Experiments were conducted across 2 years to determine the effect of harvesting methods – combine harvester and hand harvesting – and harvest time during ripening on milling quality of long grain rice grown in the rainfed lowland ecosystem in Cambodia. Head rice yield (HRY) was highest when rice was harvested 25 days after flowering and decreased with delay in harvesting at 35 and 45 days after flowering. This was accompanied by a general decline in grain moisture content at harvest, although it was still high at 24–25% at 35 days after flowering. The decline in HRY was associated with increases in fissured grain percentage observed immediately after harvest. Hand harvesting produced 2–6% higher HRY than combine harvesting. Fissured grain in hand harvested crops was lower in year 1, but was similar to combine harvested crops in year 2. Both hand and combine harvested crops were sun-dried but rough rice harvested by combine was dried on plastic sheet and this may have contributed to reduction in HRY. Maximum HRY percentage was only about 44% and the factors contributing to this low HRY were discussed. Harvesting time and methods had no significant effect on grain yield, but the field grain loss during the harvesting operation was 2–5% higher in combine than hand harvesting.

Development actors, including the African Union, the Alliance for a Green Revolution in Africa and bilateral donors, promote a technology-driven sustainable intensification of agriculture as a way to feed a growing world population and reduce rural poverty. A broader view of smallholder agriculture in the context of rural livelihoods suggests that technological solutions alone are unlikely to meet these goals. Analysis of the solution space for agricultural interventions in a high potential area of southern Mali shows that intensification can lift most farm households out of extreme poverty and guarantee their food self-sufficiency. However, the most effective options do not fit the usual definition of sustainable intensification, increasing production per unit land while protecting the natural environment. Cropland expansion combined with the good yields seen in on-station experiments can nearly eliminate extreme poverty, while the biggest impact may come from taking advantage of peak seasonal prices for crops like groundnut. Other profitable alternatives can include meat production with small ruminants or sales of milk from cows. However, off-farm employment opportunities like gold mining outperform currently attainable agricultural options in terms of profitability. Options for rural households should fit within the households’ socio-ecological niches and respond to their priorities in order to be successful. Given the relatively low impact of (sustainable) intensification technologies alone, a rethinking of the role of agricultural research in development is needed in order to align interventions with farmer priorities and meet development goals.

We investigated the occurrence and status of the leaf folder Cnaphalocrocis ruralis (Walker) (Lepidoptera: Crambidae) in accessions of Erianthus spp. maintained as a part of the world germplasm collection at the Research Center of ICAR-Sugarcane Breeding Institute, Kannur, Kerala State, India. The nature, pattern, extent and year-to-year variation in damage were examined and accessions categorized based on relative incidence. The larvae of C. ruralis caused characteristic injury by feeding on chlorophyll bearing tissues leading to the formation of white and transparent streaks on the leaf blade. The grown-up larvae folded the leaf longitudinally with the adaxial surface inside the fold and exposing the abaxial surface, the edges being held in place by bands of silk thread at regular intervals. The length of leaf folds varied from 2.6 to 27.0 cm with a mean of 9.1 cm, which roughly constituted 7.3% of the mean length of the leaf blade. Leaf length, leaf width and leaf area were not correlated with either the leaf fold length or the number of webs. However, the leaf fold length was positively correlated with the number of webs. Attack rates (infestation rate) on cane basis (up to 69.0%) were generally higher than the damage rates (intensity) on leaf basis (up to 50.0%); infestation index ranged between 0.0 and 13.7%. Correlations between infestation rate and intensity varied among the three study years. Non-parametric analysis indicated significant differences among the three years for percent of infested canes and infestation index but not percent of damaged leaves. All accessions showed C. ruralis incidence in at least one experimental year, indicating that none of the accessions tested was immune to its attack. When all 74 accessions were considered on the basis of infestation index, 85.1% were placed in low and moderate categories and only 14.9% in high incidence category. Within the accessions of Erianthus spp., leaf area was not related to infestation rate of cane or damage rate of leaves but positively related to infestation index. The dynamics of the leaf folder in the predominantly paddy ecosystem were discussed in the light of its first occurrence in Erianthus spp. accessions in India and the world.

