Crop bioengineering provides unique and dramatic opportunities for international agricultural development. However, we consider the technology not as a ‘silver bullet’ or panacea for crop improvement in the developing world but as an increasingly important tool that can be used to complement conventional methods of crop improvement. The number of bioengineered crops ready for commercial release in developing countries is expected to expand considerably in the next few years. But the multi-national life sciences companies that are leading the research, development and commercialization of bioengineered crops focus primarily on major crops that have high commercial value and extensive international markets. These companies also hold proprietary gene technology for many other crops of extreme importance to subsistence and resource-poor farmers but do not pursue product development and commercialization because of low anticipated returns. Such crops have traditionally been overlooked and are sometimes referred to as ‘orphan crops’ because of the relative lack of research and development applied to them. We propose a strategy for the development and delivery of bioengineered crops, including orphan crops, for developing countries. Consulting local public and private sector stakeholders to determine their highest priority needs for agricultural products is the first step. This ensures local stakeholder buy-in and that we do not invest in technology that is unlikely to be adopted. Next, the feasibility of developing and delivering the product is assessed. If the result is positive, the work is organized into ‘product commercialization packages’ (PCPs) that integrate all elements of the research, development and commercialization processes. The main elements of each PCP include (i) technology development; (ii) policy-related issues such as intellectual property and licensing, as well as gaining regulatory approval by the relevant national authorities; (iii) providing public information to producers and consumers about the benefits, risks and correct management of these new products; and (iv) establishing, or verifying, the existence of marketing and distribution mechanisms to provide farmers access to planting material. Our strategy involves integration of needs-based capacity building, socio-economic impact studies and product stewardship into each PCP. Whenever appropriate, opportunities are sought to create public–private partnerships to help leverage public funds, help absorb development costs and provide a broader distribution channel. To illustrate how our strategy is being translated into action we include, as a case study, examples of work by the US Agency for International Development-funded, Cornell University-led Agricultural Biotechnology Support Project II on the research, development and delivery of bioengineered fruit and shoot-borer-resistant eggplant varieties (Solanum melanogena) for South and Southeast Asia.

Growth and photosynthetic performance of banana (Musa sp.) grown in three levels of natural shade (33, 55 and 77% reduction in incoming radiation) were compared to an unshaded control treatment. Net CO2 assimilation rates generally decreased with increasing shade. Chlorophyll fluorescence revealed short-term dynamic photoinhibition under high light conditions but no evidence of sustained photoinhibitory damage to photosystem II. Dynamic photoinhibition decreased with increasing shade, with the greatest depression in the variable to maximal fluorescence ratio (Fv/Fm) occurring in unshaded plants during the middle of the day. Specific leaf area and leaf area ratio increased proportionately with increasing shade, whilst the chlorophyll a/b ratio decreased, reflecting a greater efficiency of light utilization under shady conditions. The optimum shade level for photosynthetic productivity would be one at which the level of photosynthetic photon flux density (PPFD) is high enough to saturate CO2 assimilation but low enough to induce shade acclimation and to reduce photoinhibition. Under the conditions studied here, the saturation level of PPFD was around 1000 μmol m−2 s−1, a light level typical of the tree-based intercropping systems in which banana is commonly grown in the tropics.

An on-farm trial was conducted in the northern Guinea savanna of Nigeria, over a period of five years, with the objectives of quantifying the effects on maize of applying cattle manure in combination with synthetic fertilizer with regard to soil characteristics, yield, plant nutrition and profitability. Maize grain yield was significantly increased by the annual application of cattle manure, compared to maize receiving an equal amount of N through synthetic fertilizer, but only from the third year of the experiment. The application of manure resulted in higher soil Kjel N, Bray-I P and exchangeable K values, and an increased N utilization efficiency by maize, suggesting that yield-limiting factors other than N deficiencies were of lesser importance than in the treatment receiving sole inorganic fertilizer. Nutrients other than N applied via the manure, particularly P, K and/or B, may have contributed to the higher grain yields in treatments receiving manure. A partial budgeting analysis revealed that, over a 5-year period, investments in the application of manure, in combination with synthetic fertilizer, resulted in higher margins than the application of fertilizer alone. However, analyses of marginal rates of return of changes from low urea N to high urea N or additional manure applications suggested that it was more profitable to invest in additional urea than in organic manure in the first two years of the experiment. The results suggested that manure applications, even when applied at relatively high rates, did not serve as a quick fix to on-farm soil fertility problems, but over a longer period, manure applied in combination with synthetic fertilizers did provide a significant and profitable contribution to enhanced cereal production.

