Climate change and unfavorable rice environments: overview of approaches to assess trends and future projections

The likely impacts of climate change on rice-based agroecosystems in Asia are uncertain, especially for rainfed rice systems in theunfavorable environments that are vulnerable to precipitation changes. Regional impacts of climate change are typically assessedquantitatively through spatially downscaling a global circulation model (GCM), but this approach is inherently biased through the GCMselected, which is typically not more than one. In this paper, we pursue a different approach that is based on an ensemble analysisof several GCMs. In the first section, the ensemble analysis is illustrated by using two rainfed rice environments (in eastern India andBangladesh) as examples. Although the different GCMs showed a similar overall trend of declining precipitation, major discrepancieshave occurred in seasonal aspects of climate change. The spatial downscaling of predicted changes in precipitation projected thatthe changes are varying throughout the months and regions, probably further increasing the severity and the areas already plaguedby floods and droughts. The second section of the paper assesses the potential and constraints of seasonal forecasting as a meansto alleviate losses in rice production. Drought is a major production constraint in rainfed rice, so that forecasts on drought occurrencecan be used to alleviate losses. In a broader sense, short-term and long-term climate projections could be a key for achieving rising productivity in unfavorable rice environments.Kay Sumfleth and Stephan M. Haefel

Glass-fibre-reinforced composites with enhanced mechanical and electrical properties - Benefits and limitations of a nanoparticle modified matrix

Nanoparticles and especially carbon nanotubes (CNTs) provide a high potential for the modification of polymers. They are very effective fillers regarding mechanical properties, especially toughness. Furthermore, they allow the implication of functional properties, which are connected to their electrical conductivity, into polymeric matrices. In the present paper, different nanoparticles, as fumed silica and carbon black, were used to optimise the epoxy matrix system of a glass-fibre-reinforced composite. Their nanometre-size enables their application as particle-reinforcement in FRI's produced by the resin-transfer-moulding method (RTM), without being filtered by the glass-fibre bundles. Additionally, an electrical field was applied during curing, in order to enhance orientation of the nanofillers in z-direction. The interlaminar shear strengths of the nanoparticle modified composites were significantly improved (+16%) by adding only 0.3 wt.% of CNTs. The interlaminar toughness G(Ic) and G(IIc) was not affected in a comparable manner. The laminates containing carbon nanotubes exhibited a relatively high electrical conductivity at very low filler contents, which allows the implication of functional properties, such as stress-strain monitoring and damage detection

Rice and global climate change

Climate change has many facets, including changes in long-term trends in temperature and rainfall regimes with increasing year-to-year variability and a greater prevalence of extreme events. The effects of these changing conditions on agriculture are already being seen, yet there are still considerable gaps in our knowledge of how agricultural systems will be affected directly or indirectly by the changing climate, and what implications these changes will have for rural livelihoods (IPCC 2007). Climate change gives an additional burden to the world’s agricultural and natural resource systems that must already cope with the growing food demand driven by population growth and higher incomes in developing countries. The challenge is compounded by the uncertainty and pace of climate change and its effects regionally. It is increasingly clear that climate change will affect agricultural productivity. The temperature and precipitation changes that accompany climate change will require farmers to adapt, but precisely where and how much is uncertain. At the same time, as a significant contributor of greenhouse gases and a potential sink for atmospheric carbon, agriculture can help mitigate climate change. In this chapter, we discuss the issues for rice agriculture in a world where climate change is increasingly a reality. The purpose of this review is to provide a comprehensive overview on (1) the expected impacts on rice production at different scales, (2) possible mitigation and adaptation options available to rice farmers, and (3) the economic implications of climate change and climate change policy. Many of the impacts of climate change on rice production discussed in this review are applicable to other food crops as well, but, in spite of these commonalities, we highlight several “rice-specific” aspects that warrant an in-depth discussion of the impacts of climate change as well as possible adaptation and mitigation options

Climate change affecting rice production: the physiological and agronomic basis for possible adaptation strategies

