Transcript File
Plant Growth and Development Plant Science/Horticulture I Instructor: Miss Frank Plant Tissues Vascular Bundle: A strand of tissue containing both Xylem and Phloem enclosed by a wall of cells. Xylem: Vascular tissue that carries water and minerals up from the roots to the leaves. Phloem: Vascular tissue that carries products produced by the plant to the roots. These three tissue types work together to make up the four main parts of a plant: roots, stems, leaves and flowers. ROOTS Root: part of plant that absorbs water and nutrients from the environment, stores energy for the plant and anchors plant into the ground. Root Functions A. Roots 1. Absorb water and nutrients (Note: Most of the absorption takes place through the root hairs. The rate at which water is absorbed depends on: (1) the rate at which water is lost from leaves (transpiration), (2) the amount of water in the soil, and (3) the amount of root surface in contact with soil particles. Root Functions 2. Anchor and support plant (Note: The root must anchor the plant to the extent that wind, etc. cannot knock it down.) 3. Store food (Note: Some plants store foods they have manufactured in the roots. Examples are radishes, carrots, sweet potatoes and sugarbeets.) Types of root systems Types of root systems A. Tap root system (Note: In this system, one root is larger than the rest. Examples include alfalfa, sugarbeets, beans, carrots and radishes.) B. Fibrous root system (Note: In this system, all roots are approximately the same size. Examples include all the grasses and cereal grains.) STEM Stem: Main trunk of plant that gives support and shape. Herbaceous: plants that do not produce wood. Flexible and less rigorous Woody: plants that produce wood. Constantly grow upward and outward. Xylem and Phloem grow in large rings around stem. Stem Parts Nodes: Place where a leaf is attached Internode: Part of the stem between the two nodes. Bud: An embryonic shoot of a plant Leaf Scar: A scar left when a leaf falls off Vascular Bundle Scar: A spot within a leaf scar left by the vascular bundles. STEM Parts Stem Functions Stem 1. Supports leaves, flowers, fruit and seeds 2. Conducts water, nutrients and food (Note: The stem conducts water and minerals in solution from the root system through the xylem tissue to the leaves. It also conducts food made in the leaves through the phloem tissue to the parts of the plant where it is growing or food is being stored.) 3. Stores food (Note: Examples of plants that store food in the stem include potatoes and asparagus.) Modified Stems Tuber: Stem section that stores food and bears buds for new plants. Ex: Potatoes Corms: Thick underground stem. Ex: Glads and Banana Trees Stolens/Runners: Above ground horizontally and connect plants or forms new roots. Ex: Strawberries Rhizomes: Underground horizontal stems that sends shoots upward. Ex: Bamboo, irises and lilies. Leaf Leaf: The working part of the plant. Collects sunlight, controls plant temperature and evaporation of water from the plant. Petiole: Connects the leaf to the stem Blade: Main part and shape of the leaf Veins: leaf vascular bundles Midrib: Central leaf vein Leaf Functions Leaves 1. Manufacture food for the plant (Note: Photosynthesis is the process by which leaves make food from carbon dioxide and water in the presence of sunlight.) 2. Necessary for transpiration 3. Store food (Note: Examples of plants that store food in the leaves include lettuce, cabbage, celery, rhubarb and onions.) Flower Flower: Purpose is to reproduce. Petals: Protect and Attract. Sepals: Bud leaves that make base of flower. Pistil: Female reproductive part Stamen: Male reproductive part Flower Functions Flowers 1. Serve as site of reproduction 2. Store food (Note: Examples of plants that store food in flowers include grains, fruits, nuts, berries, broccoli and cauliflower.) Seed A flowering plant’s unit of reproduction Epicotyl: Part of the embryo that becomes the leaves. Cotyledon: Embryonic leaf. Develops a plants first leaves. Seed Coat: Protective outer coat of a seed Radicle: Part of the embryo that develops into primary root. Hypocotyl: Part of the embryo that becomes the stem. Bean Seed Cross section Plant Structures Monocots: One seed leaf Dicots: Two seed leaves (two Cotyledons) Growth Cycle Annuals: Plant completes its growing cycle in one growing season. Biennials: Plant completes its growing season in two growing seasons. Perennials: Plants