HORT101 Exam One Study Guide
HORT101 Exam One Study Guide HORT 101
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This 23 page Study Guide was uploaded by Mariah Rodriguez on Monday February 9, 2015. The Study Guide belongs to HORT 101 at Purdue University taught by Michael Dana in Spring2015. Since its upload, it has received 274 views. For similar materials see Fundamentals of Horticulture in Agriculture and Forestry at Purdue University.
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Date Created: 02/09/15
HORT 101 plant classification notes Classification Carl Von Linne Swedish physician father of taxonomy Classification system called quotspecies plantarumquot In this system organisms are placed into categories called taxa Kingdomgt Divisiongt Classgt Ordergt Familygt GenusgtSpeciesbroad gtnarrow Based on morphological features especially flower structure Avoid features that can vary incorporates the concept of evolution The last two taxagenus and species are the binomial system Binomial system avoids confusion that arises from use of common names L indicates authority of person who first named species Linnaeus Botanical varieties quotvar quot indicates variety lnterspecific hybrids quotxquot indicates plants result from a cross between 2 diff plants the x is never spoken just written Cultivars cultivated varieties plants within species that share common characteristics that are maintained through propagation Each name has two components Genus species epithet species Genus describes a group of similar organisms Species members of the species will interbreed and produce similar progeny Must be written in italics or underlined and first letter of genus is capitalized Advantages of system Universal Based on international convention Uses Latin a dead language that will not change Categorizing plants It is important and convenient to group plants together based on common characteristics lifecycle Annuals plants that complete their life cycle from seed to seed in one year Eg Peas and petunias Biennials plants that require all or part of two growing seasons second growing season Eg Carrots Perennials plants that persists for more than two seasons and to not die after flowering Eg Tulips daylily Poinsettia an annual flower crop or a perennial shrub Growth Habit normally applied to perennial plants Woody plants Herbaceous perennials do not have Woody structures Vines require support Deciduous plants shed leaves for part of the year usually due to cold or dryness Evergreens never without leaves Environmental adaptation Temperature Soil conditions Halophytes adapt to salty conditions Acidophytes require acid soils Metallophytes require high levels of a specific metal Water Xerophytesrequire little water Use or function Edible plants Medical plants Plants that provide materials for various industrial uses Ornamental uses The classifications are subiective they are not understood throughout the world in different languages or across cultures HORT 101 photosynthesis notes photosynthesis and respiration In order to reproduce a plant must plants need energy water nutrients and carbon for growth and development reproduction Harvest energy Plant energy sunlight autotrophic Animal energy food heterotrophic Obtain water Acquire mineral nutrients Adapt to changes in the environment Protects against pathogens and environmental conditions plants must perform all these functions in order to grow and reproduce How do plants perform these various functions They harvest solar energy through photosynthesis primarily in leaves plants acquire water and essential mineral nutrients from the soil which are functions of roots Vascular system where water nutrients and food are distributed through the plant connects roots stems leaves flowers and all other organs Reproduction occurs and flowers The plant body Composed of m such as roots stems and leaves m various tissues m different types of cells the fundamental unit of all organisms Cells Organelles structures responsible for metabolic activity in cell No matter how big the plant is it follows the same pattern The root supports the stem stem support leaves flowers Leaves Harvest energy from sun The light drives photosynthesis the most important chemical reaction on this planet Photosynthesis is a complex series of more than 50 reactions Photosynthesis carbon dioxide6C02 water6H20 gt sugarC6H1206 oxygen602 Fixed carbonsugar produced by photosynthesis Photosynthesis is divided into 2 parts 1 Light reaction conversion of energy carried by light into chemical energy dependent on light Interception of solar radiation Absorption of light by plant pigments Chloroplasts within leaf cells contain chlorophyll which absorbs energy from light Chlorophyll absorbs red and blue light in the visible spectrum green light is not absorbed by leaves it is either transmitted or selected Energy in light is used to generate oxygen from water and produce compounds that capture energy and chemical bonds 2 Calvin cycle use of chemical energy captured in the light reaction to fix carbon dioxide from the atmosphere into sugars does not require life Chemical energy captured in ATP and NADHP is used to fix carbon dioxide in the Calvin cycle CB photosynthesis when 002 is fixed into 3 carbon sugar Rubisco catalyzes this reaction This is a cycle because this series of reactions generates the five carbon substrate Important about the Calvin cycle It removes 200 billion tons of carbon dioxide from the atmosphere every year Rubisco is the most abundant protein on earth When forests are cleared some of this capacity to remove carbon dioxide from the atmosphere was lost contributing to the greenhouse of fact and likely to global warming C4 photosynthesis alternative to carbon fixation reactionsfound in plants that grow at higher temperatures and high light intensity Photosynthesis In the experiment when light increases so does photosynthesis No photosynthesis when it39s dark but still changes in oxygen and carbon dioxide Respiration when carbon dioxide increases while oxygen decreases in the dark The metabolism of organic compounds to produce energyconsidered the reverse of photosynthesis all of the organs of a plant or continue really aspiring in both the