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1.
ABSTRACT The objective of this study was to determine the effect of silicon (Si) and rice growth stages on tissue susceptibility to sheath blight (Rhizoctonia solani Kühn) under controlled conditions. Rice plants (cv. Rio Formoso) were grown in pots containing low-Si soil amended with Si at 0, 0.48, 0.96, 1.44, and 1.92 g pot(-1) and inoculated with R. solani at the following days after emergence: 45 (four-leaf stage), 65 (eight-leaf stage), 85 (tillering), 117 (booting), and 130 (panicle exsertion). For plants inoculated with R. solani at all growth stages, Si concentration in straw increased as rate of Si increased from 0 to 1.92 g pot(-1). Concentration of calcium in the straw did not differ among plant growth stages. Although incubation period was not affected by the amount of Si added to the soil, this variable was shorter at booting and panicle exsertion stages. As the rates of Si increased in the soil, the total number of sheath blight lesions on sheaths and total area under the relative lesion extension curve decreased at all plant growth stages. The severity of sheath blight was lower at booting and panicle exsertion stages as the rates of Si increased in the soil. In general, plants grown in Si-nonamended pots and inoculated with R. solani were more vulnerable to infection at all growth stages, but especially at 45 days after emergence. Plant dry weights for inoculated plants increased as the Si rates increased from 0 to 1.92 g pot(-1). The greatest dry weight increases occurred for plants inoculated at booting and panicle exsertion stages. Si fertilization is a promising method for controlling sheath blight in areas where soil is Si deficient and when cultivars that exhibit an acceptable level of resistance to sheath blight are not available for commercial use. 相似文献
2.
FLORES, the Forest Land Oriented Resource Envisioning System, is a framework to facilitate quantitative modelling of ecological,
economic and social issues at the landscape scale. This issue ofSmall-scale Forest Economics, Management and Policy describes the evolution of FLORES from a concept to a series of models calibrated for diverse locations, and documents the
lessons learned.
The idea to construct and use landscape-scale models of the forest frontier, based on simulating household decisions and land
use at a spatial scale close to the field level, arose from a desire to add rigour to land-use policy research at CIFOR, the
Center for International Forestry Research (Vanclay 1995). This simulation modelling approach to addressing interdisciplinary
issues, where people are strongly interacting with forest resources, became known as FLORES, the Forest Land Oriented Resource
Envisioning System (Vanclay 1998). Muetzelfeldtet al. (1998) constructed a simple prototype of a FLORES model to illustrate the concept and demonstrate the ability of a system-dynamics
modelling environment to animate such a model (Muetzelfeldt and Taylor 1997, 2001, Muetzelfeldt and Massheder 2003). In 1999,
FLORES became a reality, when 50 scientists from diverse disciplines met in Bukittinggi, Indonesia to construct the first
FLORES model styled on this prototype (CIFOR 1999, Vanclayet al. 2003).
The research reported in this special issue was made possible by generous financial support from the Department for International
Development (UK), the European Community, the Asian Development Bank (under RETA 5812) and the Center for International Forestry
Research. The views expressed herein are those of the authors alone. We would like to thank the following people who have
assisted in the production of this special issue by acting as anonymous referees for these and other papers: Andy Warner,
Brendan Moran, Bruno Verbist, Chris Dake, Chris Legg, Doug Sheil, Euan Mason, Francois Bousquet, Frank Vanclay, Geoff Slaughter,
James Gambiza, John Herbohn, John Poulsen, Jungho Suh, Mike Spilsbury, Paul Phillips, Paul van Gardingen, Phil Norman, Philip
Nyhus, Roger Wheate, Ross Sigley, Steve Harrison and Tom Evans. Thanks also to the editorial staff, especially Steve Harrison,
John Herbohn and Jungho Suh, for making this special issue possible. 相似文献
3.
Niharika Mallick Vinod J. B. Sharma R.S. Tomar M. Sivasamy K.V. Prabhu 《Plant Breeding》2015,134(2):172-177
A widely grown but rust susceptible Indian wheat variety HD2932 was improved for multiple rust resistance by marker‐assisted transfer of genes Lr19, Sr26 and Yr10. Foreground and background selection processes were practised to transfer targeted genes with the recovery of the genome of HD2932. The near‐isogenic lines (NILs) of HD2932 carrying Lr19, Sr26 and Yr10 were individually produced from two backcrosses with recurrent parent HD2932. Marker‐assisted background selection of NILs with 94.38–98.46% of the HD2932 genome facilitated rapid recovery of NILs carrying Lr19, Sr26 and Yr10. In the BC2F2 generation, NILs were intercrossed and two gene combinations of Lr19+Yr10, Sr26 + Yr10 and Lr19+Sr26 were produced. A total of 16 progeny of two gene combinations of homozygous NILs of HD2932 have been produced, which are under seed increase for facilitating the replacement of the susceptible HD2932 with three of the sixteen improved backcross lines with resistance to multiple rusts. 相似文献
4.
