Lesson 3.ppt

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1、Plants and Environmental FactorsLesson 3MAIN ROOTMAIN ROOTLATERALLATERALOR SIDE OR SIDE ROOTROOTROOT ROOT SYSTEMSYSTEMLEAFLEAFSTEMSTEMFLOWERFLOWERFRUITFRUITNODENODENODENODENODENODEINTER-INTER-NODENODETERMINAL BUDTERMINAL BUDAXILLARYAXILLARYBUDBUDSHOOTSHOOTSYSTEMSYSTEMWhat are the structural differen

2、ces between dicot and monocot stems? Monocots One seed leaf Parallel veins in leaf Xylem and phloem found in bundles in stem Dicots Produce two seed leaves Branched leaf vein system Xylem and phloem cells located in separate areas of the stemWhat are the functions of roots? Whitish or tan in color M

3、ake up one-half or more of the entire plant body Absorb water and nutrients from the soil then transport them above ground Serve to anchor and support the top portion on plant Can store carbohydrates to be used later for energy by plantWhat are the parts of a root system? Primary root- first structu

4、re to emerge from germinating seed Secondary root- arises from the primary root Dont transplant seedlings or cuttings until after secondary root forms Root hairs- single cell roots located a few mm back from root tip, absorb water Root cap- mass of cells that protects root tips from coarse soilWhat

5、are the differences between taproot and fibrous root systems? Taproot One large primary root that grows down + small secondary roots Fibrous root Root develops into a number of small primary and secondary roots Grow shallow near the soil line Subjected to drought and mineral deficiencies Most landsc

6、ape plantsWhat are modified roots? Adventitious roots (不定根不定根) Begin growing from stem or leaf Grow from cuttings after being placed in growing medium Plant attaches itself totree branch or telephone wireRoots hang down in mid-air and absorb water from rainfallBanyan tree（印度榕树）（印度榕树） Schefflera bons

7、ai （鹅掌藤）（鹅掌藤）Examples : Wild Pine; Some OrchidsPROPROOTSe.g.CornSTILT（支柱）（支柱）ROOTSe.g.Mangrove红树红树Aerating root（呼吸根，通气根）Flower Where are the reproductive structures of plants and how do they work?Sepals- green leaf-like structures under the petalsPetals- brightly colored structures on flower used to

8、 attract pollinatorsStamens- male reproductive parts containing filament and anther surrounding female parts Filament-stalk that supports anther Anther- produces pollen or male sex cellsPistils- female reproductive parts containing stigma, style, and ovary Stigma- sticky surface for capturing pollen

9、 at top of styles Style- tube-like structure that connects stigma and ovary Ovary- contains ovules or eggsThe structure of flowersPollen grains How do we get seeds? Pollination- occurs when pollen grains are transferred from anther to stigma By birds, insects, bats, animals, wind Self pollination- p

10、ollen pollinates flower on same plant Cross pollination- pollen from flowers on one plant transfer to flowers on different plant Hybrid- offspring from cross-pollinating two different varieties of a species Fertilization- one sperm nucleus fuses with egg cell nucleusDouble fertilizationAngiosperm Li

11、fe cycle from seed to seedWhat are the types of flowers? Complete flower- has all four major parts (sepals, petals, stamens, pistils) ex. Apple, lily, pea Incomplete flowers- lack one or more major parts Perfect flowers- have both stamens and pistils Imperfect flowers- lacks either stamen or pistils

12、, ex. Corn, squashRue-anemone flowers lack petals, but the sepals are petal-like. Thalictrum thalictroides What are the two types of fruit? Fruit- seed-bearing organ Fleshy fruit- composed of a soft and fleshy material with seed or seeds enclosed Ex. Blueberry, peach, tomato, watermelon Dry fruit- c

13、onsists of seed enclosed in a fruit wall that is hard and brittle when mature Ex. Pea, oak, elmacornWhat are the parts of a seed? Seeds- mature, fertilized eggs contained in the fruit Seed embryo- root, stem, & one or two seed leaves called cotyledons Monocots- one cotyledon Dicots- two cotyledon En

