ANS 409 — Pasture and Range Production and Management: Lecture Note

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LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS

LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Course code: ANS 409 Course title: Pasture and Range Production and Management Course credit load: 2 Units Series 1 Adaptation and Botany of Pasture and Forage Plants Part 1.1 Adaptation of Pasture and Forage Plants • Sub-Part 1.1.1 Ecological requirements and adaptation to tropical environments • Sub-Part 1.1.2 Factors influencing adaptation (climate, soil, management) Part 1.2 Botany and Characteristics of Grasses • Sub-Part 1.2.1 Morphological features of grasses • Sub-Part 1.2.2 Growth habits and ecological roles Part 1.3 Botany and Characteristics of Legumes • Sub-Part 1.3.1 Morphological features of forage legumes • Sub-Part 1.3.2 Roles of legumes in tropical farming systems Part 1.4 Botany and Characteristics of Shrubs and Trees • Sub-Part 1.4.1 Adaptation of shrubs and tree legumes • Sub-Part 1.4.2 Importance of shrubs and trees in pasture systems Introduction Pasture and forage plants form the foundation of livestock production systems, providing the bulk of feed resources for ruminants. Their ability to adapt to different ecological conditions determines their survival, productivity, and usefulness in farming systems. Understanding their botany is equally important, as it enables us to identify species correctly, appreciate their growth habits, and manage them effectively. This Series therefore sets the stage for appreciating the diversity and resilience of pasture and forage plants in tropical environments. The aim of this Series is to introduce you to the adaptation strategies and botanical characteristics of grasses, legumes, shrubs, and trees used in pasture and forage

LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS systems. It seeks to equip you with the knowledge needed to distinguish species, recognise their ecological requirements, and appreciate their roles in animal production. We shall commence this Series by examining how pasture and forage plants adapt to tropical environments and the factors influencing their survival. Next, we will explore the botany and characteristics of grasses, focusing on their morphology and ecological roles. Following that, we will move on to forage legumes, considering their features and contributions to tropical farming systems. Finally, we will wrap up by studying shrubs and tree legumes, highlighting their adaptation and importance in pasture systems. Series Learning Outcomes Upon completing this Series, you should be able to: • SLO 1.1 define adaptation in the context of pasture and forage plants, • SLO 1.2 explain ecological requirements and factors influencing adaptation of pasture and forage species, • SLO 1.3 describe the morphological features of grasses, • SLO 1.4 analyse the growth habits and ecological roles of grasses, • SLO 1.5 describe the morphological features of forage legumes, • SLO 1.6 evaluate the roles of forage legumes in tropical farming systems, • SLO 1.7 explain the adaptation of shrubs and tree legumes, and • SLO 1.8 assess the importance of shrubs and trees in pasture systems. 1.1 Adaptation of Pasture and Forage Plants 1.1.1 Ecological requirements and adaptation to tropical environments Adaptation refers to the ability of plants to adjust and survive under specific environmental conditions. Pasture and forage plants must adapt to factors such as temperature, rainfall, soil type, and light availability in order to thrive. In tropical environments, adaptation often involves tolerance to high temperatures, seasonal rainfall patterns, and sometimes poor soils. For example, tropical grasses such as Panicum maximum are adapted to withstand high solar radiation and irregular rainfall, while legumes like Stylosanthes can tolerate acidic soils. Adaptation ensures that plants remain productive and resilient even under challenging conditions.

LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Fill in the blank: The ability of plants to adjust and survive under specific environmental conditions is called ______. Diagram showing adaptation features of tropical pasture plants (deep roots, drought tolerance, heat resistance) Figure 1.1 Adaptation features of tropical pasture plants. 1.1.2 Factors influencing adaptation (climate, soil, management) Several factors influence the adaptation of pasture and forage plants: • Climate: Includes rainfall, temperature, and humidity. Plants adapted to humid climates may not survive in arid zones. • Soil: Soil fertility, pH, and drainage affect plant growth. Some legumes thrive in acidic soils, while others require fertile, well-drained soils. • Management: Practices such as grazing intensity, fertilisation, and weed control influence how well plants adapt and persist in a pasture system. Adaptation is therefore not only a natural process but also shaped by human intervention. Farmers who manage grazing carefully and improve soil fertility can enhance the adaptation and productivity of pasture species. Fill in the blank: Soil fertility, pH, and drainage are examples of factors that influence plant ______. Table 1.1 Factors influencing adaptation of pasture and forage plants

LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Factor Description Example Climate Key atmospheric conditions, primarily rainfall (amount and distribution), temperature (extremes and average), and humidity. Tropical grasses (e.g., Panicum maximum) are well-adapted to high rainfall and high temperatures, while temperate grasses struggle in these conditions. Soil Physical and chemical properties of the soil, including fertility (nutrient content), pH (acidity/alkalinity), and drainage (water-holding capacity). Legumes (e.g., Stylosanthes) can often thrive in relatively acidic soils with low phosphorus fertility due to their nitrogen-fixing ability. Biotic Factors Living organisms in the environment, such as pests, pathogens, competing weeds, and symbiotic microorganisms. Plants develop resistance mechanisms against pests and diseases native to their adapted region, or form beneficial relationships with rhizobia bacteria for nitrogen fixation. Management Human activities influencing the plant environment, including grazing intensity, fertilization regimes, weed control, and irrigation. Improved adaptation (persistence) of a pasture stand can be achieved through controlled rotational grazing, which allows the plants adequate rest periods to recover. Pilot questions 1.1 1. What does adaptation mean in the context of pasture and forage plants? 2. Give one example of a tropical grass adapted to high solar radiation. 3. State one ecological requirement that influences plant adaptation. 4. Which soil factor can affect the adaptation of legumes? 5. How can management practices influence plant adaptation?

LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS 1.2 Botany and Characteristics of Grasses 1.2.1 Morphological features of grasses Grasses are monocotyledonous plants belonging to the family Poaceae. They are characterised by narrow leaves, hollow stems, and fibrous root systems. Their leaves usually grow in two ranks and have parallel venation. The stem, called a culm, is jointed and often hollow except at the nodes. Grasses reproduce mainly through seeds, but many species also spread vegetatively using rhizomes (underground stems) or stolons (above-ground runners). These features make grasses highly adaptable and capable of covering large areas quickly. Fill in the blank: The jointed stem of grasses, which is often hollow except at the nodes, is called a ______. Diagram showing the morphological features of grasses (culm, nodes, leaves, fibrous roots, rhizomes) Figure 1.2 Morphological features of grasses 1.2.2 Growth habits and ecological roles Grasses exhibit different growth habits, which influence their use in pasture systems. Some species are erect, while others are creeping or tufted. Creeping

LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS grasses such as Cynodon dactylon spread rapidly and provide good ground cover, while erect grasses like Panicum maximum produce tall forage suitable for cutting. The ecological roles of grasses are significant. They prevent soil erosion through their fibrous root systems, improve soil structure, and provide habitat for beneficial organisms. In pasture systems, grasses are the primary source of feed for ruminants, offering bulk energy and fibre. Fill in the blank: Grasses that spread rapidly and provide good ground cover, such as Cynodon dactylon, are described as ______ grasses. Box 1.2 Ecological roles of grasses in pasture systems Role Explanation Impact on the Ecosystem Soil Protection The dense, fibrous root system of grasses acts as a natural net, binding soil particles together and providing excellent cover against wind and water. Prevents soil erosion, especially on sloped land, and minimizes nutrient runoff into water bodies. Soil Improvement The extensive root mass adds organic matter when roots die and decompose. This activity, along with root exudates, encourages microbial growth and improves soil aggregation. Enhances soil structure, increases water infiltration, and improves the soil's capacity to hold nutrients, benefiting subsequent crops or pastures. Habitat Provision The standing canopy and ground cover create a complex microclimate and physical structure that offers shelter, food, and breeding sites for various organisms. Provides a habitat for beneficial insects (pollinators, predators), ground-dwelling birds, and vital soil fauna like earthworms. Feed Supply Grasses are the primary source of bulk energy (carbohydrates) and fiber (cellulose) for grazing ruminant livestock (cattle, sheep, goats). Sustains animal production, converting solar energy into edible biomass, and maintaining the health of the ruminant digestive system. Carbon Sequestration Grasses remove carbon dioxide ($\text{CO}_2$) from the atmosphere during photosynthesis and store it as carbon in their roots and the soil. Mitigates climate change by acting as a significant carbon sink, especially in well-managed grazing systems.

LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS

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