Rootstock growth and development for increased graft success of mango (Mangifera indica) in the nursery

The graft success of seedlings depends on rootstock size and the skills of grafters. A study was carried out to evaluate the effects of rootstock diameter (at root collar), skills and experience of grafters on mango seedling thinning and grafting. Skilled and unskilled grafters were involved in grafting mango plants for at least three consecutive months. Different rootstock sizes based on root collar diameter of mango seedlings were assessed. The results showed significant differences in graft-take among three groups of nurserymen. The skills and experience of grafters had a significant effect on graft success. The late emerging seedlings showed higher increase in height and diameter after thinning. A higher survival (> 75%) and reduced time to graft-take (19 days) were achieved with thicker rootstocks (0.7 cm) than thinner rootstocks (0.3 cm). The early emerging plants produced more leaves than late emerging plants after grafted. It was concluded that a higher graft-take can best be achieved with skilled grafters and thicker rootstocks

A decision support tool for propagating Miombo indigenous fruit trees of southern Africa

Indigenous fruit trees (IFTs) contribute to the livelihoods of rural households as sources of food, income and medicine. Conservation and domestication of IFTs involve germplasm selection, collection,multiplication and evaluation. In addition, biodiversity and genetic improvements have been realized through propagation. However, there are numerous challenges when propagating indigenous trees andthe choice of appropriate propagation techniques determines the success of domestication programme. In this paper we synthesize different propagation methods used for indigenous fruit trees,and propose a decision support tool based on desirable attributes of individual IFT, technical requirements, expertise of the propagators and relative cost of implementing the technology in addition to field performance and tree management. Depending on circumstances, this decision support tool can be used to quickly choose a propagation method for a given fruit tree so as to maximize on germplasm collection, multiplication and evaluation without compromising field performance and management of the fruit trees

Factors affecting child malnutrition in Ethiopia

Background: One of the public health problems in developing countries is child malnutrition. An important factor for children’s well-being is good nutrition. Therefore, the malnutrition status of children under the age of five is an important outcome measure for children’s health. This study uses the proportional odds model to identify risk factors associated with child malnutrition in Ethiopia using the 2016 Ethiopian Demographic and Health Survey data.Methods: This study uses the 2016 Ethiopian Demographic and Health Survey results. Based on weight-for-height anthropometric index (Z-score) child nutrition status is categorized into four levels namely- underweight, normal, overweight and obese. Since this leads to an ordinal variable for nutrition status, an ordinal logistic regression (OLR)proportional odds model (POM) is an obvious choice for analysis.Results: The findings and comparison of results using the cumulative logit model with and without complex survey design are presented. The study results revealed that to produce the appropriate estimates and standard errors for data that were obtained from complex survey design, model fitting based on taking the survey sampling design into account is better. It has also been found that for children under the age of five, weight of a child at birth, mother’s age, mother’s Body Mass Index (BMI), marital status of mother and region (Affar, Dire Dawa, Gambela, Harari and Somali) were influential variables significantly associated with underfive children’s nutritional status in Ethiopia.Conclusion: This child’s age of a child, sex, weight of child at birth, mother’s BMI and region of residence were significant determinants of malnutrition of children under five years in Ethiopia. The effect of these determinants can be used to develop strategies for reducing child malnutrition in Ethiopia. Moreover, these findings show that OLR proportional odds model is appropriate assessing thedeterminants of malnutrition for ordinal nutritional status of underfive children in Ethiopia.Keywords: BMI, Ethiopian Demographic and Health Survey (EDHS), malnutrition, proportional odds model

Water application rate and frequency affect seedling survival and growth of Vangueria infausta and Persea americana