For 50 years, ‘hybrid vigour’ in crosses involving genotypes collected from the centre of diversity of the crop in the Peruvian Amazon has been the guiding principle of cocoa breeding. In the work described here, six Amazonian genotypes and one Trinitario clone were used to produce four bi-parental crosses. Twenty-two plants of each cross were propagated from plagiotropic buds as ‘cloned seedlings’ and evaluated for growth, yield and yield efficiency (the ratio of yield to continuing vegetative growth) in replicated trials in comparison with the parental clones and the reproduced seedling family. The reproduced seedling families grew faster than and outyielded all the clones in all four crosses, although they showed no gain in yield efficiency. The vigour and yield of the ‘cloned seedlings’ of the three inter-Amazon crosses exceeded mid-parent value (MPV), but not the single Trinitario cross. The pattern of departures from MPVs was inconsistent with current understanding of the genetic distance between the parents. The superiority of the seedlings over the ‘cloned seedlings’ is interpreted as an epigenetic effect. The results suggest that simple recurrent selection is an appropriate breeding strategy in cocoa, with different optimum planting densities for the seedling and clonal phases. It is concluded that if the concept of very large ‘hybrid vigour’ did not already exist in cocoa, it would not be adopted on the evidence of this work, the first in which clones were compared to their progeny grown as clones.

In the hilly areas of eastern Gujarat, western Madhya Pradesh and southern Rajasthan, in western India, farmers are very resource-poor and cultivate small and fragmented land holdings. Maize is their main rainy season (kharif) cereal and it is grown as a rainfed crop in low-fertility fields, often on sloping land that is vulnerable to soil erosion. Its productivity is very low, averaging below 1 t ha−1. New farm technologies to increase this productivity have to be low cost to be attractive to farmers who have limited access to purchased inputs and few means to purchase them. From observations of local farming practices, intercropping of maize with legumes was identified as an attractive option because the only additional input needed is seed of the legume crop. Participatory research was conducted on intercropping of maize with improved varieties of horsegram (Macrotyloma uniflorum). Many farmers who tried this intercropping adopted it in subsequent years, while others preferred to grow the new horsegram varieties as a sole crop. Farmers reported that less weeding was required in the intercrop as the horsegram smothered weeds. All farmers used the dry stover from the horsegram as a fodder for their animals. Farmers used the whole seed as dal, which provided additional protein in their diet. Farmers also sold the grain, but it fetched a low price in the poorly developed market for horsegram. Previously intercropping had been tried with local landraces, but the acceptance of intercropping was higher with new varieties such as AK-42 that yielded over 60% more grain. Participatory trials in which only one entry was compared with the local variety did not show a difference between AK-21 and AK-42 as in all cases both were preferred over the local variety. When they were directly compared with each other, farmers' perceptions showed a significant preference for AK-42. Variety IVH-2 was found to be better than AK-42: it matured 15 days earlier, better matching the maturity of the maize, had superior grain quality and yielded about the same. The greater uptake of improved horsegram varieties for sole and intercropping is likely to be limited by the lack of seed supply.

Striga hermonthica is a parasitic weed that attacks maize, sorghum and other staple cereal crops and has long been considered one of the greatest biotic constraints to cereal production in Africa. Use of resistant or tolerant maize varieties, a maize–legume rotation using trap crops that stimulate suicidal germination of Striga and the application of nitrogen fertilizer are all effective in reducing infestation and damage. This paper reports on the use of a participatory research and extension approach in assessing the performance and scaling-up of integrated Striga control packages in three agro-ecological zones in Borno State, Nigeria. The participatory process which encourages close interaction between research, extension and farmers, involved 30 local communities and 228 farmers representing 193 farmer groups in identifying their own problems and seeking solutions to them. Results showed not only effective Striga control but productivity increases of over 200%. The involvement of local farmers and groups in the evaluation process, firstly, helped to confirm that Striga control can best be achieved using soyabean followed by Striga-resistant maize together with productivity-increasing management practices and, secondly, promoted farmer-to-farmer extension. A participatory adoption assessment exercise indicated widespread adoption of new varieties and management practices, despite the need for increased labour. Great potential exists to scale out the results to similar areas of Guinea and Sudan savannas in the West Africa region.

A series of experiments was conducted on rice seedlings in a nursery seedbed and after transplanting in order to understand root and shoot characteristics, and their contribution to the production of tillers and dry matter. At the nursery stage, the seedlings' were studied at varying densities (high and low) and fertilizer treatments (with and without nitrogen) at 12 and 24 days after sowing (DAS) in wet or dry seedbeds. After transplanting, the effects of seedling age at the time of transplanting (12 and 30 days), method of raising seedlings (dry or wet seedbed) and water regimes (flooded or non-flooded) were studied. The overall aim was to understand the benefits, if any, of this system of rice intensification (SRI) management practices over conventional methods. The study revealed that in a nursery at 12 DAS, rice seedlings raised in a dry seedbed, irrespective of seeding density and fertilizer application, showed accelerated growth with better shoot and root characteristics in terms of greater leaf number, plant height, lateral root formation and elongation, and dry mass compared to seedlings grown in a wet seedbed. At 24 DAS, a significant interaction between seeding density and fertilizer application was found for dry-seedbed plants compared to those grown in a wet seedbed. Poor shoot and root growth was seen in older seedlings grown without fertilizer. Seedling age was found to be the most important factor affecting both shoot characteristics after transplanting (number of tillers, plant height, dry matter production) and root characteristics (root length density, root weight density). Younger seedlings performed better than older seedlings transplanted into either flooded or non-flooded soils with greater uptake of nitrogen and manganese than older seedlings. These results indicate that many of the constraints previously associated with non-flooded rice cultivation may be alleviated by transplanting younger seedlings that have been raised by SRI methods.

