Development of micropropagation system for yam (Dioscorea spp.) using somatic embryogenesis

Inadequate availability of disease-free planting materials remains a major constraint to yam production. The tissue culture technique has been used to regenerate disease-free plantlets from pre-formed, heattreated meristems followed by micropropagation. This procedure, however, has a low multiplication ratio with an average of 1: 4 every eight weeks. Embryo production from somatic cells (somatic embryogenesis, SE) is a system in which each somatic cell can regenerate a complete plantlet. However, previous reports show low SE induction frequencies and significant variations in success rates among different genotypes while hardly any report exist for improved varieties that farmers desire, especially in Nigeria. Studies were carried out to evaluate the effects of different plant growth regulators (PGRs) on induction of somatic embryogenesis of the following genotypes: one improved Dioscorea alata (TDa 291) and three improved (TDr 95/19177, TDr 89/2665, TDr 95/18544) and one landrace (Obioturugo) of Dioscorea rotundata. Leaf, stem, and axillary bud explants were cultured in MS basal medium containing fifteen treatment combinations of 2,4-Dichlorophenoxyacetic acid (2,4-D), Naphthaleneacetic acid (NAA), Benzylaminopurine (BAP), Picloram, and Uniconazole-P (UP). The genotype TDr 95/19177 was tested for SE in Temorary Immersion Bioreactor System (TIBS). The incidence of induction of callus formation and plantlet regeneration from the three explants were recorded. Embryogenic callus induction was highest (87%) from axillary buds cultured on modified MS + 2 mg/l of 2,4-D + 1 mg/l of NAA while 1 mg/l of BAP + 9. 9 mg/l of UP had the highest percentage plantlet regeneration of 50% in TDr 95/18544 and an average of 37% across genotypes at a mean of 5 plantlets per explant. The genotype TDr 95/19177 was successfully regenerated via indirect somatic embryogenesis in the SETIS Type Temporary Immersion Bioreactor System

Modeling and Simulation of Temperature Profiles in a Reactive Distillation System for Esterification of Acetic Anhydride with Methanol

This paper pertains to an experimental and theoretical study of simulation of temperature profiles in a one- stage adiabatic batch distillation/reactor for the production of methyl acetate and acetic acid from the esterification of acetic anhydride with methanol. Basically it deals with the development of a mathematical model for temperature predictions in the reactor. The reaction kinetics of the process was modeled using information obtained from experimental temperature –time data during the esterification processes. The simulation results were then compared with the experimental data. The maximum deviation of the model –predicted temperature form the corresponding experimentally measured temperature was less than 4% which is quite within the acceptable deviation range of experimental results.. Keywords: Modeling, Simulation, Reactive distillation, Temperature, Esterification, Acetic anhydride, Methano

Statistical modeling of HIV, tuberculosis, and Hepatitis B transmission in Ghana

Most mortality studies usually attribute death to single disease, while various other diseases could also act in the same individual or a population at large. Few works have been done by considering HIV, Tuberculosis (TB), and Hepatitis B (HB) as jointly acting in a population in spite of their high rate of infections in Ghana. This study applied competing risk methods on these three diseases by assuming they were the major risks in the study population. Among all opportunistic infections that could also act within HIV-infected individuals, TB has been asserted to be the most predominant. Other studies have also shown cases of HIV and Hepatitis B coinfections. The validity of these comorbidity assertions was statistically determined by exploring the conditional dependencies existing among HIV, TB, and HB through Bayesian networks or directed graphical model. Through Classification tree, sex and age group of individuals were found as significant demographic predictors that influence the prevalence of HIV and TB. Females were more likely to contract HIV, whereas males were prone to contracting TB

Buffer Stock Operations and Well-Being:The Case of Smallholder Farmers in Ghana

This study investigates the possible causal relationship between buffer stock operations in Ghanaian agriculture and the well-being of smallholder farmers in a developing world setting. We analyze the differences in the objective and subjective well-being of smallholder farmers who do or do not participate in a buffer stock price stabilization policy initiative, using self-reported assessments of 507 farmers. We adopt a two-stage least square instrumental variable estimation to account for possible endogeneity. Our results provide evidence that participation in buffer stock operations improves the objective and subjective well-being of smallholder farmers by 20% and 15%, respectively. Also, with estimated coefficient of 1.033, we find a significant and robust relationship between objective well-being and subjective well-being among smallholder farmers. This relationship implies that improving objective well-being enhances the subjective well-being of the farmers. We also find that the activities of intermediaries decrease both the objective and subjective well-being of farmers. This study demonstrates that economic, social, and environmental aspects of agricultural life could constitute priorities for public policy in improving well-being, given their strong correlation with the well-being of farmers. Based on the results of this study, we provide a better understanding, which may aid policy-makers, that public buffer stockholding operations policy is a viable tool for improving the well-being of smallholder farmers in a developing country

Yam propagation using Aeroponics technology

Aims: To study yam propagation and seed yam tuber production in aeroponics system.Study Design: The experiment was conducted in a randomized complete block designand treatments were replicated three times.Place of Study: This experiment was carried out at the International Institute of TropicalAgriculture Headquarters at Ibadan in Nigeria.Methodology: The experiment tested fresh vine cuttings of five yam genotypes of twospecies in an aeroponics system. Three genotypes of Dioscorea rotundata (TDr 89/02475,TDr 89/02665 and TDr 95/18544) and two yam genotypes of D. alata (TDa 98/01176 andTDa 291) were evaluated.Results: Vines of both D. rotundata and D. alata rooted within 2 weeks in aeroponicssystem. The rooting of vine cuttings varied significantly among genotypes with a maximumof 98% for TDa 98/01176 and a minimum of 68% for TDr 89/02665. Mini-tubers harvestedafter 4 months of growth in aeroponics weighed between 0.2 and 2.7g. A second harvest 6months later gave mini-tubers of up to 110g. The analysis of variance showed significantdifference (P<0.05) among genotypes for rooting at 2 weeks after vine planting, number ofplant surviving at 90 days after planting and percentage of plants with bulbils. The best genotypes were TDr 95/18544 and TDr 89/02665 for survival at 90 days after vine plantingand percentage of plant producing bulbils in the aeroponics system respectively.Conclusion: This study revealed that yam genotypes performed differently in aeroponicssystem for vine rooting and production of mini-tubers and bulbils