosphorus Supply on Rhizosphere Microbial Community of Tea Plants." Agronomy 12, no. 10 (October 5, 2022): 2405. http://dx.doi.org/10.3390/agronomy12102405.
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Microbes play an important role in rhizosphere phosphorus (P) activation and root P absorption in low P-available soils. However, the responses of the rhizosphere microbial community to P input and its effects on P uptake by tea plants have not been widely reported. In this study, the high-throughput sequencing of the 16S rRNA gene and the ITS2 region was employed to examine the responses of tea rhizosphere microbiomes to different P input rates (low-P, P0: 0 mg·kg−1 P; moderate-P, P1: 87.3 mg·kg−1 P; high-P, P2: 436.5 mg·kg−1 P). The results showed that the P input treatments significantly reduced the soil C: N ratio and C: P ratio compared to the P0 treatment (p < 0.05). Moreover, the P2 treatment significantly increased the soil available P, plant biomass and P content of the tea plant compared to the P0 and P1 treatments (p < 0.05). Both bacterial and fungal communities revealed the highest values of alpha diversity indices in the P1 treatment and the lowest in the P2 treatment. The dominant phyla of the bacterial community were Proteobacteria, Actinobacteria and Acidobacteria, while in the fungal community they were Ascomycota and Mortierellomycota. In addition, P input enriched the relative abundance of Actinobacteria and Proteobacteria but decreased the relative abundance of Acidobacteria. The Mantel correlation analysis showed that the fungal community was influenced by P input, whereas bacterial community was affected by the soil TC and C: N ratio. Furthermore, the P input treatments enhanced the TCA cycle, amino and nucleotide glucose metabolism, starch and sucrose metabolism, and phosphotransferase system expression, which could promote C and N cycling. On the contrary, the P input treatments negatively affected the growth of arbuscular mycorrhizal fungi. The PLS-PM model revealed that the rhizosphere bacterial and fungal communities, respectively, negatively and positively affected the P content by affecting the biomass. Meanwhile, rhizosphere microbial function profiles affected the P content of tea plants directly and positively. In summary, moderate P input favors the rhizosphere microbial diversity and functions in the short-term pot experiment. Therefore, we suggest that moderate P input should be recommended in practical tea production, and a further field test is required.
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Rahman, A. S., J. Barukial, S.R. Sarmah, R.D. Baruah, and A. Bhattacharjee. "Metagenomics study of tea rhizosphere soil in elevated carbon dioxide and temperature." Ecology, Environment and Conservation 29, no. 04 (2023): 1824–30. http://dx.doi.org/10.53550/eec.2023.v29i04.062.
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One of the most pressing environmental issue of our time is climate change. Additionally, the atmospheric carbon dioxide concentrations and the global temperature are also increasing. North East India is widely known for tea. Tea cultivation is largely dependent on its distinct soil fertility and its associated microorganisms. However, little is known about how high elevated CO2 and temperature affect the rhizosphere of tea plants. This study was conducted in order to comprehend the general microbial diversity of the tea soil rhizosphere in response to rising temperatures and CO2 . The study was performed using two Open top chambers where four different tea cultivars were exposed to elevated CO2 and temperature, and only elevated temperature where microbial dynamics was studied using metagenomics of 16s rRNA analysis. The results indicated that in the treatments highest abundance was found in the phylum Proteobacteria, 32.11%, which was followed by Acidobacteria, 14.32% and Actinobacteria, 9.13%. Significant variations were observed in both treatments when compared to the control. The results of this study would thus help in understanding the culturable as well as unculturable bacteria associated with tea plant rhizosphere, which may be beneficial in planning future adaptation and mitigation strategies under climate change scenarios.
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Ye, Jianghua, Qi Zhang, Miao Jia, Yuhua Wang, Ying Zhang, Xiaoli Jia, Xinyu Zheng, and Haibin Wang. "The Effects of Rock Zones and Tea Tree Varieties on the Growth and Quality of Wuyi Rock Tea Based on the OPLS-DA Model and Machine Learning." Agriculture 14, no. 4 (April 3, 2024): 573. http://dx.doi.org/10.3390/agriculture14040573.
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Rock zones have an important influence on the yield and quality of Wuyi rock tea. In this study, OPLS-DA combined with machine learning was used to analyze the effects of different rock zones and tea tree varieties on the physicochemical properties of rhizosphere soil, the growth of the tea tree and the quality of the tea leaves using tea trees in different rock zones. The results showed that rock zones had significant effects on rhizosphere soil physicochemical indexes, soil enzyme activities, tea tree growth and tea quality indexes, while there was little difference between different tea tree varieties. The interaction analysis showed that the physicochemical indexes of rhizosphere soil in different rock zones significantly affected tea quality, while also affecting growth indexes. The main indexes affecting tea yield and caffeine content were soil pH, available nitrogen, total phosphorus, total nitrogen and available phosphorus, while the main indexes affecting tea quality were available potassium, organic matter, total potassium, protease, polyphenol oxidase and urease. Analyses of PCA, OPLS-DA models and KNN and ANN machine learning showed that different rock zones could be effectively distinguished from each other with 100% accuracy, while different tea varieties had little difference and could not be distinguished. TOPSIS analysis found that the physicochemical indexes most affected by rock zone were available nitrogen, available potassium and sucrose, and the quality indexes most affected by rock zone were tea polyphenols and theanine. The growth index most affected by rock zone was tea yield. It was evident that the key difference between tea trees in different rock zones was yield and quality, with high yields in continent zones, and good quality in semi-rock zones and rock zones. This study provides a crucial foundation for tea-plantation management, the artificial regulation of tea yield and the quality of different rock zones of Wuyi rock tea.
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Zoysa, A. K. N., P. Loganathan, and M. J. Hedley. "Effect of forms of nitrogen supply on mobilisation of phosphorus from a phosphate rock and acidification in the rhizosphere of tea." Soil Research 36, no. 3 (1998): 373. http://dx.doi.org/10.1071/s97079.