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.

Yield gaps have become a useful tool for guiding development-related agronomy, especially in the global South. While critics have challenged some aspects of the yield gap methodology, and the relevance of food security advocacy based on yield gaps, very few studies question the actual relevance, application and scalability of yield gaps for smallholder farmers (and researchers) in the tropics. We assess these limitations using two contrasting case studies: maize-based farming systems in Western Kenya and rice-based farming systems in Central Luzon, the Philippines. From these two cases, we propose improvements in the use of yield gaps that would acknowledge both the riskiness of crop improvement options and the role that yield increases might play within local livelihoods. Participatory research conducted in Western Kenya calls into question the actual use and up-scaling of yield measurements from on-station agronomic trials to derive estimates of actual and water-limited yields in the region. Looking at maize yield gaps as cumulative probabilities demonstrates the challenges of assessing the real magnitude of yield gaps in farmers’ fields and of deciding whose yield gaps count for agricultural development in Kenya. In the case of rice-based farming systems, we use a historical dataset (1966–2012) to assess changes in rice yields, labour productivity, gross margin and rice self-sufficiency in Central Luzon, the Philippines. While large rice yield gaps persist here, there appear to be few incentives to close that gap once we consider the position of crop production within local livelihoods. In this context, economic returns to labour for farm work were marginal: labour productivity increased over time in both wet and dry seasons, but gross margins decreased in the wet season while no trend was observed for the dry season. Since most households were rice self-sufficient and further increases in crop production would offer minimal returns while relying increasingly on hired labour, we question who should close which yield gap. Our case studies show the importance of contextualising yield gaps within the broader livelihood context in which farmers operate. We propose that this should be done at farm and/or farming systems level while considering the risks associated with narrowing yield gaps and looking into multiple performance indicators.

A major problem faced by small-scale farmers in northern Ethiopia is reduced crop yield due to increasing soil degradation resulting from repeated tillage and inadequate agronomic management practices. These practices have left soils and rainfed crops susceptible to hazardous climatic events such as droughts. Sustainable farm practices such as minimum tillage and surface residue retention have been shown to improve soil health and crop productivity. The objectives of this field study were thus to evaluate the impacts of conservation agriculture (CA) practices on crop yield and economic productivity over 6 years in the eastern Tigray region of northern Ethiopia. Using a barley–wheat rotation from 2010 to 2016, the applied treatments were (i) permanent raised beds (PRB); (2) semi-permanent raised beds (SPB) and (3) conventional tillage (CT). Average barley and wheat biomass and grain yields in PRB and SPB treatments were consistently greater than yields under CT each year. In addition, the highest marginal rate of return was obtained in PRB and SPB compared to CT in all years (2010–2016). These results suggest that the CA practices of PRB and SPB can improve crop yield and profit compared to CT practices in the Tigray region.

Transplanting single seedlings rather than seedlings in clumps has been increasingly attractive in hybrid rice production in China due to reduced seed requirements and higher grain yield. This study was conducted to determine grain yield and nitrogen (N) utilization in response to reductions in the N rate in hybrid rice under single-seedling transplanting. Field experiments were done in 2015 and 2016 on a moderate to high fertility soil at the Experimental Farm of Hunan Agricultural University, China. The hybrid rice cultivar Liangyoupeijiu (LYPJ) was used in 2015, and two hybrid cultivars LYPJ and Xiangliangyou 900 were used the next year. In each year, the rice plants transplanted with a single seedling per hill were grown with three N rates, including the usual N rate (150 kg ha–1) and two reduced N rates (120 and 90 kg ha–1). Grain yield, yield attributes, and N uptake and use efficiency were determined for each N rate. Significant reduction in grain yield was observed in only one of three cultivar-year combinations when N rate was reduced by 20% (from 150 to 120 kg ha–1), and the magnitude of yield reduction was only 4%. Although significant reduction in grain yield was observed in two of the three cultivar-year combinations when N rate reduced by 40% (to 90 kg ha–1), the highest yield reduction was only 7%. Yield attributes were generally changed slightly when N rate was reduced by 20%, while compensation among yield attributes and N utilization characteristics could explain why a 40% reduction in N rate did not result in substantial yield loss. Partial factor productivity of applied N (PFPN) was increased by 21–24% and 56–63% with 20% and 40% reductions in the N rate, respectively. The higher PFPN with a reduced N rate was attributed to higher recovery efficiency of applied N (REN) or to both higher REN and internal N use efficiency. Our study suggests that reducing N rate does not necessarily result in yield loss due to compensation among yield components and increased N use efficiency in hybrid rice transplanted as single seedlings under moderate to high soil fertility conditions.

