Farmers have grown barley for thousands of years, both for food and animal feed. Archaeological evidence suggests that barley was once more popular than wheat in North Africa. It had a reputation for being a 'strong' food, and was an important part of the diet of Roman gladiators-who were called 'hordearii,' meaning 'barley-men.' Today, barley is widely grown for animal feed, and for making malt. It is still an important staple food, especially in regions of high altitude and low rainfall where many of the world's poorest people live. In 2002, participatory plant-breeding research provided valuable information about farmers' knowledge on genotype x environment interactions, in the risk-prone environments in which they farm. Using a novel pictorial technique, this research also helped farmers identify varieties suited to their localities. Progress was made in controlling the considerable yield losses caused by the Russian wheat aphid in Ethiopia, through the identification of promising, resistant lines. An efficient screening technique, using allele-specific PCR markers, was also developed, and used to screen thousands of barley lines for BYDV resistance. ICARDA's barley nurseries have provided a number of lines suitable for use in Central Asia and Latin America. Collaborative breeding programs are currently testing and selecting the most suitable high-yielding, drought- and disease-resistant lines.

Participatory plant breeding (PPB) brings scientists and farmers together, and has the potential to effectively 'match' improved varieties with farmers' needs. However, the scientific basis of farmers' conceptual knowledge of plant breeding has received very little attention from researchers, even though this is the foundation of farmer-plant-breeder collaboration. This means PPB programs may often have to make assumptions that have not been empirically tested about farmer knowledge (FK) and its relationship to plant breeders' scientific knowledge (SK).
     One common assumption is that FK and SK are fundamentally different; this defines the roles of farmers and scientists in PPB and limits the insights that scientists can gain through a greater understanding of farmers' conceptual knowledge-thus limiting the benefits that farmers can gain from PPB. Therefore, with funding from the US National Science Foundation, scientists from the University of California and ICARDA's farmer participatory barley breeding project successfully developed and tested a new technique for investigating both farmers' and plant breeders' conceptual knowledge, and the contribution such knowledge could make to collaborative crop improvement.
     Efforts focused on the environmental scale for which crop varieties should be developed. Important to both parties, this decision relates directly to interactions between plant genotypes and their growing environments (GxE). It is commonly assumed that developed varieties should possess broad adaptation to a range of locations, thus increasing the impact of breeding efforts. But, such thinking also assumes the availability of inputs necessary to improve and equalize environmental conditions across locations. This may not be the case in the low-resource systems found in CWANA's variable, stress-prone environments. There, farmers often have to choose different varieties for different fields within a given planting season.
     Farmers may observe qualitative GxE interactions (crossovers) in varietal performance between fields-i.e. that different varieties are performing differently in different locations. A farmer with two fields, for example, would then have to choose whether to grow one variety or two (one at each location). The decision will be reached by comparing the advantage obtained from growing two different varieties with the extra effort required.
     Therefore, farmers were asked questions about the relationship between plant genotypes and environments. These were designed to probe the fundamental theoretical bases of plant selection and/or population choice from the perspective of farmers themselves. The results of these interviews were used to test the hypothesis that farmers have a conceptual knowledge of their crop populations and growing environments that, in part, forms the basis for their practices. The research aimed to discover whether farmers' knowledge can (a) provide insights into the fundamental design of breeding programs for their areas and (b) indicate issues requiring attention and empirical investigation.
     Researchers interviewed 40 farmers in two villages (20 per village), which represented contrasting barley-growing environments in Syria: Barshaya in the northeast (very arid and cold), and Mardabsi in the center (much less arid). Questions were based around scenarios derived from a basic biological model, which described the relationship between plant genotypes and growing environments. The scenarios considered three levels of spatial variation: (1) between locations/communities with contrasting growing conditions (including the farmer's own location); (2) among fields within the farmer's locality; and (3) within one, typical field at the farmer's location. Specifically, farmers were asked whether they thought the yields of two barley varieties-which originated in different and distant environments, but were exactly the same in all other ways-would be the same, or different, if they were grown in different environments. A rank change (in terms of yield) in response to the change in environments would indicate qualitative GxE interactions. Farmers were also asked about the potential for qualitative GxE interactions in response to annual variations in rainfall (temporal variation). The null hypothesis in each case was that farmers would not be aware of such interactions.
     The results obtained showed that significant numbers of farmers believed that qualitative GxE interactions occur between locations. Between-location GxE interactions were anticipated by the largest proportion of respondents (63% overall), and within-field interactions by the lowest (16%). Moreover, results from Mardabsi showed that a significant proportion of farmers believed that temporal GxE interactions resulted from variation in rainfall (47% of respondents).