light in the dark Carbon gain photosynthesis respiration The growth of plants depends on how much carbon is retained or gained by the plant carbon gain is not constant but is influenced by light levels the stage of development and other factors Sources net suppliers of fixed carbon leaves Sinks met users of fixed carbon fruits seeds flowers roots Photosynthate sugars fixed from carbon dioxide they must be transported from sources to these sinks High photosynthesis more fixed carbon for plant growth Low rate of photosynthesis no light reduced growth When photosynthesis provides just enough sugars for respiration the plants will not grow Photosynthesis doesn39t fix enough sugars respiration the plant will die 002 accumulation in an enclosed greenhouse night the plants are respiring producing 002 The concentration of 002 increases in the greenhouse at night 002 depletion in the light 002 is consumed Ventilation restores 002 level to Ambient 002 can fall depending on light level and temperature 002 enrichment supplying additional 002 can increase growth under some conditions 002 enrichment can be used in some controlled environmentsplants in space Low 002 limited photosynthesis especially under high light conditions HORT101 Leaves and Stems Notes Leafs required features for a leaf exposed to sunlight large surface area able to exchange gases 002 in and 02 out import mineral nutrients and water export fixed carbon to quotSINKSquot control water loss resist biotic and abiotic stresses anatomical features of a leaf blade max the surface area while minimize the volume reduce distance that gases have to get through the leaf leaf structure will vary and adapt to diverse conditions and environments leaf tissues epidermis outer later of the cells has a number of different cell types covered in a waxy cuticle the wax is secreted from epidermal cells makes the leaf impermeable to waterhelps to retain water inside the leaf cells in the epidermis epidermal cells most abundant lacks chloroplasts guard cells form stomata stomata pores in the epidermis that lead to intercellular spaces within the leaf found on both upperadaxial and lowerabaxial parts of the leaf important for photosynthesisallow gas exchange 002 in and 02 out no COZno photo the stomata have to be open for photosynthesis water is lost through this stomata cant be open all the time because interior of leaf is moist and when it is open large amount of water evaporates from the leaf like when you leave your mouth open plants can control water loss because stomata opens and closes guard cells have thickened inner cell walls when guard cells are turgid stomata are open when water comes out of guard cells stomata closes when is stomata open and closed stomata open when Calvin cycle is operating closed at night most of the time conserves water theres no need for 002 exchange plant will stop fixing carbon to retain water CAM plants plants that evolve to conserve water trichomes leaf hairs cell protrusions from epidermis have protective functions stinging globular trichomes release compounds that are toxic to insects secretory hairs allow plants to secrete compounds Mesophyll Tissue spongy parenchyma cells randomly arranges airspaces allow diffusion of gases few chloroplasts designed for interception of light energy fixing 002 exchange of gases Vascular TissueVeins transport material to and from leaf import of water and nutrients into leaf export of photosynthate from leaf vascular bundles organized as bundles containing xylem and phloem Xylem distributions of water and minerals transported from root Cells are dead Phloem quotactivequot transportenergy required of fixed carbon compounds from the leaf to rest of plant Cells are alive Sclerenchyma thickened fibers that provide structural strength to the leaf leaf morphology varies between species simple leaf single leaf blade at each node compound leaves multiple leaflets describe leaves by shapemargins stem attachment Tendrils modified leaves that allow plants to vine spines and thorns protect some plants from predation some plants have other functions fly trap to capture insects an important source of nutrients Stems vary in size vary in strength soft fleshy stems of aquatic plants to tree trunks vary in longevity annual stems to long lived stems functions of plant stems provide a structure to support other organs leaves flowers fruit transport of material throughout the plant waters and minerals from root to shoot from sourceseaves to sinks roots fruits flowers Meristems Small composed of actively dividing undifferentiated cells mitosis source of new cells for the growth of any plant tissue found at various places throughout plant Apical Meristems lie near the tipsapices of shoots and roots shoot apical meristems produce stem and leaf tissues vegetative structures can switch to a floral meristem and produce flowers switch triggered by day length temp etc cells in a meristem small thin cell walls contain little or no vacuole HORT 101 Stems and Roots Notes Stems and Roots Meristems shoot apical meristems produce stem and leaf tissues vegetative structures Small composed of actively dividing undifferentiated cells mitosis source of new cells for the growth of any plant tissue found at various places throughout plant Apical Meristems lie near the tipsapices of shoots and roots can switch to a floral meristem and produce flowers switch triggered by day length temp etc cells in a meristem small thin cell walls contain little or no vacuole Tissues of the stem epidermis external layers of cells covered with a cuticle can contain stomata and trichomes in woody places replaced with a cork layer provides stronger external surface more resistant to damage protective layer functions of epidermis prevent waterloss protect against pathogens protect internal tissues Cortex layer of cells between the epidermis and vascular tissue Func ons storage organ in many woody plants sugars and proteins made in cortex during the fall provide food to support plant growth in spring Vascular tissue transport system of the plant composed of the phloem cambium and xylem exterior gt interior organization is variable a complete ring in the stem a circle of bundles bundles distributed throughout