Adequate amount of water is critical to successful tree nursery operation among resource-constrained smallholder farmers in Africa. Two  experiments were undertaken with the objectives of evaluating effects of water application rate and frequency on seedling growth and survival of Persea americana and Vangueria infausta. In experiment 1, water was applied to seedlings at 500 ml per 1 L polyethylene bag daily and at two, four and six day intervals. In experiment 2, water was applied to seedlings every two days at the rate of 25, 50, 100 and 150 ml per polyethylene bag. The results indicated that V. infausta was more responsive to the rate than frequency of water application. Water application of 100 ml every two days was effective in promoting seedlings growth and survival for both species. Application of 500 ml of water every two days promoted growth of P. americana, while watering frequency had no significant effect on V. infausta. It is concluded that V. infausta seedlings require less frequent watering. Both species could be successfully raised with 100 ml of water applied every two days.Key words: Nursery irrigation, nutrient reserves, root collar diameter, seedling mortality

Can integration of legume trees increase yield stability in rain-fed maize cropping systems in Southern Africa?

Growing maize (Zea mays) in association with legume tree in agroforestry arrangements has been shown to increase yields in many parts of sub-Saharan Africa (SSA). However, the stability of crop yields has not been critically analyzed in the various cropping systems that integrate leguminous trees. The objective of this analysis was to compare yield stability in improved cropping systems, namely maize-Gliricidia (Gliricidia sepium) intercropping and fertilized monoculture maize, with the de facto practice of resource-poor farmers who grow maize continuously without any external input. Yield stability was determined for three long-term field trials (12-13 consecutive years) conducted at Makoka Research Station in southern Malawi and Msekera Research Station in eastern Zambia. At Makoka, the most stable yield was recorded in maize-Gliricidia intercrops. Average yield was highest in maize-Gliricidia intercropping amended with 50% of the recommended N and P fertilizer, and this was comparable with yield recorded in monoculture maize that received inorganic fertilizer. On the two sites at Msekera, the highest yield was recorded in fertilized monoculture maize followed by maize-Gliricidia intercrops. However, yields were more stable in maize- Gliricidia intercropping compared to fertilized maize on both sites at Msekera. It is concluded that maize yields remain more stable in maize-Gliricidia intercropping than in fertilized maize monoculture in the longterm although average yields may be higher with full fertilization.The government of Ireland through the Irish Aid and Irish Embassy in Malawi to the World Agroforestry Centre.https://www.agronomy.org/publications/a

