African Journal of Horticultural Science

Tailoring Climate-Smart Biofuel Crop Production Options for Ghana: A Comprehensive Review

Naomi Weimer — 2024-12-01

As countries increasingly adopt low-carbon energy strategies, bioenergy, especially biofuels, presents significant opportunities for sustainable growth. Biofuel production offers a range of benefits, including atmospheric carbon sequestration, job creation, foreign revenue, sustainable land management, biodiversity conservation, renewable energy, ecosystem stability, and land degradation mitigation. This study aims to enhance Ghana’s biofuel policies and climate-smart agricultural strategies by identifying suitable biofuel species for integration into current frameworks. Through a review of seven critical criteria, carbon balance with perennial crops, suitability for marginal lands, minimal impact on food prices, water footprint, fertilizer and/or pesticide needs, sustainable nitrogen management, and prioritization of native species, this study highlights promising indigenous biofuel perennials for agroforestry models in Ghana. Native species such as shea (Vitellaria paradoxa), baobab (Adansonia digitata), Allanblackia parviflora, Khaya senegalensis, oil palm (Elaeis guineensis), and elephant grass (Pennisetum purpureum) show strong resilience and adaptability for sustainable local cultivation. Furthermore, several non-native species with favourable agronomic traits and adaptability to marginal lands were identified as potential biofuel crops, contingent on prior ecological assessments to ensure environmental compatibility. These species include Calotropis procera, castor bean (Ricinus communis), Jatropha curcas, neem (Azadirachta indica), moringa (Moringa oleifera) and cassava (Manihot esculenta). Additionally, Ghana’s established export crops such as cocoa (Theobroma cacao), rubber (Hevea brasiliensis), cotton (Gossypium hirsutum) and tobacco (Nicotiana tabacum) offer further biofuel potential by converting underutilized by-products, such as non-edible seeds and husks, into biofuels. The study underscores a critical need for additional research on bioenergy yields, biofuel properties, and alignment with local energy systems to inform policy and investment decisions. A shortage of empirical data, particularly life-cycle and cost-benefit analyses, was identified. Consequently, emphasizing the need for rigorous research to equip farmers, policymakers, and investors with the knowledge needed for sustainable biofuel development in Ghana.

Heavy Metal Phytoremediation Potential of Wild Plant Species Naturally Growing on Dumpsite, Kenya

Lynet Orao — 2024-12-01

Soils form an essential part of life and the main sink of pollutants. Intense industrial and anthropogenic activities have led to serious environmental threats, resulting in increased heavy metal concentration in soils and, consequently, a phytotoxicity effect on plants. Phytoremediation can offer effective and eco-friendly remedies for polluted sites. This study characterized the diversity of various plants that spontaneously grow in a dumpsite and scrutinized their phytoremediation potential. The plants evaluated for phytoremediation potential were Ricinus communis, Parthenium hysterophorus, Cassia didymobotrya, and Datura stramonium. The location of the research was Kang’oki dumpsite, Kenya. Species diversity was studied using quadrat sampling thrown randomly throughout the dump site. The bioaccumulation factor (BF) and the translocation factor (TF) were calculated to determine the accumulation and mobility of the heavy metals in the plants. To determine the ability of the plants to remove, accumulate, and mobilize the selected heavy metals, soil and plant sampling was conducted within the 14 sampling sites. The samples were acid-digested, and concentrations of Pb, Zn, Cu, and Cd were analyzed using Atomic Absorption spectrophotometry. Data obtained was subjected to statistical analysis using SAS version 94. Shannon-Weaver diversity index (H’) was used for species diversity. An H’ of 0.94 and species evenness of 0.45 was found showing a high species diversity on the dumpsite. Cadmium concentration in soil samples ranged from ND to 1.63 mg/kg of soils and 0.4418 to 0.6939 mg/kg of plant tissues. Nickel concentration ranged from 7.9 to 36.33 mg/kg in soils and 9.31 to 11.38 mg/kg in plant tissue, respectively. Copper was found between 3.41 to 121.18 mg/kg of soils and 3.74 to 10.89 mg/kg of plant tissues, respectively. Lead in soils ranged from 13.25 to 8.013 mg/kg of soils and 11.48 to 13.89 of plant tissues. Leaves accumulated significantly (p < 0.05) higher amounts of heavy metals than roots and stems. The leaves and stem of Datura stramonium showed the highest concentration of cadmium and copper, while its stem showed the maximum concentration of Nickel and lead. Datura stramonium showed BCF and TF >1; hence, it can be used for phytoextraction of cadmium. All plants showed TF>1; hence, these plants can be used as hyperaccumulators.

