Numerous innovation platforms have been implemented to encourage the adoption of agricultural innovations and stakeholder interactions within a value chain. Yet little research has been undertaken on the design and implementation of innovation platforms focussing on issues other than market access and aiming to encourage agro-ecological intensification. This is the case for the development of Conservation Agriculture (CA) in West Africa, which due to its complex nature calls for technical, organizational and institutional changes at the level of both production systems and village territories. This article analyses the design and implementation process of platforms in three villages in Burkina Faso aiming to develop CA technical references with local stakeholders, and to renew rules of interaction between stakeholders within a territory. The platforms enabled farmers in the three villages to actively participate in the identification of the cropping systems that were tested and to improve their knowledge and mastery of CA. They furthermore promoted networking among producers and facilitated the development of new rules for crop residue use. The platforms thus appear to be relevant mechanisms, enabling complex innovations to be addressed. Diverse modifications and improvements are discussed that would ensure the sustainability of the platforms and the evolution of their objectives and activities beyond those of the project under which they were launched.

Farmers around the world are concerned about the effects of human-induced salinity on crop yield and quality. Therefore, researchers are actively testing wild relatives of cultivated plants to identify candidates to improve crop performance under salt stress. A study was conducted to understand the effects of salt stress (Sodium chloride, NaCl) on cultivated tomato species (Solanum lycopersicum var. cerasiforme L.) and a wild tomato relative (Solanum chilense Dun.) from the Northern part of Chile. Plants were cultivated hydroponically under controlled environmental conditions for 112 days with nutrient solution containing 0 mM (3 dS m−1), 40 mM (6 dS m−1) and 80-mM (9 dS m−1) NaCl. Salt stress reduced the shoot biomass in S. lycopersicum but not in S. chilense. Both species were able to maintain the leaf water content; however, the cultivated S. lycopersicum showed osmotic adjustment, while S. chilense did not. Salt stress reduced the total fruit yield in S. lycopersicum based on a decrease in the mean fruit weight, but it had no impact on the number of fruits per plant. In contrast, salt stress had no significant impact on the fruit yield in S. chilense. Salt stress increased the total soluble solids content in S. lycopersicum and the titratable acidity in S. chilense. It was concluded that S. chilense displays a contrasting behaviour in response to prolonged exposure to moderate salinity compared with S. lycopersicum, and that this related species could be an interesting plant for breeding purposes.

Farmers' Participatory Varietal Evaluation (PVE) was conducted on sorghum (Sorghum bicolor) crops in the Kile-Bisidimo plains of eastern Ethiopia for three consecutive years, 1995–1997. The study aimed at providing farmers with alternatives to their landrace to enable them to overcome crop losses and to identify farmers' varietal selection criteria for inclusion in future breeding work. In 1995 constraints and opportunities in sorghum growing and farmers' varietal matching characteristics were identified through an informal survey. This was followed by a search for varieties and acquisitions of seed. Subsequently, eight varieties were evaluated of which five varieties were released and three were at the pre-release stage.

In 1996 and 1997 farmer-managed on-farm trials were conducted and farmers evaluated the performance of the experimental varieties against a locally grown cultivar. Through pairwise and matrix ranking, farmers' selection criteria were listed, preferred varieties identified and initiatives taken to diffuse the varieties through the local seed system. Out of the eight varieties that research workers considered the best, farmers selected only three. The study negated the generally accepted view that farmers in lowland areas of eastern Ethiopia are reluctant to grow short-duration varieties. The selection and introduction of three new varieties into a farming system where farmers were growing only one local variety reconfirmed PVE to be a means for enhancing adoption and increasing genetic diversity. The study also confirmed that increasing farmers' access to their preferred varieties would result in a faster rate of diffusion through farmer-to-farmer seed exchange.

As cassava is grown mostly by small resource-limited farmers throughout the tropics on low-fertility soils with little fertilization and, due to the large potassium (K) export in harvested roots, genotypes that tolerate low-K soils and respond to K fertilization are warranted. The objective of this study was to evaluate cassava germplasm and identify such genotypes.

