خيارات البحث
النتائج 1 - 10 من 437
Assessment of ozone visible symptoms in the field - perspectives of quality control
2002
Bussotti, F. (University of Florence, Florence (Italy)) | Schaub, M. | Cozzi, A. | Krauchi, N. | Ferretti, M. | Novak, K. | Skelly, J. M.
Two field exercises for the assessment of foliar visible ozone symptoms were performed during the "2nd UN/ECE ICP-Forests Intercalibration Course on the Assessment of Ozone Injury on European tree Species" organised by the WSL in collaboration with the University of Florence, Linnaea ambiente, and the PSU. The exercises were conducted at the Lattecaldo OTC research facility in Southern Switzerland and on the Moggio Level II plot in Northern Italy from 22-24 August 2001. 48 participants represented 21 countries. There are given objectives and results and conclusions from both sites
اظهر المزيد [+] اقل [-]The role of roots and mycorrhizas in C-sequestration under elevated CO2 (popface)
2002
Lukac, M. | Godbold, D.L. (University of Wales, Bangor (United Kingdom). SAFS)
The need to assess the role of terrestrial ecosystems in the global C cycle and the potential change of this role as the atmospheric concentration of CO2 increases attracted considerable scientific attention over the recent decade. In order to assess ecosystem responses as a whole and to evaluate the potential role of forests and tree communities as a carbon sinks, the below-ground response to increasing levels of CO2 must be addressed
اظهر المزيد [+] اقل [-]Discussion of the effects of N with and without acidified S on a sitka spruce ecosystem after 5 years treatment
2002
Sheppard, L.J. | (CEH Edinburgh Bush Estate, Edinburgh (United Kingdom)) | Crossley, A. | Ingleby, K. | Carfrae, J. | Harvey, F. | Kennedy, V.
Significant differences in the effects of N alone compared with NS Acid have been found with respect to eutrophication and acidification. N alone had no effect on the pleurocarpous mosses, whereas NS Acid caused their death within 2 years. Both treatments enhanced stem area increment and N alone also doubled fine root growth. By contrast NS Acid treatments increased litterfall in a a dose response fashion
اظهر المزيد [+] اقل [-]Response of subarctic tree seedlings to solar UV radiation
2002
Turunen, M. (University of Lapland, Rovaniemi (Finland). Arctic Centre) | Suttinen, M. L. | Derome, K. | Norokorpi, Y. | Lakkala, K.
The response of Betula pubescens Ehr., B. pendula Roth and two provenances of Pinus sylvestris L. to solar ultraviolet radiation were investigated in a UV exclusion field experiment during the 1997-1999 growing seasons in Finnish Lapland. The seed-grown seedlings were grown under UV-B exclusion and UV-B/UV-A exclusion as compared to control treatment and ambient plants. The only significant impacts of UV exclusion were found in P. sylvestris provenance Enontekio. Longer-term field studies are needed to detect the cumulative characteristics of the UV responses
اظهر المزيد [+] اقل [-]Sensitivity of adult beech and spruce trees of a mixed forest to chronic ozone exposure: findings from a free-air ozone fumigation experiment
2002
Nunn, A. J. (Technische Universitaet Munchen, Freising (Germany). Lehrstuhl fur Forstbotanik) | Reiter, I. M. | Heerdt, Ch. | Haberle, K. H. | Langerbartels, Ch. | Werner, H. | Sandermann, H. | Fabian, P. | Matyssek, R.
