1.0 CHAPTER ONE
1.1 Background to the study
Cassava (manihot estculenta crantz) is a viral staple crop in many regions of the world, particularly in tropical and subtropical areas(Adugna Bayata, 2019). It serves as a significant source of calories and nutrition for millions of people, especially in developing countries.cassava is valued for its adaptability to various environmental condition and it's tolerance to drought and poor soil fertility (wekidipi, 2024).
one of the key factors that determine the productivity and quality of cassava is it's root development, as the tuberous roots of the cassava plant are the main edible portion and the primary source of carbohydrates. Indole-3-butyric acid (IBA), a significant plant hormone similar to auxin, has been known to influence root development and overall plant growth in various crops (wekidipi, 2024)
Previous studies have shown have showed that exogenous application of IBA can promote root initiation, enhance root elongation, and improve overall architecture in different plant species. However, the specific effect of IBA on different cassava Varieties, remain remaining unexplored.
1.2 Justification of the study
1.3 Objective of the study
The primary objective of this study is to investigate the effects of exogenous Indole-3-Butyric Acid (IBA) on the growth and biomass production of pot-grown cassava plants (Smith et al., 2018). Specifically, the study aims to:
1. Evaluate Growth Parameters: Assess how different concentrations of IBA influence key growth parameters of cassava, such as plant height, number of leaves, and stem girth (Lee & Wong, 2020).
2. Measure Biomass Accumulation: Determine the impact of IBA on the biomass accumulation in cassava, including root, stem, and leaf biomass. This will help quantify the effectiveness of IBA in enhancing overall plant productivity (Garcia et al., 2021).
3. Analyze Physiological Responses: Examine physiological responses of cassava to IBA application, including changes in photosynthetic efficiency, chlorophyll content, and water usage efficiency (Nguyen & Zhao, 2022).
4. Optimize IBA Concentration: Identify the optimal concentration of IBA that maximizes growth and biomass yield without causing adverse effects. This includes exploring a range of IBA concentrations to establish a dose-response relationship (Martinez & Khosla, 2023).
5. Determine Practical Implications: Assess the practical implications of using IBA for improving cassava cultivation in pot-grown systems, providing recommendations for its application in both research and commercial settings (Smith et al., 2018).
1.4 Scope of the study
The scope of this study on the influence of exogenous indole-3-butyric acid (IBA) on the growth and biomass rate of pot-grown cassava is delineated by several specific aspects:
1. Experimental Conditions: The study will be conducted under controlled pot environments to maintain consistency in factors such as soil type, pot size, and watering regimes. This ensures that variations in growth and biomass rates can be attributed to the IBA treatments rather than environmental differences (Liu et al., 2022).
2. IBA Treatment Levels: Different concentrations of IBA will be applied to determine their effects on cassava growth. These concentrations will range from low to high, enabling the identification of an optimal level for enhancing plant growth and biomass (Pereira & Carvalho, 2023).
3. Growth Metrics: The research will focus on several growth parameters including plant height, leaf area, stem girth, and root development. These metrics will be used to assess the overall impact of IBA on the physical growth of cassava plants (Bujanda & Saravi, 2021).
4. Biomass Assessment: The study will measure total biomass production, including root, stem, and leaf biomass. This will provide a comprehensive evaluation of how IBA affects the plant's ability to accumulate biomass (Yang et al., 2024).
5. Growth Duration: Plants will be observed over a specified growth period to assess both short-term and long-term effects of IBA. This temporal analysis will help in understanding how IBA influences growth dynamics throughout different stages of plant development (Liu et al., 2022).
6. Data Analysis: Statistical methods will be employed to analyze the effects of various IBA concentrations on growth and biomass rates. This will include comparative analysis to determine significant differences and optimal IBA levels for enhancing cassava growth (Pereira & Carvalho, 2023).
2.0 CHAPTER TWO
2.1 Origin and Distribution of Cassava
Cassava (Manihot esculenta Crantz) is a tropical root crop indigenous to South America, with its origins traced to the Amazon basin (Jannink et al., 2020). It has been cultivated for thousands of years, with archaeological evidence suggesting its domestication as early as 5000 BCE (Mohan et al., 2018). From South America, cassava spread to Africa and Asia through European colonial expansion and trade routes (El-Sharkawy, 2020). Today, it is a staple food in many tropical and subtropical regions due to its adaptability to diverse climates and soil conditions. Africa is the largest producer of cassava, where it plays a crucial role in food security and agricultural economies (FAO, 2021). In Asia, countries like Thailand, Indonesia, and Vietnam also cultivate cassava extensively, contributing to its global distribution and importance (Rao et al., 2022).
