Summaries (En)

Climate change will not only affect crop biomass production but also crop quality. While increasing atmospheric CO2 concentrations are known to enhance photosynthesis and biomass production, effects on the chemical composition of plants are less well known. This is particularly true for major crop plants with respect to harvestable yield quality. Moreover, it remains open, how these effects on quality may be realized under field conditions and how management (e.g. plant N nutrition) or environmental factors (e.g. water availability) will alter impacts of elevated CO2. Here we report on a series of free air CO2 enrichment (FACE) experiments with wheat and barley and with maize in which effects of elevated CO2 combined with different levels of N supply (wheat and barley) and with drought stress (maize) on grain and biomass quality characteristics were investigated. Winter wheat and winter barley (1st experiment) and maize (2nd experiment) were grown in the field each for two growing seasons under ambient and elevated CO2 concentration (FACE, 550μmol mol-1). Wheat and barley were grown under adequate N supply and under 50% of adequate N as sub-treatments. In the maize experiment rain shelters were used to create two different levels of plant water supply (well-watered and drought stress – about 50% of well-watered) as sub-treatments. Treatment effects on elemental composition and a variety of quality characteristics of the plant material at final harvest were investigated. This included a detailed analysis of wheat grain protein components and of different fiber fractions of maize. Compiled results of the relative effects of elevated CO2, N and drought stress treatments on different quality parameters of the crops are presented.

Ethiopia has a long history in which the food demands of rapidly growing population have periodically outstripped the productive capacity of the land, and this is particularly true in the dryland areas of the country. This has led to a decrease agricultural productivity and environmental degradation of the natural resource base. As the main source of economic activity in SSA is the agricultural production, declining soil productivity means not only less food is grown but also that production of cash crops and income are endangered. Thus, rectifying land degradation and enhancing productivity through appropriate soil management and conservation can play a major role in achieving farm household food security and agricultural development. This publication reviews issues related to land degradation, with focus on problems of soil fertility management in SSA. It highlights some successful experiences in the region, constraints and possible solutions specific to the major agro-ecological zones and the importance of holistic and participatory approaches for soil productivity improvement. The need for action and collaborative efforts of all stakeholders, within the framework of ongoing initiatives are emphasized. It is hoped that his document will contribute to increasing awareness of senior specialists and police-makers about the problems and alternative solutions towards enhanced and sustained soil productivity. This article assesses the major crop production constraints and their causes as related not only to the physical environment (climate, soils) but also in light of some of the important socioeconomic and policy problems. Details of some of the major crop production problems including drought (water stress), low soil fertility, pest infestation, lack of appropriate farm implements, and both socioeconomic and policy problems are indicated. The article also gives some examples of the available technologies and assess their practicality in relation to the low technology adoption by the smallholder farmers. Based on this research gaps are identified and future research strategies for sustainable crop production is proposed. Finally recommendation and suggestions on requirements in terms of capacity building in research and extension including trained manpower and facilities and other improvements in socioeconomic and policy issues required to improve crop production on sustainable basis for the resource poor smallholder farmers of the dry land areas of Ethiopia are forwarded.

Four plots have been planted with homogeneous material of Pinot noir cultivar on typical soils of Chamoson area (Valais, Switzerland). Conducted from 1997 to 2000, this research allowed pointing out the influence of water nutrition on agronomical and oenological potential of Pinot noir. In a situation without water restriction, vigour was clearly higher and budburst was delayed. In the must, soluble solids content was lower in absence of water constraint, while malic acid and nitrogen contents were higher. Meanwhile, pH remained relatively constant due to higher potassium content. In fact, any situation inducing regular and moderate water restriction during ripening did led to wines with more polyphenols and more qualitative tannins, which were preferred by the panel of tasters.