The large diversity of farms and farming systems in sub-Saharan Africa calls for agricultural improvement options that are adapted to the context in which smallholder farmers operate. The socio-ecological niche concept incorporates the agro-ecological, socio-cultural, economic and institutional dimensions and the multiple levels of this context in order to identify which options fit best. In this paper, we illustrate how farming systems analysis, following the DEED cycle of Describe, Explain, Explore and Design, and embedding co-learning amongst researchers, farmers and other stakeholders, helps to operationalize the socio-ecological niche concept. Examples illustrate how farm typologies, detailed farm characterization and on-farm experimental work, in combination with modelling and participatory approaches inform the matching of options to the context at regional, village, farm and field level. Recommendation domains at these gradually finer levels form the basis for gradually more detailed baskets of options from which farmers and other stakeholders may choose, test and adjust to their specific needs. Tailored options identified through the DEED cycle proof to be more relevant, feasible and performant as compared to blanket recommendations in terms of both researcher and farmer-identified criteria. As part of DEED, on-farm experiments are particularly useful in revealing constraints and risks faced by farmers. We show that targeting options to the niches in which they perform best, helps to reduce this risk. Whereas the conclusions of our work about the potential for improving smallholders’ livelihoods are often sobering, farming systems analysis allows substantiating the limitations of technological options, thus highlighting the need for enabling policies and institutions that may improve the larger-scale context and increase the uptake potential of options.

Rice (Oryza sativa L.) is an important staple crop in South Sudan. Current rice consumption in the country is approximately 23,000 mg year−1 of which more than 75% is imported. We investigated farmers’ perceived rice production and productivity constraints and choice of rice ideotypes across rainfed and irrigated rice agro-ecologies in South Sudan to guide breeding and policy interventions. Data were gathered through participatory rural approaches and a formal structured survey involving 136 rice farmers from major rice growing areas of South Sudan. Farmers generally cultivated old rice varieties with low yields varying from 0.4 to 1.6 mg ha−1. Pair-wise ranking based on respondents score indicated yield, early maturity, cooking and eating quality, nutritional importance and drought tolerance as the most desirable traits of rice ideotypes. Further, imported rice varieties were best ranked for their sweet and appealing taste, rich aroma, grain shape and size, swelling capacity and non-stickiness during cooking. Major perceived constraints to rice production were unreliable rainfall, poor access to credit facilities, poor soil and water management practices, poor rice storage facilities, inadequate and poor processing machines as well as limited technical skills in rice production. The results show a need for integration of farmers’ and stakeholders’ preferences in variety development process and the desirability of releasing site-specific rice cultivars given the differences in bio-physical, socio-cultural and farmers preferences across major rice growing areas of South Sudan.

