Phenotypic variation in fruit and seed morphology of Adansonia digitata L (Baobab) in five selected wild populations in Malawi

Adansonia digitata L (Baobab) is widely distributed throughout Sub-Saharan Africa stretching from Senegal to Sudan, and from Ethiopia to Natal. Information of phenotypic and genetic variation is a prerequisite for the domestication and improvement of baobab fruits from the wild. A study was done to determine within and between provenance variability in fruit and seed characteristics of five populations selected from four silvicultural zones and assess whether morphometric traits could delineate populations from different zones into land races. Fruits were characterized from 55 trees representing a wide geographical range. Six fruit traits and three individual seed traits were assessed. Results showed highly significant differences (P≤0.001) in fruit, pulp, and seed weight, fruit length and width, number of seed, individual seed weight, seed length and width within and between populations. Mean fruit weight ranged from 125.8 ± 3.25 g to 162.9 ± 3.25 g, seed weight ranged from 38.6 ± 2.5 g to 66 ± 2.01g and pulp weight ranged from 28.7 ± 1.33 g to 41.4 ± 1.33 g. Single seed weight showed pronounced evidence of divergence of populations into ecotypes. The rich diversity found between and within populations is important for domestication purposes and tree improvement through selection and breeding. All populations could be used for seed source but distribution should be consciously done recognizing existence of races.Universities of Mzuzu and Stellenbosch and University of Pretoria.http://www.springer.com/life+sci/forestry/journal/1045

Genetic variation among and within provenances of Adansonia digitata L. (Baobab) in seed germination and seedling growth from selected natural populations in Malawi

Baobab (Adansonia digitata L) trees have a wide variety of subsistence and economic values across sub-Saharan Africa. Knowledge of the genetic variation within and between the species is essential for management and designing domestication, improvement and conservation strategies. Fifty-nine half-sib families were evaluated in the nursery to determine the genetic variation and control within and between the populations from four silvicultural zones. Seed germination and seven seedling growth parameters were assessed. Total phenotypic variance, family variance, within family variance, individual narrow sense heritability, and additive genetic coefficient of variation (AGCV) were derived from observed and expected mean squares. There were highly significant differences in seed germination, plant height, root collar diameter, number of leaves, shoot height and diameter, tuber diameter and weight. Provenance variation in germination ranged from 46.7 ±3.3% to 68.7±3.3% while tree –to- tree variation ranged from 6.3±8.6% to 95.5±8.6%. Coefficient of variation in seedling growth variables ranged from 18.6% to 43.6%. Individual narrow sense heritabilities (h2) ranged from 0.07 to 0.71. AGCV ranged from 3.21% to 14.67%. Morphological traits showed that mainland populations were genetically distant from the island one. High and moderate additive genetic control of traits and AGCV show the potential that Baobab can also respond well to tree improvement. High phenotypic variation found in the study offers an opportunity to effect selection of superior attributes at both provenance and individual tree-to-tree level.Universities of Mzuzu and Stellenbosch.http://www.agronomy-journal.org/hb201

Harnessing innovation platforms for sustainable intensification R4D experiences from Kongwa and Kiteto, Tanzania

United States Agency for International Developmen

How to Reduce Aflatoxin Contamination in Groundnuts and Maize A Guide for Extension Workers

Many agricultural commodities are susceptible to several diseases caused by fungi, viruses and insect pests. These diseases may also contaminate the crops with deadly toxins. Fungi are of particular concern. Many fungi are free-living organisms capable of surviving in the environment (soil, air and water) and can easily find their way into crop products especially when the weather conditions are suitable. Many of these fungi are free-living organisms and can survive in the environment even without the crops we grow. The toxins produced by fungi are called mycotoxins (Myco=fungus; toxin=poison)..

Genetic differentiation and diversity of Adansonia digitata L (baobab) in Malawi using microsatellite markers

Baobab (Adansonia digitata L) belonging to Bombacaceae family, is one of the most widely used indigenous priority tree species in sub-Saharan Africa, valued in the cosmetic industry for its seed oil, and powdery fruit pulp for juice making. Baobab has high potential for domestication in southern Africa, therefore understanding its genetic diversity and population structuring is warranted. The study investigated the level of genetic diversity and differentiation of five populations of A. digitata L. sampled from four diverse silvicultural zones in Malawi. Variation at nine microsatellite loci were examined in 150 individual trees. Low mean genetic diversity was expressed through genetic diversity indices: Nei’s genetic diversity (h, 0.18 ± 0.03), Shannon Information Index (I, 0.21 ± 0.07), observed number of alleles (na, 1.47 ± 0.10), effective number of alleles (na, 1.23 ± 0.04) and percentage polymorphic loci (pp, 48%). The low genetic variation found is attributed to the population growing in marginal areas of genetic centre of diversity of the species, anthropogenic factors and founder effects. Moderate genetic differentiation was observed among populations (Gst = 0.13) indicating the presence of a large number of common alleles resulting in a homogenisation effect. Clustering of individual trees by genetic similarity coefficients indicated that mainland trees were genetically closer than the trees on Likoma Island. Mantel’s test showed a weak positive insignificant correlation (Z = 0.12; P = 0.64) between genetic distance among populations and actual distance on the ground implying that geneflow was not directly influenced by isolation by distance. The results suggest that seed distribution and tree improvement should recognise the presence of ecotypes and conservation measures should protect all the populations due to existence of private alleles which are of adaptive importance.Mzuzu University and Stellenbosch University.http://www.springer.com/life+sci/forestry/journal/1045