Yield gap analysis of field crops: Methods and case studies

The challenges of global agriculture have been analysed exhaustively and the need has been established for sustainable improvement in agricultural production aimed at food security in a context of increasing pressure on natural resources. Whereas the importance of R&D investment in agriculture is increasingly recognised, better allocation of limited funding is essential to improve food production. In this context, the common and often large gap between actual and attainable yield is a critical target. Realistic solutions are required to close yield gaps in both small and large scale cropping systems worldwide; to make progress in this direction, we need (1) definitions and techniques to measure and model yield at different levels (actual, attainable, potential) and different scales in space (field, farm, region, global) and time (short, long term); (2) identification of the causes of gaps between yield levels; (3) management options to reduce the gaps where feasible and (4) policies to favour adoption of gap-closing technologies. The aim of this publication is to review the methods for yield gap analysis, and to use case studies to illustrate different approaches, hence addressing the first of these four requirements. Theoretical, potential, water-limited, and actual yield are defined. Yield gap is the difference between two levels of yield in this series. Depending on the objectives of the study, different yield gaps are relevant. The exploitable yield gap accounts for both the unlikely alignment of all factors required for achievement of potential or water limited yield and the economic, management and environmental constraints that preclude, for example, the use of fertiliser rates that maximise yield, when growers’ aim is often a compromise between maximising profit and minimising risk at the whole-farm scale, rather than maximising yield of individual crops. The gap between potential and water limited yield is an indication of yield gap that can be removed with irrigation. Spatial and temporal scales for the determination of yield gaps are discussed. Spatially, yield gaps have been quantified at levels of field, region, national or mega-environment and globally. Remote sensing techniques describes the spatial variability of crop yield, even up to individual plots. Time scales can be defined in order to either remove or capture the dynamic components of the environment (soil, climate, biotic components of ecosystems) and technology. Criteria to define scales in both space and time need to be made explicit, and should be consistent with the objectives of the analysis. Satellite measurements can complement in situ measurements. The accuracy of estimating yield gaps is determined by the weakest link, which in many cases is good quality, sub-national scale data on actual yields that farmers achieve. In addition, calculation and interpretation of yield gaps requires reliable weather data, additional agronomic information and transparent assumptions. The main types of methods used in yield benchmarking and gap analysis are outlined using selected case studies. The diversity of benchmarking methods outlined in this publication reflects the diversity of spatial and temporal scales, the questions asked, and the resources available to answer them. We grouped methods in four broad approaches. Approach 1 compares actual yield with the best yield achieved in comparable environmental conditions, e.g. between neighbours with similar topography and soils. Comparisons of this type are spatially constrained by definition, and are an approximation to the gap between actual and attainable yield. With minimum input and greatest simplicity, this allows for limited but useful benchmarks; yield gaps can be primarily attributed to differences in management. This approach can be biased, however, where best management practices are not feasible; modelled yields provide more relevant benchmarks in these cases. Approach 2 is a variation of approach 1, i.e. it is based on comparisons of actual yield, but instead of a single yield benchmark, yield is expressed as a function of one or few environmental drivers in simple models. In common with Approach 1, these methods do not necessarily capture best management practices. The French and Schultz model is the archetype in this approach; this method plots actual yield against seasonal water use, fits a boundary function representing the best yield for a given water use, and calculates yield gaps as the departure between actual yields and the boundary function. A boundary model fitted to the data provides a scaled benchmark, thus partially accounting for seasonal conditions. Boundary functions can be estimated with different statistical methods but it is recommended that the shape and parameters of boundary functions are also assessed on the basis of their biophysical meaning. Variants of this approach use nitrogen uptake or soil properties instead of water. Approach 3 is based on modelling which may range from simple climatic indices to models of intermediate (e.g. AquaCrop) or high complexity (e.g. CERES-type models). More complex models are valuable agronomically because they capture some genetic features of the specific cultivar, and the critical interaction between water and nitrogen. On the other hand, more complex models have requirements of parameters and inputs that are not always available. “Best practice” approaches to model yield in gap analysis are outlined. Importantly, models to estimate potential yield require parameters that capture the physiology of unstressed crops. Approach 4 benchmarking involves a range of approaches combining actual data, remote sensing, GIS and models of varying complexity. This approach is important for benchmarking at and above the regional scale. At these large scales, particular attention needs to be paid to weather data used in modelling yield because significant bias can accrue from inappropriate data sources. Studies that have used gridded weather databases to simulate potential and water-limited yields for a grid are rarely validated against simulated yields based on actual weather station data from locations within the same grid. This should be standard practice, particularly where global scale yield gaps are used for policy decisions or investment in R&D. Alternatively, point-based simulations of potential and water-limited yields, complemented with an appropriate up-scaling method, may be more appropriate for large scale yield gap analysis. Remote sensing applied to yield gap analysis has improved over the last years, mainly through pixel-based biomass production models. Site-specific yield validation, disaggregated in biomass radiation-use-efficiency and harvest index, remains necessary and need to be carried out every 5 to 10 years

