Debate on the Exploitation of Natural Plant Diversity to Create Late Blight Resistance in Potato

This paper reports on a debate on intriguing propositions relating to the scientific, agronomic, societal and economic impact of the BIOEXPLOIT project, focusing on late blight resistance in potato. It discusses (i) whether identifying pathogen effectors will facilitate selecting durable R genes, (ii) whether breeding for durable late blight resistance requires deploying Rpi (for Resistance to P hytophthora i nfestans) genes, (iii) whether breeding strategies and cultural practices determine the durability of new resistance genes, (iv) whether marker-assisted breeding for Phytophthora infestans resistance is already in the stage of adoption, (v) to what extent genetically-modified organism technology can advance realizing late-blight resistant potato cultivars, and (vi) whether modifying R genes will result in novel broad spectrum resistanc

HIV and orientation of subsistence and commercial home gardens in rural Ghana: Crop composition, crop diversity and food security

An empirical study was conducted to explore differences and similarities in biodiversity in subsistence and commercial home gardens of HIV-positive and HIV-negative rural households in the Eastern Region of Ghana and their significance in household food security. Data were obtained through a household and home garden survey of a purposive sample of 32 HIV-positive and a random sample of 48 HIV-negative rural households and through in-depth interviews. A higher proportion of species common to all four home garden types consisted of food crops: vegetables, staples and fruits. In HIV-positive households, commercial home gardens were significantly larger, had significantly more species and individual plants, more perennial food crops and more species that were harvested all year round and evenness was lower, but there was no significant difference in species diversity compared with subsistence home gardens. Significantly, more HIV-positive and HIV-negative households with a commercial home garden consumed a staple crop cultivated in the home garden in the 24-h period prior to the survey than HIV-positive households with subsistence home gardens. Rural households with HIV that manage commercial home gardens cultivate a dual purpose home garden which supplies subsistence food and also provides cash income; such households may have better food security than households that cultivate subsistence home garden

Effects of shade on growth, production and quality of coffee (Coffea arabica) in Ethiopia

The research work was conducted to evaluate the effect of shade on growth and production of coffee plants. To achieve this, growth and productivity of coffee plants growing under shade trees were compared with those of coffee plants growing under direct sun light. Different physiological, environmental and quality parameters were assessed for both treatments. Shade trees protected coffee plants against adverse environmental stresses such as high soil temperatures and low relative humidity. Shade, however, also triggered differences in physiological behaviour of the coffee plants, such as improved photosynthesis and increased leaf area index, resulting in better performance than possible in direct sun light. Consequently, coffee plants grown under shade trees produced larger and heavier fruits with better bean quality than those grown in direct sun light. Moreover, shaded plants had greater biochemical and physiological potential for high dry matter production which would help them to maintain high coffee yields in the long term. If growing coffee under shade trees would allow other sources of income such as fruits, fuel wood and timber to be produced, it could be socially more acceptable, economically more viable and environmentally more sustainable. Since in Ethiopia people are moving towards replacing coffee by ‘chat’ and/or growing coffee in an open sun, we support the recommendations of growing coffee in the shade and suggest that the future research should be directed toward deterring the development of fungal diseases and increase of coffee yields under shaded conditions

Nitrogen phytoremediation by water hyacinth (Eichhornia crassipes (Mart.) Solms)

The phytoremediation potential of water hyacinth, Eichhornia crassipes (Mart.) Solms, was examined in two independent studies under nitrogen (N) rates of 0, 40, 80, 100, 150, 200, and 300 ppm. A modified Hoagland solution was added to ponds containing water hyacinths which were rated and measured weekly for 4 weeks. The hyacinths accounted for 60¿85% of the N removed from solution. Net productivity, as measured by dry matter gain, increased with an increase in N rate until 80 ppm. Above that level dry matter productivity was similar. Tissue N increased linearly with dry matter gain, but total nitrogen removal from the water increased exponentially with net dry matter gain or with an increase in canopy cover. The relation between total N in plant tissue and N removal from the water was similar for the two experiments

Wheat and barley seed system in Syria: farmers' varietal perceptions, seed sources and seed management

A total of 206 wheat and 200 barley farmers were interviewed in northeastern Syria to understand farmer perceptions and practice relating to modern varieties, seed sources and seed quality. Wheat farmers had better awareness and grew modern varieties (87%), applied fertilizers (99.5%), herbicides (93%), seed treatment (90%) or insecticides (41%). In contrast barley growers had low awareness (36%) and use (0.5%) of modern varieties, herbicides (4%), insecticides (3%) and fertilizers (56%). Grain yield, grain size, food quality and tolerance to lodging, drought and frost were the agronomic characteristics farmers sought from new wheat varieties. For barley, grain yield, grain size, grain color, feed quality, marketability and tolerance to diseases and drought were the key traits sought. The informal sector-seed retained from the previous harvest or obtained from neighbors or local traders/markets-was the main source of seed for both wheat and barley. Most farmers practiced onfarm seed selection, cleaning, treatment, separate storage or quality assessment of seed that was obtained locally. Farmers’ perceptions and preferences of new varieties/technologies and their seed sources and seed management practices must be taken into account in any efforts to develop or to strengthen seed sector developmen

Unlocking the potential of contract farming: lessons from Ghana

This paper analyses sorghum contract farming in north-east Ghana in order to explore ways of making such arrangements viable for small farmers. The analysis draws on the convergence of sciences approach, which sees both science and social relations (interactions among the relevant stakeholders) as important for developing small farmer-relevant agricultural innovations (technology, procedures, new forms of organisation). The study reveals that the failure and problems encountered in this particular contracting scheme were both technical and institutional. The technical issues were a combination of pest problems, the environment and the sorghum variety chosen. The institutional issues involved the contractual arrangements and relations between the contracting parties. The authors argue that if contracts are to be fair, they must allow for compensation, contingencies and production risks. But scientific knowledge is required in order to adequately incorporate these elements