Fourteen cultivars of cassava (Manihot esculenta) selected from the core germplasm at CIAT were grown under rainfed conditions for ten months over five consecutive seasons in Inceptisols either with no K application or with 50, 100 or 200 kg K ha−1 applied annually together with adequate nitrogen and phosphorus. All cultivars responded to K application both in terms of root and shoot biomass with the highest yields obtained by CM 507-37 and M Ven 25 in the absence of K application and at high K levels. These cultivars had the highest adaptation indices to low K and the highest K use efficiency for total biomass production. CM 507-37 had the highest K use efficiency for root production at all K levels. Thus, it is desirable to use this material for breeding cassava which is adapted to low-K soils and is able to respond to fertilizer application. However, because of the high hydrocyanic acid (HCN) content in their roots, these cultivars should be crossed with genotypes that are low in HCN, such as HMC-1 and M Cub 74, in order to select lines with both high K use efficiency and low HCN for fresh cassava consumption. Root HCN contents were significantly reduced by application of K across all cultivars. Application of K fertilizer to low-K soils is warranted to minimize health hazards when fresh cassava is used for human consumption.

Results from field experiments showed that number of mature grains per plant was related to the plant growth rate during the pre-flowering period. This relation was further improved when growth rate was expressed relative to the rate of plant development. This evidence supports the theory that grain abortion is linked with assimilate production.

Plant growth, development and yield were monitored in sorghum/cowpea intercropping trials in Botswana during the drought seasons of 1982/3 and 1983/4. The cowpea proved to be more competitive than sorghum in these arid conditions, resulting in substantial increases in sorghum mortality and developmental delay, and substantial decreases in sorghum leaf area indices, dry weight production and grain yield. Intercropping in standard rows at medium plant densities resulted in Land Equivalent Ratios considerably less than 1.0, in contrast to earlier trials in Botswana in higher rainfall years which demonstrated intercropping advantages. Low density, wide row intercropping resulted in some small intercropping advantages, suggesting that this treatment may have potential in Botswana's variable climatic conditions.

The physiological basis for responses to daylength of a photoperiod sensitive groundnut genotype (NC Ac 17090) was investigated by comparing its growth and development in natural daylength with that in an artificially manipulated photoperiod in three field experiments. Photoperiod did not influence the thermal time to flowering, or the subsequent appearance of flowers until 900–950 flowers m−2 had appeared. Thereafter flowers continued to appear in short, but not in long, days. In each experiment, long days increased the thermal time between the initiation of each peg and pod, and the thermal time required for each fruit to mature. These fruit initiation and developmental changes were reflected in the partitioning of assimilates to pods, this being substantially less in long days than in short. Changes in pod initiation rate, partitioning co-efficient, and the thermal time taken for a pod to mature were related to mean daylength.

The diversity of cropping patterns on smallholder farms in southern Malawi was analysed using a framework that explicitly incorporates the extent of intercropping in each field. Diversity is defined as the relative abundance of each crop in the overall cropping pattern. Six indices of diversity were constructed for 208 farms and used in a model of a welfare-maximizing farm household to examine the reasons for diversity in cropping patterns; multiple regression techniques were used to determine the effect of different household characteristics on diversity. The results suggest that an increase in labour availability over the production period is associated with a more diverse cropping pattern. Landholding size also influences diversity, which rises to a maximum and then falls as the area cultivated per capita increases. Farmers who grow a non-food cash crop (tobacco) have more diverse cropping patterns than those who do not. As diversity increases, farmers use intercrop patterns that are more substitutive than additive.

Eight genotypes of cultivated mung bean, black gram and rice bean (Vigna mungo, Vigna radiata ssp. radiata and Vigna umbellata, respectively) were sown at six sites in Australia on various dates in order to provide a range of photothermal environments. In addition, four accessions of the related wild species Vigna radiata ssp. sublobata were sown on five occasions. Times from sowing to first flowering (f) varied between environments from 34 to 317 d; pre-flowering temperature and photoperiod means ranged from 12.7° to 29.1°C and from 11.8 to 15.5 h d−1. No effect of photoperiod was detected on rate of progress towards first flowering (1/f) in four genotypes, but in each case a significant positive relation was detected between 1/f and mean temperature. These simple thermal time relations did not differ significantly among these four genotypes; the common base temperature was 7.9°C. In two genotypes observations were well described by a thermal response plane when the mean photoperiod was less than 13 h d−1 (p < 0.01) but photoperiods greater than 14 h d−1 delayed flowering. In each of the remaining genotypes the observations were best described by photothermal planes, that is, 1/f was modulated by temperature and photoperiod. Predictions from the models based on our data were in good agreement with the times to first flowering observed in three genotypes in an earlier controlled environment study.

