A technology for improving the productivity of short fallows using herbaceous legumes as cover crops was evaluated with farmers in the forest and savannah transition zones of Ghana. Legumes were relayed in maize 5–8 weeks after planting maize, depending on the legume species. An economic analysis of the technology compared with natural fallow over two cropping seasons (2001–2002) showed that the legume fallows were more profitable under the scenarios tested. Farmer assessment of the biological performance of the technology revealed the benefits of weed suppression and soil moisture conservation potential of the legume biomass as well as an improvement in the yield of the succeeding maize crop. However, farmers realized that planting legumes at close spacing and weeding before and after relaying are essential in the development of an appreciable biomass cover. The technology is suitable for farmers of all strata, in several major ecological zones of Ghana, and for planting on land with poorly secured tenure. However, at least two years of tenancy is required for the landless to derive some benefits from the legume fallow.

My first encounter with Francis Lupton was as one of a group of students from Aberystwyth visiting the Plant Breeding Institute (PBI) at Cambridge, UK, as part of an Easter vacation tour in 1954. We were given a presentation, delivered with military precision, on wheat breeding by a tall, rather thin young man with a distinctly authoritative voice. Lupton had returned to Cambridge after the war to complete his interrupted studies, after seeing active service in the Middle East, Italy and Greece where he took part in some of the bitterest fighting, about which he characteristically said little. After graduating, he joined the PBI, under the directorship of G. D. H. Bell, in 1948. The Institute, which had previously been part of Cambridge University, had been hived off after the war to come under the aegis of the Agricultural Research Council. Lupton was assigned to the wheat breeding programme, thereby inheriting the mantle of Biffen and Engledow.

A two-year study was undertaken in a tropical dryland agro-ecosystem to evaluate the effect of the application of soil amendments with contrasting chemical natures on crop productivity, grain yield, N-uptake and N-use efficiencies. The treatments involved the addition of equivalent amounts of N (80 kg N ha−1) through chemical fertilizer and three organic inputs at the beginning of the annual cycle: Sesbania aculeata shoots (high quality, C/N 16), wheat straw (low quality, C/N 82) and Sesbania+wheat straw (high and low quality combined, C/N 47), together with a control treatment. Test crops consisted of an annual sequence of rice and barley, sown in the rainy and winter seasons, respectively. Fertilizer and Sesbania inputs resulted in higher total net productivity (TNP) for the rice crop (47 % and 32 % increases over the control, respectively) than the combined (+28 %) and wheat straw treatments (+10 %). During the succeeding barley crop, maximum TNP was recorded in the Sesbania+wheat straw treatment (+52 %), followed by wheat straw (+43 %), fertilizer (+19 %) and Sesbania (+17 %). The TNP and grain yields of both crops added together were higher in Sesbania+wheat straw and fertilizer treatments compared to a single applications of either Sesbania or wheat straw. The Sesbania+wheat straw and fertilizer treatments resulted in more efficient utilization of N compared to the other treatments. Crop roots played a pivotal role in N-recovery from the soil and their N concentrations differed significantly (p < 0.05) due to the application of soil amendments. Across different treatments, crop root biomass was strongly correlated with crop N-uptake (r = 0.81, n = 10, p < 0.05), recovery efficiency (r = 0.81, n = 8, p < 0.05) and agronomic efficiency (r = 0.81, n = 8, p < 0.05). It is suggested that the combined application of high and low quality resources modulated N release, resulting in relatively higher productivity through the annual cropping cycle. Such combined inputs may prove useful in developing low input, environment friendly soil management practices in tropical dryland agro-ecosystems.

Drought is one of the major factors limiting crop production worldwide. Dry areas are a much less homogeneous population of target environments than areas with high and reliable rainfall. In this paper we argue that a decentralized participatory plant breeding programme can address the complexity of dry areas, characterized by high and repeatable genotype × locations and genotype × years within locations interactions, more efficiently and effectively than a centralized non-participatory plant breeding programme. This is because varieties can be tailored not only to the multitude of target environments typical of dry areas, but also to diverse clients needs. In addition, varieties can be delivered in a shorter time and with a higher probability of adoption. Decentralized participatory plant breeding also has beneficial effects on biodiversity because selection is for specific adaptation rather than for broad spatial adaptation. The paper gives examples of methodological aspects including the modes of farmer selection, the precision of the trials, the efficiency of selection, the response to selection, the role of the type of germplasm and the role of molecular breeding in a participatory breeding programme. The paper gives the example of drought-resistant barley lines identified through extensive field testing and selection in a decentralized participatory breeding programme, and concludes that this type of plant breeding may be better targeted, more relevant and more appropriate for poor farmers in marginal areas.