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Nitrogen (N) is the main fertiliser input to tea plantations because of the large removal of this element with regular harvests of young shoots in the field. The form of N supply is known to influence the uptake of other plant nutrients, notably phosphorus (P), through its effect on soil pH in the rhizosphere. A glasshouse study was conducted to test the effect of N form (NH +4, NO-3 , or both) on the transformation of soil P in the rhizosphere and its availability to tea (Camellia sinensis L.) plants fertilised with sparingly soluble Eppawala phosphate rock (EPR). Four-month-old tea (TRI 2025) plants were grown in rhizosphere study containers containing an Ultisol from Sri Lanka (pH 4 ·5 in water) amended with EPR and KCl at 200 g P or K/g soil, and mixed with (NH4)2SO4 (100% NH+4 -N), NH4NO3 (50% NH+4 -N and 50% NO-3 -N), and Ca(NO3)2 (100% NO-3 -N) at the rate of 200 g N/g soil, with a control (no N fertiliser), as treatments. Rhizosphere pH decreased compared with the bulk soil when N was supplied as NH+4 or NH+4 +NO-3 forms, and increased when N was supplied as NO-3. The cation{anion balance estimations in the plants showed that the plants had taken up more NO-3 than NH+4 even in (NH4)2SO4 treated soil, suggesting high nitrification rates, especially in the rhizosphere, in spite of using a nitrification inhibitor. More EPR dissolved in the rhizosphere compared with that in the bulk soil, regardless of the N form applied. The (NH4)2SO4 treatment had the highest dissolution rate of EPR in the rhizosphere, whereas Ca(NO3)2 treatment had the lowest, reflecting the degree of acidification in the rhizosphere. Resin-P and NaOH-Pi (inorganic P) concentrations were lower and NaOH-Po (organic P) concentration was higher in the rhizosphere than in the bulk soil. Plant and possible microbial uptake of P is the main reason for the decrease in resin-P and NaOH-Pi. The increase in NaOH-Po concentration in the rhizosphere is believed to be due to transformation of Pi to Po by the high microbial activity in the rhizosphere. The (NH4)2SO4 treatment caused the highest depletion of resin-P but lowest depletion of NaOH-Pi, probably due to the fixation of P by the soils at the low pH in the rhizosphere. The study revealed that the use of the NH+4 form of fertiliser can increase acidification in tea rhizosphere compared with bulk soil and this can enhance the effectiveness of PR fertiliser utilisation by tea plants.
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Wei, Sirou, Boheng Liu, Kang Ni, Lifeng Ma, Yuanzhi Shi, Yang Leng, Shenghong Zheng, Shuilian Gao, Xiangde Yang, and Jianyun Ruan. "Rhizosphere Microbial Community Shows a Greater Response Than Soil Properties to Tea (Camellia sinensis L.) Cultivars." Agronomy 13, no. 1 (January 11, 2023): 221. http://dx.doi.org/10.3390/agronomy13010221.
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Rhizosphere microbes play pivotal roles in regulating the soil ecosystem by influencing and directly participating in the nutrient cycle. Evidence shows that the rhizosphere microbes are highly dependent on plant genotype and cultivars; however, their characteristics in soils with different tea (Camellia sinensis L.) cultivars are poorly understood. Therefore, the present study investigated the rhizosphere soil properties, microbial community composition, and their potential functions under four tea cultivars Huangjinya (HJY), Tieguanyin (TGY), Zhongcha No.108 (ZC108), and Zijuan (ZJ). The study found a minor impact of cultivars on rhizosphere soil properties but a significant influence on microbial community structure. Except for available potassium (AK) (HJY > TGY > ZC108 > ZJ), tea cultivars had no significant impact on other soil properties. The tea cultivars resulted in substantial differences only in the diversity of soil bacteria of lower taxonomic levels (family to species), as well as significantly changed communities’ structure of bacteria and fungi (R2 = 0.184, p = 0.013 and R2 = 0.226, p = 0.001). Specifically, Proteobacteria, Actinobacteria, Chloroflexi, Acidobacteriota, and Firmicutes accounted for approximately 96% of the bacterial phyla in the tea soils, while Ascomycota, Mortierellomycota, Rozellomycota, Basidiomycota, and Monoblepharomycota (90% of the total) predominated the soil fungal community. Redundancy analysis (RDA) identified soil pH (14.53%) and ammonium-nitrogen (NH4+-N; 16.74%) as the key factors for the changes in bacterial and fungal communities, respectively. Finally, FAPROTAX analysis predicted significant differences in the carbon, nitrogen, and sulfur (C-N-S)-cycling among the soils with different tea cultivars, specifically, ZJ cultivar showed the highest C-cycling but the lowest N- and S-cycling, while FUNGuild analysis revealed that the pathotroph group was significantly lower in ZC108 than the other cultivars. These findings improve our understanding of the differences in microbial community characteristics among tea cultivars and provide a basis for precisely selecting and introducing excellent tea varieties in the agriculture practices.
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Zhang, Qi, Yuhua Wang, Yiling Chen, Ying Zhang, Meihui Chen, Jishuang Zou, Pengyao Miao, et al. "Effects of Pruning on Growth, Rhizosphere Soil Physicochemical Indexes and Bacterial Community Structure of Tea Tree and Their Interaction." Agriculture 13, no. 10 (October 10, 2023): 1972. http://dx.doi.org/10.3390/agriculture13101972.
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Pruning is an agronomic practice that contributes to tea tree yield during cultivation, but little is known about how pruning improves yield through shifting bacterial communities in rhizosphere soil. Therefore, Meizhan tea (Camellia sinensis) was used as the research object to analyze the effect of unpruning and pruning on the growth and rhizosphere soil physicochemical indexes of the tea tree, and sequencing technology was used to obtain the diversity of soil bacterial communities. The results showed that leaf area, hundred bud weight and yield of pruned tea trees increased by 1.32, 1.40, and 1.84 times, respectively, and pH and available N, available P, and available K contents increased by 1.10, 1.07, 1.30, and 1.07 times, respectively, compared with unpruned treatment, while total N, total P, and total K contents decreased by 1.20, 1.37, and 1.13 times, respectively. Analysis of the bacterial community structure showed that the key differential bacteria between pruned and unpruned tea trees were Candidatus Solibacter, Acidibacter, Rhizomicrobium, Bryobacter, Solanum torvum, Mizugakiibacter, Nitrospira, Sphingomonas, and Granulicella. Among them, the bacterial abundance of Candidatus Solibacter, Bryobacter, and Nitrospira showed an upward trend and the rest showed a downward trend after pruned treatment. Interaction network analysis showed that the correlation between the total key genera of microorganisms and organic matter, total N, total K, and total P content in rhizosphere soil did not reach a significant level, whereas the correlation with soil available N, available K, available P, pH, and tea tree growth indexes were all positively and significantly correlated. It can be seen that pruning changed the structure of the rhizosphere soil microbial community of tea trees, promoted soil nutrient transformation, increased the content of soil available nutrients, and promoted the growth of tea tree.