Productivity of Acacia angustissima accessions at two sites in the subtropics

Low leaf biomass yields coupled with small land sizes are some of the major constraints faced by smallholder farmers that grow protein-rich fodder trees and shrubs. Given these challenges, availability of highly productive seed sources would be important to enable farmers to produce leaf fodder in sufficient quantities. 14 accessions of Acacia angustissima were evaluated for leaf, wood and total biomass production at two subtropical sites with uni-modal rainfall in Zimbabwe, with the objective of identifying high leaf biomass yielding accessions. There were up to fourfold difference in biomass yield between the accessions. Leaf dry matter yield ranged from 1.65 to 8.81 Mg ha-1 and 3.7 to 12.4 Mg ha-1 for wood biomass at the higher altitude site (1530 m a.s.l.) but were much lower at 1272 m a.s.l. where they ranged between 0.37 and 4.88 Mg ha-1 for leaf and 0.4 and 7.2 Mg ha-1 for wood. The most productive accessions for leaf biomass were 16231 and 18579 at the higher altitude site, while 18586 and 18501 had the highest yields at the lower altitude. Although no one accession was consistently high yielding across the two sites, the least productive accessions were consistently poor at both sites. The advantage of using selected superior accessions over the unselect bulk seed was up to 85%. These findings underscore the need to promote the use of only high yielding accessions rather than unselect bulk seed. This study identified new, more productive accessions of A. angustissima that potentially widens the genetic base of the germplasm assembled in Zimbabwe.Key words: Leaf biomass, accession, accession × site interaction, Acacia angustissima

Molecular epidemiology of tuberculosis in the Somali region, eastern Ethiopia

Background: Tuberculosis (TB) is one of the leading causes of morbidity and mortality in low-income countries like Ethiopia. However, because of the limited laboratory infrastructure there is a shortage of comprehensive data on the genotypes of clinical isolates of Mycobacterium tuberculosis (M. tuberculosis) complex (MTBC) in peripheral regions of Ethiopia. The objective of this study was to characterize MTBC isolates in the Somali region of eastern Ethiopia. Methods: A cross-sectional study was conducted in three health institutions between October 2018 and December 2019 in the capital of Somali region. A total of 323 MTBC isolates (249 from pulmonary TB and 74 from extrapulmonary TB) were analyzed using regions of difference 9 (RD 9)-based polymerase chain reaction (PCR) and spoligotyping. Results: Of the 323 MTBC isolates, 99.7% (95% CI: 99.1-100%) were M. tuberculosis while the remaining one isolate was M. bovis based on RD 9-based PCR. Spoligotyping identified 71 spoligotype patterns; 61 shared types and 10 orphans. A majority of the isolates were grouped in shared types while the remaining grouped in orphans. The M. tuberculosis lineages identified in this study were lineage 1, 2, 3, 4, and 7 with the percentages of 7.4, 2.2, 28.2, 60.4, and 0.6%, respectively. Most (87.9%) of the isolates were classified in clustered spoligotypes while the remaining 12.1% isolates were singletons. The predominant clustered spoligotypes identified were SIT 149, SIT 21, SIT 26, SIT 53, and SIT 52, each consisting of 17.6, 13.3, 8.4, 7.4, and 5%, respectively. Lineage 3 and lineage 4, as well as the age group (15-24), were associated significantly with clustering. Conclusion: The MTBC isolated from TB patients in Somali region were highly diverse, with considerable spoligotype clustering which suggests active TB transmission. In addition, the Beijing spoligotype was isolated in relatively higher frequency than the frequencies of its isolation from the other regions of Ethiopia warranting the attention of the TB Control Program of the Somali region

Modelling CD4 counts before and after HAART for HIV infected patients in KwaZulu-Natal South Africa

Background: This study aims to make use of a longitudinal data modelling approach to analyze data on the number of CD4+cell counts measured repeatedly in HIV-1 Subtype C infected women enrolled in the Acute Infection Study of the Centre for the AIDS Programme of Research in South Africa. Methodology: This study uses data from the CAPRISA 002 Acute Infection Study, which was conducted in South Africa. This cohort study observed N=235 incident HIV-1 positive women whose disease biomarkers were measured repeatedly at least four times on each participant. Results: From the findings of this study, post-HAART initiation, baseline viral load, and the prevalence of obese nutrition status were found to be major significant factors on the prognosis CD4+ count of HIV-infected patients. Conclusion: Effective HAART initiation immediately after HIV exposure is necessary to suppress the increase of viral loads to induce potential ART benefits that accrue over time. The data showed evidence of strong individual-specific effects on the evolution of CD4+ counts. Effective monitoring and modelling of disease biomarkers are essential to help inform methods that can be put in place to suppress viral loads for maximum ART benefits that can be accrued over time at an individual level