Fresh Fruit Handling Practices: A Case Study of Banana Value Chain in the Nairobi Metropolitan Fresh Produce Markets

Cherono Kipchumba — 2024-12-01

Fresh banana fruit value chains play an important role in nourishing the nutrition of millions of people globally. With the growth in the demand of fresh fruits, challenges relating to the quality and safety due to unconventional practices such as increased prevalence of illicit ripening of fresh banana fruit in some of the markets emerge. In this study, fruit handling storage and ripening practices in fresh banana fruit value chains in some of the largest fresh fruit markets in Kenya were evaluated to establish some of the factors that drive food quality and safety problems. A semi-structured questionnaire was used to collect data. Stratified random sampling was used to identify the participants. Thirty traders were selected from each of the five markets and zones situated in three densely populated counties in the Nairobi metropolitan area. Data was analysed using SPSS. Fruit characteristics varied depending on the source of fruit, with the farm being the most popular point of sourcing fruit by traders across the five zones. All the traders had knowledge of the exact source of their fruit and the time the fruit was harvested. About 97% of the traders assessed the maturity of the fruit before sourcing them, with 73% and 24% of the traders using colour and fruit size as the criteria for assessing fruit maturity, respectively. A one-way ANOVA of the data showed that the source of fruit did not have a significant (p>0.05) effect on the time the fruit took to ripen, quantities ripened by traders or time before fruit spoilt. Low sales (70%), poor storage conditions (13%) and use of poor ripening methods (3%) were reported to be the major causes of fruit spoilage. The use of passion fruit as a natural fruit ripening agent was associated with relatively higher fruit spoilage. The majority (96%) of players in fresh banana value chains had poor attitudes towards training in fruit handling, ripening and storage. This study recommends training of fresh fruit value chain players, the development of low-cost cooling solutions and the establishment of fruit storage and ripening infrastructure to mitigate against fruit spoilage within the fresh fruit markets in Kenya.

Influence of Socio-economic Factors on Prevalence of Ochratoxin A in Dry Coffee Cherry in Tharaka Nithi County, Kenya

Tabitha K. Gitonga — 2024-12-01

Coffee is a vital cash crop worldwide, contributing significantly to foreign exchange earnings and offering potential health benefits. However, concerns over contamination with mycotoxins, particularly Ochratoxin A (OTA), have grown due to its serious health risks. This study investigated the influence of socioeconomic factors on the prevalence of OTA in dry Coffee Cherry from Tharaka Nithi County, Kenya. A cluster random sampling method was used to collect the dry coffee cherry samples and survey data from 143 farmers across three agroecological zones, employing a semi-structured questionnaire. Pathogens were isolated on Potato Dextrose Agar (PDA) media and OTA production assessed according to the International Commission on Microbiological Safety for Foods. Data was analysed using the SPSS version 28 and SAS version 9.4. The study found out that socio-economic factors significantly (p < 0.05) influenced coffee farming practices and prevalence of OTA. Ochratoxin A prevalence was strongly associated with agro-ecological zones, farm size, and altitude. Larger farms and lower altitudes were linked to higher OTA risks. Gender, farm size and coffee variety also influenced OTA contamination levels. The study revealed that 88.3% of coffee farmers recognized mold in dry coffee cherries, yet 22.8% consuming moldy cherries, with 64.1% unaware of the health risks. Additionally, 87.6% of farmers identified poor drying and storage practices as key contributors to OTA contamination. Key indicators of contamination included discoloration, moldy smell, and moldiness with wetness. Roasting practices varied, with 35.1% roasting dried cherries after fermentation. The study highlights significant socioeconomic factors influencing OTA contamination in coffee. To mitigate risks, it is recommended to improve farmers' awareness of mold-related health risks and implement targeted interventions in high-risk areas to reduce OTA prevalence.