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Hu, Zhenmin, Lingfei Ji, Qing Wan, Huan Li, Ronglin Li, and Yiyang Yang. "Short-Term Effects of Bio-Organic Fertilizer on Soil Fertility and Bacterial Community Composition in Tea Plantation Soils." Agronomy 12, no. 9 (September 13, 2022): 2168. http://dx.doi.org/10.3390/agronomy12092168.
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Overuse of chemical fertilizers to maintain tea production has caused many adverse effects in tea plantations and largely hampers the sustainable development of the tea industry. Applying bio-organic fertilizer (BOF) to achieve the goal of sustainable agriculture has become popular because of its advantages, such as its pollution-free nature, considerable amount of beneficial microbes and soil-friendly organic materials. However, the effects of BOF application on tea plantation soil remain an open question. Herein, we carried out a 3-year pot experiment with four treatments, including control without fertilization (CK), 100% chemical fertilizer (CF), 50% chemical fertilizer +50% BOF (CFOF) and 100% BOF (OF), to explore the effects of BOF application on soil fertility and bacterial community in tea plantations. The results showed that BOF application could increase soil fertility in both bulk and rhizosphere soils and improve the biomass of tea leaves. In addition, the nutrient level change caused by BOF application significantly changed bacterial community diversity and composition and accounted for 74.91% of the community variation. CFOF and OF treatments significantly increased the bacterial Chao1 and Shannon indices compared to CF treatment (p < 0.05). Moreover, bacterial community composition was dominated by Betaproteobacteria (46.88%), Acidobacteria (11.29%), Alphaproteobacteria (9.69%) and Gammaproteobacteria (9.59%). BOF application increased the relative abundance of Alphaproteobacteria, Acidobacteria, Deltaproteobacteria and planctomycetes and decreased the relative abundance of Betaproteobacteria (p < 0.05). Furthermore, bacterial function prediction revealed that BOF application improved the N and C cycling processes and enhanced the co-occurrence network complexity in the bulk soils. Bacterial community functions and co-occurrence networks in the rhizosphere did not show similar results, indicating that rhizosphere bacterial communities were more affected by the rhizosphere effect than BOF application. All these findings verified our hypothesis that applying BOF in tea plantations could increase the biomass of tea plants by improving soil fertility and influencing the soil bacterial function groups. In summary, we suggested that BOF application could be a promising way to achieve the sustainable development of the tea industry.
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Zhang, Sihai, Xuemei Han, Yangchun Zhu, and Xiangfeng Tan. "Coordination of Root Traits and Rhizosphere Microbial Community in Tea (Camellia sinensis L.) Plants under Drought and Rehydration." Forests 14, no. 11 (October 26, 2023): 2134. http://dx.doi.org/10.3390/f14112134.
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Soil drought and rehydration have an immense impact on plant physiology and productivity, whereas the response of plant–microbe interactions to varied water availability remains largely elusive. In this study, two tea (Camellia sinensis L.) cultivars, Longjing43 and Yingshuang, were subjected to drought followed by rehydration. Soil drought significantly induced the elongation of taproots in the Yingshuang cultivar after two weeks of drought. Moreover, the four-week drought significantly reduced the root dry mass and root nitrogen, phosphorus, and potassium concentrations in both tea cultivars. Two-week rehydration recovered the root potassium concentration in the two tea cultivars, revealing the rapid response of root potassium levels to water conditions. Drought and rehydration also resulted in shifts in rhizosphere microbial diversity. A four-week drought reduced microbial alpha diversity in Longjing43 but not in the Yingshuang cultivar, and rehydration was effective in restoring alpha diversity in Longjing43. The rhizosphere microbial community tended to recover to the initial stages after rehydration in Longjing43 but not in the other cultivar. In addition, 18 microbial genera were identified as the featured microbial taxa in response to varied water availability, and a rare genus Ignavibacterium was significantly increased in the Longjing43 cultivar by rehydration after a four-week drought. Furthermore, root nitrogen, phosphorus, potassium levels, and dry mass were positively correlated with the microbial alpha diversity, while the taproot length was negatively correlated, suggesting the crucial role of plant–microbe interactions in response to drought and rehydration. Moreover, the root phosphorus concentration and taproot length also had significant effects on microbial beta diversity, further confirming their effects on the community structure of the rhizosphere microbiome. Overall, this study provides insights into the effects of drought on plant–microbe interactions in the rhizosphere of tea plants. These findings are important for harnessing the roles of the tea rhizosphere microbiome under drought.
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Motaghian, H. R., and A. R. Hosseinpur. " Copper release kinetics: Effect of two extractants and wheat (Triticum aestivum L.) rhizosphere." Plant, Soil and Environment 58, No. 10 (October 12, 2012): 471–76. http://dx.doi.org/10.17221/365/2012-pse.
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The greenhouse experiment was performed to determine Cu release characteristics in the bulk and the rhizosphere of some calcareous soils using rhizobox. The kinetics of Cu release in the bulk and the rhizosphere soils were determined by successive extraction with diethylenetriaminepentaacetic acid-triethanolamine (DTPA-TEA) and 10 mmol/L citric acid in a period of 1 to 504 h at 25 ± 1°C. The results of kinetics study showed that Cu extracted using DTPA-TEA in the rhizosphere soils was significantly (P < 0.01) lower than the bulk soils, while Cu extracted using citric acid in the rhizosphere soils was significantly (P < 0.01) higher than the bulk soils. The mean of released Cu after 504 h using DTPA-TEA were 8.59 and 7.46 mg/kg in the bulk and the rhizosphere soils, respectively. The mean release of Cu after 504 h using citric acid was 14.73 and 16.05 mg/kg in the bulk and the rhizosphere soils, respectively. Release kinetics of Cu in two extractants conformed fairly well to parabolic diffusion, power function, and first order equations. The results of correlation analysis illustrated that a significant correlation between Cu desorption after 504 h with citric acid and Cu concentration in wheat was found (r = 0.96 and r = 0.90 in the rhizosphere and the bulk soils, respectively, P < 0.01). Therefore, application of 10 mmol/L citric acid extractant would be recommended in the future study on the kinetics of release of Cu in calcareous soils.