Scaling up Agroforestry to Achieve Food Security and Environmental Protection among Smallholder Farmers in Malawi

Malawi is a land-locked country in southern Africa. Three-fourths of Malawi’s 13 million people rely on smallholder agriculture for their livelihoods. Increasing population, accelerating deforestation, poor soil and water management, and increasing poverty and land degradation directly impact the food security and human health of millions of Malawians. Cropping systems which combine cereal crops, agroforestry and small doses of inorganic fertilizers produce food-crop yields greater than inorganic fertilizers alone on degraded soils, as well as recuperating soil nutrients over a period of years. These agroforestry practices improve the livelihoods of farm families, lower risks associated with fertilizer price increases and drought and at the same time improve biodiversity and nutrient and water cycling in the agro-ecosystem. The World Agroforestry Centre (ICRAF) has a long history of agroforestry research and development in Malawi dating back to the 1980s. In 2007-2011, ICRAF implemented the Malawi Agroforestry Food Security Project (AFSP) through financial support from Irish Aid. ICRAF’s task in AFSP was to build a strong partnership to reach 200,000 farming families in 11 districts. The purpose of AFSP was to combine tested agroforestry practices, effective partnership and informed policies to increase food security and income, and improve livelihood opportunities for rural communities in Malawi, through accelerated adoption of fertilizer trees, fruit trees, fodder trees and fuel-wood trees. To accomplish these purposes, ICRAF provided the farming communities with planting material (tree seeds and seedlings), and the knowledge of how to care for them and effectively combine them with food crops. The beneficiaries of the project saw increases in household food security and nutrition. However, difficulties were encountered in transporting tree seeds and seedlings across eleven districts in a timely fashion, and in managing the flow of reporting and disbursements of funding among such a large group of collaborators. Several solutions were implemented which improved performance in these areas, and which allowed the group to reach very near the targeted number of participants, and to plan for a second phase of the project.Le Malawi est un état enclavé dans le Sud de l’Afrique. Les trois-quarts des 13 millions de Malawites sont de petits exploitants agricoles qui vivent de leur production. L’accroissement de la population, l’accélération de la déforestation, la mauvaise gestion des sols et de l’eau, et l’essor de la pauvreté et de la dégradation des terres ont des conséquences directes sur la sécurité alimentaire et la santé de millions d’habitants du pays. Les systèmes de culture qui associent cultures céréalières, agroforesterie et faibles doses d’engrais non organiques produisent des rendements de cultures vivrières plus importants que ceux obtenus avec des engrais non organiques utilisés seuls sur des sols dégradés, et permettent de récupérer des nutriments du sol au bout d'une certaine période. Ces pratiques d’agroforesterie améliorent les moyens de subsistance des foyers agricoles, réduisent les risques associés à l’augmentation du prix des engrais et à la sécheresse, et améliorent la biodiversité et le cycle des nutriments et de l’eau dans l’écosystème agricole. L’ICRAF (World Agroforestry Centre) travaille depuis les années 1980 sur la recherche et le développement en agroforesterie au Malawi. En 2007-2011, l’ICRAF a lancé au Malawi le projet « Agroforestry Food Security Project » (AFSP), financé par le programme Irish Aid et mis en place par le gouvernement irlandais pour soutenir les pays en développement. Dans le cadre de ce projet, l’ICRAF a eu pour mission d’établir un solide partenariat pour mettre en place l’agroforesterie dans 200 000 foyers agricoles répartis dans 11 