     Which varieties farmers choose to grow in a given location depends both on average yield and on their perception of variation in yield (and income) over time for that location (temporal GxE). To clarify farmers' attitudes to the risks posed by qualitative temporal GxE, researchers asked which of two varieties would best suit them: a highly responsive variety (HRV), with high potential yields but high yield variance in variable-rainfall environments; or, a stable variety, with relatively low potential yields but higher yield stability. Simple visual aids were used to help both researchers and farmers when presenting and discussing the scenarios (Fig. 1a and b).
     Farmers' responses were nearly evenly divided between the HRV and the stable variety (Table 1). However, a significantly higher percentage in the 'difficult' environment (Barshaya) preferred the stable variety. More farmers in that environment had experienced crop failure (Table 1), although farmers' estimates of the proportion of wet and dry years were similar at both locations. The HRV represents a greater risk for those farmers who have few resources to rely on when insufficient rain leads to poor harvests. So, other potentially important factors not considered by this research also affect the decision to plant HRV or stable varieties. These require further investigation, and include the socioeconomic characteristics of households, social structure, community support networks, cultural values concerning risk, storage capability, and markets.

Fig. 1(a). Farmer Juri Aboud describing rainfall distribution and risk in her barley production, using stones of different sizes as visual aids. (b). Varietal yields in response to temporal environmental variation, i.e. year-to-year variation in rainfall.

     The findings of this research support the hypothesis that farmers have a conceptual knowledge of qualitative spatial and temporal GxE. The spatial scales considered important by farmers for varietal discrimination may indicate their receptivity to new material and the extent to which it may be used across a range of local growing environments. Overall, the methodology used appears to be a rapid, inexpensive way of eliciting, from farmers, knowledge which is both relevant to the basic assumptions of PPB projects and able to provide scientists with insights that can improve experimental design.

Specific adaptation: how specific?

Farmer participation has played a key role in the success of ICARDA's efforts to breed crops suitable for specific environments: the process of breeding for specific adaptation. While decentralized selection (selection in the target environment) is a powerful and effective methodology, it can still fail to achieve its objectives if farmers are not actively involved. Therefore, to maximize potential gains from its breeding efforts, ICARDA ensured that farmers participated in the process from the start, when the large base of genetic variability created by the breeders was, as yet, virtually untapped. Merging farmers' and breeders' knowledge of the crop proved to be extremely effective.

climatic conditions, soil type and management in Mardabsi were reflected in a genotype x farmer's field interaction which was slightly less important (47.6%) than the genotypic effects (52.4%). Under these conditions it was possible to identify lines which performed well in all farmers' fields (lines 1, 10, 8 and 4; Fig. 2a). Line 10 performed particularly well: it outyielded both the local landrace 'Arabi Abiad' and the improved cultivar 'Arta' in all the farmers' fields, with a yield advantage ranging from 19% to 42% over 'Arabi Abiad,' and from 1% to 37% over 'Arta.' In Mardabsi, because the genotype x farmer's field interaction was small, farmers chose the four lines that had performed well across all fields for further testing.
     In Al Bab village, eight farmers each planted 30 different barley varieties for testing, plus a further two check varieties (Fig. 2b). In this village, farmers usually either crop barley continuously or in rotation with legumes. Interestingly, at the beginning of the PPB program, the farmers decided to test the breeding lines within these two different rotations, because they felt that each barley variety might perform differently under the two different rotations. In the trial, farmers' barley yields were low (1.2 t/ha, on average), a consequence of low temperatures occurring in the wet season. In contrast to the findings from Mardabsi village, the genotype x farmer's field interaction in Al Bab was found to be seven times more important (87.6%) than genotypic effects (12.4%). This was partly due to the effect of the different rotations used. Figure 2b clearly shows the difference between two adjacent fields cropped by one farmer, Abdo. Lines 19, 23, 10 and 30 were the highest yielding in the field previously cropped with barley (B); however, lines 3, 17 and 14 were the highest yielding in the field previously cropped with lentil (L). In this village, because the genotype x farmer's field interaction was so large, farmers chose the top-yielding lines from every field for further testing. These results demonstrate the value of quantifying GxE interactions and presenting them pictorially. They also demonstrate that participatory plant breeding can result in crops adapted to highly specific environmental conditions.

Progress in barley breeding for resistance to Russian wheat aphid in Ethiopia

Russian wheat aphid (Diuraphis noxia) is a major pest of barley in Ethiopia, where yield losses of 40-70% have been observed. Recognizing that host-plant resistance is the most economical and practical means of controlling the damage caused by this insect, scientists at ICARDA have focused on identifying, breeding and testing resistant lines of barley.