In cotton (Gossypium hirsutum), it is hard to determine the exact date when reproductive growth ceases on the basis of field observations, as compared to more visible factors such as the onset of flowering or boll opening. It is, however, essential to characterize the growth cycle in order to determine what varieties are suitable for planting in different climatic and local cropping conditions. We estimated the end of the effective flowering period on the basis of the opening date of the last flower giving rise to a first-position boll on fruiting branches (LFP1), and propose a simple method for estimating this date. This study, conducted in 2002 and 2003 at Okpara, Benin, involved a comparison of six cotton varieties planted at two different dates (June and July). Plants were monitored to determine the dates when flowers opened at each position on fruiting branches. The LFP1 indicator made a clear distinction between varieties. This highly heritable trait, which was found to be closely correlated with other earliness criteria, could be used to characterize the length of the growth cycle in cotton varieties.

Legume species are uniquely suited to enhance soil productivity and provide nutrient-enriched grains and vegetables for limited-resource farmers. Yet substantial barriers to diversification with legumes exist, such as moderate yield potential and establishment costs, indicating the need for long-term engagement and farmer-centered research and extension. This review and in-depth analysis of a Malawian case study illustrates that farmer experimentation and adoption of legumes can be fostered among even the most resource-poor smallholders. Multi-educational activities and participatory research involving farmer research teams was carried out with 80 communities. Over five years more than 3000 farmers tested legumes and gained knowledge of legume contributions to child nutrition and soil productivity. The average area of expansion of legume systems was 862 m2 in 2005; 772 m2 for women and 956 m2 for men indicating a gender dimension to legume adoption. Farmers chose edible legume intercrops such as pigeonpea and groundnut over the mucuna green manure system, particularly women farmers. Interestingly, expansion in area of doubled-up edible legumes (854 m2 in 2005) was practiced by more farmers, but was a smaller area than that of mucuna green manure system (1429 m2). An information gap was discovered around the biological consequences of legume residue management. Education on the soil benefits of improved residue management and participatory methods of knowledge sharing were associated with enhanced labour investment; 72 % of farmers reported burying legume residues in 2005 compared to 15 % in 2000. Households reported feeding significantly more edible legumes to their children compared with control households. Participatory research that incorporated nutritional education fostered discussions within households and communities, the foundation for sustained adoption of legume-diversified systems.

We demonstrated experimentally that Sufetula, a root-mining insect, has a depressive effect on coconut yields on peat soils. The impact of the pest resulted in a shortfall in earnings that warranted taking control measures. We considered control methods suitable for rehabilitating infested mature coconut plantings and for preserving young coconut plantings. Currently, cultural control is the only effective method. It involves eliminating all identified shelters for the adult insect, i.e. fern cover and heaps of coconut waste (dry fronds and husks). The aim is to achieve totally bare soil, with moss cover that does not attract the pest, or planted with an unattractive intercrop such as pineapple.

A reconnaissance survey and participatory varietal selection trials (PVS) were conducted in four major pearl millet-growing countries of the Sahel between 2001 and 2003. The studies aimed to identify farmers' preferences in improved pearl millet varieties, increase awareness, test new varieties and enhance farmers' access to the improved varieties. Farmers selected five out of 10 tested varieties, with preferred characteristics, namely, maturity cycles of 80–90 d in the Sahel and 90–100 d in the Sudanian agro-ecozones, acceptable grain yield, compact and long (30–100 cm) panicles, a large number of tillers with panicles, adaptation and an acceptable taste. Farmers indicated that their local varieties were of superior adaptation and taste. They mentioned that hindrances to uptake and sustained use of improved varieties were due to lack of awareness, traditional values, seed unavailability, early maturity, bird damage and lack of fertilizer. The strong genotype × environment interactions in the Sahel suggests that breeding should be directed towards producing varieties adapted to specific zones rather than for wide adaptation. Notably, since farmers often cultivate pearl millet without any soil amendments, it may be advisable to disseminate varieties as a package (with fertilizer and agronomic instructions) rather than as varieties alone in a PVS programme, in order to achieve the full potential of improved varieties. The PVS trials are synergistic to plant breeding in identifying varieties suitable for harsh environments, which are difficult to duplicate in the research station. However, in the absence of formal distribution seed systems in the trial countries, village- or community-based seed production of varieties selected by farmers appears critical to the sustainable adoption of selected varieties.