The effect of pre-soaking common bean (Phaseolus vulgaris) seeds in gibberellic acid solution on germination and seedling growth

Pesanai Zanamwe — 2024-12-01

Poor seed germination and early seedling growth often limit common bean production. Pre-treatment with plant hormones, such as gibberellic acid (GA₃), can improve germination and seedling vigour in many plants. However, its effects on common bean seeds are not well understood. This study evaluated GA₃’s potential to promote germination and seedling growth in common beans. Laboratory germination tests and greenhouse trials were conducted using two varieties, Gloria and Nua45. Seed from each variety was divided into two groups and the other group was soaked in 60 ml/L GA₃ solution for 5 min and the other group was left untreated and used as a control. Treatments were arranged in a completely randomized design with three technical and two biological replicates. Data on germination percentage were collected every 24 hours for 120 h, along with measurements of rootlet length, seedling vigour indices, root length, shoot length, and dry weight. Results indicated that GA₃-treated Nua45 seeds had significantly higher germination percentages than untreated seeds after 48, 72, and 96 h, while treated Gloria seeds showed lower germination than untreated seeds within the same time frames. By 120 h, both treated and untreated seeds of both varieties reached a minimum of 90% germination. Nua45 seeds treated with GA₃ showed significantly greater rootlet length (5.29 cm) than untreated seeds (4.12 cm), while Gloria seeds showed no significant difference in rootlet length between treated (2.49 cm) and untreated seeds (2.86 cm). For Nua45, GA₃-treated seedlings had higher shoot length (46.7 cm), dry weight (4.10 g), and seedling vigour index II (3.7) than untreated seedlings (28.5 cm, 2.34 g, and 2.25, respectively). In contrast, untreated Gloria seedlings had greater root length (35.1 cm) than treated seedlings (14.4 cm), with no shoot length difference. These findings suggest that pre-soaking Nua45 seeds in GA₃ solution enhances germination and growth, while pre-soaking Gloria seeds reduces them. These findings suggest a hormone-genotype interaction effect warranting further study.

Secondary Metabolites as Biomarkers in Breeding for Biotic and Abiotic Stresses in Plants

Joyce N Njihia — 2024-12-01

Understanding the relationships between metabolite profiles and plant responses to various environmental stresses is a major goal in plant breeding. However, linking molecular markers patterns of plants to environmental pressures and trait variation remains difficult due to ecological driven plasticity. Integrating metabolite profiles as biomarkers alongside molecular markers presents an opportunity to address this challenge. Plants mitigate various biotic and abiotic stresses by activating multiple protective mechanisms. The diversity of secondary metabolites, shaped by environmental selection pressures, plays a critical role in these adaptive responses. Despite their significance, current functional classification systems for plant metabolites remain limited. A more comprehensive understanding of secondary metabolites as integrated components of metabolic networks, shaped by dynamic environmental pressures, can provide insights into plant metabolism and plant-environment interactions across multiple trophic levels. This review explores the complex networks of pathways involved in the production of protective secondary metabolites. These networks represent novel opportunities for crop improvement, particularly in breeding for drought tolerance and insect resistance. By examining key signalling networks and their interactions with abiotic and biotic stress pathways, this paper offers a resource for developing more effective strategies. Integrating metabolite profiling in breeding programs can enhance efforts to select and breed varieties that are more resilient to environmental challenges.

