Four standard Nigerian varieties of sorghum were grown in trials together with local varieties representative of sorghums from each of the five main ecological zones. Analysis of the data showed a relation within each zone between mean yield and time of heading. When the standard varieties and the local varieties flowered simultaneously, yields were similar. When the standard varieties flowered later—or in some cases earlier—than the local varieties, the local varieties out-yielded them.

Post-anthesis trends in yield and forage quality of dry matter in components of the maize shoot were studied in experiments with barren and fertile plants grown at 10 plants/m2. In fertile plants, which had a maximum shoot DW 6 or 7% higher than barren ones, the stems (including leaf sheaths) yielded 5 t/ha (42% shoot DW) 30 days after flowering, declining to 3·5 t/ha (26% DW) at final harvest 60 days later. During this period the ear increased by more than 4 t/ha, from 23 to 50% of shoot DW, whereas in barren plants there was little change in DM distribution, with the stem representing about 48% shoot DW, leaf and husk together 40–45% and the ear (rachis only) less than 10%. DM percentage of shoots was similar in barren and fertile plants until maximum DW was attained about 60 days after flowering, after which fertile plants dried more rapidly. In vitro dry matter digestibility was as high in barren as in fertile plants, and the analytical data on forage quality do not suggest that it was positively associated with grain content.

Grain yield of maize (Zea mays L.) was decreased by 30, 38 and 34 kg ha−1 for each day by which sowing was delayed after the first planting in March in 1978, 1980 and 1981, respectively. Yield reduction was associated with reduced plant size (plant and ear heights, tassel weight and branch numbers), ear number, ear weight, grain weight, ear length, ear diameter and kernel weight. High yields can thus be obtained by planting with the first rains of the year, especially if a good rate of emergence and seedling vigour under relatively hot, dry soil conditions can be ensured either culturally or genetically.

The design of field trials sometimes raises queries (which often go unanswered) about alternative designs and the best ways of allowing for environmental variation in the area allotted to the experiment. It is shown how recent developments in iterative methods for working out analyses of variance make possible the determination of error for systems of blocks other than the one actually used, and also for the row-and-column case. Some suggestions are also made for judging the error to be expected if plots were made larger.

Three varieties of rice, selected for their differences in height and tillering ability, were grown side by side in 10-row plots to determine the effect of varietal competition on plot yields. Plants in border rows performed differently from those in the centres of plots, higher-tillering or taller varieties tending to depress the performance of adjacent plants. Comparisons among varieties based on plot yields, determined with and without excluding the border rows, gave different results. Excluding two rows on each side of a plot was sufficient to eliminate the effects of varietal competition on yield data.

Stages in oil palm inflorescence development which determine the number and weight of the fruit bunch components were identified by thinning to intervene in development and dissection of a sample of the felled palms. This showed that the ratio of female to total inflorescences and the number of flowers per spikelet were determined eight leaves prior to spikelet initiation. The number of spikelets per inflorescence was linked with the meristematic development of the primary axis. Inflorescences were prone to abortion at the onset of rapid expansion of the primary axis. The weight of the frame responded to thinning at these three developmental stages. The weight of single fruits responded shortly after the fruit set was fixed at anthesis; the response levelled off in axils of the six older leaves. At the start of an abortion phase nearly all aborted inflorescences were female, but subsequently female and male inflorescences aborted in equal proportions. Our study suggests that the number and weight of fruit bunch components are determined at a specific developmental stage but that the time to anthesis may vary considerably as a result of fluctuations in the speed of inflorescence development.

Cotton–wheat (CW) is the second most important cropping system after rice–wheat in South Asia. Sowing of wheat after cotton is usually delayed due to late pickings coupled with time needed for seedbed preparation, resulting in low wheat yield. Lack of suitable machinery is a major constraint to direct drilling of wheat into the heavy cotton stubbles. An innovative approach with much promise is the ‘2-wheel tractor-based self-propelled relay seeder’ with seed-cum-fertilizer attachment. On-farm trials were conducted at four locations during 2009–2010 and at 10 locations during 2010–2011 to evaluate the following four wheat establishment methods in CW-dominated areas of south-western Punjab, India: (1) zero till seeding in standing cotton using a self-propelled relay seeder, (2) relay seeding in standing cotton with a manual drill without prior tillage (2010 only), (3) relay broadcast seeding in standing cotton following light manual tillage and (4) conventional sowing of wheat after cotton harvest (conventional tillage and sowing with a seed–fertilizer drill). Planting of wheat under conventional practice was delayed by 20–44 days compared with relay seeding. Seed cotton yield was also significantly higher with relay seeding due to opportunity for one additional picking. Yield of wheat sown with the self-propelled relay seeder was 41.2% and 11.8% higher than with conventional practice in 2009–2010 and 2010–2011 respectively. The increase in wheat yield under relay seeding of wheat was primarily due to higher spike density and more grains per spike. The net income from the CW system was 28.2% higher for the self-propelled relay seeder than with conventional sowing.

