Geostatistical and Geotechnical Analyses of the Terrain of Onitsha Metropolis and its Environs in Anambra State, Southeastern Nigeria | Chapter 8 | Research Advances in Environment, Geography and Earth Science Vol. 2

Studies have shown that there are still growing concerns about global population growth and the direction of the growth. Latest population figures show that India has overtaken China presently as the most populated country in the world. Malthus's theory of population growth even though food production is becoming true in all aspects of human existence. The suggested measures of Malthus's critics – new lands, international trade, and industrialization are among the attractions of the new population direction – the urban centers with massive accommodation pressure and subsequently unplanned urban growth especially in developing countries. The study aimed at carrying out geostatistical and geotechnical analyses of the terrain of Onitsha Metropolis and its environs in Anambra State, Southeastern Nigeria and to determine if the terrain can support the growth and expansion of the city occasioned by the influx of people in recent years. The study used both primary and secondary data. The primary data comprises physical observation, measurements, soil sample extraction, and photographs. The secondary data include satellite images from USGS - SRTM for image analysis of the geology, and geomorphology of the area. The soil results for the geotechnical parameters were analyzed using multiple linear regression analysis in Statistical Package for the Social Sciences (SPSS) version 25.0 and Microsoft Excel, 2007. The study identified areas of strong and weak geology and concluded that Onitsha Metropolis requires executable plans for the Metropolis to attain the status of a sustainable city.

Author(s) Details:

Dominic Chukwuka Ndulue,
Department of Geography, University of Nigeria, Nsukka, Enugu State, Nigeria and Department of Geography, University of Ibadan, Ibadan, Oyo State, Nigeria.

Romanus Udegbunam Ayadiuno,
Department of Geography, University of Nigeria, Nsukka, Enugu State, Nigeria.

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In-vitro Effect of Some Plant Extracts and Synthetic Fungicide in the Control of Cocoyam Leaf Necrotic Fungi in Nigeria | Chapter 5 | Innovations in Microbiology and Biotechnology Vol. 5

The goal of this study was to see how various plant extracts and synthetic fungicides worked in vitro to reduce cocoyam leaf necrotic fungus in Nigeria. Farmers' fields in two communities in Anambra State's Ekwulobia local government area yielded cocoyam leaves of two tropical crops: taro (old cocoyam, Colocasia esculenta (L.) Schott) and blue or purple taro (new cocoyam tanier, Xanthosoma sagittifolium (L.) Schott). Among the communities were Ula and Okpo. Cocoyam leaves and petioles with microscopic dark-brown or black lesions were used to isolate the causal pathogen. The fungus discovered on the damaged cocoyam leaves was identified as Aspergillus niger. Wounds created by harvesting instruments and bugs may have allowed this bacteria to enter these cocoyam leaves. The antifungal effects of ethanol, methanol, and petroleum ether extracts of lemon grass leaves and stalks (Cymbopogon citratus) and fruits of pepper fruit (Dennettia tripetala) on Aspergillus niger growth were investigated in vitro at concentrations of 1, 1.5, and 2 g/ml, with the synthetic fungicide (Apron plus) serving as a control. The data was analysed using the ANOVA method. In a completely randomised design with three replications, split – split – plots were used, and means were separated using least significant difference (LSD) at a 5% probability level. The findings of this study revealed that phytochemical antifungal activity increases with increasing concentration, with 2.0 g/ml having the highest percentage growth inhibition value on day 1, and this pattern continued throughout the culture. All plant extracts and Apron plus were found to be effective in suppressing the fungus. Apron plus had the highest level of inhibition (75%) followed by lemon grass (49.04%) and pepper fruit had the lowest level of inhibition (25%). (39.48 percent ). The study also discovered that the higher the concentration, the stronger the inhibition, with synthetic fungicides having the maximum inhibition (72.58 percent) at 2g/ml. The extract of lemon grass (Cymbopogon citratus) exhibited a higher % inhibition value during the culture days, although Soxhlet extraction using Pet ether as the extracting solvent had the highest level of inhibition (53.03 percent ). As a result, the plant extracts employed in this study could be recommended as a substitute for synthetic fungicides. More research into the active ingredients of these plant extracts should be conducted in order to facilitate commercial production and availability to farmers, as these extracts are expected to be biodegradable and may reduce the rate of application of synthetic fungicides, which are harmful to human health and persist in the environment.

Author (s) Details

Dr. C. C. Iwuagwu
Department of Crop Science and Horticulture, Nnamdi Azikiwe University, Awka, Anambra State, Nigeria


A. C. Nwogbaga
Department of Crop Production and Landscape Management, Ebonyi State University, Abakaliki, Nigeria.


F. C. Onejeme
Department of Crop Science and Horticulture, Nnamdi Azikiwe University, Awka, Anambra State, Nigeria.


U. F. Nduka
Department of Crop Science and Horticulture, Nnamdi Azikiwe University, Awka, Anambra State, Nigeria.


D. E. Iheaturu
Department of Crop Science and Horticulture, Nnamdi Azikiwe University, Awka, Anambra State, Nigeria.

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