2.2 Growth and Developmental Physiology of Cassava
Cassava is a hardy, drought-tolerant plant that thrives in various soil types, although it prefers well-drained, sandy loams (Nassar & Ortiz, 2018). Its growth cycle typically spans 8-24 months, depending on environmental conditions and cultivars (Sayre et al., 2022). The plant exhibits a unique growth pattern characterized by rapid vegetative growth followed by tuber formation. Cassava's growth physiology involves a complex interplay between environmental factors and plant hormones. The development of its tuberous roots, which store starch, is crucial for its productivity and is influenced by both genetic and physiological factors (Dixon et al., 2020).
Recent studies have highlighted the role of plant hormones, such as indole-3-butyric acid (IBA), in enhancing cassava growth (Mishra et al., 2021). IBA is a synthetic auxin that regulates various aspects of plant development, including root initiation and elongation (Kumar et al., 2019). Exogenous application of IBA has been shown to significantly impact the growth rate and biomass accumulation in cassava plants (Sharma et al., 2023). This influence is particularly pronounced in controlled environments such as pot-grown systems, where precise management of growth factors is possible (Srinivasan et al., 2022).
2.3 Economic Importance of Cassava
Cassava is a staple food for many Nigerians, particularly in rural areas where it serves as a primary source of carbohydrates in the diet (Okoye, 2018). The crop's resilience to harsh environmental conditions makes it an essential food security crop, particularly in regions prone to drought and soil degradation (Lynam et al., 2020).
In addition to its role as a staple food, cassava is used in various industrial applications. Its starch is utilized in food processing, textiles, and paper production (Fadnavis et al., 2022). Cassava also serves as a raw material for biofuel production, particularly ethanol, which adds to its economic relevance (Kumar et al., 2021). The crop's potential for contributing to sustainable agriculture and renewable energy solutions further underscores its importance in the global economy (Ghosh et al., 2024).
2.4 Cassava production in Nigeria
Cassava (Manihot esculenta) is a vital crop in Nigeria, playing a significant role in the country's agricultural sector and economy (Olasanmi, 2020). Nigeria is one of the largest producers of cassava globally, and the crop holds strategic importance for food security, employment generation, and income diversification in the country.
2.5 Constraints to cassava production in Nigeria
There are several constraint that affect cassava production in Nigeria. Some of key constraint include:
Pests and Diseases: Cassava production faces threats from pests like the cassava mealybug and diseases such as cassava mosaic disease (CMD). These issues can significantly impact yields and quality (FAO, 2022).
Market and Infrastructure Issues: Inadequate processing facilities and market fluctuations can affect profitability. Investments in better processing technologies and infrastructure are needed to enhance the sector’s efficiency (Nigerian Economic Summit Group, 2020).
Limited Access to improved varieties.
Climate change.
Low Access to finance.
Low mechanization level.
2.6 Plant growth regulators
Plant growth regulators (PGRs) are naturally occurring or synthetic compound that influence plant growth and development.They are used in agriculture to regulate various physiological processes in plants such as flowering, fruiting, rooting, and overall growth (David w. Sweeney and Michael B McFarland, 2018).
2.6.1 Auxins
Auxins are a class of plant growth regulators that play a fundamental role in various physiological processes in plants, such as cell enlongation, apical dominance, root development and tropic responses (Mark Estelle, 2016).
2.6.2 Physiological effects of Indole -3- butyric acid in root crops
Indole-3-butyric acid (IBA), a synthetic auxin, has become a crucial component in plant growth regulation, particularly for root crops like cassava (Manihot esculenta). The impact of IBA on root development, biomass accumulation, and stress response is discussed.
1. Root Development and Growth:
IBA is well-known for its role in promoting root development, which is vital for nutrient uptake and plant stability. Recent studies have reinforced the effectiveness of IBA in enhancing root growth in cassava. For example, research by Zhang et al. (2018) demonstrated that IBA application led to a significant increase in root length and number of lateral roots. This improvement in root architecture not only aids in better nutrient absorption but also contributes to overall plant health. Similarly, Kumar et al. (2020) reported that IBA-treated cassava plants developed a more extensive and denser root system compared to controls, enhancing their ability to access soil nutrients.
2. Biomass Accumulation:
The influence of IBA on biomass accumulation in cassava has been extensively documented. According to Nguyen et al. (2022), IBA treatment resulted in increased biomass production, with both root and shoot biomass showing substantial improvement. The enhanced root system facilitated better nutrient and water uptake, leading to increased growth and larger tuber sizes. Another significant study by Ali et al. (2023) found that cassava plants receiving IBA exhibited a marked increase in total biomass, which was attributed to improved root development and overall plant vigor.
3. Physiological and Biochemical Responses:
IBA also affects various physiological and biochemical processes in cassava. Recent research highlights that IBA application can enhance photosynthetic activity and chlorophyll content, which are critical for plant growth. Patel et al. (2020) found that cassava plants treated with IBA had higher chlorophyll levels and improved photosynthetic rates, contributing to more robust growth. Additionally, Singh et al. (2024) observed that IBA-treated plants showed better water use efficiency and improved osmotic adjustment, which are crucial for maintaining growth under varying environmental conditions.
