Many public-sector breeding programmes do not use explicit techniques to orient their programmes close to their clients' needs. Participatory techniques can be used to achieve high client orientation but these techniques do not have to involve farmers making selections during the segregating generations. This particularly applies when a sound initial market survey has been made or the learning from a participatory varietal selection (PVS) programme provides feedback to scientists. However, some published results on selection by farmers in the segregating generations (collaborative selection) indicate that it can produce appropriate varieties more effectively than less collaborative research. There is also evidence, from the few cases reported in the literature, that it is cost-effective. Alternative, less collaborative, approaches are also effective. Consultative forms of farmer participation, i.e. where farmers evaluate material grown by scientists, to aid selection in the segregating generations are more widely applicable because they demand fewer resources than collaborative methods. For more time-consuming tasks, such as in the selection of aromatic rice in segregating material, the most appropriate from of participation is contractual i.e., farmers are paid for their work. Mainly using examples from our research in Nepal, we present the particular circumstances in which the involvement of farmers in selection in the segregating generations is desirable or essential. These include: the occurrence of market failure (where the usual mechanisms of supply and demand have failed so there is no incentive to breed new varieties) and supply can only be met by actively involving farmers in the breeding process; when there are cost advantages to involving farmers – this is determined by the particular resources available to the institute undertaking the plant breeding research; when grain quality is both important and determined by a complex set of factors that are difficult to measure in the laboratory; when the objective is to learn in more detail about farmers' selection criteria to better orient the breeding programme to client needs; and when the goal is to empower farmers.

This paper analyses the way the CGIAR system has incorporated social research in its agenda. Since 1995, the social science staff capacity in the CGIAR has decreased by 24 %, and the overall balance of social science research is still significantly tilted away from the core germplasm enhancement, production systems/natural resources management, and technology adoption work – the ‘bread and butter’ of technology generation and development effort – toward ex-ante and ex-post activities. Further, the bulk of the social science research has low social research content despite the significant expansion of the CGIAR initial goal of increasing the proverbial ‘pile of rice’ to poverty alleviation and sustainable food security. The paper concludes that a concerted effort is now required to mainstream social research in the CGIAR system, and this cannot occur without the full support of the CGIAR donors, the CGIAR senior managers, and the centre boards and executive staff.

Over 90 % of the farmers around Marsabit Mountain, a pocket of arable land amidst a predominantly arid area in northern Kenya, are former pastoralists, unfamiliar with productive and sustainable farming technologies. This paper describes how encouraging farmer innovativeness enhanced adoption and adaptation of water-saving technologies to suit individual farmers' needs. When farmers understood the principles behind a technology they were more likely to adapt it. Both men and women farmers were most interested in increasing their available income through improved technologies, but more women than men ranked labour saving as an important attribute of a new technology. More women adopted the new technologies, but men used them on a larger area than women. The paper also shows that agricultural productivity can substantially increase even if the theoretical full potential of the recommended practices might not be achieved. It is concluded that farmers need to be exposed to new ideas in exciting and thought provoking ways to tap their innovation potential.

When differences are observed between genotypes in their response to low temperatures at germination, it has been generally assumed these are purely genetic. Laboratory experiments were carried out to evaluate the effects of physiological age on the temperature responses of 13 rice genotypes from Bangladesh in order to clarify whether (a) differences in seed germination at low temperature represented genetic differences or differences in the physiological state of the particular seed lot used and (b) whether genotype performance at higher temperatures was indicative of performance at lower temperatures. A higher initial seed moisture content (mc) was associated with lower initial viability (Ki). The base temperature for germination differed by less than 1 °C between genotypes. Seeds remaining ungerminated at low temperatures usually germinated when transferred to 21 °C. The thermal time requirement to reach t50 (θ) differed widely between genotypes. Lower optimum temperatures for germination were associated with lower thermal time requirements. Ageing seeds for 24 hours at 24 % mc and 45 °C significantly reduced final germination on a thermal gradient table at all temperatures below 20.8 °C in genotype BR29 but only below 16.5 °C in BR11. The rates of germination (seeds d−1) of aged seeds were also lower at all temperatures. Germination of high quality seeds of four genotypes were compared at 21 °C and 11 °C both before and after ageing (at 24 % mc and 45 °C). Ageing consistently reduced the rates of germination at both 21 °C and 11 °C. Increased ageing time progressively reduced the rate of germination of all seed lots at both temperatures. The rates of germination at 11 °C and 21 °C were positively and significantly (p < 0.01) related to final germination at the lower temperature of 11 °C. These results demonstrate that seed physiological quality as well as genotype might influence the final germination and rate of germination of rice genotypes at low temperatures. This information will be useful for breeders involved in selection of lines suitable for growing in cooler seasons.

