Michael Osei Adu

Analysis of root growth from a phenotyping data set using a density-based model

Major research efforts are targeting the improved performance of root systems for more efficient use of water and nutrients by crops. However, characterizing root system architecture (RSA) is challenging, because roots are difficult objects to observe and analyse. A model-based analysis of RSA traits from phenotyping image data is presented. The model can successfully back-calculate growth parameters without the need to measure individual roots. The mathematical model uses partial differential equations to describe root system development. Methods based on kernel estimators were used to quantify root density distributions from experimental image data, and different optimization approaches to parameterize the model were tested. The model was tested on root images of a set of 89 Brassica rapa L. individuals of the same genotype grown for 14 d after sowing on blue filter paper. Optimized root growth parameters enabled the final (modelled) length of the main root axes to be matched within 1% of their mean values observed in experiments. Parameterized values for elongation rates were within ±4% of the values measured directly on images. Future work should investigate the time dependency of growth parameters using time-lapse image data. The approach is a potentially powerful quantitative technique for identifying crop genotypes with more efficient root systems, using (even incomplete) data from high-throughput phenotyping systems.

Effects of rooting media on root growth and morphology of Brassica rapa seedlings

Rooting media used in current root phenotyping studies can have substantial effect. In this study, the effects of three different nutrient conducting papers (Black construction paper, Anchor blue germination paper and Kimpak paper) and soil-filled boxes on root growth and root system architecture (RSA) of Brassica rapa (cultivars ‘R500’ and ‘IMB211’) were investigated. Seedlings of the two B. rapa genotypes were supplied with nutrients on the nutrient conducting papers and in the soil-filled boxes. The papers and soil-filled boxes were fixed to flatbed scanners and two-dimensional images of roots were periodically taken and analysed. Root media effects on shoot and root biomass and on topological indices (TI) were observed. For example, root branching was more pronounced on the construction paper. Mean TI of 0.82 and 0.93, recorded for R500 and IMB211, respectively, on the construction paper indicated that substrates affect the herringbone pattern of brassica roots. Whilst it was indicated that different results could be obtained for the same RSA when different germination papers are used, the results showed that Anchor blue germination paper is an ideal proxy for soil in phenotyping seedlings for RSA traits and root growth.

Virtual water and phosphorus gains through rice imports to Ghana: implications for food security policy

This study estimated the gains of virtual water, Phosphorus (P) and Phytic Acid (PA) through rice and wheat import to Ghana for the period 1998– 2005, and assessed the implications of increasing rice import coupled with declining domestic production for food security. The total virtual water of Ghana associated with rice and wheat import for the study period was 5574 Mm3, while the total P and PA was 1,364,097 and 3,825,438 tonnes, respectively. Domestic paddy rice production started declining from 2003, but was exceeded by import from 2001 onwards. Particularly for rice, the combination of factors such as surging demand and per capita consumption, low yield resulting from less land under cultivation and irrigation, and high import bill, necessitates policy actions to remove constraints on domestic production. The paper, therefore, suggests policy actions to increase domestic rice production and to minimise Ghana’s exposure to the risks inherent in rice import.

Characterising shoot and root system trait variability and contribution to genotypic variability in juvenile cassava (Manihot esculenta Crantz) plants

The development of cassava genotypes with root system traits that increase soil resource acquisition could increase yields on infertile soils but there are relatively few work that has quantified cassava root system architecture (RSA). We used an easily adaptable and inexpensive protocol to: (i) measure genotypic variation for RSA and shoot traits of a range of cassava genotypes; and (ii) identify candidate variables that contribute the largest share of variance. Cassava genotypes were grown in soil-filled pots, maintained at 70% field capacity. Shoot and RSA traits were measured on plants grown up to 30, 45 and 60 days. Multivariate analysis was used to determine major traits contributing to variation. The study showed that cassava roots are adventitious in origin consisting of a main root axis and orders of lateral roots, and therefore the historically used term “fibrous roots” are redundant currently not contributing to clarity. There were significant differences (P < 0.05) for traits evaluated. The highest relative root growth rate occurred over the first 30 days and ranged from 0.39 to 0.48 cm day−1. Root fresh weight was significantly correlated with other traits, including root length (r = 0.79), leaf area (r = 0.72), number of lower nodal roots (r = 0.60), indicating that direct selection based on these traits might be sufficient to improve root biomass. Up to the first six principal components explained over 80% of the total variation among the genotypes for the traits measured at 30, 45 and 60 days. Leaf area, root diameter and branching density-related traits were the most important traits contributing to variation. Selection of cassava genotypes based on shoot and root biomass, root diameter and branching density at juvenile growth stage could be successful predictors of nutrient and water-use efficiency in the field. Further studies are required to relate studied juvenile cassava root traits with the performance of field-grown-mature plant with regard to drought, nutrient-use efficiency and yield.