The study aims at assessing response patterns to chronic O3 exposure in adult forest trees, examining physiological and structural responses at the organ and whole-tree level for consistency by means of biochemical and ecophysiological analyses. Through comparison between the two O3 regimes, conclusions can be drawn about processes, which are at risk or already affected by ozone under the unchanged, prevailing stand conditions. Responses are related to the O3 influx into leaves as a measure of the physiologically effective O3 dose and cross-compared with the AOT 40 concept which is being validated on the two O3 fluxes and AOT40-related responses in biochemical, ecophysiological and structural tree parameters
اظهر المزيد [+] اقل [-]Arsenic accumulation in rice: Alternative irrigation regimes produce rice safe from arsenic contamination النص الكامل
2022
Rokonuzzaman, MD. | Ye, Zh | Wu, C. | Li, Wc
The natural occurrence of arsenic (As) in groundwater & soils and its bioaccumulation in rice grains is a major health concern worldwide. To combat the problem, best combination of irrigation management and suitable rice variety altering As content in grains must be ensured. With this aim, a field trial was conducted with two rice varieties and water management including alternate wetting and drying (AWD) and continuous flooding (CF) irrigation regimes with As contaminated groundwater (AsW) and temporarily stored groundwater (TSG) and river water for only CF (as control). Results revealed that As content in different portions of paddy plant was significantly different (P < 0.001) with irrigation practices and rice varieties. AWD irrigation with TSG accumulated lower As in rice grains compared with CF-AsW for both varieties. Data showed that AWD-TSG practice led to 61.37% and 60.34% grain As reduction for BRRI dhan28 and BRRI dhan29, respectively, compared with CF-AsW. For Principle Component Analysis (PCA), first principle component (PC1) explained 91.7% of the variability and irrigation water As, soil total and available As, straw As, root As and husk As were the dominating parameters. With significant (P < 0.05) variation in yields between the genotypes, AWD increased grain yield by 29.25% in BRRI dhan29 Compared with CF. However, translocation factor (TF) and bioconcentration factor (BCF) for both varieties were less than one for all the treatments. The addition of this study to our knowledge base is that, AWD-TSG with BRRI dhan29 can be an As–safe practice without compromising yields.
اظهر المزيد [+] اقل [-]A 3-year field study on lead immobilisation in paddy soil by a novel active silicate amendment النص الكامل
2022
Zhao, Hanghang | Zhang, Jianxin | Wu, Feng | Huang, Xunrong | Liu, Fuhao | Wang, Lu | Zhao, Xin | Hu, Xiongfei | Gao, Pengcheng | Tang, Bo | Ji, Puhui
Lead (Pb) is a toxic metal in industrial production, which can seriously threat to human health and food safety. Thus, it is particularly crucial to reduce the content of Pb in the environment. In this study, raw fly ash (FA) was used to synthesise a new active silicate materials (IM) employing the low-temperature-assisted alkali (NaOH) roasting approach. The IM was further synthesised to form zeolite-A (ZA) using the hydrothermal method. The physicochemical characteristics of IM and ZA amendments before and after Pb²⁺ adsorption were analysed using the Scanning electron microscope-Energy Dispersive Spectrometer (SEM-EDS), Fourier Transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) apparatuses. The results revealed the considerably change in the microstructure and functional groups of IM and ZA amendments, conducive to Pb²⁺ removal. Moreover, a 3-year field experiment revealed that the IM and ZA significantly improved the growth of rice and reduced available Pb by 21%–26.8% and 9.7%–16.9%, respectively. After 3 years of remediation, the Pb concentration of the rice grain reached the national edible standard (≤0.2 mg kg⁻¹) of 0.171 mg kg⁻¹ and 0.179 mg kg⁻¹, respectively. Meanwhile, the concentration of acid-exchangeable Pb reduced, while those of reducible and residual fractions of Pb increased. There was no significant difference between the IM and ZA treatments. The potential mechanisms of remediation by the amendments were ion-exchange, complexation, precipitation, and electrostatic attraction. Overall, the results indicate that IM is suitable for the remediation of contaminated soil and promotes safe food production, and develops an environmentally friendly and cost-effective amendment for the remediation of polluted soil.
اظهر المزيد [+] اقل [-]Prokaryotic community formation on polyethylene films incubated for six months in a tropical soil النص الكامل
2021
Zhelezova, A.D. | Zverev, A.O. | Zueva, A.I. | Leonov, V.D. | Rozanova, O.L. | Zuev, A.G. | Tiunov, A.V.
Polyethylene film is one of the most common types of recalcitrant plastic waste materials. Information regarding the fate of plastic films in soil is scarce compared to the fate of plastic films in aquatic environments. The aim of this study was to evaluate the effects of soil fauna and of impregnation of polyethylene films with oil on the colonization of low-density polyethylene films by prokaryotic communities. The field experiment was performed in a monsoon tropical forest (Vietnam). Polyethylene films were incubated in thermally pre-defaunated soil isolated from the surrounding soil by a stainless steel mesh. Three mesh sizes were used, allowing access to different size groups of soil fauna. The diversity, taxonomic structure and co-occurrence patterns in prokaryotic communities were studied using high-throughput sequencing of 16S rRNA gene libraries. The prokaryotic communities that formed on polyethylene films were slightly different from those inhabiting the surrounding soil. Contrary to our expectations, no difference in the diversity of prokaryotes was observed between microcosms with different mesh sizes. Oil impregnation also had only a minor influence on the prokaryotic community structure. Polyethylene films incubated in microcosms with soil appeared to be colonized by various consortia of prokaryotes as a barren and inert surface.