Maize (Zea mays L.) grain yield is severely constrained by drought and this study was conducted to assess gains in grain yield and other traits of released maize cultivars. Twenty-three maize cultivars plus a check were evaluated under drought and well-watered conditions at Zaria and Kadawa during 2015/2016 and 2016/2017 dry seasons. The 24 cultivars were evaluated using 6 x 4 lattice design with three replications. Genotypes differed significantly for all measured traits except anthesis-silking interval (ASI), husk cover, and number of ears per plant under drought, and ASI, husk cover, and ear aspect under well-watered conditions. Under drought, grain yield ranged from 2251 kg ha−1 for SAMMAZ 31 to 4938 kg ha−1 for SAMMAZ 19, with a genetic gain of 1.93% yr−1. Under well-watered conditions, grain yield varied from 3082 kg ha−1 for SAMMAZ 37 to 5689 kg ha−1 for SAMMAZ 51, with the same genetic gain found under drought conditions. Grain yield reduction as a result of drought was 28.4% and performance under drought predicted performance under well-watered conditions better than vice versa with regression coefficient value of 0.8. Grain yield had significant correlations with all measured traits under both water conditions, except for husk cover, plant and ear heights under drought. Our data revealed that substantial genetic gains have been made in breeding for high grain yield cultivars under drought and well-watered conditions over a period of 16 years in Nigeria.

Remote sensors permit forecasting the nutrient status and yields in crops of economic importance in Colombia. The objective of this study was to determine the relationships between normalized difference vegetation index (NDVI) and yield as well as concentrations of ${\rm {N - NO}}_3^ - $ and K+ in stem sap of potato cultivars Diacol Capiro and Pastusa Suprema (Solanum tuberosum L., Group Andigenum) in relation to different fertilizer rates. Increasing doses (0, 1450, 1900 and 2375 kg ha–1) of macro- and micronutrient fertilizers were applied to determine NDVI behavior at 55, 75, 100, 125 and 150 days after planting. For Capiro, significant differences in NDVI readings (0.84–0.88) were found between phenological stages. In both cultivars, NDVI correlated positively with yield and K+ concentrations in stem sap during tuber filling and maturation, while in Capiro no correlation was established between NDVI values and ${\rm {N - NO}}_3^ - $ concentrations in stem sap. The NDVI readings could be used to forecast productivity and K status in potato Group Andigenum.

The increasing tropospheric ozone concentration [O3] strongly affects plant growth. However, the response of belowground processes in rice (Oryza sativa L.) systems to higher O3 is not well understood. The grain production, belowground biomass partitioning, root morphology and activity of rice (cv. Shanyou 63) were investigated in a free-air O3 enrichment platform at four key growth stages. Elevated O3 (EO3, 50% above the ambient O3) significantly decreased the grain yield and total biomass at the grain milky mature stage, root biomass at the tillering stage and root to shoot ratios (RRS) at the flowering and grain filling stages. The effects of EO3 on root morphology and activity varied among rice growth stage. EO3 significantly decreased root length, density, area, diameter and volume at the flowering stage, but EO3 significantly decreased various root morphological indices at the tillering, grain filling and milky mature stages. EO3 significantly increased the specific root respiration rate (root activity) and root respiration rate (autotrophic respiration) at grain filling and milky mature stages. Higher root autotrophic respiration and lower RRS in response to EO3 would reduce allocation of assimilated carbon to root growth, adversely affecting rice productivity. Our findings are critical for understanding the O3-induced impairment of belowground processes and carbon cycling in rice cropping systems and breeding of O3-tolerant cultivars under higher [O3] scenarios.

Climatic change affects global agriculture and is a severe threat to global food security due to variability of the three factors measuring climate change (CO2, temperature and precipitation) with temperature being the most crucial one. Wheat is severely affected by high temperatures with reproductive and grain-filling phases being most sensitive, impacting grain number, size and weight. Seed size and weight are the key agronomic traits subjected to artificial selection and involved in the domestication process since the origin of agriculture. Three genotypes Banks, EGA Gregory and Fang-60 with the latter known to be heat tolerant were grown under glass house conditions and subjected to heat stress for 3 days during early- (11–14 dpa – days post anthesis) and late- (27–30 dpa) grain filling stages in a mutually exclusive fashion. The impact of heat stress during early- and late- grain filling on the four major grain characteristics, thousand grain weight (TGW), grain length, grain width and grain thickness was assessed. The tolerant genotype Fang-60 exhibited significantly higher TGW during early-grain filling heat stress than the control possibly due to an ability to exploit the accelerated release of fertilizer under high temperature. Banks and EGA Gregory were moderately tolerant to susceptible to heat stress, respectively, at early- and late-grain filling with Fang-60 being tolerant to both early- and late- grain filling heat stress. This study confirms the availability of significant genetic variation in heat stress response in wheat that might be exploited to adapt wheat to higher growth temperatures.