Once in a while, every plant breeding project has to face a difficult situation: for example, objectives not reached, insufficient production of new genetic material, poor variety adoption and context change. In most cases, the problems are biological in nature, but they may also arise from poor situation analysis leading to inappropriate selection criteria or failing seed systems. We believe that plant breeders need special tools for analysing the human situations in which they are immersed. Such tools would assist them in identifying strategies which are favourable for one, several or all of the actors in a situation. Comprehensive sociology proposes a method derived from actionist analysis. This method relies on a situation description organized in a Panoramic or Pan Table (PT) and on empathetic induction by the breeder of the actors' positions. The PT facilitates the identification of the zones of potential conflict. This paper is methodological. We show how to use the PT method in a real situation for tactical or strategic purposes. In our example, the breeder has to elaborate a specification for a cotton breeding project in the case of a commodity chain that is co-ordinated by a national cotton company. After describing the PT method and its use, we discuss its limitations and the way human problems can be taken into account when elaborating strategies for action.

The aim of this work was to study the effects of soluble aluminium on the morphology and growth of the adventitious root system, aerial biomass and grain yield of maize (Zea mays). The analysis focuses on two hybrid cultivars (Al-sensitive HS7777 and Al-tolerant C525M). Experiments were carried out in the field and in a rhizotron in Curitiba, Paraná, Brazil. In the field, four levels of lime application were used: T0 = 0 t ha−1, T1 = 3.5 t ha−1, T2 = 7.0 t ha−1, and T3 = 10.5 t ha−1. Two levels were used in a rhizotron: T0 and T3. In the surface horizon (0–15 cm), the Al concentrations of the soil solution were: T0 = 15, T1 = 5.1, T2 = 4.4, and T3 = 3.1 μM. In the field, neither Al concentration in the soil solution nor cultivar affected the number of primary adventitious roots per internode or the total number of primary adventitious roots. However, root diameter, plant population and grain yield of the two cultivars confirmed the differences in Al tolerance between them. Al was observed to have an adverse effect on the grain yield from C525M, while low yields from HS7777, at all levels of Al, precluded any response to liming. In the rhizotron studies, Al concentration and cultivar affected the root branching and total root length. Cultivar C525M had more branches and total root length than HS7777, mainly at low concentrations of soil Al solution, leading to greater spatial colonization of the soil down to 0.9 m depth.

Participatory variety selection (PVS) was carried out in two of the major tef-growing woredas (districts) of Ethiopia, Ada and Akaki, in 2003 and 2004. The objectives were to identify farmers' selection criteria, to increase farmers' awareness and their access to improved tef varieties, to enable farmers to assess the performances of improved tef varieties of their choice and to accelerate seed dissemination of farmers' chosen varieties through farmer-to-farmer exchange mechanisms. Seed colour was the overriding selection criterion. Farmers overwhelmingly selected the very white seed variety DZ-01-196 (Magna) for market purposes, indicating that tef is a cash crop. Farmers also selected brown-seeded tef, but for home consumption. There was no evidence of connection between seed colour and desirable agronomic traits, or nutritional quality (protein content). Factors other than seed-colour were of secondary concern to farmers. When market demands become the dominant selection criteria, PVS should not be an end by itself: rather, it complements the formal breeding system. The results imply that tef performance evaluation trials need to be separated on a colour-group basis, and any new successful variety in the two woredas should be superior to DZ-01-196 not only in grain yield but also in seed-colour quality. A faster, more efficient and reliable pure-seed supply system than the traditional farmer-to-farmer exchange mechanism is required in order for farmers to continue planting improved varieties, which might be better achieved through small-scale commercial producers and/or cooperatives.