Reports of cassava root rot disease from different African countries have increased in recent times. Field studies were conducted from July 1998 to October 1999 to determine a reproducible disease assessment method that would allow the comparison of results from different locations and an evaluation of the relationship between disease severity and root yield. Single point disease assessments at 6, 9, 12 and 15 months after planting (MAP) were compared to multiple points assessment based on the area under a disease progress curve (AUDPC). Single point assessments at 12 and 15 MAP, and the AUDPC identified continuous variation (p≤0.01) among the genotypes. However, a consistent result across trials was obtained only with the assessment based on AUDPC. Root dry yield (DYLD) at 15 MAP showed a strong negative correlation with AUDPC (r=−0.74). Regression analysis also confirmed the negative relationship between yield and root rot severity. The five genotypes compared were separated into resistant (91/02324, 30572 and 92/0427) and susceptible (92/0057 and TME-1) groups. It was concluded that root rot disease may cause significant yield loss; however, the magnitude of the yield loss will depend on the susceptibility of the cassava genotype.

Research has proved that integrated soil fertility management (ISFM) can increase crop yields at the field and farm scales. However, its uptake by smallholder farmers in Africa is often constrained by lack of technical guidelines on effective starting points and how the different ISFM options can be combined to increase crop productivity on a sustainable basis. A 4-year study was conducted on sandy soils (<10% clay) on smallholder farms in eastern Zimbabwe to assess how sequencing of different ISFM options may lead to incremental gains in soil productivity, enhanced efficiency of resource use, and increase crop yields at field scale. The sequences were primarily based on low-quality organic resources, nitrogen-fixing green manure and grain legumes, and mineral fertilizers. To enable comparison of legume and maize grain yields among treatments, yields were converted to energy (kilocalories) and protein (kg) equivalents. In the first year, ‘Manure-start’, a cattle manure-based sequence, yielded 3.4 t ha−1 of maize grain compared with 2.5 and 0.4 t ha−1 under a woodland litter-based sequence (‘Litter-start’) and continuous unfertilized maize control, respectively. The ‘Manure-start’ produced 12 × 106 kilocalories (kcal); significantly (p < 0.05) out-yielding ‘Litter start’ and a fertilizer-based sequence (‘Fertilizer-start’) by 50%. A soyabean-based sequence, ‘Soya-start’, gave the highest protein production of 720 kg against <450 kg for the other sequencing treatments. In the second year, the sequences yielded an average of 5.7 t ha−1 of maize grain, producing over 19 × 106 kcal and 400 kg of protein. Consequently, the sequences significantly out-performed farmers’ designated poor fields by ~ fivefold. In the third year, ‘Soya-start’ gave the highest maize grain yield of 3.7 t ha−1; translating to 1.5 and 3 times more calories than under farmers’ designated rich and poor fields, respectively. In the fourth year, ‘Fertilizer-start’ produced the highest calories and protein of 14 × 106 kcal and 340 kg, respectively. Cumulatively over 4 years, ‘Manure-start’ and ‘Soya-start’ gave the highest calories and protein, out-performing farmers’ designated rich and poor fields. Sunnhemp (Crotalaria juncea L.)-based sequences, ‘Green-start’ and ‘Fertilizer-start’, recorded the highest gains in plant available soil P of ~ 4 mg kg−1 over the 4-year period. Assessment of P agronomic efficiencies showed significantly more benefits under the ISFM-based sequences than under farmers’ designated rich and poor fields. Based on costs of seed, nutrients and labour, ‘Soya-start’ gave the best net present value over the 4 years, while ‘Fertilizer-start’ was financially the least attractive. Overall, the ISFM-based sequences were more profitable than fields designated as rich and poor by farmers. We concluded that ISFM-based sequences can provide options for farm-level intensification by different categories of smallholder farmers in Southern Africa.