Understanding farm diversity is essential to delineate recommendation domains for new technologies, but diversity is a subjective concept, and can be described differently depending on the way it is perceived. Historically, new technologies have been targeted primarily based on agro-ecological conditions, largely ignoring socioeconomic conditions. Based on 273 farm households' surveys in Ethiopia, we compare two approaches for the delineation of farm type recommendation domains for crop and livestock technologies: one based on expert knowledge and one based on statistical methods. The expert-based typology used a simple discriminant key for stakeholders in the field to define four farm types based on Tropical Livestock Unit, total cultivated surface and the ratio of these two indicators. This simple key took only a few minutes to make inferences about the potential of adoption of crop and livestock technologies. The PCA-HC analysis included a greater number of variables describing the farm (land use, household size, cattle, fertilizer, off-farm work, hiring labour, production). This analysis emphasized the multi-dimensional potential of such a statistical approach and, in principle, its usefulness to grasp the full complexity of farming systems to identify their needs in crop and livestock technologies. A sub-sampling approach was used to test the impact of data selection on the diversity represented in the statistical approach. Our results show that diversity structure is significantly impacted according to the choice of a sub-sample of 15 of the 20 variables available. This paper shows the complementarity of the two approaches and demonstrates the influence of data selection within large baseline data sets on the total diversity represented in the clusters identified.

A large body of evidence demonstrates the agronomic superiority of maize hybrids over open-pollinated varieties (OPVs) in intensive monoculture. However, comparisons of the performance of hybrids and OPVs in agroforestry systems are scarce. In this study, the performance of four maize hybrids and four OPVs is compared in sole crop and under mature trees. Experiments were conducted on-farm during four seasons in Bugesera, Rwanda and two seasons in Meki, Ethiopia. Two tree species were selected in Bugesera (Grevillea robusta and Senna spectabilis) and one in Meki (Acacia tortilis), and three farms were selected for each tree species, each including two plots with almost identical trees in their centre and two plots without tree. In Bugusera, grain yield was higher for hybrids (2 Mg ha−1) than for OPVs (1.5 Mg ha−1), and the presence of trees reduced the harvest index more in OPVs than in hybrids. In this region, the estimated reduction in grain yield due to the presence of trees was 0.9 and 1.1 Mg ha−1 in hybrids and OPVs, respectively, while estimated reduction in biomass was 1.5 and 1.7 Mg ha−1, respectively. In Meki, the grain yield of OPVs (2.08 Mg ha−1) and hybrids (2.04 Mg ha−1) did not differ and the presence of trees reduced their grain yields in the same manner. Our results showed that hybrids yielded more than OPVs under G. robusta and S. spectabilis in Bugesera but performed equally well under A. tortilis in Meki. We conclude that agroforestry farmers could benefit from growing hybrids in the equatorial savannahs of Rwanda, but that the choice between hybrid and OPV in equatorial savannahs of Ethiopia can simply be based on other factors such as seed costs and availability.

This paper follows the progress made in India for research and farmer adoption of conservation agriculture (CA) since the publication of Erenstein (2012), who contested the idea that zero-till (ZT) establishment of wheat in rice–wheat systems could be further developed into full CA systems. Data presented in this paper show that research has successfully found solutions for both the wheat and rice phases of the rice–wheat systems of the Indo-Gangetic Plains (IGP) in the past 8 years. It shows that by finding solutions in both the rice and wheat phases, yields, water use efficiency and profits increased, while labour needs reduced. Indian scientists have also confirmed these benefits in participatory on-farm research in various locations, both east and west regions of the IGP. Farmers see for themselves through experimentation that they get higher yields with less cost and with more efficient use of inputs and water. A key factor has been the development of improved seed drills with the help of Indian private sector manufacturers of agricultural equipment. Indian scientists have also successfully conducted CA research on several other crops and in other regions besides the IGP. The paper shows that it is better to introduce parts of the CA management practices in a step-wise fashion first, rather than introducing the entire package at once since farmers first have to test and evaluate a new technology to understand how it benefits them personally before they will adopt it. The paper concludes that in the rice–wheat systems of South Asia, adoption of CA is indeed possible to achieve although it is still a work in progress. CA is a complex technology package and it takes time to overcome all of the contested issues mentioned in Erenstein (2012).