Dissertations / Theses on the topic "Tea rhizosphere"
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Muofhe, Mmboneni Leonard. "N2 fixation and rhizosphere ecology of aspalathus linearis subsp. linearis(rooibos tea)." Master's thesis, University of Cape Town, 1997. http://hdl.handle.net/11427/19646.
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Summary in English.Bibliography: pages 117-138.
Aspalathus linearis subsp. linearis grows in acid sands of the Cedarberg with pH ranging from 3.8-5.5. Under these conditions:, some essential nutrients are likely to be limiting. In this study, the response of Aspalathus linearis subsp. linearis to N, P, Ca and B was investigated I under field and glasshouse conditions to determine whether provision of supplemental mineral nutrients promotes growth and N2 fixation for increased tea production, and whether this legume from low nutrient environment responds to fertilization. Interestingly, provision of N and P stimulated plant growth and symbiotic performance under field and glasshouse conditions. However, like most legumes, there was sensitivity to high levels of N which resulted in a decline in nodulation and N2 fixation. Unlike P and N nutrition, Ca supply led to a significant decrease in symbiotic performance of the legume under both glasshouse and field conditions. The amounts of N fixed ranged from 50 to 225 mg N/plant under glasshouse conditions and 3.8 to 7.1 g N/plant in the field. When inoculated with soils collected from different areas outside the Cedarberg, Aspalathus linearis subsp. linearis failed to nodulate, suggesting the possible absence of specific bradyrhizobia which nodulate this legume.
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Couillerot, Olivier. "Compatibilité des bactéries phytobénéfiques Azospirillum et Pseudomonas dans la rhizosphère." Phd thesis, Université Claude Bernard - Lyon I, 2009. http://tel.archives-ouvertes.fr/tel-00876883.
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Les bactéries rhizosphériques qualifiées de PGPR (Plant Growth-Promoting Rhizobacteria) forment des symbioses associatives avec les plantes, stimulant la croissance de ces dernières. Les PGPR présentent différents mécanismes phytobénéfiques (production de phytohormones, fixation non symbiotique de l'azote, etc.). Plusieurs PGPR sont susceptibles d'interagir avec la même plante hôte, et il est possible que leurs effets phytobénéfiques soient influencés par les interactions qu'elles auront les unes avec les autres. L'objectif de cette thèse était de caractériser la compatibilité des PGPR dans la rhizosphère d'une même plante hôte, dans le cas de modèles bactériens appartenant aux genres Azospirillum et Pseudomonas. Certains Pseudomonas phytobénéfiques produisant des métabolites antimicrobiens, comme le 2,4-diacétylphloroglucinol (DAPG), nous avons tout d'abord examiné si la capacité à produire du DAPG pouvait inhiber Azospirillum. Les expériences de confrontation réalisées in vivo avec P. fluorescens F113 et un mutant DAPG-négatif, en système gnotobiotique, ont montré que la colonisation racinaire et l'activité phytostimulatrice de certaines PGPR Azospirillum pouvaient effectivement être diminuées en présence de Pseudomonas producteurs de DAPG. Pour évaluer la colonisation racinaire par Azospirillum en sol non stérile, des outils de PCR quantitative en temps réel ont été développés et validés pour trois souches de premier plan (A. lipoferum CRT1, A. brasilense UAP-154 et CFN-535). L'utilisation de ces outils a permis la comparaison de ces trois souches d'Azospirillum, chacune co-inoculée avec la souche P. fluorescens F113 productrice de DAPG, sur du maïs cultivé en sol non stérile. Les niveaux de colonisation racinaire différaient selon la souche d'Azospirillum, et la combinaison de microorganismes phytobénéfiques conduisait à une meilleure croissance du maïs par comparaison avec des plantes non inoculées. Les résultats suggèrent que des PGPR des genres Pseudomonas et Azospirillum peuvent être compatibles dans la rhizosphère d'une même plante, même si les premiers ont le potentiel d'inhiber certains des seconds par la production de métabolites secondaires antimicrobiens
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Obeidy, Carole. "Effet de la végétation sur la mobilité de l'arsenic dans la rhizosphère." Phd thesis, Ecole Nationale Supérieure des Mines de Saint-Etienne, 2011. http://tel.archives-ouvertes.fr/tel-00715910.
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La pollution des sols par l'Arsenic (As) est une préoccupation environnementale grandissante dans plusieurs pays du monde : États-Unis, Canada, Mexique, Chine, Vietnam et France. L'émergence des techniques écologiques dites " phytoremédiation " constitue à l'heure actuelle une des solutions aux problématiques de décontamination des sols pollués par l'As. Aussi, elle permet de rallier le respect de l'état écologique des sites d'une part et le coût financier de traitement d'autre part. Pour cela, l'appréhension des interactions entre le végétal et l'As à l'interface racine-sol est nécessaire afin d'accélerer la mise en place de la phytoremédiation et de tester son efficacité. D'où l'objectif général de ce travail est d'étudier l'effet de quatres espèces végétales Holcus lanatus, Dittrichia viscosa, Lotus corniculatus et Plantago lanceolata sur la mobilité de l'As dans un sol à contamination géochimique en As (2000 mg kg-1). Notre étude a permis au départ de comparer et de caractériser la tolérance et la capacité accumulatrice des espèces séléctionnées à l'égard de l'As en milieu de culture et en sol contaminé chimiquement par l'As. Ensuite, l'étude de la mobilisation de l'As dans la rhizosphère a été réalisée par deux approches d'étude complémentaires : l'approche " rhizopot-rhizons " et l'approche " tapis racinaire ". L'approche " rhizopot-rhizons " nous a permis d'identifier d'intéressantes corrélations entre l'As et les paramètres suivis (NO3-, SO42- , Ca, Mg, P, pH, COD) tout au long de la période de croissance. Nous avons identifié et caractérisé plusieurs processus ifluençant la mobilisation de l'As dans la rhizosphère (alcalinisation/acidification, compétition anionique...). L'avantage de l'approche " rhizopot-rhizons " réside dans le fait que les plantes se sont développées sans prétraitement du substrat de croissance (contamination artificielle, ajout de solutions nutritives...). Par ailleurs, l'approche " tapis racinaire " a permis d'identifier quelques anions organiques dans les racines de P. lanceolata et de mettre en évidence le rôle du Phosphore dans la mobilisation de l'As dans la rhizosphère. Elle permet d'amplifier l'effet du système racinaire sur la mobilité de l'As dans le sol d'une part, et de récupérer entièrement le système racinaire tout en limitant les artefacts liés à la contamination des racines par le sol d'autre part.