14、dosperm- contains stored food for seed Seed coat- tissue surrounding embryo and endosperm to protect seed from moisture loss, injuryDiagram of the internal structure of a dicot seed and embryo: (a) seed coat, (b) endosperm, (c) cotyledon, (d) hypocotylThe inside of a Ginkgo seedHow do we go from see

15、d to plant? Germination- seed embryo goes from dormant state to active growing state Seed absorbs water and swells Primary root develops and emerges Stem or shoot emergesPlant Growth EnvironmentClimate & plant growth Climate average weather of an area Air, Moisture, Temperature, LightRegional climat

16、e vs. microclimateAir Humidity Wind Air pollution Elevation (temperature)Air and elevationMoisture and plant growth Amount Distribution patterns Access (location) Bodies of water and climate Moisture stress Deficiency, excessGrowth responses to temperature Vernalization Period of low temperature ind

17、uces flowering (e.g. “forcing” bulbs) Thermoperiodism Sugar/starch content varies with temperature (cooler temps promote starch conversion to sugars); some plants grow better if night temperatures are cooler than day temperaturesTemperature and germination Stratification Period of cold required to i

18、nduce germination Required by many types of perennials, woody species Specific temp. and length of stratification varies by speciesTemperature stress Low temperature stress Chilling Freezing Premature bolting Cold water stressPreventing low temp. stress Timing of planting Zone rating of species Prot

19、ective measures Covers Mounding mulch, soil Hardening (cold frame)Heat stress Sunscald Plant relocationLight Intensity Quality DaylengthPhotoperiodism Growth responses to daylength Flowering, germination, dormancy Mediated by pigment molecule phytochromePhytochrome and floweringManipulation of photo

20、period Poinsettia industry Chrysanthemums Why wont my Christmas cactus bloom?Photoperiodic houseplantsCommon nameGardenia Strawberry begoniaSpider plantBotanical namePhotoperiodic classificationRemarks Phytochrome and stem growthEtiolation occurs in low light or darkwhy?Biotic environmental factors

21、Insects MicroorganismsMedia, Nutrients, and FertilizersWhy is growing media important? Growing medium- material where plants grow Media Provides nutrients by absorption through roots Anchors plants Contains pore spaces which provide oxygen for roots Provides favorable environment for microorganismsW

22、hat are the different types of growing media? Soil Thin layer of earths curst that provides for growth of plants Soilless medium Contains no topsoil Usually made of:Vermiculite Heat treated mica Holds moisturePerlite Volcanic material Provides drainage and aeration Sterilized organic compoundsLoosen

23、 the mediumCreate larger air spaces between the particlesInclude:Peat MossSphagnum MossLeaf MoldBark Hydroponics- growing plants in a nutrient solution consisting of water and dissolved nutrient salts Advantages Complete control of nutrient solution Greater yield per unit area through closer spacing

24、 of plants Less spreading of roots Reduced need for control of weeds, disease, and insects due to absence of soil Hydroponic systems are classified according to substrate systems Substrate systems Sand culture- plants grown in sterilized sand with individual drip irrigation Gravel culture- involves

25、irrigating plants grown in gravel for mechanical support Bag culture- uses plastic bags that are filled with substrate, such as rockwool, peat-lite, and sawdust. Drip irrigation used to supply nutrient solution Bare root systems: Aeroponic system Involves plant roots suspended in air with a fine mis

26、t of oxygen-rich nutrient solution sprayed on them a regular intervals Continuous flow system Involves using shallow pools with panels containing plants floating on the surface Nutrient film technique (NFT) Involves using a recirculating, shallow stream of nutrient solution that moves through channe

27、ls in which the plants grow. The roots are usually covered with a plastic sheetWhat are the contents of soil? Mineral matter Formed from inorganic sources, such as rocks and minerals Organic matter Decayed or partially decayed plant and animal matter; high in nutrients Water AirKinds of mineral matt

28、er Sand Large particle Assists in drainage but may not hold enough moisture for plants Silt (泥沙泥沙) Medium-sized particle Preferred mineral component in most situations Clay (粘土粘土) Smallest particle Holds water and keeps soil moist May be too slow to dry and may be too compactWhat is the structure of

