Transcript File
How plants live, work, play and reproduce. • Four Life Processes • Respiration • Breathing • Photosynthesis • Food Production • Transpiration • Plant Sweat • Reproduction • Making Babies • A series of processes in which light energy is converted to a simple sugar. • The MOST IMPORTANT life-sustaining plant process. • This complex chemical process permits both plants and animals to live and support each other. • Chlorophyll: the green material insides the leaves and stems of plants. • Essential to the process of photosynthesis. • The substance that gives plants their green color. • Chloroplasts: small, membrane bound bodies inside cells that contain the green chlorophyll pigments. • Located in the mesophyll of the leaf. (Mesophyll: tissue of the leaf where photosynthesis occurs.) • Site of actual conversion of solar energy into light energy. • The conversion of carbon dioxide and water in the presence of light and chlorophyll into glucose, oxygen and water. • Glucose: a simple sugar that contains the building blocks for other nutrients. • The rate of food processing depends on light intensity, temperature and concentration of carbon dioxide in the atmosphere. • Light intensity or brightness of light is about the quality of light • Light must be present with sufficient brightness • Must understand the specific light needs of plants to be successful • Photosynthesis best happen as temps between 65* to 85* • Extreme temps may slow down or completely slow down the process • Lack of carbon dioxide will effect the process • CO2 is very important, especially in the beginning of the process • Only a real concern in enclosed areas. • Can be created by a carbon dioxide generator • All living cells carry on respiration (breathing) • Respiration: process by which living cells take in oxygen and give off carbon dioxide. • Breathing happens both day and night • A breaking down process • Uses the sugars and starches produced by photosynthesis, converting them into energy. • Water saturates all the spaces between cells in the plant. • Only 10% of water in a plant is used in chemical processes and in the plant tissue for plant development • Functions of water in a plant • • • • Transport minerals throughout plant Cooling the plant Moving sugars and plant chemicals Maintaining turgor pressure • Turgor: swollen or stiffened condition in stems and leaves due to plant cells being filled with water. • When turgor pressure is lost, plant wilts • Transpiration: the process in which a plant gives up water vapor to the atmosphere. • Gasses must be exchanged for photosynthesis to occur • Water vapor must exit the plant to draw dissolved nutrients into the roots. • Both of these things occur through the stomas. (Plant pores) • Stomas are surrounded by guard cells which control the size of the openings in the surface of the leaf. • During Transpiration: • The stoma open to allow water vapor and air to be exchanged • Most plants transpire (sweat) about 90% of water brought in by roots • Transpiration is influenced by: • Humidity • Humidity increases=transpiration decreases • Humidity decreases=transpiration increases • Temperature • Temperature increases=transpiration increases • Wind • Increased air movement=transpiration increases • Productive soil provides air, water and nutrients for plants. • Osmosis: water moves from an area of high concentration to an area of low concentration. • Root hairs move water and nutrients into the plant through osmosis • The skin layer of the root hairs are covered with semipermeable membrane • Certain substances travel into the roots while others do not • Water, minerals and nutrients are allowed into the plant Water: the right amount is essential for plant growth. Air: Carbon dioxide is as important as oxygen. • Propagation: the process of increasing the numbers of a species. • Sexual Reproduction: the union of an ovule (egg) and pollen (sperm) to create an egg. • Involves floral parts of one or two plants. • Quickest way of plant propagation • Only way to provide new varieties • Good way to avoid plant diseases • Asexual Reproduction: Part or parts of only one parent plant. • Parent plant produces a duplicate of itself (exact copy) • Known as Vegetative Propagation • Uses the vegetative parts of a plant: stem, root or leaf • Hybrid Vigor: tendency of hybrid plants to be stronger and survive better than plants of a pure variety. • Seed: • Seed Coat • The protector of the seed • Can be thin and soft or hard and impervious • Endosperm • Functions as food reserve • Supplies the new plant with food for a few days • Embryo • The young plant • Once a seed is fertilized and mature it goes dormant • Good plants are based on quality seed • Most of today’s plants are the result of hybridization • Plants made from cross pollination • Cost more • More • Seeds collected from plants are NOT ideal • Seeds are often small • Improper storage and handling • Environmental Conditions must be right • • • • Water Air Light Temperature • Water • Imbibition-adsorption of water • Dormant seeds contain little water • Water must be absorbed to fill all seed cells with water • For germination, soil cannot be too wet or too dry • Some seeds need to be scarified • Nick the seed with a knife or file • Soak seeds in sulfuric acid • Soak in hot water till water cools • Air • Respiration (breathing) is always taking place in viable seeds • Even in dormancy seeds need oxygen, just less • If oxygen is limited during germination, germination will be reduced or inhibited. • Light • • • • Some seeds need light to germinate Some seeds are inhibited by the presence of light Many crops do not require light for germination Ornamental bedding plants require light • Temperature • • • • Germination rate is determined