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San, miguel Angelique. "Phytoremédiation des organochlorés. Etude mécanistique et fonctionnelle des capacités épuratrices du système plante-rhizosphère." Phd thesis, Université de Grenoble, 2011. http://tel.archives-ouvertes.fr/tel-00680031.
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Les organochlorés (OCs) -molécules utilisées dans des procédés industriels et en applications agricoles dont la plupart sont interdites d'utilisation de nos jours- sont considérés comme des polluants très persistants représentant une menace pour les eaux de surfaces et souterraines, le sol et l'atmosphère. Des méthodes alternatives de décontamination de sites pollués aux OCs sont développées utilisant des technologies in situ d'écoremédiation. L'objectif du projet de thèse est d'étudier les capacités de phytoremédiation des OCs par deux plantes modèles, Zea mays et Phragmites australis. Les OCs choisis dans cette étude sont, le lindane (γHCH), le monochlorobenzène (MCB), le 1,4-dichlorobenzène (DCB) et le 1,2,4-trichlorobenzène (TCB). Notre approche a été de considérer l'impact sur les fonctions physiologiques des plantes de chaque OC en mono-exposition, puis de comparer ces mêmes réponses physiologiques en multi-exposition. Ce travail a permis de mettre en évidence un effet synergique de l'action du mélange des OCs. Toutefois, Z. mays et P. australis tolérent des concentrations OCs largement supérieures aux concentrations environnementales mesurées in situ. La phytoextraction des OCs a été démontrée par nos expériences en conditions contrôlées et en utilisant des molécules 14C-OCs. Les OCs sont majoritairement bioconcentrés au niveau des organes souterrains des plantes. Enfin, cette étude montre une adaptation de la microflore bactérienne de la rhizosphère en présence d'un gradient d'exposition aux OCs (multi-exposition). Les approches d'isolement et d'études d'empreintes moléculaires (ARNr 16S, SSCP, pyroséquançage 454) ont permis de détecter des souches potentiellement capables d'assurer une rhizodégradation des OCs.
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Bouffaud, Marie-Lara. "Histoire évolutive des Poaceae et relations avec la communauté bactérienne rhizosphérique." Phd thesis, Université Claude Bernard - Lyon I, 2011. http://tel.archives-ouvertes.fr/tel-01002644.
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Depuis l'apparition de la vie sur terre, les pressions de sélection liées aux interactions biotiques et abiotiques ont généré une forte diversité des formes de vie. Ainsi, chaque espèce eucaryote coévolue avec sa communauté microbienne associée. Dans le cas des plantes, la diversité génétique se traduit au niveau de multiples traits phénotypiques (exsudation de substrats carbonés, architecture racinaire, densité et aération du sol, acidification, etc.) susceptibles d'influer sur les interactions avec les populations microbiennes du sol, et donc sur la composition et le fonctionnement de la communauté microbienne rhizosphérique. Notre hypothèse est que les différences entre communautés bactériennes rhizosphériques sont proportionnelles aux distances évolutives entre partenaires végétaux. L'objectif de cette thèse était donc de déterminer l'importance, dans le cas des Poacées et notamment du maïs, de l'histoire évolutive de la plante dans la capacité de sélection des communautés bactériennes de la rhizosphère. Les analyses faites à l'aide d'une puce à ADN taxonomique 16S indiquent que la composition de la communauté rhizobactérienne dépend du groupe génétique de maïs mais n'est pas liée aux marqueurs microsatellites de diversité du maïs. Par contre, à l'échelle des Poacées, une corrélation a été trouvée entre la phylogénie végétale et la composition de la communauté bactérienne (voire la prévalence de taxons bactériens particuliers). Cette corrélation n'était pas significative quand l'étude était limitée à l'effectif, le niveau de transcription de nifH ou la diversité du groupe fonctionnel des bactéries fixatrices d'azote. En conclusion, l'histoire évolutive du partenaire végétal à l'échelle des Poacées (mais pas à celle du maïs) est un facteur conditionnant les interactions avec les groupes bactériens taxonomiques (mais pas nécessairement fonctionnels) de la rhizosphère
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Tannières, Mélanie. "Interruption de la communication bactérienne dans la rhizosphère par la dégradation enzymatique des signaux quorum sensing." Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-00803936.
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L'identification, chez divers organismes, d'enzymes de dégradation des N-acyl homosérineslactones (NAHLs) impliquées dans la signalisation QS pose la question de leurs rôles dans lesinteractions bactéries-eucaryotes. Dans une première partie, une synthèse bibliographique analyse lesconnaissances acquises sur ces enzymes dégradant les NAHLs. Dans une seconde partie, la croissancedes bactéries dégradant les signaux NAHLs a été stimulée par l'application de g-caprolactone (GCL)dans la rhizosphère de plants de pommes de terre à des fins de phytoprotection. L'effet de cetraitement sur la diversité des communautés bactériennes rhizosphériques a été évalué en combinantdifférentes approches d'écologie microbienne moléculaire comme la DGGE, le pyroséquençaged'amplicons rrs, et la métagénomique fonctionnelle. Cette dernière approche appliquée à une banquede 30 000 clones environ a conduit à l'identification d'un gène qsdB codant la dégradation des signauxNAHL. Ce travail révèle ainsi l'existence d'une nouvelle classe d'enzymes de dégradation des NAHLsappartenant à la famille des enzymes possédant une signature amidase (AS) dont des membres sontpar ailleurs impliqués dans la dégradation de composés xénobiotiques. Dans une troisième partie, unsystème expérimental a été développé afin de mesurer le transfert conjugatif du plasmide de virulenceTi (tumor inducing) chez des dérivés du pathogène Agrobacterium tumefaciens, appelés "tricheurs",incapables de produire des signaux NAHLs mais utilisateurs de ceux produits par les autres bactéries.Ce modèle a permis de montrer l'effet modérateur de lactonases dégradant les NAHLs exprimées chezdes agrobactéries produisant les NAHLs, chez des bactéries réceptrices du plasmide Ti, ou des planteshôtes des agrobactéries sur le transfert conjugatif initié par les tricheurs. L'ensemble de ce travailrévèle à la fois une nouvelle famille d'enzymes impliquées dans la dégradation des NAHLs, ainsiqu'un nouveau rôle de ces enzymes dans la modulation des flux de gènes entre bactériesphytopathogènes en interaction avec une plante hôte.