Accessing the potential of the African spider plant (Cleome gynandra) to control Salmonella typhi

Gladys Rotich — 2024-12-01

The African spider plant (Cleome gynandra) is an erect tender annual herb that is highly branched. This popular and nutritious leafy vegetable has been commercialized as a major African indigenous vegetable in Kenya. The African spider plant has also been an antidote for typhoid and poor sanitation-related illnesses. Salmonella typhi is common with an estimated annual global incidence of 26.9 million cases, and causes 200,000 deaths annually due to mismanagement of water resources and poor sanitation. To validate the medicinal myth, this study aimed to evaluate the efficacy of crude extracts from the African Spider plant, Cleome gynandra against Salmonella typhi the leaf extracts of this vegetable were tested for activity against cultures of Salmonella typhi haplotype H58 in vitro. Fresh leaves were homogenized in sterile distilled water (SDW) at 1:2 wt/vol ratios. Extraction was done overnight at 4^○C and then centrifuged at 1500rpm for 5 minutes. The supernatant was sterilized through 0.2µm Millipore filters and diluted up to x10 ^-3. About 40µlof each diluted extract was loaded onto sterile discs and allowed to air dry under sterile conditions. Similar volumes of Ampicillin at 10µl and SDW were used as positive and negative controls respectively. About 100µl of x10 ^-7 diluted suspensions of Salmonella typhi were inoculated and spread dry on Muller Hilton agar plates. The preloaded discs were then placed radially at a 6cm circumference on the inoculated 9cm Petri plates. The plates were then incubated at 37^○C for 24 hours and growth inhibition zones measured (mm) values were compared statistically using one-way ANOVA to the controls and inference made. All the test crude extracts suppressed the growth of Salmonella typhi significantly compared to SDW controls (p=0.00000136). Straight extracts at 20mg bioactive compound had significantly high (p=0.00000136) bioactivity compared to x10 ^-1 and x10 ^-2 dilutions but significantly lower than the Ampicillin control. Interestingly, extracts diluted to x10 ^-2 with 5mg bioactive compounds suppressed salmonella typhi significantly (p< 0.001). Cleome gynandra has therefore demonstrated antibacterial properties against Salmonella typhi, thus gradually utilizing these plant leaves at high concentrations is recommended to suppress the infections caused by Salmonella typhi pathogenic bacteria.

Management of Meloidogyne javanica in Tomato using Extracts from Asteraceous Plants for Enhanced Productivity and Quality

Tobias Alubi — 2024-12-01

The Javanese root knot nematode, Meloidogyne javanica (Treub) Chitwood, is a major threat to solanaceous plants globally, particularly impacting smallholder tomato farmers in Africa due to its rapid reproduction and resistance to synthetic nematicides. This study assessed the impact of extracts from three asteraceous plants (Tithonia diversifolia, Bidens pilosa, and Tagetes minuta) on M. javanica in tomato cultivation. Various plant parts (roots, stems, flowers, and leaves) were ground and mixed with sterile soil in pots. Tomato plants were grown in these pots and inoculated with second-stage juveniles (J2s) and eggs of M. javanica three weeks post-transplanting. The treatments were evaluated for nematode numbers, damage, plant growth, yield, and soil organic carbon and nitrogen content. Results showed that extracts from the three plants had significant effects (P <0.001) on the nematode’s reproduction and development. Root extracts of T. diversifolia and B. pilosa reduced the J2 population by 89.1% and 84.7%, respectively. Moreover, T. minuta and T. diversifolia root extracts decreased the reproductive potential of M. javanica by 69.8% and 72.3%, respectively. A significant (P = 0.001) interaction effect between time and treatment on tomato root growth was observed. The highest yield was achieved with T. minuta leaf extracts (0.461±0.039 kg/plant). Ascorbic acid content in tomato varied significantly (P <0.001) with T . minuta stem extract treatments showing doubled levels at the mature green stage. Soil analysis revealed that T. minuta root extracts significantly (P = 0.001) increased soil organic carbon content to 1.96%, with B. pilosa leaf extracts (1.8%) and B. pilosa root extracts (1.4%) also contributing positively. T. diversifolia stem and leaf extracts had the most significant (0.4%, P < 0.001) impact on soil organic nitrogen content. This study highlights the potential of organic extracts from T. diversifolia, T. minuta, and B. pilosa in managing RKNs, improving tomato yield, and enhancing soil properties, offering promising avenues for sustainable agriculture.