Biopesticide efficacy of four plant essential oils against papaya mealybug, Paracoccus marginatus Williams and Granara de Willink (Hemiptera: Pseudococcidae)

This research article was published by Heliyon in 2023Worldwide, P. marginatus causes 75% of estimated economic loss in papaya farming, with an increase in production costs. The extract of plant essential oils (PEO) has the potential to control P. marginatus by degrading its wax coatings to death; however, it is less studied in the East African agroecosystem. Therefore, this study was conducted to evaluate the efficacy of four PEO from (neem, citrus, garlic, and castor) against P. marginatus at different concentrations (0.5%, 1%, and 1.5%) with and without 0.2% adjuvants separately as a biopesticide. The experiment was con ducted in a completely randomized design with four replications per treatment concentration. The papaya seeds (Carina variety) were used in the experiment. After 3 weeks from transplanting, 50 P. marginatus specimens were inoculated in each plant. Before treatment application, insect abundance, leaf curling, yellowing, and soot mold were assessed. Then, 24 h, 48 h, and 72 h after biopesticide application, insect mortality was assessed. The results showed a significant difference (p = 0.001) for all assessment intervals in PEOs. However, for the PEOs in combination with the adjuvants, the results were significantly different (p = 0.001) only at 24 h. It was found that among the biopesticides, neem oil (1.5%) + isopropyl alcohol was highly effective (95.5%) after 72 h followed by (Imidacloprid (91%), citrus oil 1.5% (90.7%) and neem oil (1.5%) + paraffin oil (81.0%). But also, there were significant differences among treatments on leaf curling, yellowing, and soot mold reduction in papaya plants 21 days after spray. We conclude that neem oil (1.5%) + 0.2% isopropyl alcohol, neem oil (1.5%) + paraffin oil, and citrus oil (1.5%) significantly controlled P. marginatus. Thus, we recommend adopting these formulations for papaya farmers to control P. marginatus in their farms; however, simple formulations which can be easily accessed by smallholder farmers are essential

Lablab purpureus: Analysis of landraces cultivation and distribution, farming systems, and some climatic trends in production areas in Tanzania

This research article was published by De Gruyter Open Access, 2023Lablab is a multifunctional crop that is underutilized in Africa. This study was performed to assess Lablab landraces cultivation and distribution, farming systems, and some climatic trends in Lablab production areas in Tanzania. A socio-economic survey was engaged to locate the main production areas using Global Positioning System, while participatory research tools were used to assess farming systems, practices, and challenges perceived in Lablab production. Some weather data were collected to establish climatic trends in Lablab production areas. The study revealed a wide cultivation and distribution of Lablab landraces in five agro-ecological zones with some variations. These variations were influenced by market demand for Lablab in Kenya and its role in subsistence farming. Lablab was mainly produced for conservation agriculture and enhanced soil fertility (27.9%), marketing (22.1%), livestock feeding (21.5%), food during drought conditions (15.4%), traditional purposes (7.4%), regular consumption (3.8%), and other minor uses (1.8%) varied significantly across the zones (χ 2 = 37.639, p = 0.038). The farming systems included intercropping (59.0%), mono-cropping (31.0%), home based gardening (5.0%), crop rotation (3.0%), and relaying cropping (2.0%) with no significant difference across the zones (χ 2 = 15.049, p = 0.314). A wide range of farmers’ practices were noted in Lablab production zone-wise. Unavailability of improved varieties and poor market channels were the farmers’ key challenges in Lablab production. It was further noticed that Lablab was mainly produced in areas with dry conditions. Finally, it was suggested that effort should be enhanced to improve genetic resource conservation, value addition, and market channels to other countries while developing improved varieties in terms of high yielding and drought tolerance

Evaluating Rhizobium and Bradyrhizobium species as potential biocontrol agents for root rot fungi in soybean seedlings