Improved upland rice cultivars introduced in Volta Region, Ghana, have been perceived to store poorly compared to farmers' traditional cultivars. A survey was conducted in 2003 in the Hohoe district of this region, where a Participatory Varietal Selection programme had started in 1997, to gain insight into farmers' seed production and storage practices that are likely to affect seed quality in storage. Farmers rated keeping quality (p < 0.001), tolerance to storage pests (p < 0.001), seed quality (p < 0.001) and establishment of their local cultivars Kawomo, Viono and Wuwulili as much better than the improved cultivar IDSA 85. Initial seed moisture content ranged from 12.8 to 18% and germination from 0 to 82%. There was a significant relationship between seed moisture content and duration of drying prior to storage (p < 0.001) and storage method (p = 0.015). Germination loss in storage was rapid at high moisture content and slow at low moisture content. Between 60 and 80% of seeds germinated after six months storage at 12.8% moisture content. The viability equation predicted accurately germination of farmer-saved seed stored under ambient temperature in Ghana. Except for the japonica rice cultivar WAB 126-18-HB, the traditional cultivars Kawomo, Viono and Wuwulili survived better in storage than improved cultivars. There is a need to improve seed quality of improved cultivars if farmers are to benefit from their higher yields and grain quality and to improve storage practices.

Broad sense heritabilities were estimated in three long-term cocoa clone trials in Ghana, with 20, 18 and 15 entries. They were 0.15, 0.05 and 0.15 for yield in pods per plant, and 0.26, 0.19 and 0.40 for incidence of ‘bad’ pods, mostly due to black pod disease, caused by infection with Phytophthora spp. The low heritability of single plant yield, which has been known for 80 years, has been widely overlooked in cocoa research and extension, compromising the success of clone selection programmes. The heritability of the incidence of black pod disease is high enough to justify mass selection where family level data are not available. The findings will be applied in a new large-scale programme in Ghana to select clones that are high yielding in the presence of P. megakarya.

Effective flowering time in Gossypium hirsutum cotton plants was studied with the aim of enhancing decision making on the best varieties to plant according to the planting date under rainfed cropping conditions. Trials were conducted at two sites in a cotton-growing area of Benin in 2002 and 2003. A split-split plot design with three replicates was used to compare 10 cotton varieties, with different growth cycle lengths and morphology, at three stand densities (42 000, 125 000, 167 000 plants ha−1) and two planting dates (standard planting in June and late planting). The flowering period was characterized by the mean first flower opening date (FF), which is an indicator of flowering earliness, and by the opening date of the last flower giving rise to a first-position boll on fruiting branches (LFP1). Effective flowering time (EFT) was calculated as the difference between LFP1 and FF. EFTs differed markedly in the 10 cotton varieties tested and this parameter could not be predicted on the basis of flowering earliness. Late planting and high planting rates delayed first-flower opening, accelerated last-boll development and reduced the effective flowering time. This latter factor should be taken into account in cotton breeding programmes so that varieties adapted to local rainfall constraints can be recommended to growers while also enhancing crop management sequences.

This research set out to find ways to increase wheat production in Bangladesh. The approaches were (1) to increase the area planted to wheat, concentrating on developing a suitable management system for the very hot, often saline and hitherto largely untested fallow lands of the south; and (2) to increase economic and sustainable yield of wheat in the traditional rice-wheat zones. Five mechanized reduced tillage and planting systems were compared. They were used to enable 200 co-operating farmers at 11 locations to plant on time and avoid the reduction in yield that accompanies delays, found in this study to average 2 % d−1. Methods that placed seeds in rows were zero tillage, full or strip surface shallow till, and raised beds. A partially mechanized version of the traditional manual system called New Conventional, in which seeds and fertilizers were broadcast, was also tested. Farmers' wheat yields averaged more than 3.5 t ha−1 for the two seasons of the study. Farmers in the untested lands averaged more than 2.5 t ha−1 on their farms, well above the 0.5 t ha−1 needed to cover all costs and equal to normal production levels in traditional wheat areas. Surprisingly, full and strip till did not produce higher yields overall than New Conventional in either season. Reasons for the lack of difference are discussed in relation to other aspects of management and variation between the farmers themselves. Farmers had varying opinions and mixed success with zero till and beds. The economic consequences to farmers of using the different systems are also discussed with the suggestion that the low-tech New Conventional method will be preferable for novice wheat farmers in the historically fallow lands where the study indicated potential production is 1 million tonnes.