ICARDA has developed a quick, effective method of screening for Barley yellow dwarf virus (BYDV), using allele-specific PCR markers. This could be used both to screen thousands of barley lines for BYDV resistance based on the Yd2 gene and to identify resistance based on genes other than Yd2.
     Resistant (symptomless) and susceptible (showing typical BYDV symptoms) plants in the F2 populations, as well as selected resistant plants in the F3 to F5 families, were tested for the presence of the Yd2 gene using the

Over the last four years, barley breeders in Central Asia and the Caucasus (CAC) have identified promising lines which have been distributed by ICARDA through the International Nursery System. Many of them have been widely used in breeding programs, as sources of valuable traits and qualities. An example is the spring barley variety 'Mamluk.' Identified as a result of collaboration between ICARDA and the Krasnodar Research Institute, Russia, 'Mamluk' was officially released in Armenia in 2000. The Armenian Government has purchased 1000 tonnes of seed of this variety from Russia for fast dissemination to farmers.
     Over the last two years, Armenian barley breeders have selected four promising lines from ICARDA nurseries. These lines were tested in demonstration nurseries and in on-farm trials. The seed was planted for multiplication.
     Azerbaijan breeders have identified a promising new variety 'Baharly' from ICARDA nurseries. The variety has, over the last three years, outyielded the local check ('Siklon') by 35-40%. Based on the results of these three-year trials, 'Baharly' was submitted for release to the State Variety Testing Commission in 2001. In Azerbaijan, breeders produced 1.5 tonnes of 'Baharly' seed, all of which was planted in the fall of 2002 for on-farm testing and seed multiplication.
     Kazakstan is the largest producer of barley in the CAC region. In fact, before the country gained independence, the crop covered almost 7 million hectares. Most of Kazakstan's barley crop is spring barley, and is grown, for use as feed, in the semi-arid climate of the steppes under rainfed conditions (250-350 mm per year).
     In northern Kazakstan, the rains normally fall in the spring. However, this is followed by periods of drought, leading to severe soil dryness-to a depth of 7-8 cm. Rain begins to fall again in the area in July. To avoid planting in dry soil, and also to protect seeds from drought stress during the booting period, it is recommended that barley be sown at a depth of 8-10 cm, either in mid-May or at the end of that month. Two selected lines of spring barley ('Batir-1' and 'Batir-2') have been found to be well adapted to conditions in North Kazakstan. During three years of testing, these lines yielded 20-30% more than the control ('Akmolinskaya-25'). Based on the results of these trials, the two varieties were submitted to the official State Variety Testing Commission in 2002. Another new spring barley variety ('Birlik-1'), also for use in northern Kazakstan, was selected from ICARDA nurseries in 2002. This variety outyielded the control variety ('Akmolinskaya-25') by 90-95%, and yielded 5.6 t/ha during the last two years of testing. Four hundred kilograms of seed has become available for on-farm testing and multiplication.
     In South Kazakstan, winter barley is grown, and the Kraniy Vodopad Breeding station is responsible for the improvement of this crop. Three winter barley (Aziret-114, Sultan-118, and Ortai-111) were selected from ICARDA nurseries for testing in this region. Of the selected lines, Ortai-111 (CWB117-77-9-7//Hml-02/ArabiAbiad*2) demonstrated a high level of resistance to diseases, pests and lodging, and was found to be cold tolerant. It also produces particularly large kernels, with a 1000-kernel weight of 52 g. From each line, 200 kg of available seed was planted in the fall of 2002, for the purposes of seed multiplication and on-farm testing.
     Efforts made by a collaborative barley program undertaken by ICARDA and the national breeding project in Kyrgyzstan have also resulted in the identification of new, promising lines of spring and winter barley. 'Adel' (MV46/Mazurka/3/Roho//Alger/Ceres), the best line identified, outyielded the standard check 'Osnova' by 20-25% in advanced yield trials. The 400 kg of seed available from this line will be tested in a wide range of environments in order to assess its level of adaptation.
     In 2000/01, in Turkmenistan, local breeders selected three promising barley lines (Sonata, Alpha/Durra, Lignee 131) from ICARDA nurseries that were suitable for local conditions. Selection was based on the results of trials conducted in previous years. Over the last two years, these lines have shown advantages in terms of disease resistance, heat and drought tolerance, and productivity. Available seed from these barley lines was then planted for seed multiplication and testing in on-farm trials (Sonata, 0.18 ha; Alpha/Durra, 0.29 ha; Lignee131, 0.14 ha).
     Uzbekistan's main breeding center for the improvement of barley under rainfed conditions is the Galla-Aral Branch of the Andijan Research Institute of Grain. From ICARDA's nurseries, breeders from Galla-Aral identified three lines of barley for use under rainfed conditions: Arizona 5908/Aths// Avt, 7028/2759/3/69-82//Ds/Apro/4/OP/Zy//Alger/ Union 385-2-2 and Arar/Lignee527//Arar/Rhn. The lines demonstrated some advantages, in terms of disease resistance and heat and drought tolerance. They also outyielded the local check variety ('Lalmikor') by 60-65%. Three other lines (GkOmega/3/Roho/Masurka//ICB-103020, 73TH/ 105//E10BulkCI7321/3/CWB117-5-9-5 and Wieselbuger/Ahor1303-61//Ste/Antares, from IWBON02) were also selected for use in irrigated areas, where these lines outyielded the local check ('Mavlona') by 7-10%. Available seed from promising lines (3-5 kg per line) has been planted for further multiplication.