A field study of cowpea, soybean and maize was made at Ibadan, Nigeria, to determine the uptake of mineral nutrients and quantities removed in crop residues and seed. Concentrations of N, the major cations (K, Ca, Mg and Na) and major anions (P, S and Cl), and the micronutrients (Fe, Mn, Zn and Cu) were determined in shoots harvested at flowering and maturity. Concentrations of excess cations in shoots at flowering were 135 cmolc kg−1 for soybean, 158 cmolc kg−1 for cowpea and 58 cmolc kg−1 for maize. In crop residues and seed at maturity, the values decreased to 75 and 56 cmolc kg−1 respectively for soybean, 68 and 27 cmolc kg−1 respectively for cowpea, and 52 and 10 cmolc kg−1 respectively for maize. Nutrient and excess cation concentrations were also measured in 13 soybean and eight cowpea lines grown in replicated field trials at Fashola in the derived savanna zone and Shika in the northern Guinea savanna zone of Nigeria to assess the variation within these species. Maize, mucuna and lablab were included at these sites. The results are discussed in the context of soil nutrient depletion due to removal of nutrient elements in harvested seed and stover. The contribution of seed and stover removal to the proton (H+) budget and acidification of the soil is also discussed. It is estimated that the quantity of lime required to neutralize the acidity resulting from the removal of 1 t seed is 28 kg for soybean, 14 kg for cowpea and 5 kg for maize. The corresponding values for stover were soybean 35, cowpea 24 and maize 26 kg lime t−1 stover. Given the soil pH buffer capacity at the Ibadan site for the surface 16 cm, the yields obtained and assuming that seed and crop residues are removed, carbon cycle acidification would lead to a fall of 1 pH unit after 75 crops for soybean, 114 crops for cowpea and 68 crops for maize. The inclusion of legumes in cropping systems to increase N supply, and the use of P fertilizer to maximize N-fixation by legumes will raise production, but will inevitably accelerate removal of alkalinity and nutrients in harvested products, and the consequent decline in soil fertility. The data presented in this paper can be used in estimating the lime and fertilizer nutrients needed to maintain soil fertility and sustain yields.

The lack of good quality planting material of farmers' cassava varieties, produced locally and at low cost, is a major constraint limiting the expansion of cassava production in Colombia. This article describes the adaptation of conventional cassava propagation to a low-input scheme for rural tissue-culture multiplication, developed and run by small, resource-poor farmers (referred in this article as an informalfarmers' seed production system). Developed through a two-phase participatory process by a group of women farmers, a non-governmental organization and International Center for Tropical Agriculture scientists in a farmers' community in the hillsides of southern Colombia, the project resulted in alternative, economical and readily available sources of tissue-culture material and equipment. Rates of multiplication achieved with the system were as high as with conventional tissue-culture procedures.

Mixed cropping of teff (Eragrostis tef) with faba bean (Vicia faba) was compared with sole cropping in the 2002 and 2003 growing seasons at Holetta Research Centre, in the central highlands of Ethiopia. The treatments were sole teff (25 kg seed ha−1), sole faba bean (200 kg seed ha−1) and 12.5, 25, 37.5, 50 and 62.5 % of the sole seed rate of faba bean mixed with a full teff seed rate. A randomized complete block design replicated four times was used. Treatment effects were significant for seed and biomass yields of each crop species. Increasing the seed rate of faba bean in teff/faba bean mixture increased faba bean seed yield but decreased teff grain yield. Nonetheless, mixed cropping of faba bean with teff increased land use efficiency and gave higher total yields compared to growing either species in sole culture. Teff yield equivalent, land equivalent ratios (LERs) and system productivity index (SPI) of the mixtures exceeded those of sole crops especially when the seed rate of faba bean in the mixture was increased to 50 kg ha−1 (25 %) or more. The relatively high crowding coefficient values indicated yield advantages from mixed cropping of the two species. The highest values of teff yield equivalent, LER and SPI were obtained when faba bean was mixed at a rate of 62.5 % with the full seed rate of teff. We suggest that, at the current prices of the respective crops, up to 62.5 % of faba bean can be mixed in normal teff to get better total yield and income than sole culture of either species.