districts. L’objectif de l’AFSP était d’associer des pratiques d’agroforesterie ayant fait leurs preuves, un partenariat efficace et des politiques éclairées afin d’améliorer la sécurité alimentaire et les revenus, ainsi que les moyens de subsistance des communautés rurales du Malawi, via l’utilisation de plus en plus massive d’arbres fertilisants, d’arbres fruitiers, d’arbres fourragers et d’arbres donnant du bois combustible. Pour atteindre ces objectifs, l’ICRAF a fourni aux communautés agricoles du matériel de plantation (graines et plants), et leur a expliqué comment s’en occuper et les associer efficacement aux cultures vivrières. Les bénéficiaires du projet ont pu constater une amélioration de la sécurité alimentaire et de la nutrition dans leur foyer. Il a fallu toutefois faire face à certaines difficultés notamment assurer le transport en dû temps des graines et plants dans les onze districts, et gérer le flux de rapports d’information et d’allocations de fonds entre un tel nombre de collaborateurs. Plusieurs solutions ont été mises en œuvre afin d’améliorer les performances dans ces domaines, ce qui a permis au groupe d’atteindre pratiquement l’objectif du nombre de bénéficiaires fixé, et de planifier une seconde phase pour le projet.Malaui es un país rodeado de tierra en el sur de África. Tres cuartos de los 13 millones de pobladores de Malaui dependen de la agricultura a pequeña escala para ganarse el sustento. El aumento de la población, la aceleración de la deforestación, la mala gestión del suelo y el agua y el aumento de la pobreza y la degradación de la tierra afectan directamente a la seguridad alimentaria y la salud humana de millones de Malauitas. Los sistemas de cultivo que combinan cultivos de cereal, agrosilvicultura y pequeñas dosis de fertilizantes inorgánicos producen rendimientos de cultivos alimentarios mayores que los fertilizantes inorgánicos en solitario en suelos degradados, así como la recuperación de los nutrientes del suelo durante un periodo de años. Estas prácticas de agrosilvicultura mejoran las condiciones de subsistencia de las familias de granjeros, reducen los riesgos asociados con aumentos de precio de los fertilizantes y sequías y al mismo tiempo mejoran la biodiversidad y el desarrollo del ciclo de los nutrientes y del agua en el ecosistema agrario. El ICRAF (Word Agroforestry Centre) cuenta con un largo historial de investigación y desarrollo en agrosilvicultura en Malaui que se remonta hasta la década de 1980. En 2007-2011, el ICRAF implementó en Malawi el proyecto de “Agroforestry Food Security” (AFSP) mediante apoyo financiero de Irish Aid. La tarea del ICRAF en AFSP consistía en construir una fuerte sociedad para alcanzar las 200.000 familias dedicadas a la agricultura en 11 distritos. El objetivo de AFSP era combinar prácticas de agrosilvicultura probadas, una sociedad eficaz y políticas fundadas para aumentar la seguridad alimentaria y los ingresos, y mejorar las oportunidades de ganarse el sustento para las comunidades rurales en Malaui, mediante la adopción acelerada de árboles fertilizantes, árboles frutales, árboles forrajeros y árboles madereros para combustible. Para conseguir estos objetivos, el ICRAF proporcionó a las comunidades agrícolas material para plantar (semillas y plantones de árboles), y el conocimiento de cómo cuidarlos y combinarlos de forma eficaz con los cultivos alimentarios. Los beneficiarios del proyecto percibieron un aumento de la seguridad alimentaria y la nutrición doméstica. Sin embargo, surgieron dificultades a la hora de transportar las semillas y plantones de los árboles a través de once distritos a tiempo, y de gestionar el flujo de informes y desembolsos de fondos entre un grupo tan grande de colaboradores. Se implementaron varias soluciones que mejoraron el rendimiento en estas áreas, y que permitieron al grupo alcanzar un número de participantes muy cercano al objetivo, y planificar una segunda fase del proyecto