The new Brazilian Forest Code obliges farmers to restore degraded lands on conservation set-asides required on all rural properties, known as Permanent Preservation Areas and Legal Reserves. While farmers can do so through agroforestry systems (AFS) to improve their livelihoods and offset the costs of restoration, these areas must also maintain basic ecological functions. How this can be done in practice, however, stills need to be regulated at the state level, but there are few scientific studies in Brazil on the costs and benefits of restoration through AFS. These knowledge and policy gaps have left ample room for interpretation and thus discouraged technicians from recommending — and policymakers from regulating — AFS for restoration. Aiming to bridge these gaps, this study draws from a comprehensive literature review, expert knowledge, stakeholder participation and analyses of agroforestry-based restoration efforts in the field. First, we discuss the social and ecological benefits of AFS as well as key constraints to upscaling agroforestry-based restoration. Focusing on different biophysical and social contexts within the Brazilian Cerrado and Caatinga biomes, we conclude that AFS can provide win–win solutions for reconciling livelihoods needs with conservation goals and propose practical options to do so, which vary according to farmer objectives, resource constraints and opportunities. In order to guide implementation of these agroforestry options, we propose design principles and criteria as well as key species and management practices most suited to different contexts and farmer objectives.

Due to the lack of basic information on water required by maize (Zea mays L.) in Brazil, the large amount of water applied usually exceeds crop requirements, wasting water and energy. In this study, we measured crop evapotranspiration (ETc) as evaporative heat flux from a centre pivot-irrigated maize plantation in Southern Brazil during winter and summer seasons, using the Bowen ratio method to evaluate how the degree of canopy-atmosphere coupling affects crop water needs and irrigation management. Irrigation requirements were determined by comparing ETc with reference evapotranspiration (ETo), derived from the Penman–Monteith equation and expressed as the ETc/ETo (Kc) ratio. In this study, the average Kc values obtained were 1.31 and 0.90 for the winter and summer, respectively. Using aerodynamic and canopy resistance measurements, the decoupling factor (Ω) was computed. Ω values tending to zero (0.09 and 0.20 for winter and summer, respectively) showed that strong coupling of maize plants to the atmosphere and sensitivity to high air temperatures, vapour pressure deficits and wind speed caused variations in Kc in relation to ETo ranges. During the experimental period, the Kc value ranged from 0.92 when the ETo exceeded 4 mm d−1 to 1.64 when the ETo was less than 2 mm d−1.

The success of scaling out depends on a clear understanding of the factors that affect adoption of grain legumes and account for the dynamism of those factors across heterogeneous contexts of sub-Saharan Africa. We reviewed literature on adoption of grain legumes and other technologies in sub-Saharan Africa and other developing countries. Our review enabled us to define broad factors affecting different components of the scaling out programme of N2Africa and the scales at which those factors were important. We identified three strategies for managing those factors in the N2Africa scaling out programme: (i) testing different technologies and practices; (ii) evaluating the performance of different technologies in different contexts; and (iii) monitoring factors that are difficult to predict. We incorporated the review lessons in a design to appropriately target and evaluate technologies in multiple contexts across scales from that of the farm to whole countries. Our implementation of this design has only been partially successful because of competing reasons for selecting activity sites. Nevertheless, we observe that grain legume species have been successfully targeted for multiple biophysical environments across sub-Saharan Africa, and to social and economic contexts within countries. Rhizobium inoculant and legume specific fertiliser blends have also been targeted to specific contexts, although not in all countries. Relatively fewer input and output marketing models have been tested due to public–private partnerships, which are a key mechanism for dissemination in the N2Africa project.