This review addresses possible adaptation strategies in rice production to abiotic stresses that will aggravate under climate change: heat (high temperature and humidity), drought, salinity, and submergence. Each stress is discussed regarding the current state of knowledge on damage mechanism for rice plants as well as possible developments in germplasm and crop management technologies to overcome production losses. Higher temperatures can adversely affect rice yields through two principal pathways, namely (i) high maximum temperatures that cause-in combination with high humidity-spikelet sterility and adversely affect grain quality and (ii) increased nighttime temperatures that may reduce assimilate accumulation. On the other hand, some rice cultivars are grown in extremely hot environments, so that the development of rice germplasm with improved heat resistance can capture an enormous genetic pool for this trait. Likewise, drought is a common phenomenon in many rice growing environments, and agriculture research has achieved considerable progress in terms of germplasm improvement and crop management (i.e., water saving techniques) to cope with the complexity of the drought syndrome. Rice is highly sensitive to salinity. Salinity often coincides with other stresses in rice production, namely drought in inland areas or submergence in coastal areas. Submergence tolerance of rice plants has substantially been improved by introgressing the Sub1 gene into popular rice cultivars in many Asian rice growing areas. Finally, the review comprises a comparative assessment of the rice versus other crops related to climate change. The rice crop has many unique features in terms of susceptibility and adaptation to climate change impacts due to its semiaquatic phylogenetic origin. The bulk of global rice supply originates from irrigated systems which are to some extent shielded from immediate drought effects. The buffer effect of irrigation against climate change impacts, however, will depend on nature and state of the respective irrigation system. The envisaged propagation of irrigation water saving techniques will entail benefits for the resilience of rice production systems to future droughts. We conclude that there are considerable risks for rice production stemming from climate change, but that the development of necessary adaptation options can capitalize on an enormous variety of rice production systems in very different climates and on encouraging progress in recent research. © 2009 Elsevier Inc. All rights reserved.R. Wassmann, S.V.K. Jagadish, S. Heuer, A. Ismail, E. Redona, R. Serraj, R.K. Singh, G. Howell, H. Pathak, and K. Sumflet

Regional vulnerability of climate change impacts on Asian rice production and scope for adaptation

Also cited as: Advances in Agronomy, vol. 102, 2009 / D.L. Sparks (ed.), Ch.3 pp. 91-133Rice is the principle staple crop of Asia and any deterioration of rice production systems through climate change would seriously impair food security in this continent. This review assesses spatial and temporal vulnerabilities of different rice production systems to climate change impacts in Asia. Initially, the review discusses the risks of increasing heat stress and maps the regions where current temperatures are already approaching critical levels during the susceptible stages of the rice plant, namely Pakistan/north India (Oct.), south India (April, Aug.), east India/Bangladesh (March-June), Myanmar/Thailand/Laos/Cambodia (March-June), Vietnam (April/Aug.), Philippines (April/June), Indonesia (Aug.) and China (July/Aug.). Possible adaptation options for heat stress are derived from regions where the rice crop is already exposed to very high temperatures including Iran and Australia. Drought stress is also expected to aggravate through climate change; a map superimposing the distribution of rainfed rice and precipitation anomalies in Asia highlights especially vulnerable areas in east India/Bangladesh and Myanmar/Thailand. Then, the review gives emphasis to two rice growing environments that have outstanding importance for food supply in Asia and, at the same time, are particularly vulnerable to climate impacts. The mega-deltas in Vietnam, Myanmar and Bangladesh are the backbone of the rice economy in the respective country and will experience specific climate change impacts due to sea level rise. Significant improvements of the rice production systems, that is, higher resilience to flooding and salinity, are crucial for maintaining or even increasing yield levels in these very productive deltaic regions. The other ‘hotspot’ with especially high climate change risks in Asia is the Indo-Gangetic Plains (IGP) which will be affected by the melting of the Himalayan glaciers. The dominant land use type in the IGP is rice-wheat rotation, and we discuss specific vulnerabilities and possible adaptation options in the different sub-regions of the IGP. We conclude that geo-spatial vulnerability assessments may become crucial for planning targeted adaptation programs, but that policy frameworks are needed for their implementation.R. Wassmann, S. V. K. Jagadish, K. Sumfleth, H. Pathak, G. Howell, A. Ismail, R. Serraj, E. Redona, R. K. Singh and S. Heue

Zum Einfluss von kooperativem Arbeiten auf Interesse und Kognition im Chemieunterricht

Sumfleth E, Rumann S, Butler N, Wild E, Gerber J, Exeler J. Zum Einfluss von kooperativem Arbeiten auf Interesse und Kognition im Chemieunterricht. In: Bayrhuber H, Gelhaar K-H, Harms U, et al., eds. Biowissenschaften in Schule und Öffentlichkeit. Kiel: IPN; 2001: 195-198