This research article was published by Technology in Agronomy, 2024Soybean (Glycine max) is among the legumes which are highly prone to soil-borne pathogens which causes root-rot diseases limiting the growth and development resulting to low yield of plants. This study was conducted to test the ability of three rhizobia strains, Rhizobium sp. TZSR12C, Rhizobium sp. TZSR25B and Bradyrhizobium sp. TZSR41A, in comparison with the commercial biocontrol (Trichoderma harzianum in suppressing the growth of root rot fungal pathogens (Fusarium solani, Rhizoctonia solani, Fusarium oxyporum, and Macrophominaphaseolina) under in vitro and greenhouse conditions. The rhizobium cell filtrates were used in testing their activities against fungal pathogens under in vitro while the solid biofertilizer formulations containing the respective rhizobia inoculants were used to inoculate the soybean seeds sown in pathogen contaminated soil under greenhouse conditions. Results showed that all rhizobia isolates and T. harzianum were capable of suppressing the fungal pathogens both under in vitro and greenhouse conditions with the highest inhibition zone (8.3 mm) and colony diameter (25.0 mm) being in Rhizobium sp. TZSR25B against F. oxyporum under in vitro conditions. Under greenhouse experiment, Rhizobium sp. TZSR12C had the highest performance in inhibiting the infection of plant up to 27.78% with severity of 5.56% in roots and 0.00% infection in foliage against the combination of F. solani, R. solani, F. oxyporum, and M. phaseolina. We found that, on their performance, the tested rhizobia strains can potentially be utilized as biocontrol agents against the fungal pathogens in the rhizosphere of soybean plant

Soybean-Nodulating Rhizobia: Ecology, Characterization, Diversity, and Growth Promoting Functions

This research article was published by Frontiers in Sustainable Food Systems in 2022The worldwide increase in population continues to threaten the sustainability of agricultural systems since agricultural output must be optimized to meet the global rise in food demand. Sub-Saharan Africa (SSA) is among the regions with a fast-growing population but decreasing crop productivity. Pests and diseases, as well as inadequate nitrogen (N) levels in soils, are some of the biggest restrictions to agricultural production in SSA. N is one of the most important plant-limiting elements in agricultural soils, and its deficit is usually remedied by using nitrogenous fertilizers. However, indiscriminate use of these artificial N fertilizers has been linked to environmental pollution calling for alternative N fertilization mechanisms. Soybean (Glycine max) is one of the most important legumes in the world. Several species of rhizobia from the four genera, Bardyrhizobium, Rhizobium, Mesorhizobium, and Ensifer (formerly Sinorhizobium), are observed to effectively fix N with soybean as well as perform various plant-growth promoting (PGP) functions. The efficiency of the symbiosis differs with the type of rhizobia species, soybean cultivar, and biotic factors. Therefore, a complete understanding of the ecology of indigenous soybean-nodulating rhizobia concerning their genetic diversity and the environmental factors associated with their localization and dominance in the soil is important. This review aimed to understand the potential of indigenous soybean-nodulating rhizobia through a synthesis of the literature regarding their characterization using different approaches, genetic diversity, symbiotic effectiveness, as well as their functions in biological N fixation (BNF) and biocontrol of soybean soil-borne pathogens

Insecticidal Activity of Selected Plant-Derived Essential Oils against Papaya Mealybug (Paracoccus marginatus)

This research article was published in the Journals of Sustainability, Volume 15, Issue 23, 2023The current study aims to assess the effectiveness of three essential oils derived from neem, citrus, and garlic against papaya mealybug. Papaya seedlings were transplanted in the field in a completely randomized block design with eight treatments with four replications. The treatments included neem, citrus, and garlic oils in combination with isopropyl alcohol or paraffin oil as an adjuvant. Results from this study showed that neem oil at 1.5% + 0.2% isopropyl alcohol was effective against papaya mealybug by 93.0% equivalent to the positive control (imidacloprid) (99.4%), followed by citrus oil at 1.5% + isopropyl alcohol (76.3%) and citrus oil at 1.5% + paraffin oil (68.8%), compared with the untreated 0.01%. Similarly, application of the plant-derived essential oils and adjuvants resulted in positive effects on plant parameters (plant height, number of leaves, flower buds, number of fruits, and fruit weight) and, hence, increased papaya yield from an average of 38 to 90 fruits/plant at first harvest. The finding from this study provides an understanding of papaya farmers towards the use of natural plant products, particularly plant-derived essential oils, and their benefits, which may encourage farmers to increase papaya production and minimize the usage of synthetic pesticides to avoid pest resistance

