Do we know enough about all crops of the world before we step into teasing evolution within the pool of a tiny number of species? Not well discussed and not well understood, an important tropical crop in Africa and other parts of the world reports: "Yam not a grain, yet I feed 60 million people every day. Yam a productive and valuable crop for farmers, getting as large as 2.5 meters long and weigh up to 70 kilograms. However, you know so little about how much I can give". Read the full story about the efforts of the Global Crop Diversity Trust (GCDT) for saving endangered yams in this month's Scientific American.

In recognition of the United Nations' declaration of 2010 as the 'International Year of Biodiversity', the Association for Tropical Biology and Conservation (ATBC) has included a special section on biodiversity in its September 2010 issue of Biotropica. The section includes 16 commentaries assembled by Jaboury Ghazoul, an ecologist at ETH Zurich and Editor-in-Chief of Biotropica. The editorials cover a wide range of issues relating to tropical biodiversity.

Starting the session, Ruben Kretzschmar talked about the „largest mass poisoning in human history“, the arsenic (As) crisis in Bangladesh. For Boro rice production, which makes up 50% of total, shallow ground water polluted with As is used for irrigation. The long-term study revealed an As input due to irrigation, on the other hand monsoon flooding that counteracts the As accumulation but does not prevent it. Thus current agricultural practices in rice production are not sustainable. Jan Jansa’s study subject was the arbuscular mycorrhizal fungi (AMF) symbiosis for maize in humid Cameroonian soil. AMF help the maize with nutrient acquisition, soil structure and soil biological activity. Soil of forest, short fallow and crop land was compared in regard to AMF. It revealed that the more intensified the practise, the higher the AMF impact on maize growth. Further, fungal communities in forest soil differed from other cropping systems and proved to be least beneficial to maize. Conservation agriculture of maize in salt-affected irrigation systems of Uzbekistan carries great potential to make a crop production system sustainable. Mina Dekota compared two tillage systems (permanent bed vs conventional tillage) and two residue levels (retained vs harvested). The results were remarkable: Compared to conventional tillage, the permanent bed had greater biomass production, higher grain yield, higher water productivity and lower soil salinity.

Using well recorded data of 42 years from a former cattle ranch at the coast of Tanzania, Peter J. Edwards showed impressively how farm management can influence a very fragile ecosystem. Changes in soil nutrient relationships and changes in vegetation mainly due to the grazing and the penetrating bush encroachment of Acacia zanzibarica were the result. Lutz Merbold’s case study in Miombo woodlands of Western Zambia unraveled the Charcoal Trap. An increase in energy demand and the migration of the people to the urban areas for employment call for an increased demand of charcoal since it has a higher energy density and is cheaper for transport. He concluded that the resulting increase of deforestation and thus additional carbon emissions are very large in developing countries. Depending on the resilience of woodlands, the lost carbon from forest degradation may be regained by reestablishment of forests and the consideration of alternative energy sources. The third talk took the audience to India’s coffee production. Virgine Boreux introduced the relationship between bee pollination of three main pollinators identified and the fruit set of coffee plantations. Pollination by bees has a long term impact extending until harvest. The study showed that the fewer sites that are flowering simultaneously, the higher bee abundance was found. In conclusion, irrigation triggering the flowering of the coffee could be used to attract bees. Thus asynchronous irrigation to the monsoon rains can be used in effective plantation management.

SUSANNE UFER: The Impact of Rice and Maize Price Volatility on Farm Households’ Income and Consumption in Northern Vietnam Since world food prices were fluctuating massively between 2006 and 2009, there was the concern that the income of farmers’ households in developing countries would decrease highly. According to a study conducted in Northern Vietnam, there was only a moderate impact of rice and maize price changes on the net income in rural areas. TIMOTHY J. KRUPNIK: Adaptive On-farm Evaluation of Resource Conserving Rice Cultivation Practices in the Middle Senegal River Valley Because of sub-optimal rice production in Sahelia, three quarters of the rice consumed in the country is imported. According to this, it is very important, to re-define the rice cropping system to increase the productivity of Sahelian rice farmers. Research has shown that farmers appreciate new cropping systems, but the best results were achieved by combining different systems like the Adapted System of Rice Intensification (ASRI) as well as the recommended management practices with the farmers’ former cropping practices. A side note to Rice Research: Ubud Rice Farmer

This is a sample of some of the great mixed cropping, agroforestry and biofuels oral presentations at Tropentag Strategies to Use Biofuel Value Chain Potential in Sub-saharan Africa to Respond to Global Change Enhancing Low-productivity Farming in Tanzania and Linking to SMEs – Stefan Sieber Some of the most significant global drivers stem from energy demands. This study examined new strategies to improve value chains and biofuel potential in order to provide communities in Sub-Saharan Africa with multiple energy services. The study took place in Tanzania, however global applications of the findings was one of the overall objectives. One way to improve energy demands in developing countries is though linking small scale farmers with small- to medium-scale enterprises. This research project worked with stakeholders in order to develop feasible strategies to maximize profit. The output from this collaborative effort was the development of global scenarios (applications in other countries), biomass production, consumption patterns, as well as a participatory biomass value chain. The objective of the research was to conduct a sustainability impact analysis and an information system for policy/decision support.

Gum arabic production by growing Hashab trees (Acacia senegal), contributs 12% to the GDP of Sudan and is threatened by drought and insect attack. To solve this problem, Maymoona Ahmed Eisa suggested to increase knowledge diffusion on insect pests in A. senegal and call for governmental and non governmental effort to encourage farmers to reestablish Hashab trees. Broomrape Phelipanche ramosa is an obligate root parasite. It is considered to be the most pestiferous of all Phelipanche spp due to ist high seed production, vigorous growth and lack of natural enemies. In a pot experiment, Tilal Abdelhalim studied arbuscular mycorrhizal fungi as a possible biological control agent in tomatoes. Colonization of tomato roots with three myccorhizal fungi Glomus spp suggested a potential to reduce seed germination. Still talking of tomatoes, there is no single control measure for bacterial wilt. Taking on this challenge, Henok Kurabachew tested the effect of silicon and a rhizobacteria. Silicon proved to be more effective than the rhizobacteria. Further, a dual apllication showed antagonistic effects unlike the application of one agent only.

This is a flavour of one of the six presentations that occurred in the Genetic Resources Oral Presentations on Wednesday, September 15th. Genetic Diversity and Adaptation of Date Palm (Pheonix dactylifera L.) – Sakina Elshibli The date palm produces sugar rich fruits which are cultivated in arid areas of the world. One kilogram of dates produces approximately 3000 calories. Palm dates also contain a wide range of nutrients, vitamins, and amino acids. The date palm can tolerate drought, but when the fruit is cultivated irrigation is needed. Date palms are useful because they provide small microclimates through shade. They also have a wide range of social and economic values, such as a housing material. This is especially true in Sudan where this study was carried out. There is an apparent diversity of date palms (fruit shape, side leaf structure, and morphology stages.) Dates are usually divided into two groups: dry and soft. In Sudan there is no genetic characterization of morphological variability in date palms. Over past twenty years production has increased, however stresses have also increased. These stresses include: floods, spread of diseases, desertification, and drought. Propagation is also a main constraint to increased cultivation. Date palm seeds are not suitable for cloning. It is only possible for few cultivars to be cloned, leading to date palm monocultures. A high percentage of off-types increase the risk of contamination for traditional cultivars.