Wheat is fundamental to human civilization and has played an outstanding role in feeding a hungry world and improving global food security The crop contributes about 20 % of the total dietary calories and proteins worldwide Food demand in the developing regions is growing by 1 % annually and varies from 170 kg in Central Asia to 27 kg in East and South Africa The developing regions (including China and Central Asia) account for roughly 53 % of the total harvested area and 50 % of the production Unprecedented productivity growth from the Green Revolution (GR) since the 1960s dramatically transformed world wheat production, benefitting both producers and consumers through low production costs and low food prices Modern wheat varieties were adopted more rapidly than any other technological innovation in the history of agriculture, recently reaching about 90 % of the area in developing regions One of the key challenges today is to replace these varieties with new ones for better sustainability While the GR “spared” essential ecosystems from conversion to agriculture, it also generated its own environmental problems Also productivity increase is now slow or static Achieving the productivity gains needed to ensure food security will therefore require more than a repeat performance of the GR of the past Future demand will need to be achieved through sustainable intensification that combines better crop resistance to diseases and pests, adaptation to warmer climates, and reduced use of water, fertilizer, labor and fuel Meeting these challenges will require concerted efforts in research and innovation to develop and deploy viable solutions Substantive investment will be required to realize sustainable productivity growth through better technologies and policy and institutional innovations that facilitate farmer adoption and adaptation The enduring lessons from the GR and the recent efforts for sustainable intensification of cereal systems in South Asia and other regions provide useful insights for the future

/pdf/crops-that-feed-the-world-6-past-successes-and-future-57mr5z3ily.pdf

Crops that feed the world 6. Past successes and future challenges to the role played by maize in global food security

Food security is an urgent challenge It is a global problem that is set to worsen with current trends of population, consumption, climate change and resource scarcity The last 50 years have seen remarkable growth in global agricultural production, but the impact on the environment has been nsustainable The benefi ts of this green revolution have also been distributed unevenly; growth in Asia and America has not been matched in Africa Science can potentially continue to provide dramatic improvements to crop production, but it must do so sustainably Science and technology must therefore be understood in their broader social, economic and environmental contexts The sustainable intensifi cation of crop production requires a clear defi nition of agricultural sustainability Improvements to food crop production should aim to reduce rather than exacerbate global inequalities if they are to contribute to economic development This report follows other recent analyses, all arguing that major improvements are needed to the way that scientific research is funded and used

Reaping the Benefits: Science and the sustainable intensification of global agriculture

Species of Orobanche and Striga are among the most damaging parasitic weed species worldwide, but there are few reliable statistics on the full extent of the economic losses they cause. The distribution, host range and economic importance of the major species of Orobanche and Striga are briefly summarised. A review of literature over the period since 1991 suggests that many million hectares are infested and that the losses amount to $ US billions annually. Unfortunately there are almost no fully reliable figures on which to base these figures precisely. Meanwhile, there is little evidence of any significant change in intensity, range or losses caused over this period. Any reduction in the importance of these damaging weeds is sporadic, and alleviation of the problems is mostly localised. Furthermore, while the importance of Orobanche species may be broadly static, Striga species on cereals continue to become more serious in many countries owing to continued loss of soil fertility. It is suggested that new techniques may be needed for measurement of the extent of losses caused by these genera and their economic impact. There is continued urgency to develop control measures appropriate to the farming systems involved, and to reduce the risk of spread of both groups of parasite to new areas.

Observations on the current status of Orobanche and Striga problems worldwide

While witchweed is nearing eradication in the United States, it continues to thrive in other parts of the world, especially in Africa, together with other witchweed species. The continuing problems from witchweeds and other parasitic weeds, the broomrapes, dodders and mistletoes, are outlined, including their extent, the degrees of damage caused, and the difficulties in their control. While a small minority are being successfully controlled by the use of immune varieties, most are currently controlled by existing techniques only partially, or on a local basis, and they may even be spreading or intensifying. The challenges they present are emphasised. Nomenclature: witchweed, Striga asiatica (L.) Kuntze; dodders, Cuscuta spp.; broomrapes, Orobanche spp.; mistletoes, Viscaceae, Loranthaceae.

https://bioone.org/journals/Weed-Science/volume-60/issue-2/WS-D-11-00068.1/Parasitic-Weeds-A-World-Challenge/10.1614/WS-D-11-00068.1.pdf

Parasitic Weeds: A World Challenge

Molecular breeding in developing countries: challenges and perspectives.

Quality protein maize (QPM) describes a range of maize cultivars with twice the content of limiting amino acids lysine and tryptophan compared with conventional maize, and has been developed to help reduce human malnutrition in areas where protein deficiency is prevalent and where maize is the major protein source in the diet, as in various parts of Sub-Saharan Africa (SSA). The International Maize and Wheat Improvement Center (CIMMYT), in collaboration with the International Institute of Tropical Agriculture (IITA) and the National Agricultural Research Systems (NARS) in 17 countries of SSA, has developed a broad range of QPM cultivars responding to the needs of different countries and agroecological zones. Commercial QPM seed is currently available in all collaborating countries and, based on average 2003-2005 seed production, approximately 200,000 hectares of land are being planted to QPM cultivars.

	 

	Key words: Quality protein maize, opaque-2, en-modifiers, aa-modifiers, genetics, plant breeding, dissemination, impact assessment, human nutrition.

Breeding and disseminating quality protein maize (QPM) for Africa

Marker assisted selection in combination with conventional breeding can greatly accelerate the introgression of modified opaque2 genotype into herbicide resistant maize. By combining these two approaches, time and costs are greatly minimized. The application of opaque2 allele specific SSR markers was done on materials already undergoing selection in a breeding program for converting herbicide resistant maize lines into quality protein maize (QPM) which is the equivalent of modified opaque2 phenotype. The breeder had selected QPM lines using the light table in the previous cycle and we used leaf samples to extract DNA for analysis of the presence of the opaque2 gene using SSR markers. Two co-dominant SSR markers phi057 and umc1066 and a dominant marker phi112 were used. Umc1216, a modifier marker was also tested in combination with the opaque2 markers with the objective of using the marker to select for modifiers for the opaque2 phenotype. The modified FTA paper technology protocol was applied in field sampling. The results showed 97% of the lines were opaque2 while 3% were non-opaque2. Both methods of conventional breeding using light table and marker assisted selection (MAS) were comparable. However, the application of SSR markers and the FTA technology offers the breeder a fast, time saving, reliable and less labour intensive method of screening QPM maize during the early growing stages instead of having to wait to screen the kernels on the light table after harvesting. Moreover, the routine biochemical analysis for high lysine and tryptophan levels need not be carried out at each backcross since the presence of the opaque2 gene is confirmed with markers.

/pdf/marker-assisted-introgression-of-opaque2-gene-into-herbicide-4x7gm90md2.pdf

Marker assisted introgression of opaque2 gene into herbicide resistant elite maize inbred lines

Participatory plant breeding for drought resistant maize varieties in eastern Kenya

Breeding and agronomic approaches to managing abiotic stresses in maize.

Recent developments in participatory plant breeding for maize in Eastern Africa: experiences from Eastern Kenya.

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