Projections suggest that annual per capita water availability in the Indo-Ganga Basin (IGB) will reduce to a level typical for water-stressed areas. Producing more crop and livestock products, per unit of agricultural water invested, is advocated as a key strategy for future food production and environmental security in the basin. The objective of this study was to understand the spatio-temporal dynamics of water requirements for livestock feed production, attendant livestock water productivity (LWP) and implications for the future sustainable use of water resources. We focused on three districts in the IGB representing intensive (higher external inputs, e.g. fertilizer, water) and semi-intensive (limited external input) crop-livestock systems. LWP is estimated based on principles of water accounting and is defined as the ratio of livestock beneficial outputs and services to the water depleted and degraded in producing these. In calculating LWP and crop water productivity (CWP), livestock, land use, land productivity and climatic data were required. We used secondary data sources from the study districts, field observations and discussions with key informants to generate those data sets. Our result showed that the volume of water depleted for livestock feed production varied among the study systems and was highly affected by the type of feed and the attendant agronomic factors (e.g. cropping pattern, yield). LWP value was higher for intensive systems and affected by agricultural water partitioning approaches (harvest index, metaolizable energy). LWP tended to decrease between 1992 and 2003. This can be accounted for by the shift to a feeding regime that depletes more water despite its positive impacts on animal productivity. This is a challenging trend with the advent of and advocacy for producing more agricultural products using the same or lower volume of water input and evokes a need for balanced feeding, by considering the nutritive value, costs and water productivity of feed, and better livestock management to improve LWP.

In a long-term fertility study it was observed that judicious use of chemical fertilizers maintained the levels of soil pH, total N, organic C, CEC and exchangeable Ca. Highest accumulation of exchangeable Ca and Mg was found in the 40–60 cm layer. Absence of Mg and K from the fertilizer schedule resulted in a decrease in the amounts of those elements in the soil. Profile CEC and exchangeable Ca were not affected much by the application of K or trace elements. Compared with adjacent grass fallow or virgin bush land, only the values of C/N ratio, CEC and exchangeable Mg decreased on cultivation. All the crops responded well to fertility levels but not to K; trace element response was confined to cotton and groundnut.

Drought resistance in terms of yield and its components was studied in the field in twenty-one agronomically-adapted high-performance grain sorghum (Sorghum bicolor Moench) hybrids. Resistance was considered to be indicated by a minimal decrease in yield under stress as compared with non-stress conditions. Water stress, imposed by a decreasing amount of stored soil moisture during the growing season, decreased grain yield and number of panicles per unit area, increased the number of grains per panicle, the number of branches per whorl and the number of grains per branch, and decreased the number of whorls per panicle. Thus a compensatory effect was observed in some components for reduction in tillering under stress. Resistant hybrids performed better than susceptible ones under stress by producing a relatively higher number of panicles per unit area, and more grains per panicle branch. Susceptible hybrids performed better than resistant ones under non-stress (irrigated) conditions due to the relatively higher number of panicles per unit area and larger 1000-grain weight. Some of the implications regarding selection for yield performance under drought are discussed.