Intensity of harvest in tea can be defined in terms of the number of leaves or axillary buds left behind after a shoot is harvested; we describe a simple method for measuring it. Application of the method in trials confirms that yield increases with more intense (harder) harvesting. Differences in intensity of harvest explain much of the variation in yield between different harvesting treatments, including semi-mechanical and mechanical harvesting methods. We recommend that measurements of intensity of harvest should be made routinely in experiments with tea.

A breeding programme for resistance to Striga hermonthica in maize (Zea mays) was initiated in Côte d'Ivoire in 1994. Two extra-early populations, white (TZEE-W Pop STR) and yellow (TZEE-Y Pop STR), were formed from diallel crosses of the best adapted extra-early maturing maize germplasm in the West and Central African subregion. In an effort to improve the populations for Striga resistance, TZEE-W Pop was crossed to inbred 1368 STR (Tzi 3 STR), and TZEE-Y Pop to 9450 STR (Tzi 25 STR). The resulting F1 populations were carried through two backcross (BC) generations. S1 lines were developed from the BC2 and subjected to two cycles of random mating to generate TZEE-W Pop STR C0 and TZEE-Y Pop STR C0. These two populations were subjected to three cycles of S1 recurrent selection under artificial Striga infestation and several experimental varieties were extracted from the different cycles of the selection programme. The original populations (C0), improved populations, and experimental varieties were evaluated in two experiments under Striga-infested and Striga-free conditions. The primary objective was to determine the effectiveness of S1 recurrent selection in developing Striga-resistant extra-early maize varieties. Results of the performance tests showed that the populations were good sources of Striga-resistant varieties with high-yield potential under both Striga-infested and Striga-free conditions. The results have also confirmed the effectiveness of inbreeding, selection and hybridization, as well as the backcross breeding methods, as tools for the development of extra-early populations, synthetic varieties and inbred lines.

This four-year evaluation of the introduction of the System of Rice Intensification (SRI) in northern Myanmar through Farmer Field School (FFS) methods found that these agronomic and pedagogical strategies gave positive results in a complementary way, although their individual contributions to the documented improvement in rice productivity could not be partitioned. The rice production of 612 farmers who had participated in 30 FFSs was tracked, along with that of farmers in the same communities who learned through farmer-to-farmer interaction. Average SRI yields on FFS study-fields in the wet season, without any supplementary irrigation, were 6.4 t ha−1 compared with farmers' prior average yields of 2.1 t ha−1. Three years after one third of the farmers in a community had received FFS training, almost all of its farmers were using SRI methods. This study confirmed many previously reported benefits from SRI practices, particularly important for limited-resource households.

The aim of this work was to assess the effects of N levels and intercropping of two common bean (Phaseolus vulgaris) varieties (Carioca and Rio Tibagi) with maize (Zea mays) on accumulated N, grain yield and biomass of both crops, and nodulation of common bean inoculated or not with Rhizobium. Two field experiments were conducted simultaneously: common bean–maize intercropping and common bean in sole cropping. Intercropping increased common bean nodulation and biomass, mainly with Rhizobium, but mineral N was deleterious to nodulation. Inoculation also increased the Carioca cultivar yield most in sole cropping (+72%), but N levels did not affect common bean yield in either cultivar. Although intercropping reduced maize grain yield by 17%, the equivalent yield increased by 31%, whilst Rhizobium increased it by 11%. Despite the reduction of maize yield in intercropping, this system was shown to be more economically viable, in particular when common bean was inoculated with Rhizobium.