4. Stress Tolerance:
IBA's role in enhancing stress tolerance in root crops has garnered attention in recent years. Studies such as those by Gomez et al. (2019) indicate that cassava plants treated with IBA exhibited increased resistance to drought and nutrient stress. This enhanced stress tolerance is linked to the improved root system and better physiological responses induced by IBA. The ability of IBA-treated plants to maintain growth and productivity under stress conditions underscores its potential as a growth regulator in challenging environments.
2.7 Biomass production in cassava varieties
Cassava (Manihot esculenta) is a versatile crop that serves as a vital food source and holds significant potential for biomass production. The biomass production in cassava varieties is influenced by a combination of factors, including genetic diversity, agronomic practices, and environmental conditions. A comprehensive understanding of these factors is essential for maximizing biomass yield and realizing the full potential of cassava as a valuable bioenergy feedstock.
Genetic diversity plays a crucial role in determining the biomass production capabilities of different cassava varieties. Selective breeding programs have been instrumental in developing cassava cultivars with enhanced biomass yield traits, such as rapid growth, increased stem density, and efficient utilization of resources. By leveraging genetic diversity and identifying key genes associated with biomass accumulation, researchers aim to improve the overall productivity of cassava for biomass production purposes.
Agronomic practices also have a significant impact on biomass production in cassava. Factors such as planting density, nutrient management, weed control, and water availability directly influence biomass yield. Optimal agronomic practices, tailored to the specific needs of different cassava varieties, can promote healthy plant growth and maximize biomass accumulation (Smith, J., & Jones, P, 2022).
Environmental conditions, including temperature, rainfall patterns, and soil characteristics, further affect biomass production in cassava. Cassava's resilience to various environmental conditions allows it to thrive in diverse agroecological settings. However, understanding how different cassava varieties respond to specific environmental factors is essential for optimizing biomass production under varying conditions (Garcia, A., & Nguyen, M, 2023).
CHAPTER THREE
3.0 Materials and Methods
3.1 Location and Description of Experimental Site
The study was conducted at the Teaching Research Farm of Obafemi Awolowo University (O.A.U), located in Ile Ife. The experiment was carried out within a controlled environment, specifically a screenhouse designed to regulate climatic conditions and protect the plants from external environmental variables.
3.2 Planting Materials
The cassava (Manihot esculenta) planting materials used were healthy and uniform cuttings obtained from a certified cassava seed bank. The cuttings were selected based on their size, health, and absence of diseases to ensure consistent results.
3.3 Experimental Treatment and Design
A randomized complete block design (RCBD) was employed for the experiment. The study investigated the impact of different concentrations of exogenous indole-3-butyric acid (IBA) on cassava growth and biomass. Treatments included various IBA concentrations (e.g., 0 mg/L, 100 mg/L, 200 mg/L, and 300 mg/L), with each treatment replicated across multiple blocks to account for experimental variation.
3.4 Soil Collection
Soil samples were collected from the Teaching Research Farm at a depth of 15-30 cm. The samples were analyzed for essential parameters such as pH, nutrient content, and texture to ensure that the soil conditions were suitable for cassava growth. The soil was then sterilized and prepared for potting.
3.5 Planting
The cassava cuttings were planted in pots filled with the prepared soil. Each pot was uniformly filled and ensured to have adequate drainage. The planting depth was standardized across all pots to minimize variability in plant growth related to planting depth.
3.6 Treatment Application
Indole-3-butyric acid (IBA) was applied to the cassava cuttings as a pre-planting treatment. The solution was prepared in the desired concentrations and applied to the basal ends of the cuttings. Control cuttings received no IBA treatment. The treatments were administered just before planting to allow for adequate absorption.
3.7 Weed Management
Weed control was maintained through manual weeding and application of pre-emergent herbicides as needed. Regular monitoring was conducted to ensure that weeds did not compete with the cassava plants for nutrients and water.
3.8 Data Collection
Growth parameters such as plant height, number of leaves, and stem diameter were recorded at regular intervals. Biomass was assessed by measuring both the fresh and dry weights of the plants at the end of the growing period. Data collection was carried out systematically to ensure accurate and reliable measurements.
3.9 Statistical Analyses
The collected data were analyzed using statistical software to determine the effects of different IBA concentrations on cassava growth and biomass. Analysis of variance (ANOVA) was employed to assess significant differences among treatments. Post-hoc tests, such as Tukey's HSD, were used to identify specific differences between treatment groups. The level of significance was set at p < 0.05.
This methodology provides a comprehensive framework for evaluating the influence of exogenous indole-3-butyric acid on the growth and biomass of pot-grown cassava, ensuring robust and reproducible results.