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Bazot, Stéphane. "Contribution à l'étude de l'allocation des photoassimilats récents dans la plante et la rhizosphère chez une graminée pérenne (Lolium perenne L. )." Phd thesis, Institut National Polytechnique de Lorraine - INPL, 2005. http://tel.archives-ouvertes.fr/tel-00137743.
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L'objectif de notre travail a été étudié le transfert de C dans la plante et vers la rhizosphère de Lolium perenne afin d'expliciter le couplage entre le fonctionnement de la plante et la rhizodéposition.Nous avons d'abord déterminé la contribution du carbone récemment assimilé par la plante à la rhizodéposition. Nous avons ainsi réalisé un double marquage long des parties aériennes des plantes (14CO2 et 13CO2) afin d'estimer la répartition dans la plante et les compartiments rhizosphériques du C récent et le C plus anciennement assimilé. Contrairement à ce qui est admis généralement, le C ancien, probablement issu de la remobilisation de composés de réserve, contribue significativement à la rhizodéposition.
Nous avons ensuite évalué sur des dispositifs expérimentaux de terrain l'influence de contraintes subies par les parties aériennes de la plante sur les flux de C récent vers la rhizosphère (augmentation de la concentration en CO2 atmosphérique et défoliation). La disponibilité en azote dans le sol est un facteur déterminant de la réponse des plantes à l'élévation des concentrations en CO2 ou à la défoliation. A l'automne, une diminution de la rhizodéposition de C est observée pour les plantes soumises au doublement de CO2. Les composés organiques libérés par les racines sont minéralisés plus rapidement sous CO2 élevé que sous CO2 ambiant. La défoliation n'induit pas de variations notables de la disponibilité en C dans la rhizosphère, suggérant aucune influence significative de ce facteur sur la rhizodéposition.
Les interactions entre les facteurs de l'environnement et de gestion de la parcelle cultivée déterminent le fonctionnement de la plante et modulent les efflux de C à partir des racines, ce qui rend la rhizodéposition difficile à prédire et à modéliser. Il s'avère que les effets nets du doublement de CO2 ou de la défoliation sur la rhizodéposition sont beaucoup moins marqués au champ qu'en conditions contrôlées. Au delà de la contribution quantitative de la rhizodéposition au bilan de C dans le sol, les interactions entre la nature biochimique des rhizodépôts et l'activité biologique des sols nécessitent d'être approfondies.
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Portier, Perrine. "Sélection d'écotypes bactériens pathogènes et non-pathogènes par la plante en relation avec la différenciation en espèces génomiques chez Agrobacterium spp." Phd thesis, Université Claude Bernard - Lyon I, 2004. http://tel.archives-ouvertes.fr/tel-00350502.
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Ce travail avait pour but : 1) de vérifier l'existence d'une relation entre espèces génomiques et écotypes associés aux plantes chez Agrobacterium spp.; 2) d'identifier les zones génomiques impliquées dans la différentiation en écotypes et, partant, en espèces génomiques dans ce taxon. Nous avons d'abord cherché et caractérisé au niveau génomique (par AFLP) des écotypes non-pathogènes et pathogènes (hébergeant un plasmide Ti), dans différents biotopes. Nos résultats montrent que la plante sélectionne des écotypes spécifiques au sein de la communauté des agrobactéries du sol. De plus, il apparaît que c'est parmis les écotypes spécifiques d'une plante donnée que sont recrutées certaines agrobactéries pathogènes isolées des tumeurs. L'AFLP prédictive réalisée sur le génome de la souche C58 nous a ensuite permis d'identifier les fragments AFLP caractéristiques de l'espèce G8. Les gènes et fonctions ainsi révèlées pourraient effectivement concerner des relations plantes-bactéries.
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Panfili, Frédéric. "Etude de l'évolution de la spéciation du zinc dans la phase solide d'un sédiment de curage contaminé, induit par phytostabilisation." Phd thesis, Université de Provence - Aix-Marseille I, 2004. http://tel.archives-ouvertes.fr/tel-00718487.
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Le curage des sédiments des cours d'eau est nécessaire pour limiter les risques d'inondations et permettre la navigation fluviale. A cause des activités humaines, les sédiments de curage sont souvent contaminés en métaux, ce qui rend leur gestion problématique. Dans ce contexte,la phytostabilisation, une technique de traitement consistant à utiliser des plantes et des amendements minéraux pour réduire la mobilité des métaux dans des matrices solides contaminées, a été testée sur un sédiment de curage prélevé à proximité d'une fonderie de zinc et contaminé principalement par cet élément. Les plantes (Agrostis tenuis et Festuca rubra) ont été cultivées en serre, dans des mésocosmes d'environ 40 kg, qui contenaient l'un des trois substrats suivants : sédiment, sédiment + hydroxylapatite et sédiment + amendement sidérurgique ; des mésocosmes témoins non-végétalisés ont été placés dans les mêmes conditions. L'objectif principal de ce travail était de caractériser l'évolution de la spéciation du zinc induite par deux ans de phytostabilisation. Dans un premier temps, les associations géochimiques du zinc dans les différents milieux ont été observées sur des lames minces à l'échelle du micromètre grâce à l'utilisation combinée de techniques de micro-analyse (MEB-EDS, μXSRF). La spéciation du zinc dans chacune de ces associations a ensuite été déterminée par spectroscopie EXAFS résolue latéralement (μEXAFS). Le traitement des spectres μEXAFS par analyse en composantes principales (ACP) a permis l'identification de la sphalérite (ZnS), de la gahnite (ZnAl2O4) et de la franklinite (ZnFe2O4), qui sont des minéraux primaires certainement d'origine anthropique, et de la ferrihydrite (oxyhydroxyde de fer mal cristallisé) zincifère, d'une association zinc-phosphate, d'un phyllosilicate zincifère et de l'hydrotalcite (oxyhydroxyde d'aluminium) zincifère. Dans un second temps, les espèces zincifères ainsi identifiées ont été quantifiées à l'échelle macroscopique par spectroscopie EXAFS sur poudre. Les spectres EXAFS ainsi obtenus ont été simulés par combinaisons linéaires des spectres EXAFS des espèces zincifères précédemment identifiées, ce qui a permis d'évaluer l'effet du traitement sur la spéciation moyenne du zinc. En deux ans, elle a évolué de façon significative dans les mésocosmes amendés non-végétalisés, puisque l'on observe une diminution de la proportion de ZnS, la phase zincifère initialement majoritaire dans le sédiment, et la néoformation d'un phosphate de zinc. L'évolution de la spéciation du zinc est spectaculaire dans les mésocosmes végétalisés (amendés ou non), puisque dans ce cas, ZnS a été totalement oxydée et d'autres phases zincifères, telles qu'un phosphate de zinc et un phyllosilicate zincifère et / ou de l'hydrotalcite zincifère, se sont formées. La gahnite et la franklinite n'ont été observées qu'à l'échelle microscopique et sont donc des phases minoritaires. L'étude de la surface des racines des plantes par MEB-EDS, μSXRF et μEXAFS a permis de mettre en évidence la présence de précipités d'oxydes de manganèse (birnessite) riches en zinc, et parfois en plomb et en cuivre. Cette espèce chimique a été observée uniquement à la surface des racines et représente probablement une contribution minoritaire au processus global de l'immobilisation du zinc. Au bout de deux années, la phytostabilisation a permis la formation de phases zincifères plus stables que ZnS dans les conditions atmosphériques d'un dépôt de surface, indiquant que le zinc présent dans le sédiment phytostabilisé est potentiellement moins mobile que dans le sédiment seul. Ainsi, dans notre cas, la phytostabilisation limiterait donc la dispersion du zinc dans l'environnement.