Experiments were conducted in both the greenhouse and the field on highly weathered (Orthic Ferralsol) soils to evaluate the effect of combining on-farm organic residues (chicken manure, farmyard manure, sugar bagasse) with Minjingu phosphate rock (MPR) on soil pH, extractable (available) and sorbed phosphorus (P), and to assess the cost benefit for maize production. The greenhouse study results indicated that, in the first eight weeks of incubation, soil pH increased linearly with increase in MPR rates and decreased thereafter. The available P also increased linearly. Chicken manure and sugar bagasse were most and least effective respectively in reducing P sorption, while there was a significant negative relationship between P adsorption maxima and extractable P. The field experiment data showed that the available P values increased significantly above the control in all the treatments where MPR and organic materials were applied separately or combined. Treatment effects on Langmuir sorption maxima (Smax) in the field were variable. An increase in Smax with an increase in MPR rates was noted. However, there was a positive relationship between Smax and available P (r = 0.52 to 0.69), suggesting the diversity of factors affecting the complex nature of P dynamics under field conditions. MPR applied alone in the first season gave a significant residual positive effect on maize grain yield for two additional seasons. The economic analysis revealed that a single application of chicken manure (2 t ha−1) combined with MPR at 60 kg P ha−1 gave the highest incremental net benefit equivalent to US$ 657 ha−1 during the three maize cropping seasons.

The feasibility of commencing tapping (‘opening’) of rubber trees for latex extraction at a lower stem girth (40 and 45 cm) than the currently recommended 50 cm was investigated in three different genotypes. The possibility of combining early opening with low frequency tapping and yield stimulation using Ethrel (LFT + E) was also examined. One of the genotypes tested, RRIC 121, gave a higher dry rubber yield, both per tapping and cumulatively over a given period, when opened at 40 cm than at 50 cm. Of the other two genotypes, one (RRISL 211) showed a clear reduction in yield with early opening, while the other (RRIC 102) did not show a significant yield response. Among the three genotypes tested, RRIC 121 showed the minimum depression in trunk girth increment. Analysis of yield components showed that the response of a given genotype to early opening and LFT + E is determined by the interaction between latex volume per tapping and dry rubber content (DRC), which were negatively correlated. RRIC 121 had a significantly greater DRC, which enabled it to maintain a higher dry rubber yield under early opening and LFT + E despite producing a lower latex volume than both the other genotypes. In contrast, despite producing a substantially greater latex volume than the other two genotypes, RRISL 211 did not produce a higher dry rubber yield because of its lower DRC. The higher DRC was also responsible for the greater response of RRIC 121 to yield stimulation with Ethrel, which reduced the plugging index and increased the initial latex flow rate. Early commencement of tapping in combination with LFT + E is therefore possible in rubber when amenable genotypes are selected, offering the potential of improving the economics of rubber production, especially for smallholders, in West Asia.

Simultaneous deficiencies of nitrogen (N) and phosphorus (P) which limit crop production in western Kenya can be overcome through a combined application of organic and inorganic fertilizers. An experiment was conducted with maize (Zea mays) for two seasons to compare two methods of applying inorganic P fertilizer (broadcast versus spot) in a factorial combination with three N sources, i.e. farmyard manure (FYM), Tithonia diversifolia green manure (tithonia) and urea. Net financial benefits of the tested practices were computed using partial budgeting. Maize yield was not significantly affected by the P fertilizer application method in the first season, but the broadcast method was generally superior to spot application in the second season. The three N sources produced maize yields that were comparable in both seasons. FYM integrated with P fertilizer applied using the broadcast method, however, had the highest cumulative net benefit and was therefore the most economically attractive input combination.

The effects of nematodes on root morphology and the association of root characteristics with resistance to nematodes of seven banana varieties were investigated in two experiments. Banana plants were grown in controlled conditions within polytunnels and harvested on three occasions for the measurement of root morphology and biomass. Varieties differed in their resistance to nematodes, from resistant (Yg Km5, FHIA 17, FHIA 03) and partly resistant (FHIA 01, FHIA 25) to not resistant ((FHIA 23, Williams). Nematodes reduced the root dry weight of FHIA 01, FHIA 17 and FHIA 23 at some harvests. Primary root number was on average 9.5% lower in nematode-infected plants than controls, with no differences among the varieties. Thus, there was no simple association between the resistance of these varieties and their tolerance to nematodes. Varieties differed in root morphology. Root dry weight was greatest for resistant varieties Yg Km5 and FHIA 03, and least for non-resistant varieties FHIA 23 and Williams. Thus, resistance to nematodes was associated with varieties with greater root mass and more and larger primary roots.