Ghanaians Might Be at Risk of Inadequate Dietary Intake of Potassium.

Adequate dietary intake of potassium (K) helps fight noncommunicable diseases (NCDs), mainly hypertension and cardiovascular diseases. This paper (i) estimated the K intake of Ghanaian population using food supply and food composition data and (ii) compared this estimate with the WHO recommended requirement for K in order to assess if there is a risk of inadequate K intake. Food supply data (1961–2011) was obtained from the FAO Food Balance Sheet (FBS) to derive trends in food and K supply. The average food supply in the FBS for 2010 and 2011 was used in assessing the risk of inadequate dietary intake of K. The K contents of the food items were obtained from food composition databases. The mean K supply per capita per day was approximately 856 mg. The assessment suggests a potentially large risk of inadequate dietary K supply at both individual and population levels. The results suggest the need for assessing options for managing K deficiency, including assessment of K supplying power of soils and K fertilizer management in food crop production systems, as well as empirical estimates of K content of food items (including those underreported in the FBS) and mixed diets in Ghana.

Systematic review of the effects of agricultural interventions on food security in northern Ghana

Background Food insecurity and poverty rates in Ghana are highest in the districts from latitude 8° N upwards. These have motivated several interventions aimed at addressing the food insecurity via promoting agricultural growth. An assessment of the overall impact of these interventions on food security is necessary to guide policy design and future interventions. Methods and findings A systematic review was used to assess the cumulative evidence of the effect of development interventions, implemented from 2006 to 2016 on food security, especially in Northern Ghana. Information were retrieved from over 20 Government and non-Governmental organisations through online search and actual visits. The number of studies included in systematic review was 22. The study showed that a large number of interventions have been implemented in Northern Ghana over the study period. Access to quality extension services, training and capacity building was a major intervention strategy. About 82% of studies considered increasing production but only 14% of the studies reported on changes in yield. About 42% of the included studies used market access as a strategy but about 44% reported increase in incomes of beneficiaries (with only seven studies providing numerical evidence for this claim). The ranking of frequency of intervention strategies was in the order extension and capacity building > production > postharvest value addition > water and irrigation facilities > storage facilities > input supply. A substantial number of the studies had no counterfactuals, weakening confidence in attributing impacts on food security for even the beneficiaries. Conclusions It is concluded that evidence for impacts of the interventions on food security was weak, or largely assumed. A logical recommendation is the need for development partners to synchronise their measurement and indicators of food security outcomes. It is also recommended that some food security indicators are explicitly incorporated into intervention design while bearing in mind the potential need for counterfactuals.

Ghanaians Might Be at Risk of Excess Dietary Intake of Potassium Based on Food Supply Data

The World Health Organization (WHO) has highlighted the beneficial role of adequate intake of potassium (K) in combating the global burden of noncommunicable diseases (NCDs), mainly hypertension and cardiovascular diseases. Diets are the main source of K supply to humans and can contribute to both K deficiency (hypokalemia) and excess (hyperkalemia). While global attention is currently devoted to K deficiency, K excess can be even more dangerous and deserves equal attention. The objectives of this paper were to (i) estimate the K intake of Ghanaian population using food supply and food composition data and (ii) compare this estimate with the WHO-recommended requirement for K in order to assess if there is a risk of inadequate or excess K intake. Food supply data (1961–2011) were obtained from the Food Balance Sheet (FBS) of the Food and Agriculture Organization of the United Nations to derive trends in food and K supply. The average food supply in the FBS for 2010 and 2011 was used in assessing the risk of inadequate or excess dietary intake of K. The K content of the food items was obtained from food composition databases. Based on 2010-2011 average data, the K supply per capita per day was approximately 9,086 mg, about 2.6-fold larger than the WHO-recommended level (3,510 mg). The assessment suggests a potentially large risk of excess dietary K supply at both individual and population levels. The results suggest the need for assessing options for managing K excess as part of food security and public health strategies. The results further underscore a need for assessment of the K status of staple food crops and mixed diets, as well as K management in food crop production systems in Ghana.