اظهر المزيد [+] اقل [-]High level of zinc triggers phosphorus starvation by inhibiting root-to-shoot translocation and preferential distribution of phosphorus in rice plants النص الكامل
2021
Ding, Jingli | Liu, Lu | Wang, Chuang | Shi, Lei | Xu, Fangsen | Cai, Hongmei
Since the urbanization and industrialization are wildly spread in recent decades, the concentration of Zn in soil has increased in various regions. Although the interactions between P and Zn has long been recognized, the effect of high level of Zn on P uptake, translocation and distribution in rice and its molecular mechanism are not fully understood. In this study, we conducted both hydroponic culture and field trial with different combined applications of P and Zn to analyze the rice growth and yield, the uptake, translocation and distribution of P and Zn, as well as the P- and Zn-related gene expression levels. Our results showed that high level of Zn decreased the rice biomass and yield production, and inhibited the root-to-shoot translocation and distribution of P into new leaves by down-regulating P transporter genes OsPT2 and OsPT8 in shoot, which was controlled by OsPHR2-OsmiR399-OsPHO2 module. High Zn supply triggered P starvation signal in root, thereafter increased the activities of both root-endogenous and -secreted acid phosphatase to release more Pi, and induced the expression OsPT2 and OsPT8 to uptake more P for plant growth. On the other hand, high level of P significantly decreased the Zn concentrations in both root and shoot, and the root uptake ability of Zn through altering the expression levels of OsZIPs, which were further confirmed by the P high-accumulated mutant osnla1-2 and OsPHR2-OE transgenic plant. Taken together, we revealed the physiological and molecular mechanisms of P–Zn interactions, and proposed a working model of the cross-talk between P and Zn in rice plants. Our results also indicated that appropriate application of P fertilizer is an effective strategy to reduce rice uptake of excessive Zn when grown in Zn-contaminated soil.
اظهر المزيد [+] اقل [-]Paddy-upland rotation with Chinese milk vetch incorporation reduced the global warming potential and greenhouse gas emissions intensity of double rice cropping system النص الكامل
2021
Zhong, Chuan | Liu, Ying | Xu, Xintong | Yang, Binjuan | Aamer, Muhammad | Zhang, Peng | Huang, Guoqin
It is a common practice to maintain soil fertility based on the paddy-upland rotation with green manure in the subtropical region of China. However, rare studies are known about greenhouse gas (GHG) emissions from the paddy-upland rotation with green manure incorporation. Therefore, we conducted a field experiment of two years to compared with the effect of two kinds of green manure (CV: Chinese milk vetch and OR: Oilseed rape), and two kinds of cropping system (DR: double rice system and PR: paddy-upland rotation) on greenhouse gases emissions. We have found that the annual accumulation of CH₄ of Chinese milk vetch-rice-sweet potato || soybean was significantly reduced by 32.95%∼63.22% compared with other treatments, mainly because Chinese milk vetch reduced the abundance of methanogens by reducing soil C/N ratio. Meanwhile increasing soil permeability resulting from paddy-upland rotation also reduced soil CH₄ emission. However, The annual accumulation of N₂O of Chinese milk vetch-rice-sweet potato || soybean was increased by 17.39%∼870.11% compared with other treatments, mainly attributed to paddy-upland rotation decreased soil pH and nosZ abundance and increased nirK and nirS, thus enhancing N₂O emission, meanwhile the Chinese milk vetch incorporation and its interaction with the paddy-upland rotation has greatly enhanced the contents of NO₃⁻-N and abundance of ammonia-oxidizing archaea (AOA). The area-scaled global warming potential (GWP) and the biomass-scaled greenhouse gas emissions intensity (GHGI) of Chinese milk vetch-rice-sweet potato || soybean was reduced by 19.01%∼50.69% and 5.38%∼35.77% respectively. Thereby, the Chinese milk vetch-rice-sweet potato || soybean cropping system was suitable for agricultural sustainable development.
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