At its International Centres Week in October 2000 (ICW2000), the Consultative Group on International Agricultural Research (CGIAR) adopted a new Vision and Strategy. This paper is about Plank 4 of the CGIAR's Vision and Strategy which calls for the adoption, in collaboration with national and regional partners, of a regional approach to research planning, priority setting and implementation. Given the poverty and impact focus of international public goods research, both national agricultural research systems (NARS) and the CGIAR have advantages in pursuing a regional approach as a component of their respective activities. For the NARS in the region, this means seeking advantages at the regional level that they could not derive solely from a national-level approach. For the CGIAR, this means seeking complementary gains that it could not achieve exclusively through a global or ecoregional approach. These mutual advantages open the door for partnerships in regional research between NARS and their regional organizations, and the CGIAR. The paper highlights the advantages as well as risks and limitations of a regional approach to research. Since ICW2000, all regional and sub-regional organizations and CGIAR Centres have taken action to facilitate consultation processes that could eventually lead to the establishment of a regional approach to research for the CGIAR and NARS. The paper notes some emerging lessons, and takes a forward look.

A survey of barley and barley-based farming systems was carried out in Palestine during the 2000 growing season to assess traditional cultivation methods and to analyse developments in the production systems. Seventy-six farmers in the three barley growing agro-ecological zones in the West Bank were included in the study. The research area encompasses a range of agro-ecological conditions, from high to low potential environments, strongly related to precipitation. Estimated grain yields varied from below 1000 kg ha−1 in the driest part of the Eastern Slopes zone to above 4000 kg ha−1 in the more fertile areas in the Central Highlands and Semi-Coastal zones. Barley was found to be closely linked to the dominant crop-livestock farming systems. Thus 84% of the farmers interviewed grew barley as a feed for their own livestock during the dry season. In the more fertile agro-ecological zones, the traditional farming system is shifting towards more intensive production methods with increased mechanization, mainly for land preparation, sowing, harvesting and use of fertilizer. Here animal production is becoming more intensive and a larger proportion of the farm products, including barley, is now produced for the market. Despite the relatively high yields, in comparison to other barley growing areas in the region, local barley landraces, particularly 6-rowed types, persist well and were preferred by 86% of the farmers interviewed. However attempts to modernize agriculture may result in the replacement of traditional barley landraces, and even the barley-livestock cropping system in the more fertile agro-ecological zones. An effort should therefore be made to conserve this valuable genetic resource.

In this study, different levels of defoliation were imposed on a determinate species (maize) and a relatively indeterminate species (cotton). The aim was to quantify the effects of defoliation on plant growth and production, under either optimum or water-stressed conditions. Under well-watered conditions, 33% defoliation twice (conducted 28 and 35 days after emergence) resulted in a 16% reduction in grain yield of maize while 67% defoliation once (conducted 28 days after emergence) had no significant effect on yield. Under water stress, the grain yields of maize plants with 33% (twice) and 67% defoliation were 13.5% and 25% greater than that of non-defoliated control plants, respectively. For cotton, the reproductive yields (seed and lint) with 33% and 67% defoliation (conducted 43 days after emergence) were reduced, under well-watered conditions, by 28% and 37% of that of the non-defoliated control, respectively. Defoliated cotton plants lost less fruiting forms (squares and young bolls) than non-defoliated plants during water stress. Therefore, under water stress the harvestable product of cotton plants with 67% defoliation was double that of non-defoliated control plants. In non-defoliated cotton plants, a second flush of flowering after release from water-stress permitted further compensatory fruit set and boll harvest. Defoliated plants did not show such levels of compensation. Defoliation significantly reduced water use by maize and cotton. The relative yield advantage of defoliated plants under water-stress conditions can be attributed to defoliation-induced improvement in water status as reflected in measures of photosynthetic rate and stomatal conductance. Under anticipated drought stress, defoliation could be an important management practice to reduce drought-induced yield decrease, but this needs to be tested under field conditions.

Growth and water use of sole crops and intercrops of morphologically contrasting maize and pea cultivars were measured in two years. The maize cultivars were Nancis with erectophile and Sophy with planophile leaves and the pea cultivars Maro a leafy pea and Princess a semi-leafless pea. In the first part of the season water use was lower for sole maize but intercrops and sole pea used similar amounts of water. By 90 days after sowing, when peas had matured, all crops had used similar amounts of water. Maize had slightly greater water use efficiency than peas. Cultivars Nancis and Princess tended to have greater water use efficiency than Sophy and Maro respectively. Intercrops produced more dry matter than sole crops and therefore had consistently greater water use efficiencies.