Soil-Transmitted Helminths in Top Soils Used for Horticultural Purposes in Cape Coast, Ghana

This paper investigated the concentrations of eggs of three helminths (roundworm, hookworm, and whipworm) in the so-called black soils used for domestic and urban landscaping, home gardening and as growth medium for potted plants and pot experiments. The black soils are largely collected from active or abandoned waste dumpsites and fallowed or vegetated idle sites in the urban fringe or rural areas. Users buy black soils from dealers. Samples of black soils used for various purposes and at different places were collected for analysis of helminth eggs. The Modified EPA Method, which combines flotation and sedimentation, was used to isolate the eggs. The results show that these black soils have substantial loads of helminth eggs, with roundworm being dominant, followed by hookworm. Mean concentrations of helminth eggs were 2.45 (roundworm), 1.38 (hookworm), and 0.25 (whipworm) g−1 soil, respectively. The helminth egg loads also declined with duration of use of the black soils. It is concluded that black soils used for horticultural purposes in Ghana can be a potential source of helminth infestation. Therefore, treatment of black soils, regulation of black soil market and use, and development of growth media industry should be important components of helminth control strategy.

Agronomic biofortification of selected underutilised solanaceae vegetables for improved dietary intake of potassium (K) in Ghana

Agronomic biofortification is the deliberate use of mineral fertilizers to increase the concentration of a target mineral in edible portions of crops to increase dietary intake of the target mineral. Globally, increased dietary intake of potassium (K) is becoming a part of the strategy to address hidden hunger and related non-communicable diseases such as hypertension and cardiac disorders. This study aimed at demonstrating the efficacy of increasing the concentration of K in the edible portions of three commonly consumed but underutilized solanacea vegetables (Solanum aethiopicum, S. macrocarpon and S. torvum) in Ghana. The effects of different types and rates of K fertilizer application on the leaf- and fruit-K contents of the vegetables, as well as the K loss between the raw and cooked fruits were investigated. Five levels of each of three types of K fertilizer (liquid drench of potassium chloride, granular Muriate of potash and Sulphate of potash) were applied to each of the three field-grown vegetables. Yield data were collected and the fruits and leaves were analysed for the content of K, N, P, Ca, Fe, Zn and Cu. The results showed the rate of fertilizer application had significant effect on the yields of S. aethiopicum and macrocarpon but the yield of S. torvum was significantly affected by type, rate and interactive effect of type and rate of fertilizer application. Fruit K concentrations were greatest for S. aethiopicum (2130 mg K kg−1 DW) and S. torvum (1883 mg K kg−1 DW) with liquid KCl but with Sulphate of Potash for S. macrocarpon (1801 mg K kg−1 DW). There were higher K concentrations in leaves than in fruits of all the vegetables. Household cooking of the fruits resulted in the retention of over 70% of the K content in the raw fruits. Potassium fertilization increased the Ca, Fe, and Zn contents of S. aethiopicum and S. torvum. It is concluded that agronomic biofortification may be a useful strategy to increase K intakes and other important elements (e.g. Fe and Zn) in the vegetables studied.

Demucilaging Freshly Stored Seeds of Cocoa (Theobroma cacao L.) Improves Seedling Emergence and Growth

Fresh seeds of cocoa (Theobroma cacao L.) are covered by a large amount of mucilage, which plays important ecological roles. However, for stored seeds, mucilage can adversely affect germination. This study investigated the effect of mucilage removal (demucilaging) and seed storage of freshly extracted cocoa seeds on seedling emergence and growth. The study showed that demucilaging cocoa seeds confers several advantages over mucilage intact seeds provided the seeds have been stored for at least three days before sowing. Demucilaging increased germination rate (T50) and percentage germination and presence of mucilage increased days to seedling emergence and cessation of germination when seeds were stored for over two days. For up to 21 days of seed storage, there was generally no difference in many traits for demucilaged seeds. Demucilaged seeds had 80–100% germination after 21 days of storage, and rate of germination increased with increasing duration of seed storage. Intact mucilage seeds maintained 80–100% germination for only 2 days after seed extraction and rate of germination decreased with increasing seed storage duration. We conclude that (i) if seeds are sown on the day of extraction demucilaging before sowing would be superfluous and (ii) demucilaging and storage can provide advantages to smallholder farmers when environmental or socioeconomic conditions preclude immediate sowing.