A field experiment was conducted in 2002/03 (year 1) and repeated in 2003/04 (year 2) to study the competitive ability of 10 winter barley (Hordeum vulgare) cultivars against common poppy (Papaver rhoeas) and ivy-leaved speedwell (Veronica hederifolia). The phytotoxic (or allelopathic) activity of barley extracts was also determined in the laboratory using a perlite-based bioassay with barnyard grass (Echinochloa crus-galli). In the field, biomass of both weeds was reduced more (65–79%) by the competition of Alpha, Esterel, Terova or Lignee 640 barley cultivars, than with Aspen or Tersey. Biomass of ivy-leaved speedwell in competition with each barley cultivar was significantly lower than that of common poppy. In year 1, the six-row barley cultivars caused greater weed biomass reduction than the two-row, but this was not the case in year 2. Grain yield of Tersey, Aspen and Goldmarker cultivars in herbicide treatments was greater by 41, 33 and 17%, respectively, than from the corresponding herbicide untreated plots. However, grain yield of Terova, Alpha, Esterel and Lignee 640 was not significantly affected by the presence of weeds. In the laboratory, barley extracts affected the total fresh weight or root length of barnyard grass more than its germination. The germination, root length or total fresh weight inhibition on barnyard grass caused by the two six-row barley extracts was greater (43, 48 and 56%, respectively) than that caused by the eight two-row extracts (22, 34 and 43%, respectively). The results of this study indicated that barley cultivars with great competitive and/or phytotoxic ability could be used in sustainable cereal production systems in order to minimize herbicide usage.

Small ruminants are an integral part of mixed-farming systems throughout southern Ethiopia. Yet, they have received little research attention or institutional support. Characterizing the existing small ruminant production systems and analysing their production constraints are important tools to diagnose the status and trends of the systems, and thus to identify areas for future interventions. A survey was conducted between April and July 2004 in the Adilo and Kofele areas of the southern mixed-farming systems of Ethiopia to explore reasons for keeping small ruminants and to evaluate the existing status of and the prospects for the small ruminant sector. Additional information was obtained during discussions with key informants who had experience of small ruminant keeping. Small ruminants fill several roles in the study area. However, the principal purpose of keeping sheep and goats was to generate cash income. Sheep milk consumption was widespread around Kofele unlike most agricultural systems in the country. Nearly all respondents in Adilo reported fattening their sheep before sale, while such a practice was uncommon in Kofele. Informal insurance schemes were evolving among the sheep keepers in Adilo, and these can be considered as entry points for future interventions. The common problem identified from both individual interviews and group discussions was feed shortage. The identification of alternative feed resources and strategic feeding management might be options for development. Small ruminant disease was the major constraint in Kofele, where marshy areas are increasingly assigned for grazing in the rainy season as suitable land is more and more used for cropping. The growing demand for meat from small ruminants, the improving transportation infrastructure and the experience of farmers in small ruminant keeping are providing opportunities to enhance the contribution of the sector. A thorough monitoring of the productive and economic performance of small ruminants is required to capture the full picture of their contribution thereby directing possible intervention areas to maximize benefits to the farmers.

This study examines the role, structure and effectiveness of informal seed systems in the diffusion of new barley varieties. It uses data collected by tracing farmers who received new barley varieties and other farmers who purchased seeds through farmer-to-farmer seed trade over a period of five years. The principal finding was that informal farmer-to-farmer seed dissemination was an important vehicle for the diffusion of new barley varieties, which were grow on 27% of the barley area of monitored farmers, despite a complete lack of extension support. Almost all seed exchanges were undertaken through purchases at market prices, highlighting the importance of markets in informal seed systems. The second main finding was the high concentration of seed sales among a few key seed suppliers, who established reputations as reliable sources of seed and had contacts with research organizations. The importance of market-based local seed transactions implies that farmers specializing in seed sales can invest in local seed enterprises and provide sustainable services at affordable prices. The results of this study indicate great potential for supporting local seed suppliers in order to ensure a sustainable flow of new crop varieties to smallholder farmers in the dry areas. The study also examined farmers' criteria in evaluating and eventually adopting a new variety. These criteria depend on agro-ecological zones with more complex criteria in drier areas with high rainfall variability. These findings will help plant breeding programmes to target dry and marginal areas, where access to new varieties is low, more effectively.