Pre-Breeding Prospects of Lablab (Lablab purpureus (L.) Sweet) Accessions in Tanzania: Morphological Characterization and Genetic Diversity Analysis

This research article was published by MDPI, 2022Under-exploited crops such as Lablab purpureus are regarded a pathway towards alleviating the food and nutritional security in Sub-Saharan Africa. This study aimed at evaluating the morpho-agronomic diversity present in 277 lablab accessions based on 38 morpho-agronomic traits. The experiment was laid out in an Augmented design across two main cropping seasons in Tanzania. Qualitative data was analysed using pivot tables. The Generalized Linear Model (PROC GLM), Agglomerative Hierarchical Clustering (AHC) and Principal Component Analysis (PCA) were used to analyse variation of 14 quantitative traits. The findings revealed the presence of wide variability of the qualitative traits in the studied accessions. Significant differences were observed among accessions, between seasons, the interaction of blocks and season, and the season and accession effects in most of the traits. Most of the traits had high significant differences in relation to contrast among accessions, among checks and between accessions and checks. The first five principal components cumulatively accounted for 61.89% of the total variability among the accessions studied. Furthermore, cluster analysis grouped the accessions into four major clusters. This results suggest the 14 morpho-agronomic traits can successfully discriminate and show presence of wide diversity vital for selection and hybridization program of lablab species

Farmers’ Participatory Plant Selection of Lablab (Lablab purpureus (L.) Sweet) in Tanzania

This research article was published by Frontiers in Plant Science in 2022Farmer-participatory breeding approach is an important component in the crop improvement of lablab (Lablab purpureus (L.) Sweet). The study was carried out to obtain the knowledge, practices and preferences of lablab through 31 lablab growing farmers from Arusha, Kondoa, Karatu, Same and Babati districts of Tanzania toward initiating a lablab breeding program. Semi-structured questionnaires were administered and focused group discussions were held to collect data on the socio-demographic factors, production practices, constraints and farmer’s preferred traits of lablab. Selection of preferred traits and accessions was also done by the farmers in the field. Results showed that the chief constraints of lablab production are pests and diseases, poor marketability, low seed quality, inadequate rainfall, expensive agrochemicals, low yield, and poor storage facilities. The major pests are pod borer (field) and bruchids (storage). Preferred traits for lablab improvement include the development of insect pests and disease-resistant varieties, early maturing, high yield, black colored seed for market, short cooking time, and dense foliage. Genotypes EK2, D360, HA4, and D96 with preferred traits were identified by farmers, which forms critical decisions in crop improvement. This study describes the current view of lablab production and generates the understanding of farmers’ perceptions and preferences vital for breeding priorities and programs to increase its production, utilization and consumption

Enhancing Food Grains Storage Systems through Insect Pest Detection and Control Measures for Maize and Beans: Ensuring Food Security Post-COVID-19 Tanzania

This research article was published by MDPI, 2024COVID-19 poses a significant threat to the present and future of mankind. The emergence of diverse strains during the pandemic creates uncertainty regarding their disappearance or resurgence. Lockdown measures and travel restrictions impact national and household food systems, hindering the movement of people and goods. Effective COVID-19 control requires science-based preventive measures and consideration of food availability. In Tanzania, resource-constrained farmers rely on the self-storage of food crops. Precise pest control information and tailored detection/storage systems are essential for preserving major staple foods such as maize and beans, which face frequent infestation by beetles and moths. Traditional methods used before the pandemic are insufficient compared to advanced global alternatives. This paper reviewed about 175 publications from different databases, dated from 1984 to 2023 (2023 to 2014 = 134, 2013 to 2004 = 26 and 2003 to 1984 = 15), assessing storage management for maize and beans. Identifying gaps between Tanzania and global advancements aiming to empower farming communities with the latest technologies and ensuring food security amid the pandemic