by favorable ambient temps Some seeds are picky about heat and others not so much Crops have a specific time frame to be planted Many ornamental plants have zones to be planted in • Use of the vegetative part of plant. Primary methods are cuttings, layering division, grafting and tissue culture. Cuttings: vegetative plant parts that are used to generate new plants Types of cuttings are named for the parts of the plant from which they are obtained. Stem tip cuttings Stem cuttings Cane cuttings Leaf Cuttings Leaf Petiole Cuttings Root Cuttings • Cuttings are simple with knowledge and proper tools • A sharp knife or razor blade • This protects the parent plant from damage • Cutting tools should be immersed in bleach water • Or rubbing alcohol to keep diseases from spreading • Flowers and flower buds should be removed • This allows for plant energy to be diverted to new plant growth • Rooting hormone: A chemical that will react with the newly formed cells and encourage the plant to develop roots faster. • Use a rooting hormone mixed with a fungicide to stimulate new root growth. • Use the correct medium for new cuttings: soil, coarse sand, perlite, vermiculite or a mixture of peat and perlite. • Rooting material must be sterile and well drained but be able to retain moisture. • • • • • • Must be watered in small frequent amounts Wet cutting before placing in moist Stem and leaf cuttings do best in light Root cuttings do best in dark until new roots form For most plants, stem cuttings are most popular Different plants need to be used at different times • Stem Tip Cuttings • Normally includes the terminal bud • Piece of stem 2-4 inches long at the end of the stem or branch • At least one node should be paced below the rooting medium • Lower leaves must be removed • Stem Section Cuttings: Cuttings taken from behind the tip cutting. • • • • Cutting should be 2-4 inches long Lower leaves must be removed Cuttings made just beyond nodes on both ends Treat as tip cutting • Heel Cutting • This is used with woody plants • Cutting is placed horizontally • Single-eye Cuttings • Used with alternate leaf plants • Cut below and above single node • Double-eye Cuttings • Used on plants with opposite leaves • Cut above and below single node • Leaf Cuttings • A cutting made from a leaf with a petiole cut to less than ½ inch • Cut leaf from plant, dip into rooting hormone • New plants will form at base • Leaf Petiole Cuttings • Petiole is over ½ inch long • New plants form at base • Leave original cutting to form more plants • Leaf Section Cuttings • Used with Begonias-leaves cut into sections containing a vein • New plants will form from vein • Remove new plants as soon as roots develop Root Cuttings Best used with plants older then two years. Should only be done in the plant’s dormant stage. If plant has large roots: Root section should be 4-6 inches long. Should be stored for 2-3 weeks in moist peat moss or sand at a temp of 40* Then placed in medium. For smaller roots: Root section should be 1-2 inches long This cutting is placed horizontally about ½ inch below the medium’s surface • Layering • Most plants develop roots where the plant is in contact with the media while still attached to the parent plant. • After roots form, shoots will develop from same spot • Advantages, less water stress and enough energy for new plant formation • Simple Layering • Bend stem to ground and cover with medium. • Wound the lower side of stem • Last several inches exposed to sun • Tip Layering • Raspberries and Blackberries • Hole made in medium and tip placed in hole and covered • Plant will grow down and then up to surface • Roots will form at bend • When tip appears above surface of medium it is ready to transplant • Remove new plant from parent plant • Air Layering • A thick trunk is scored about one inch • The bark is removed from scored area • Dust the entire wound with rooting hormone and pack with damp sphagnum moss. • Plastic wrap the entire trunk and wound and tie at both ends • Few weeks, roots will show through moss • Cut stem below root ball • Division • Some plants can simple be divided • If plants have root crowns-crowns are simply pulled apart • If plants come from bulbs, separate newly formed plant parts • Grafting • Procedure for joining two plants to produce one plant. • Grafting allows for unusual plant pairings • One apple tree can produce several varieties of apples • Dwarf varieties are made this way • How it works • Top part is called the scion • Second part is the rootstock • The graft union is where two parts meet • Following Conditions must be met: • • • • Scion and rootstock must be compatible Same stage of growth Living layer of pieces must touch Graft union must be kept moist • Many types of grafts • Whip or Tongue Bark • Cleft Bridge • Bud • Bud Grafting • Easiest, fastest and strongest grafting method • A small piece of bark with bud attached joined to rootstock • Cut T shaped cut into bark of rootstock • Small shield piece of bark, bud and living wood • Insert shield into T cut • Leaving the bud exposed, wrap rubber band around rootstock • After bud starts growing stem is cut off above the bud • • • • • • Also called micropropagation A small actively growing part of the plant is used Many new plantlets can be formed from a section of a leaf Requires an Aseptic (sterile) atmosphere This work can only be done in a lab Biggest advantage is that large numbers of new plants can be grown from a single disease free plant. • Propagation is efficient and cost effective • Disadvantage is that the equipment and labs are expensive • Material needed: • • • • Clean sterile area Multiplication medium Sterile Glassware Scalpel, razor, X-acto Knife Clean plant tissue Transplanting medium Sterile tools Tweezers