that grow for several growing seasons. Germination of Seeds What looks dead, will become a new plant. Germinate: to sprout. Baby plant that emerges from seed Four Environmental factors that effect germination: Water: Adequate water is needed to start the process and keep the baby plant alive. Light: Will inhibit or stimulate germination. Oxygen: All seeds have to breath. Heat: Warmth is needed for germination. Germination in Dicots The primary root emerges through the seed coats while the seed is still buried in the soil. The hypocotyl emerges from the seed coats and pushes its way up through the soil. It is bent in a hairpin shape - the hypocotyl arch - as it grows up. The two cotyledons protect the epicotyl structures - the plumule - from mechanical damage. Once the hypocotyl arch emerges from the soil, it straightens out. This response is triggered by light. The cotyledons spread apart exposing the epicotyl, consisting of two primary leaves and the apical meristem In many dicots, the cotyledons not only supply their food stores to the developing plant but also turn green and make more food by photosynthesis until they drop off. Germination in Dicots Germination in Monocots When grass seeds, e.g. corn (maize) or oats (shown here), germinate the primary root pierces the seed (and fruit) coverings and grows down; the primary leaf of the plant grows up. It is protected as it pushes up through the soil by the coleoptile - a hollow, cylindrical structure. Once the seedling has grown above the surface, the coleoptile stops growing and the primary leaf pierces it. Corn Germination Steps How Much N-P-K is there? Using the previous fertilizer label as a tool what are the percentages of N-P-K? N=20% P=10% K=20% If this is a 50 pound bag of fertilizer how many pounds of N-P-K are there in the bag? How do you know? 50lbs X .20 = 10lbs of Nitrogen 50lbs X .10 = 5lbs of Phosphorus 50lbs X .20 = 10lbs of Potassium How much do you apply? Time for some simple math… You have a corn field that needs some food. You determine that you need 120lbs of Nitrogen and 65lbs of Phosphorus. You have two fertilizers available for use 12-18-8 46-0-0 How do you know how much of each to apply to meet your needs? This is how it works First let’s figure out how much fertilizer to apply to meet our Phosphorus needs. Formula: Rate Required =Pounds of Fert % of Nutrient needed 65lbs P =361 pounds of fertilizer .18 REMEMBER THE DECIMAL!! How much Nitrogen have you applied in your 361 pounds? How do you know? Formula: Pounds applied X % of Nutrient So: 361 X .12 = 43.12 (round to 43) With you required phosphorus application you also applied 43 pounds of the required Nitrogen. You still need 77 pounds of nitrogen to meet the N requirement. 77lbs of N = 167 pounds of fertilizer .46 Types of flowers A. Complete--Has stamens, pistils, petals and sepals on same flower; common to dicots B. Incomplete--Has stamens and pistils, but no petals or sepals; common to monocots Parts of a complete flower Pistil--Female part where egg cell originates 1. Stigma--Upper part of pistil that catches pollen 2. Style--Supports stigma 3. Ovary--Produces ovules which develop into seeds Parts of a complete flower Stamen--Male part of flower 1. Filament--Supports anther 2. Anther--Bears the pollen Parts of a complete flower Accessory organs 1. Corolla--Petals of the flower 2. Calyx--Sepals of the flower 3. Pedicel--Stalk of an individual flower Types of flowers Perfect flower--Has both stamens and pistils on the same flower Imperfect flower--Has either stamens or pistils, but not both on the same flower Staminate--Has only male flower parts Pistillate--Has only female flower parts Types of pollination A. Self-pollination--Transfer of pollen from the anthers to the stigma of the same flower on the same plant B. Cross-pollination--Transfer of pollen from the anthers of one plant to the stigmas of another plant (Note: Cross-pollination usually requires an insect or bee to transfer the pollen from one plant to the other.) Pollen is moved by A. B. C. D. E. Gravity Wind Insects Birds Man Fertilization After a pollen grain alights on the surface of the stigma, it forms a pollen tube. The pollen tube grows down the style to the ovary. It penetrates the ovary and the male cell unites with the ovule. This is called fertilization, the union of the male and female cells. The result is a zygote. Cell division takes place and the zygote becomes the embryo of the seed