Characterization of Provitamin A Status and Distribution in Commercial Grown Maize Varieties in Tanzania

This research article was published in East African Journal of Science, Technology and Innovation, vol 3, 2022Provitamin A carotenoids are important as precursors for vitamin A, essential for stronger immune system and eyesight. Consumption of a plant-based diet rich in provitamin A such as provitamin A maize is an easy and affordable source of vitamin A. The majority of the commercially grown maize varieties in Tanzania are white whose provitamin A status is uncertain and undocumented. The existing current information suggests that white maize varieties have low provitamin A, an active form of vitamin A, thus putting maize consumers at risk of vitamin A deficiency (VAD). Characterization of provitamin A status in commercial maize varieties grown and consumed in Tanzania is important to provide baseline information required for vitamin A rich-maize improvement programs. Therefore, this study was conducted to map the status of provitamin A in commercial maize varieties to accrue the information needed to improve maize nutrition quality toward controlling VAD in the country. The study involved 14 maize varieties including commercial yellow and white pigmented maize from 3 regions of Tanzania. From maize samples, carotenoid extraction was conducted based on published protocol. The concentration of beta carotene (BC), beta-cryptoxanthin (BCX), alpha-carotene (AC) were determined by an ultraviolet spectrophotometer and provitamin A computed for the individual carotenoids components. The study found that the concentration of provitamin A and associated carotenoids significantly differed (p<0.001) among varieties studied. The mean concentration (in μg/g) for provitamin A and its components in range as provitamin A (2.64-6.50), BC (1.91-4.66), BCX (0.649-1.21), and AC (0.819-1.46). The concentrations of provitamin A in the studied maize varieties were below the recommended levels (15 μg/g). The low concentrations of provitamin A among commercial maize varieties signify the need for introgressions of provitamin A in the adapted maize genotypes for ensured intake of vitamin A

Lablab purpureus: Evaluation and Selection of Drought-tolerant - High-yielding Accessions in Dry Farming Systems Based on Drought Tolerance Indices and Multi- environmental Yield Trials

This research article was published in Journal of Agricultural Sciences, volume 29, issue 2, 2023.Breeding for drought tolerance in crops requires responding knowledge on the moisture regimes of crops. This study was conducted to evaluate and select the drought tolerant - high yield Lablab accessions in the dry farming systems of Tanzania based on drought tolerance indices and field performance. Three sites from different agro-ecological conditions were selected for the study and each site involved trials with moisture stress-free (MSF) and early terminal moisture stress (TMS) conditions. The experimental design consisted of a randomized complete block design. The twelve accessions used in the study were the best genotypes selected from the former moisture screening experiment at the seedling stage. Data collections included days to 50% flowering and maturity, seed yield plant-1 and seed yield ha-1. The responses of the accessions to TMS conditions were quantified through ten developed indices whose correlation coefficients were computed from the mean of the seed yield plant-1 under MSF and TMS conditions. ANOVA and post-hoc tests were used to analyze the variation among the accessions and their field parameters as well as to compare their means, respectively. Based on this analysis, three indices; mean productivity, geometric mean productivity, and stress tolerance index were discovered with higher correlation coefficients (>0.5), and thus effective for selecting the TMS tolerant accessions with high seed yield plant-1 under both conditions. Through the combined rank mean method, D147, D363, HA4, D349, D352, D348, and D359 were generally selected as Lablab TMS tolerant accessions with high seed yield plant-1 across the evaluation sites. Although the significant difference (p<0.05) in field performance was noted among the accessions and across the sites, promising trends were found among the above selected TMS tolerant accessions. It is therefore suggested that, further evaluation of the above-selected accessions should involve farmers in their fields before releasing them as commercial varieties