Probabilistic dietary based estimation of the burden of aflatoxin-induced hepatocellular carcinoma among adult Malawians

This research article published by Wageningen Academic Publishers, 2019The risk of aflatoxin-induced hepatocellular carcinoma (HCC) among adults (average body weight of 60 kg) in Malawi was assessed based on aflatoxin B1 (AFB1) exposure through groundnut and maize consumption, by Monte Carlo simulation. The risk (cases per year per 100,000 people) of aflatoxin-induced HCC was estimated based on the AFB1 exposures estimated by this study and hepatitis B virus infection prevalence published for Malawi. AFB1 exposures were estimated by probabilistically combining data of AFB1 contamination in 338 groundnut and 604 maize samples with data of per capita groundnut and maize consumption in 274 households. Aflatoxins in the samples were analysed using validated LC-MS/MS, HPLC and VICAM based methods. The groundnut and maize consumption survey was based on household expenditure technique. The simulated mean AFB1 exposures through consumption of groundnuts, maize, and combination thereof were 28±65, 42±174, and 71±211 ng/kg. body weight (bw)/day, respectively. The estimated HCC risks were 1.26±2.72, 1.86±6.66 and 3.10±6.85 cases per 100,000 persons per year, respectively. Further, hypothetical eradication of hepatitis B virus (HBV) reduced the risk of HCC by 78%. This reaffirms the need for integrating HBV vaccination in the fight of aflatoxin induced HCC

Aflatoxin contamination: Knowledge disparities among agriculture extension officers, frontline health workers and small holder farming households in Malawi

The aims of this study were to assess the state of knowledge and perceptions regarding aflatoxin contamination among frontline workers in direct contact with small holder farming households in Malawi as well as among the households themselves. The study first investigated and documented demographic profiles of agriculture extension workers (n = 22) and frontline health workers (n = 161) both from Ntchisi district and small holder farming households (n = 915) from Dedza, Balaka and Mzimba districts. Structured questionnaires were administered to document knowledge and perceptions. Majority of the respondents in Ntchisi were frontline nutrition and health workers as follows: care group promoters (31.7%), cluster leaders (51.9%) and health surveillance assistants (4.4%). Only 12% of the respondents were agriculture extension officers. Among frontline workers, using factor analyses, factors highly associated with the knowledge on domestic management of aflatoxin contamination and the impact of aflatoxin contamination on child linear growth and health in general were most prominent. Whereas, their knowledge of pre & post-harvest practices that pre-dispose crops to aflatoxin contamination and impact of aflatoxin contamination on trade and income losses was relatively low. On the other hand, among small holder farming households, lowest knowledge was related to occurrence of aflatoxin contamination pre and post-harvest. Highest knowledge was observed on issues around loss of income due to aflatoxin contamination. Across all districts over 50% of surveyed respondents reported that they perceived aflatoxin contamination severity as low. Majority of the households (>50%) did not perceive aflatoxin contamination as a problem that could be controlled. This is the first study to investigate knowledge, attitudes, practices and perceptions on aflatoxin contamination among a combination of agriculture extension officers and frontline health workers in parallel with the households they usually are in contact with. The current investigation is crucial because it elucidates knowledge gaps in aflatoxin critical control across agriculture extension, health workers and the small holder farming households. This is especially crucial among agriculture extension workers and frontline health workers as they have direct contact with households and therefore serve as an important source of information that could influence behavior change

Genotype-by-environment interactions for grain yield of Valencia groundnut genotypes in East and Southern Africa

Grain yield is a quantitatively inherited trait in groundnut (Arachis hypogea L.) and subject to genotype by environment interactions. Groundnut varieties show wide variation in grain yield across different agro-ecologies. The objectives of this study were to evaluate Valencia groundnut genotypes for yield stability and classify environments to devise appropriate breeding strategies. Seventeen multi-location trials were conducted in six countries, viz., Malawi, Tanzania, Uganda, Zimbabwe, Mozambique and Zambia, from 2013 to 2016. The experiments were laid out following a resolvable incomplete block design, with two replications at each location (hereafter referred to as ‘environments’) using 14 test lines and two standard checks. The additive main effects and multiplicative interaction (AMMI) analysis was conducted. Variation attributable to environments, genotypes and genotype × environment interaction for grain yield was highly significant (P<0.001). Genotype, environment and genotype × environment interactions accounted for 7%, 53 % and 40% of the total sum of squares respectively. Superior-performing genotypes possessing high to moderate adaptability and stability levels included ICGV-SM 0154, ICGV-SM 07539, ICGV-SM 07536, ICGV-SM 7501, ICGV-SM 99568 and ICGV SM 07520. Nachingwea 2013 in Tanzania, Nakabango 2014 in Uganda and Chitedze 2015 in Malawi were the most representative and discriminative environments. Considering the implications of interactions for Valencia groundnut breeding in East and Southern Africa we propose that different varieties should be targeted for production in different environments and at the same time used for breeding in specific environments