Lack of effective chilling during the dormant season is one of the major problems when apples are growing under a tropical climate. We evaluated the response of different apple cultivars (Golden Delicious, Gala, Fuji, Granny Smith and Jonagold) grown on M9 rootstock with different dormancy-management practices. The trials were carried out between 2004 and 2006 in a tropical mountain area (Tigray, Ethiopia), where chilling conditions are poor with the aim of improving and synchronizing the bud break and the blossoming period of these apple cultivars. Two-year-old well-feathered trees were planted in two experimental trial sites in a randomized complete block design. Trees were subjected to the following treatments in two sets of experiments: one defoliation per year only; two defoliations per year, one defoliation followed by 1% hydrogen cyanamide (Dormex) treatment; one defoliation followed by 2% Dormex treatment; one defoliation followed by 4% winter oil; one defoliation followed by 0.5% Dormex and 2% winter oil; and a control with no defoliation or dormancy breaking treatments. The results show positive effects of the dormancy breaking agents on the productivity of the trees after defoliation, with comparable results for the effectiveness of both Dormex and winter oil. There were no statistically significant differences between the Dormex doses. The defoliation treatment alone was not sufficient to break dormancy for the cultivars Golden Delicious, Granny Smith or Gala but showed promising results with dormancy breaking on Jonagold. Yields increased as a result of better flowering time synchronization within a tree but even with the dormancy treatments the length of the flowering period was still spread over five weeks, where under a more temperate climate it lasted two to three weeks. The average fruit weight of Jonagold and Granny Smith can be considered as a good fruit quality while the fruit of other diploid cultivars like Golden, Gala and Fuji were rather small, which indicates that fruit thinning by hand will be a necessity for these cultivars. Red colouration of the apples on the cultivars Gala and Jonagold was excellent and meets the standards necessary for commercialization of these fruits. The sugar concentration of the fruits and the fruit firmness at harvest was high. The results of these first trials indicate that it is possible to develop new apple production in the mountain region of Tigray, Ethiopia.

Improving farmers’ knowledge of new technologies and creating conducive learning opportunities, with particular attention to the marginalized poor (women and youth), are major factors in the move towards sustainable agriculture. To explore the gender gap in agricultural knowledge acquisition and adoption in West Africa, we used baseline data collected in 2013 and 2014 in five countries (Benin, Côte d'Ivoire, Niger, Nigeria and Togo) with 499 surveyed households. The t-test and Kruskal–Wallis test were used for analysis. The most quoted source for acquiring knowledge on rice farming methods was ‘other farmers’, showing the importance of social capital for rural African farmers. In Benin, a gender gap was noted in rice farmers’ access to agricultural knowledge sources, with women being more advantaged. In Côte d'Ivoire, Niger, Nigeria and Togo, no significant gender gap was observed in rice farmers’ access to agricultural knowledge sources. Regarding the level of knowledge and use of rice farming methods in Côte d'Ivoire and Niger, significant gender gaps were observed. The gender approach to rural development is having impact in West Africa with regard to farmers’ access to agricultural information. However, interactive rural learning approaches (such as farmer-to-farmer video) need to be resorted to make the technologies’ principles well known and improve the ability of marginalized poor to adopt and or innovate with local or limited resources. This study leads to a better understanding of the relationship between gender, knowledge and use of agricultural technologies in order to enhance marginalized farmers’ adoption of improved innovations.

Poor soil fertility is a constraint to coffee production. Targeting fertiliser recommendations to nutrient deficiencies can contribute to improved crop response to fertiliser. This study aimed to derive and compare the Compositional Nutrient Diagnosis (CND) and Diagnosis and Recommendation Integrated System (DRIS) norms for Arabica and Robusta, and to investigate nutrient interactions using data derived from 164 plots. The high-yield sub-populations of Arabica had significantly (p < 0.01) higher P (0.23 vs. 0.14) and K (2.87 vs. 2.04), and lower N (2.96 vs. 3.61), Ca (0.99 vs. 1.50) and Mg (0.40 vs. 0.23) than those of Robusta. With respect to the CND norms, Arabica had significantly (p < 0.001) higher P and K, and lower N, Ca and Mg means of row-centered log ratios than Robusta. The relationship between the CND and DRIS indices had coefficient of determination (R2) = 0.75–0.99 for both coffee types. The relationship between nutrient imbalance indices for CND and DRIS had R2 of 0.95 (Arabica) and 0.76 (Robusta). Both coffee types had negative N–Ca, P–Mg and K–Mg interactions. Arabica had positive N–Mg and K–Ca interactions and Robusta had positive N–K, P–K and Ca–Mg interactions and negative N–P, N–Mg, P–Ca and K–Ca interactions. The study concludes, there is a need for cultivar-specific norms, but such norms developed under one set of conditions may not be applicable under different conditions. The study also concludes that both CND and DRIS can be used to determine nutrient imbalances, and fertiliser requirements could be cultivar-specific.

Experiments with farmers' traditional practice of growing cereals with groundnuts demonstrated that the system consistently produced greater cash returns than sole-crop groundnuts. Increasing the proportion of cereal, and incorporating maize in addition to sorghum and millet, increased cash returns even further.