The parasitic angiosperms, Striga hermonthica and S. gesnerioides, obligate root parasites endemic in sub-Saharan Africa, constitute severe constraints to cereal and legume production in West and Central Africa. Over the years, a range of effective component technologies has been identified for Striga control in Africa. The potential of these technologies has been demonstrated under researcher-managed conditions. To promote farmer testing of the technologies, community workshops were conducted in 42 rural communities in Kaduna State, northern Nigeria. These revealed that agriculture was the main source of livelihood for most households. The three most important crops, maize, sorghum and pearl millet are attacked by S. hermonthica, regarded as the major constraint to crop production, often causing 70–100% crop loss. Farmers recognised two types of Striga damage (underground and aboveground), with greater damage being caused by underground Striga. Farmers attributed increasing incidence and severity of Striga damage to lack of capital, poor soil fertility, infestation of previously uninfested land by Striga seeds, and continuous cropping of host crops. The most widely used among the 15 existing Striga control techniques identified by the farmers were hoe weeding and hand pulling, application of inorganic fertilizer and manure, crop rotations, fallowing, and early planting. In assessing possible control measures farmers considered increased crop yield, reduced Striga reproduction and Striga emergence, greater crop vigour, and increased soil fertility as positive attributes. Negative attributes comprised increased labour requirement, higher costs, increased risk of crop damage or yield reduction, and lower quantity and quality of produce. Overall, a legume-cereal rotation was the most highly rated control option for S. hermonthica management evaluated by the farmers. The implications of these results are examined with respect to farmers' adoption and adaptation of Striga control options beyond the experimental plots.

The effect of ‘on-farm’ seed priming – soaking seeds in water before surface-drying and sowing them – was tested for mungbean (Vigna radiata) in 15 irrigated on-station trials and four sets of rainfed, paired-plot, farmer-participatory trials over four contrasting years from 1999 to 2002 in the North West Frontier Province of Pakistan. The optimum soaking time was found to be between six and eight hours; eight hours was used in all the trials. Of the 19 trials, priming was significantly better than non-priming in 14 with a mean yield increase of 56%. In the remaining five trials there was no difference between treatments but in no case was priming worse than not priming. In a subset of 11 on-station trials in which management was considered to be optimal, yield declined in a linear fashion as the date of sowing was delayed. The rate of decline of about 30 kg ha−1 d−1 after 1st June was similar for both non-primed and primed crops, although the latter declined from a higher base. Farmers' yields were proportional to rainfall over the four years and the mean increase in grain yield due to priming in the 39 trials was 30%. Benefits from priming were the result of a combination of faster germination and emergence and more vigorous growth and development, leading to better crop stands and bigger, more productive plants. It was concluded that ‘on-farm’ seed priming is a low-cost, low-risk technology that has the potential to raise mungbean yields substantially thus making it a more attractive crop for farmers.

Mineral fertilizer application and consequent plant nutrition has long been observed to influence associated plant-parasitic nematode population densities, offering the potential as a nematode management option. Observations were made on the influence of mineral fertilizer application on nematode populations on three separate long-term rice experiments, (differential mineral application on upland and on lowland rice, and P application on upland rice) undertaken between 1994 and 1997 in Côte d'Ivoire. In 1995, on upland rice, treatments with K or N withheld from the comprehensive mineral application treatment (range of elements including N, P, K, Ca, Mg and Zn) led to lower densities of Pratylenchus zeae at harvest than the comprehensive mineral application. By withholding K or Mg, Helicotylenchus pseudorobustus densities were greater than with either the control (no mineral application) or comprehensive mineral application in the same year. No differences were observed between treatments in 1994, or between treatments for densities of other nematode species present (Meloidogyne incognita, Criconemella tescorum) or for total nematode density. In the lowland rice trial, no treatment effects on nematode species (Hirschmanniella oryzae and Uliginotylenchus palustris) were observed. In the P application trial on a P-deficient Ultisol, Heterodera sacchari densities were lower in treatments receiving 180 kg P ha−1, than untreated in 1995; in 1996 no differences were observed between untreated and 135 kg P ha−1, while in 1997 higher densities of H. sacchari were present in 135 kg P ha−1 than untreated. Regression analysis of nematode densities against the mineral straw content in the P application trial revealed a negative correlation between M. incognita and Mn and Ca, and between P. zeae and Zn or Fe. A positive correlation was observed between Helicotylenchus spp. and Mg. This study provides strong arguments for taking plant parasitic nematodes into account when planning and executing long-term research trials.

The legume Arachis pintoi has a number of characteristics which enable it to make a valuable contribution to the development of sustainable and productive pastures in the tropics. It was introduced to Costa Rica for this reason, in 1987. The objective of this study was to analyse the adoption of A. pintoi as a forage legume in Huetar Norte, a region in the north of Costa Rica. The adoption process was analysed to identify the contributory factors and to make recommendations for measures which could be taken to promote the process. To collect the data, 115 randomly selected livestock holders and an additional 34 farmers known to have planted A. pintoi were interviewed. Farmers see improved pastures to be the most important technology to enhance forage and cattle production. It was confirmed that A. pintoi is a potential improved pasture alternative. Although A. pintoi was well known., the adoption rate was low. Lack of availability of seed, technical assistance and information about the use and management of A. pintoi hinder adoption. Difficulties in establishment and maintenance were also recorded.