SCAR marker tagged to the alien leaf rust resistance gene Lr19 uniquely marking the Agropyron elongatum-derived gene Lr24 in wheat: a revision 总被引：3，自引：0，他引：3
A sequence characterized amplified region (SCAR) marker tagged to an Agropyron elongatum‐derived leaf rust resistance (Lr) gene Lr19 was validated on 18 known alien Lr gener in near‐isogenic lines (NILs) in the variety ‘Thatcher’, along with three wheat cultivers carrying Lr24 and two carrying Lr19. The marker was expressed only in the Lr24 lines confirming that the marker tagged the geneLr24. The monomorphic expression of the SCAR marker in 10NIL pairs for Lr19 and Lr24 revealed that each NIL pair possessed the same gene, Lr24. The donor parents used in the NIL pairs for Lr19 (‘Sunstar*6/C80‐1′) and Lr24 (‘TR380‐14*7/3Ag#14′) amplified the same fragment. Nonsegregation for leaf rust in the F2 population of the cross between the above donor parents confirmed the presence of the same gene in the two parents. Apparently, a genuine parent stock of ‘Sunstar*6/C80‐1’ was not involved in the development of the NIL pairs for Lr19 due to an improper maintence bredding protocol either at source or destination which went undetected in the absence of signs of virulence for either gene in the region. 相似文献
5.
E. Fritsch C. R. Montes-Lauar R. Boulet A. J. Melfi E. Balan & P. Magat 《European Journal of Soil Science》2002,53(2):203-217
The soils and sediments of the uplands in the Manaus region are described and analysed along a representative cross‐section. There are two broad types of features, lateritic and redoximorphic. Their formation is linked to two main processes acting under contrasted hydrological regimes. The first process, acting under well‐drained conditions, is lateritization. It has transformed strongly weathered sediment into soil and led to depletion of silica (mainly quartz) as well as to relative accumulation of both kaolinite and iron oxides (haematite and goethite). Crystallographic changes observed in the latter have resulted from alternating dissolution and crystallization cycles without significant transfer of iron and alumina. However, in the uppermost soil, dissolution of kaolinite has prevailed over crystallization, leading to depletion of clay and the formation of tiny crystals of gibbsite disseminated throughout the groundmass. The second process results from the development of reducing conditions in groundwater giving redoximorphic features in lateritic soils and sediments. In the sediments, iron has been depleted by regional aquifers to form a pallid zone. In the soil, large amounts of iron and minor amounts of alumina, mainly from aluminous goethite, have been mobilized at first in small patches, which with further mobilization and vertical transfer of these elements have increased in size and have led to the formation of bleached horizons over thin iron pans. Iron has crystallized predominantly as haematite in the iron pans and alumina as large crystals of gibbsite in soil voids. Formation of impervious iron pans holds up fluctuating perched groundwater in the overlying horizons depending on rainfall events. Neotectonic events (formation of uplifted blocks and small grabens) have markedly altered the hydrological regimes. In the uplifted blocks, the soil has been deeply truncated and iron loss has been checked in the uppermost sediment. By contrast, mobilization of iron has been initiated at various places in the soil of the small grabens. In this way tectonic events have checked mobilization of iron in sediments but activated it in soils, leaving spectacular fingerprints on the landscape. 相似文献
6.
7.
Mandy Haggith Ravi Prabhu Happyson Mudavanhu Frank Matose Tendayi Mutimukuru Richard Nyirenda Wavell Standa-Gunda 《Small-Scale Forestry》2003,2(2):155-169
This paper explores the challenge of defining the scope of a systems model, emphasising three aspects: boundary, granularity
and conceptual scope. The significance of these is illustrated by reference to a model of land-use decisions made in villages
bordering on the Mafungautsi forest in Zimbabwe. The purpose of this model was to help policy players (Forestry Commission
staff, non-governmental organisations, researchers and local people) to understand the impact of policy interventions on local
people’s livelihoods. Scoping decisions that were made in building the Mafungautsi model were deliberately liberal, to encompass
the interests of all participants in the modelling process. These decisions now present a range of serious challenges: the
difficulty of model calibration, the computational expense of running simulations, and the difficulty for new users to understand
the model. Facilitators of modelling teams need to consider the serious implications of giving everyone what they want and
including all participants’ ideas in a model. In the long run, it may be better to be tough and reject many suggestions at
the outset. The former approach is unlikely to lead to a tractable model, while the latter may ultimately offer greater satisfaction
for all.