This study was conducted to improve wheat production under vegetative (early season) drought stress. Hydroprimed and osmoprimed (with CaCl2) seeds of wheat cultivars Lasani-2008 (LS-2008) and Triple Dwarf-1 (TD-1), were sown in 20 (narrow), 25 (medium), and 30 cm (wider) spaced rows. Crop was grown under well-watered conditions till physiological maturity or was subjected to drought stress (50% field capacity) during vegetative phase and then grown under well-watered conditions. Drought stress caused substantial reduction in grain and biological yields, related traits, harvest index (HI) and water use efficiency (WUE). Nonetheless, planting osmoprimed seeds in narrowly spaced rows significantly improved the grain yield, HI and WUE. However, wheat planted in wider rows had bold grains. Furthermore, wheat cultivar LS-2008 produced better yield, even under drought stress, than cultivar TD-1. Economic analysis indicated that planting osmoprimed seeds of wheat cultivar LS-2008 in narrowly spaced rows under early season drought yielded maximum economic benefits. In conclusion, planting osmoprimed seeds of cultivar LS-2008 in narrowly spaced rows is a good agronomic option to improve the wheat performance under early season drought stress.

Spatial variability in soil parameters and plant growth in the Sahel are still poorly understood and may hamper the interpretation of experimental results. This paper examines whether or not soil amendments such as phosphorus and crop residues affect the variability of final dry matter production in pearl millet (Pennisetum glaucum). Within- and between-plot variation in millet growth was studied in a three-year experiment with three levels of crop residues and four levels of phosphorus. The effects of different rates of application on within-plot variation in number of tillers, number of heads, maximum tiller height, and total above-ground dry matter of single mature millet plant stands (pockets) were calculated. Above-ground dry matter, estimated non-destructively using an equation derived from numbers of tillers and heads and from maximum plant height, gave good predictions of total dry matter for a range of genotypes across the 12 treatments. Crop residue and phosphorus application reduced the number of missing pockets, leading to a more uniform stand with fewer pockets which did not produce grain. With amendments, pockets were also taller and of more uniform height but a decrease in variability of total dry matter production only became evident after standardization of the data. The results show the need for a clear definition of ‘growth variability’ in millet and indicate that both chemical and non-chemical factors govern its expression in the Sahel.

Efectos de los residuos de las cosechas y del fósforo en la variabilidad del mijo

This paper draws on the results of farming systems research (FSR) conducted over five years at eight sites distributed throughout Pakistan. The main research findings with respect to the irrigated plains, or favoured areas (four sites), and the marginal mountainous and rainfed areas (four sites) are summarized, with emphasis on the role of system interactions in technology development. In favoured areas, most system interactions occur between crops grown in multiple cropping patterns, whereas in marginal areas, crop-livestock interactions dominate. Appropriate research strategies for each kind of environment are discussed. It is concluded that although there is a need for quite different research strategies for favoured and marginal areas, the methods and perspective of FSR are equally appropriate and even critical for achieving future gains in agricultural productivity in each type of environment.

Estrategias de investigación agricola en zonas favorecidas y marginales: Experiencias recogidas durante la investigación de sistemas agrícolas en Pakistán

An experiment was carried out to assess the benefits of native arbuscular mycorrhizal fungi (AMF) for banana plants cv. ‘Nendran’. The AMF species applied were Funneliformis mosseae and Glomus microcarpum, which were identified in a previous survey as the most common root associates of Musa spp. in traditional monoculture banana fields. Spores of both the AMF species isolated from the natural banana fields were mono-cultured and used in the experiment, individually and in combination, at two inoculum spore levels (2500 or 5000 spores). We evaluated the root colonising potential of AMFs and their effects on plant height, chlorophyll content and leaf N, P and K concentrations at regular intervals up to 90 days after inoculation. All the inoculated plants showed more than 80% root colonisation. Increase in chlorophyll content in the leaves was found significant in all treatments, with the exception of the combination of 5000 spores of F. mosseae and 5000 spores of G. microcarpum each. Increases in leaf N, P and K were found in all the inoculated plants as compared to control (sterile soil without any AMF). While a significant reduction in soil available nitrogen and soil pH was observed in all treatments with inoculation, the soil available phosphorus and soil total organic carbon were increased by inoculation. Overall data revealed positive effects of AMF species in banana, especially during its early growth. As AMF species were isolated from fields differing in relation to banana variety and soil type and have positive effects in banana nutrition, an integrated soil fertility management using AMF appears promising.