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Voinot, Alexandre. "Contribution des isotopes du bore à l'étude des mécanismes et bilans de l'altération des minéraux des sols." Phd thesis, Université de Strasbourg, 2012. http://tel.archives-ouvertes.fr/tel-00873615.
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L'objectif de cette thèse est d'estimer la capacité du bore et de ses isotopes à évaluer les mécanismes et bilans de l'altération des minéraux dans les sols. Pour ce faire, trois axes ont été développés : 1) une approche expérimentale, durant laquelle un minéral-test (la biotite) est soumis à l'action de différents agents altérants représentatifs de ceux trouvés dans les sols. 2) une approche in-situ dans un sol forestier acide, menée sur des minéraux séparés (biotite, muscovite,feldspath potassique et albite), au cours de leur altération à différentes profondeurs (site de Breuil-Chenue, France). L'objectif de cette étude est de déterminer la sensibilité du bore aux processus de la formation des sols. 3) une seconde approche in-situ sur le même site expérimental, menée cette fois-ci sur les horizons superficiels (horizon A et horizon d'accumulation des oxy-hydroxydes d'aluminium), dont le but est de déterminer la sensibilité du bore et de ses isotopes aux processus liés à la proximité de la végétation (variations saisonnières, proximité des racines). Le bore permet, grâce à sa très grande réactivité durant les mécanismes d'altération par rapport aux éléments majeurs constitutifs du réseau cristallin (observable aussi bien en conditions expérimentales qu'en milieu naturel), de tracer avec une grande sensibilité les mécanismes de dissolution ou de transformation des différents minéraux primaires, et ouvre de nouvelles perspectives quant à la compréhension et la modélisation des sols.
Book chapters on the topic "Tea rhizosphere"
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Duan, Dechao, Mingge Yu, Yingxu Chen, Luying Dai, Dongyan Long, and Chen Xu. "Does the Compositional Change of Soil Organic Matter in Rhizosphere and Bulk Soil of Tea Plant Induced by Tea Polyphenols Have Some Correlation with Pb Bioavailability?" In Functions of Natural Organic Matter in Changing Environment, 555–59. Dordrecht: Springer Netherlands, 2012. http://dx.doi.org/10.1007/978-94-007-5634-2_100.
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Mallick, Rwitabrata. "Tea Rhizospheres and Their Functional Role in Tea Gardens." In Data Science for Agricultural Innovation and Productivity, 163–74. BENTHAM SCIENCE PUBLISHERS, 2024. http://dx.doi.org/10.2174/9789815196177124010011.
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Darjeeling tea (Camellia sinensis) is famous worldwide for its excellent aroma and taste, and out of that, the best quality tea is produced in the Kurseong hill area. A year-long analysis of soil samples collected from different sites was done by applying the plate-count method in terms of colony-forming units for determining the presence of microbial population within soils cultivating tea on a monthly basis. Coordination in specific microbes might also be responsible for the impact. Fungi, bacteria, and actinomycetes – these three groups of microbes were tested during the process. Results showed that the neo tea plant, rhizosphere and rhizosphere of several other perpetual plants of various ages, flourishing in age-old tea gardens, seemed to expedite the growth of microbes. At present, the tea rhizosphere has been tested thoroughly, specifically in relation to plant-microbe response. Counter to the common outcomes, rhizosphere and soil ratios were found to be regularly less than 1 in samples collected from age-old tea gardens, showing an overall -ve rhizosphere impact. The finding of the 'negative rhizosphere effect' in old tea bushes is a significant and novel nature of the tea rhizosphere. The -ve impact on the rhizosphere of aged tea bushes does not seem to be a regular phenomenon that is related to the aging of plants generally but might be distinctive particular to tea plants. Other important and associated features include colonization of tea, rhizosphere, soil pH, etc. Supremacy of a certain population of microbes, an affinity towards a section of general opponents constitutes a good instance of reciprocated selection in the natural environment. These discoveries have unlocked newer paths for extended research in the field of 'rhizosphere microbiology'. The present study is an attempt to evaluate the transforming features coupled with the microbial activity and diversity in the tea rhizosphere and significant implications in the tea industry.
Conference papers on the topic "Tea rhizosphere"
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Rawat, Monika. "Soil Respiration Variation under the Canopy of Dominant Tree Species across different seasons in Temperate Forest." In Qatar University Annual Research Forum & Exhibition. Qatar University Press, 2020. http://dx.doi.org/10.29117/quarfe.2020.0021.
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Soil respiration is defined as the production of carbon dioxide when soil organisms are active. It is an important process in the ecosystem and has direct influence on climate change. Therefore understanding it under different vegetation types is an essential goal in soil science. The major sources which effect the soil respiration rate are plant roots, the rhizosphere, microbes and soil fauna and these sources are control by various factors like temperature, moisture, nutreint content and oxygen in the soil. Soil respiration rate is important for understanding soil biological activity, nutrient cycling, soil microbial biomass, soil organic matter and its decomposition.Therefore soil respiration was studied under the canopy of ten dominant tree species of temperate forest. Our study determined that highest soil respiration was under the canopy of Eunonymous pendulus (EP) i.e. 20.01 μmolm−2 s−1 and across season it was high during the rains.