We are grateful to the UK’s Department for International Development (DFID) and the European Community for financial support
of this project. Thanks also to all of the ACM team who have contributed ideas on the process and content of the modelling
work and who make it fun to undertake collaborative research. Thanks also to the participants in the Zimbabwe FLAC workshops
for their input into the specification of the Mafungautsi model. Finally thanks to Robert Muetzelfeldt, Jasper Taylor, Jonathan
Massheder, Fergus Sinclair and Jerry Vanclay for helping us to ride on the FLORES bandwagon. 相似文献
8.
玉米秸秆水解残渣厌氧消化的产气性能 总被引：1，自引：1，他引：0
为了考察玉米秸秆水解残渣(Unhydrolyzed solid,UHS)的厌氧消化产甲烷潜力,研究了接种物类型、接种比例以及发酵温度对UHS产气性能的影响。结果表明,餐厨垃圾厌氧消化液作为接种物时,UHS具有较高的产气能力,累积甲烷产量达到208.06 m L·g~(-1)VS;UHS的累积甲烷产量与接种物对底物的比值(Inoculum to substrate ratios,RI/S)有关,其值随着接种比例的减小而逐渐降低,当接种比例RI/S为0.1∶1~3∶1时,累积甲烷产量为111.20~224.48 m L·g~(-1)VS,UHS的生物降解率为27.89%~56.29%,其降解能力随着底物浓度的升高而降低;在高温发酵(55℃)和中温发酵(35℃)条件下,相同接种比例的对照组中,UHS累积甲烷产量较为接近,但高温发酵的产气速率明显高于中温发酵。 相似文献
9.
Biology, damage pattern, incidence levels and status of the leaf miner Aphanisticus aeneus Kerremans (Coleoptera: Buprestidae) were studied in accessions of Saccharum spp. Egg, grub and pupal periods of the miner lasted 6.0 ± 0.8, 18.5 ± 1.9 and 7.0 ± 1.3 days, respectively; adults lived for 8–10 days. The grub tunneled the leaf on the lower surface just above the epidermis forming a linear channel; infested tissues showed brownish discoloration. The extent of leaf miner attack among the 331 accessions of Saccharum spp. ranged 4.00%–76.47% on cane basis and 7.14%–100.00% on leaf basis; the mined leaf area ranged 3.22–11.00 cm2. When the accessions were grouped on the basis of an infestation index developed with the above three parameters, 267 occupied very low category, 51 were in low category, 11 were in moderate category and 2 were placed in high incidence category. All accessions showed miner attack in at least one study year. Within each of the four Saccharum spp., accessions differed significantly among the three study years for all infestation parameters. Among the four species, while S. robustum accessions recorded significantly highest infestation index, the other three species remained on par. 相似文献
10.
Divya M. P. Shridhar Girish B. Mahajan Vijayendra P. Kamat Chandrakant G. Naik Rajashri R. Parab Nidhi R. Thakur Prabhu D. Mishra 《Marine drugs》2009,7(3):464-471
2-(2′,4′-Dibromophenoxy)-4,6-dibromophenol isolated from the marine sponge Dysidea granulosa (Bergquist) collected off the coast of Lakshadweep islands, Indian Ocean, exhibited potent and broad spectrum in-vitro antibacterial activity, especially against methicillin resistant Staphylococcus aureus (MRSA), methicillin sensitive Staphylococcus aureus (MSSA), vancomycin resistant Enterococci (VRE), vancomycin sensitive Enterococci (VSE) and Bacillus spp. Minimal inhibitory concentration (MIC) was evaluated against 57 clinical and standard strains of Gram positive and Gram negative bacteria. The observed MIC range was 0.117–2.5 μg/mL against all the Gram positive bacteria and 0.5–2 μg/mL against Gram negative bacteria. The in-vitro antibacterial activity observed was better than that of the standard antibiotic linezolid, a marketed anti-MRSA drug. The results establish 2-(2′,4′-dibromophenoxy)-4,6-dibromophenol, as a potential lead molecule for anti-MRSA and anti-VRE drug development. 相似文献