In many experiments which compare a large number of different treatments or varieties, it is necessary to decide which sub-sets of treatments or varieties do not differ significantly from each other. Multiple comparison procedures provide a commonly used, but much criticized, way of tackling this problem. As an alternative, techniques known collectively as cluster analysis can be used. An advantage of using certain types of cluster analysis is that their results can be displayed as a dendrogram or tree diagram which gives a very useful picture of the overall relationship between treatments or varieties. These procedures can also be extended readily to multivariate observations from each plot.

Knowledge of agro-physiological traits associated with drought tolerance would be useful for developing breeding materials for drought-prone environments. This study was conducted (i) to estimate genetic variability among 25 durum wheat genotypes in response to drought based on grain yield and 15 agro-physiological traits in single and multi-year trials; and (ii) to compare genotypes on the basis of multiple investigated traits using genotype by trait (GT) biplot technique and then recommend possible selection strategies. We found large genetic differences among durum wheat genotypes for agro-physiological traits in response to drought stress within and between single years, which revealed good promise in their further exploitation for selection in durum wheat breeding program. High broad-sense heritability and expected genetic advance as percent of mean observed in plant height (90.8%; 52.7%), grain yield (53.6%, 23.5%) and relative water loss (47.2%, 41.3%), respectively, indicated a major role of additive gene action. The results showed that the performance of genotypes was influenced by the year. The traits with high consistence across years were heading date, plant height and peduncle length. The potential quantum efficiency of photosystem II (Fv/Fm) and thousand-kernel weight (TKW) were positively associated with grain yield, while heading date, plant height and canopy temperature (CT) were negatively associated with grain yield under the drought conditions. In conclusion, based on across-year analyses, Fv/Fm, TKW, heading date, plant height and CT are the most promising traits for indirect selection.

The contribution of root and leaf litter to soil nitrogen dynamics, nitrogen uptake and balance was evaluated under cereal–legume rotations in a tropical moist savanna soil. Two legumes, soyabean (Glycine max) and stylo (Stylosanthes hamata), and maize (Zea mays) as a control were grown in four farmers' fields of different native fertility in 1993. At the end of the season, soyabean grain and stover were harvested and stylo biomass was removed for fodder. At the beginning of the 1994 season levels of total mineral nitrogen at a soil depth of 0–30 cm were 75, 52 and 44 kg ha−1 following soyabean, stylo and maize respectively. Total nitrogen uptake by maize was over 25% higher following legumes than following maize. Maize yield was 20 and 24% higher when grown after stylo and soyabean than after maize in spite of the removal of the standing legume biomass from the plots. Sorghum grain yield and nitrogen uptake were not significantly affected by the previous crops. Nitrogen balance estimates indicated that loss of nitrogen, probably due to leaching, was lowest in the plots previously planted with stylo. Results indicated opportunities to integrate appropriate legume-based technologies into the farming systems based on an identification of inherent nitrogen-release patterns.

Long-term fertilization experiment has been conducted since 1981 to study the effect of soil management practices on soil fertility, soil carbon and nitrogen sequestration, soil culturable microbe counts and crop yields at the Nanhu Experimental Station in the Hubei Academy of Agricultural Sciences (situated in the middle reach of the Yangtze River and the rice–wheat cropping system). The experiment was designed with the following eight treatments: (1) unfertilized treatment: Control; (2) inorganic nitrogen fertilizer treatment: N; (3) inorganic nitrogen plus inorganic phosphorus fertilizer treatment: NP; (4) inorganic nitrogen, inorganic phosphorus plus inorganic potassium fertilizer treatment: NPK; (5) pig dung compost (manure) treatment: M; (6) inorganic nitrogen fertilizer plus manure: NM; (7) inorganic nitrogen, inorganic phosphorus fertilizer plus manure treatment: NPM and (8) inorganic nitrogen, inorganic phosphorus, inorganic potassium fertilizer plus manure treatment: NPKM. The results showed that long-term application of organic manure in combination with inorganic fertilizer significantly (p < 0.05) increased soil organic C concentrations compared with the corresponding inorganic fertilizers alone. Soil organic C contents were significantly (p < 0.05) increased in balanced application of NPK fertilizers in comparison to unbalanced application of fertilizers. After 30 years of experiment, soil organic C and total N sequestration rate averagely were 0.48 t ha−1 year−1 and 28.3 kg ha−1 year−1 in the fertilized treatments respectively; nevertheless, it were 0.27 t ha−1 year−1 and 9.7 kg ha−1 year−1 in the unfertilized treatment. Application of organic fertilizer in combination with inorganic fertilizer significantly (p < 0.05) increased culturable microbial counts compared with the corresponding inorganic fertilizers alone. The balanced application of NPK fertilizers significantly (p < 0.05) increased culturable microbial counts compared with unbalanced application of fertilizers. The average grain yield of wheat and rice was significantly (p < 0.05) higher in organic manure combined with inorganic fertilizer treatment than in inorganic fertilizer alone and unfertilized control. Therefore, long-term application of organic manure combined with inorganic fertilizer and balanced application of NPK fertilizers could increase soil organic C and total N sequestration, culturable microbial counts and crop grain yields.