Reports on the topic "Tea rhizosphere"
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Crowley, David E., Dror Minz, and Yitzhak Hadar. Shaping Plant Beneficial Rhizosphere Communities. United States Department of Agriculture, July 2013. http://dx.doi.org/10.32747/2013.7594387.bard.
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PGPR bacteria include taxonomically diverse bacterial species that function for improving plant mineral nutrition, stress tolerance, and disease suppression. A number of PGPR are being developed and commercialized as soil and seed inoculants, but to date, their interactions with resident bacterial populations are still poorly understood, and-almost nothing is known about the effects of soil management practices on their population size and activities. To this end, the original objectives of this research project were: 1) To examine microbial community interactions with plant-growth-promoting rhizobacteria (PGPR) and their plant hosts. 2) To explore the factors that affect PGPR population size and activity on plant root surfaces. In our original proposal, we initially prqposed the use oflow-resolution methods mainly involving the use of PCR-DGGE and PLFA profiles of community structure. However, early in the project we recognized that the methods for studying soil microbial communities were undergoing an exponential leap forward to much more high resolution methods using high-throughput sequencing. The application of these methods for studies on rhizosphere ecology thus became a central theme in these research project. Other related research by the US team focused on identifying PGPR bacterial strains and examining their effective population si~es that are required to enhance plant growth and on developing a simulation model that examines the process of root colonization. As summarized in the following report, we characterized the rhizosphere microbiome of four host plant species to determine the impact of the host (host signature effect) on resident versus active communities. Results of our studies showed a distinct plant host specific signature among wheat, maize, tomato and cucumber, based on the following three parameters: (I) each plant promoted the activity of a unique suite of soil bacterial populations; (2) significant variations were observed in the number and the degree of dominance of active populations; and (3)the level of contribution of active (rRNA-based) populations to the resident (DNA-based) community profiles. In the rhizoplane of all four plants a significant reduction of diversity was observed, relative to the bulk soil. Moreover, an increase in DNA-RNA correspondence indicated higher representation of active bacterial populations in the residing rhizoplane community. This research demonstrates that the host plant determines the bacterial community composition in its immediate vicinity, especially with respect to the active populations. Based on the studies from the US team, we suggest that the effective population size PGPR should be maintained at approximately 105 cells per gram of rhizosphere soil in the zone of elongation to obtain plant growth promotion effects, but emphasize that it is critical to also consider differences in the activity based on DNA-RNA correspondence. The results ofthis research provide fundamental new insight into the composition ofthe bacterial communities associated with plant roots, and the factors that affect their abundance and activity on root surfaces. Virtually all PGPR are multifunctional and may be expected to have diverse levels of activity with respect to production of plant growth hormones (regulation of root growth and architecture), suppression of stress ethylene (increased tolerance to drought and salinity), production of siderophores and antibiotics (disease suppression), and solubilization of phosphorus. The application of transcriptome methods pioneered in our research will ultimately lead to better understanding of how management practices such as use of compost and soil inoculants can be used to improve plant yields, stress tolerance, and disease resistance. As we look to the future, the use of metagenomic techniques combined with quantitative methods including microarrays, and quantitative peR methods that target specific genes should allow us to better classify, monitor, and manage the plant rhizosphere to improve crop yields in agricultural ecosystems. In addition, expression of several genes in rhizospheres of both cucumber and whet roots were identified, including mostly housekeeping genes. Denitrification, chemotaxis and motility genes were preferentially expressed in wheat while in cucumber roots bacterial genes involved in catalase, a large set of polysaccharide degradation and assimilatory sulfate reduction genes were preferentially expressed.
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Michel Jr., Frederick C., Harry A. J. Hoitink, Yitzhak Hadar, and Dror Minz. Microbial Communities Active in Soil-Induced Systemic Plant Disease Resistance. United States Department of Agriculture, January 2005. http://dx.doi.org/10.32747/2005.7586476.bard.
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Induced Systemic Resistance (ISR) is a highly variable property that can be induced by compost amendment of potting media and soils. For example, previous studies showed that only 1 of 79 potting mixes prepared with different batches of mature composts produced from several different types of solid wastes were able to suppress the severity of bacterial leaf spot of radish caused by Xanthomonas campestris pv. armoraciae compared with disease on plants produced in a nonamended sphagnum peat mix. In this project, microbial consortia in the rhizosphere of plants grown in ISR-active compost-amended substrates were characterized. The plants used included primarily cucumber but also tomato and radish. Rhizosphere microbial consortia were characterized using multiple molecular tools including DGGE (Israel) and T -RFLP (Ohio) in both ISR-active field plots and potting media. Universal as well as population-specific bacterial and fungal PCR primers were utilized. T -RFLP analyses using universal bacterial primers showed few significant differences in overall bacterial community composition in ISR-active and inactive substrates (Ohio). In addition, the community members which were significantly different varied when different ISR-activecomposts were used (Ohio). To better characterize the shifts in microbial community structure during the development of ISR, population specific molecular tools were developed (Israel, Ohio).-PCR primers were designed to detect and quantify bacterial groups including Pyrenomycetes, Bacillus, Pan toea, Pseudomonas, Xanthomonas and Streptomyces as well as Trichoderma and Fusarium; two groups of fungi that harbor isolates which are ISR active (Isreal and Ohio). Bacterial consortia associated with cucumber plants grown in compost-amended potting mixtures were shown to be dominated by the phylogenetic taxon Bacteroidetes, including members of the genus Chryseobacterium, which in some cases have been shown to be involved in biocontrol (Israel). Nested-PCR-DGGE analyses coupled with long l6S rDNA sequencing, demonstrated that the Chryseobacteriumspp. detected on seed and the root in compost-amended treatments were derived from the compost itself. The most effective ISR inducing rhizobacterial strains were identified as Bacillus sp. based on partial sequencing of l6S rDNA. However, these strains were significantly less effective in reducing the severity of disease than Trichoderma hamatum382 (T382). A procedure was developed for inoculation of a compost-amended substrate with T -382 which consistently induced ISR in cucumber against Phytophthora blight caused by Phytophthora capsiciand in radish against bacterial spot (Ohio). Inoculation of compost-amended potting mixes with biocontrol agents such as T -382 and other microbes that induce systemic resistance in plants significantly increased the frequency of systemic disease control obtained with natural compost amendments.