29、 soil? Soil texture Coarseness or fineness of soil particles Affect many properties of the soil and its usefulness Medium-textured soil is most preferred Soil structure Physical arrangement of soil particles Contributes to aeration or the movement of air into the soil Soil profile Vertical cross-sec

30、tion of the soil at a particular location Makes visible the different layers of soil referred to as horizons O horizon- Organic matter: Litter layer of plant residues in relatively undecomposed form, 2”. A horizon- topsoil; humus, roots, organisms, 10” B horizon- subsoil; fine particles, leached mat

31、erials, some roots, 30” C horizon- parent material; weathered bedrock and some leached materials, 48” R horizon- bedrock; underlying solid rock What are the nutrients needed for plant growth? Macronutrients MicronutrientsMacronutrients Primary- nutrients needed in large amounts N- nitrogen P- phosph

32、orus K- Potassium Secondary- nutrients needed in small amounts Ca- calcium Mg- Magnesium S- sulfurMicronutrients Nutrients needed in very small amounts B- boron Cu- copper Cl- chlorine Fe- iron Mn- Manganese Mo- Molybdenum Zn- ZincSoil test Used to determine which nutrients are present in the soil a

33、nd to what degree Important to determine the availability of nutrients Shows you what nutrients are deficient and the kinds and amounts of fertilizer needed to replenish the nutrients Primary Nutrients Nitrogen Determines greenness color and density in plant Needed for chlorophyll, which is needed f

34、or photosynthesis Improves plants ability to resist disease and tolerate effects of heat, cold, and drought Deficiency symptom: yellowing of leaves called chlorosis Phosphorus Helps plants hold and transfer energy for metabolism Affects cell division, root development, and flowering Deficiency sympt

35、om: purple coloring of leaves or stems Potassium Activates enzymes Regulates opening and closing of stomata Regulates water uptake by root cells Deficiency symptom: brown scorching and curling of leaf tips as well as chlorosis (yellowing) between leaf veins; Purple spots may also appear on the leaf

36、undersides.What is pH? pH- measure of amount of alkalinity or acidity in soil pH scale 1 to 14 1 is extremely acidic 14 is extremely alkaline 7 is neutral pH affects the availability of nutrients to plantsHow is pH modified? pH can be lowered or elevated depending on present conditions of the soil a

37、nd the pH requirements of the plant crop To lower pH- add sulfur To increase pH- add limestone Most plants require a pH of 5.5 to 8.0What is fertilization and fertilizer? Fertilizer- any material used to provide nutrients plants need Fertilization- cultural practice of adding plant nutrients to the

38、soil or other growing mediaFertilizers Complete fertilizers- those containing all three primary nutrients (N, P, K) Incomplete fertilizers- lacks one or more primary nutrients Active ingredient- total percentage of nutrients being applied Inert ingredient- carrier of filler ingredientFertilizer Anal

39、ysis The composition of active ingredients in a fertilizer formulation A fertilizer with an analysis of 16-4-8 has an analysis of: 16% Nitrogen 4% Phosphate 8% Potash 72% Inert materialWhat is the association between soils and nutrients? Leaching Downward pulling of nutrients through the soil by per

40、colating water (渗滤水) Available nitrogen Affected by pH and amount and form of nitrogen present N is lost by leaching, removal of plat material, gaseous loss by volatilization of ammonia, and denitrification (脱硝作用) Available phosphorus Affected by pH and generally immobile in soil May be tied up in i

41、nsoluble forms Available potassium Affected by pH and is readily soluble in water Leaching losses can be high in sandy soilsHow is fertilizer used? Apply fertilizer so that you dont waste it Apply fertilizer when the plants can best use the nutrients Apply small amounts of fertilizer frequently Be c

42、areful not to over fertilizeForms of Fertilizer LiquidApply with a sprayer Granular Apply with a spreader FertigationApplication of fertilizers through an irrigation systemQuestions What are the structural differences between dicot and monocot stems? What are the differences between taproot and fibr

43、ous root systems? Where are the reproductive structures of plants and how do they work? What are the two types of fruits? What is Vernalization and Photoperiodism?Questions What are the different types of growing media? What are the contents and structure of soil? What nutrients are needed for plant growth? What is pH and how is it modified? What is fertilization and fertilizer? What is the association between soils and nutrients?