In two cultivar × density trials for oil palms (Elaeis guineensis) planted in Indonesia, single leaf area, number of green leaves per tree, leaf opening rate per year and rachis length of leaves were followed over fourteen years. The data were analysed to determine the time course of canopy leaf area and to predict the moment of canopy closure.

Growth functions were fitted to the observed data. Estimates of leaf area index (L) were based on single leaf area, number of green leaves, leaf opening and planting density. The time course of L was modelled on the basis of the fitted functions to the components. The moment of canopy closure was calculated from the planting density and the functions fitted for rachis length.

The modelled time course of L was considerably different from the function fitted to the single leaf area data. The expansion of L was not as rapid as expected from the area growth of single leaves and, after maximum L was reached, a steady decline was observed. The continuously declining number of green leaves was the main cause of these two observations.

The time course of L differed considerably between the two experiments. Not only were there large differences in the number of green leaves maintained per tree in the experiments but also the final area of single leaves differed between both experiments. The first factor was a result of the management of the experiments, whereas the second factor was most likely influenced by a difference in soil-related factors at the two locations.

Leaf areas and numbers of leaves per tree were different for each cultivar, as was L. This was also the parameter most sensitive to planting density. Individual leaf area and leaf number per tree were not affected by planting density, but rachis length was affected by the planting density treatment. The moment of canopy closure was similar in both experiments. Planting density was the main factor that determined the onset of canopy closure.

Land degradation is one of the major problems related to low productivity in Ethiopia. Vertisols are potential agricultural lands but are underutilized due to waterlogging during the rainy season and are prone to soil erosion due to the traditional practices of planting crops at the end of the rainy season exposing bare land to heavy rains. An animal-drawn implement, the broadbed maker (BBM), was tested to facilitate drainage of the Vertisols. Improved drainage enables earlier planting of crops to use the resultant prolonged growing period for attaining higher yields. In order to further improve the BBM package, the frame of the BBM was used for attachment of other implements to minimize tillage practices and reduce seed and fertilizer rates, labour and animal power requirements and soil erosion. The attachments were tested both on-station and on-farm with positive results.

Five genotypes of barley (Arabic Abiad, Beecher, Cytris, Rihane ‘S’ and Swanneck) were grown under rainfed conditions at Breda and Ghrerife in northern Syria. During the winter, rates of shoot growth were similar at both sites but by anthesis crops at Breda were almost twice as large as crops at Ghrerife. Overall, Arabic Abiad was heavier and had a greater green area than other genotypes at both stem elongation and anthesis and, by maturity, had the greatest shoot dry mass and grain yield.

Differences in root dry mass between sites were small so that crops at Ghrerife had a higher ratio of root:total plant mass at anthesis and maturity than those at Breda. Rooting depth was shallower at Ghrerife but root length densities in the layers below 15 cm were greater than at Breda. Arabic Abiad had the longest root system below 15 cm at both sites. The genotypes did not differ in total seasonal water use at either site but there were differences in the patterns of water use during the early spring. Arabic Abiad used more water below 15 cm in the period from mid-February to mid-March and less during grain-filling than other genotypes.

The greater yields of Arabic Abiad may be associated with the greater root lengths below 15 cm and the correspondingly faster rates of water use during early spring. Yields of barley were greater when more water was used before anthesis; there appeared to be no advantages in saving water for use during grain-filling in this region.