Pearl millet is a staple cereal cultivated mainly by subsistence farmers on 14 million ha of the West African semi-arid tropics. Increasing pressure on the land has reduced the length of the fallow periods, which are necessary to restore soil fertility, resulting in declining yields. To investigate ways of reversing this decline, three systems combining phosphorus fertilizer application, improved varieties of millet and cowpea, and improved agronomic practices were compared with the traditional millet–cowpea intercrop system in a three year experiment. The most productive system involved the rotation of fertilized millet and cowpea. Pre-sowing tillage increased hay and fodder yields in all the improved systems. The application of fertilizer increased the amount of available phosphorus in the soil. Soil pH declined somewhat in all treatments, although the initially low soil organic matter did not change.

The extent to which coffee agroforestry systems provide ecosystem services depends on local context and management practices. There is a paucity of information about how and why farmers manage their coffee farms in the way that they do and the local knowledge that underpins this. The present research documents local agro-ecological knowledge from a coffee growing region within the vicinity of the Aberdare Forest Reserve in Central Kenya. Knowledge was acquired from over 60 coffee farmers in a purposive sample, using a knowledge-based systems approach, and tested with a stratified random sample of 125 farmers using an attribute ranking survey. Farmers had varying degrees of explanatory knowledge about how trees affected provisioning and regulating ecosystem services. Trees were described as suitable or unsuitable for growing with coffee according to tree attributes such as crown density and spread, root depth and spread, growth rate and their economic benefit. Farmers were concerned that too high a level of shade and competition for water and nutrients would decrease coffee yields, but they were also interested in diversifying production from their coffee farms to include fruits, timber, firewood and other tree products as a response to fluctuating coffee prices. A range of trees were maintained in coffee plots and along their boundaries but most were at very low abundances. Promoting tree diversity rather than focussing on one or two high value exotic species represents a change of approach for extension systems, the coffee industry and farmers alike, but is important if the coffee dominated landscapes of the region are to retain their tree species richness and the resilience this confers.

The response of the latest wheat cultivars to irrigation regimes was studied between 1970 and 1975 in a heavy soil of the Yaqui Valley of north-west Mexico. Yield showed greatest sensitivity to water shortage in the period 65–110 days after seeding (spike emergence around 90 days), due largely to responses in grains/m2. More frequent irrigation increased yields 5–10% over the average of 7 t/ha obtained with the commonly-adopted five irrigation regime. Various irrigation criteria were tested: potential evapotranspiration calculations seemed the most useful. Measurement of leaf permeability (with an air flow porometer) showed more promise than the use of plant water potential (measured with a pressure chamber).

Recent years have seen increasing political interest and growing public health awareness and advocacy for diversifying diets into highly nutritious traditional vegetables, fruits and other nutrition-sensitive crops as a more viable approach to mitigate the growing scourge of malnutrition due to unhealthy and imbalanced diets. These foods contribute essential micronutrients, vitamins, antioxidants, and other health-related phytochemicals to staple-based diets and their consumption is crucial for the attainment of several Millennium Development Goals. Despite their nutritional benefits and the high farm gate values per unit of land, the production and marketing of traditional vegetables from Tanzania and other countries in sub-Saharan Africa are constrained by factors such as poor quality seeds, lack of appropriate market information and support systems, and lack of consumer awareness of their nutritional importance. This paper investigates the determinants and pathways for smallholder participation in traditional African vegetable production and identifies entry points for farmers to increase traditional vegetable production by linking nutritional awareness and promotion with potential high value markets. A primary survey of 181 traditional vegetable growers from five regions of Tanzania indicates that perceptions about the nutritional value of traditional African vegetables are a main driver of household production decisions in the sector. The results of this study provide evidence that farmers tend to grow more African traditional vegetables as compared to other crops based on their increased level of perception towards nutritional value of traditional vegetables along with other factors such as their market value, timely availability of quality certified seeds, willingness to invest in labour, required training for women and better access to credits. Farm size negatively affects growing traditional vegetables, implying that on a comparative basis, smallholders tend to grow more traditional vegetables than larger-farm operators. Thus, more attention should be given to reducing production and its associated transaction costs by ensuring timely access to quality certified seeds, ensuring optimal use of inputs and increasing labour productivity, particularly for smallholders.