the stem Phloem normally localized towards the outside of the vascular bundle composed of two major cell types companion cells support activity in sieve tube sieve tube members does transporting but cells lack nuclei these are elongated cells tubes are connected end to end Function distribute photosynthate from leaves to the rest of plant Cambium meristem tissue thin layer of undifferentiated cells between the phloem and xylem can produce new cells for phloem or xylem after division essential for radial expansion of the stem Function to provide a source of new cells for growth of the vascular system Xylem localized towards the inside of vasc bundle required for transport of water and nutrients from roots throughout the plant xylem cells die after differentiation walls are thickened for strength before they die rings of lignin provide reinforcement contains several cell types arranged end to end where nutrients and water move tracheids long and thin primary component of soft woods pines xylem vessels short and fat fibres in xylem provide structural support and important for hardwoods Pith innermost tissue of the stem made of undifferentiated parenchyma cells can function as storage tissue may be lostreduced in many woody plants Stem Problems girdling used to deliberately improve production in some tree fruitspeach nectarine disrupts the vascular system blocks movement of water nutrients and photosynthate throughout the plant restrict plant growth may result in plant death retains more fixed carbon in the shoot for fruit development By human intervention deliberate inadvertent ties tags weed whackers By natural factors girdle roots animals insects rodents deer Stem modifications Spurs modified stems that support flowers and fruits in apple trees and some other tree fruits as well Stolons modified stems that grow horizontally along the ground and are useful for propagation 39 ROOTS Func ons anchorage of the soil absorbs water acquisition of mineral nutrients tissue for energy storage for propagation and dispersal in some species Root Morphology highly variable most plants with two seeds leaves have a primary root plants with one seed leaf typically have a more diffuse fibrous root system How extensive are roots 40ft oak tree root 14ft into the soil lateral roots radius of 60ft desert shrubs more than 100ft into the soil root system important because many plants are transplanted good transplanting depends on a vigorous and healthy root system many horticultural products are roots Growth of root system growth depends on the activity of root apical meristem located behind root cap at tip of root provides source of new cells for extension and elongation of the root Tissues of the root series of concentric rings of different tissues Epidermis single layer of cells on exterior of the root not covered with a cuticle cuticle is a barrier to water but root is designed for water uptake epidermis doesn39t contain stomata root hairs are specialized epidermal cells they contribute the largest fraction of root surface areafacilitates uptake of water Cortex compromised of large undifferentiated parenchyma cells functions in the storage of food reserves in root tissues Endodermis single layer of cells outside vascular system spaces between the cells are covered with a waxy layersuberin looks and acts like grout between tiles Caspian strip blocks simple diffusion of water and dissolved nutrients into vascular system water nutrients and other solutes can only enter the vascular system through the endodermis Pericycle thin layer of undifferentiated cells a meristem tissue source of new lateral or secondary roots Vascular Tissue Phloem Cambium Xylem Phloem living cells comprised of sieve tube elements and companion cells Cambium a meristematic tissue supplying cells that will develop into vascular structures Xylem dead cells with thickened cell walls typically larger than phloem cells functions in the transport of water and mineral nutrients Transpiration stream there is a continuum of water from the soil into the root system through the plant via the vascular system and into the atmosphere by evaporation from leaves HORT 101 Growth and Development Part 1 Manipulating plant growth 1 pruning to develop an effcient structure to bear fruit and max interception of light 2 training trained for decorative and practical reasons 3 shaping for commercial reasons Two things contribute to plant growth 1cell division source of new cells for growth of an organ or tissue 2 cell enlargement increase in volume of cell Growth of root system occurs at the tip meristem remains at the apex of the root meristem pushed through the soil by expansion of cells behind meristem primary growth growth that leads to increased height of shoots and length of roots growth occurs at the apices of organs cells in the apical meristems divide and provide cells for growth meristems contain actively dividing cells cells are smallundifferentiated thin cell walls etc they maintain their position relative to the shoot or root apex cell expansionelongation occurs behind the apical meristem cell differentiation comes after division occurs behind the meristem after differentiation cells dont normally change into another cell type and plant cells are fixed in place surrounded by rigid cell walls and glued together root capprotects apical meristem mucilage produces by root cap cells helps the root move through soil division zoneapical meristem contributes new cells for the root elongation zonecells elongatedifferenciate expansion of cells pushes root tip through soil maturization zone cells develop their final form root hairs form xylem cells thicken phloem tissue formed Branching of rootsinitiated in pericycle same idea for stem growth cell division in meristems elongation of cells differ into specific types of cells branching of shoots where do branches come from in axillary buds contain unactive meristem apical dominance growth at apex suppresses growth at lateral shoots high concentrations of auxin suppresses growth of axillary buds near the apex further from apex where auxin is lower growth of axillary buds no inhibited these buds grow into branches weak apical dominance leads to a mroe branched plant form pinching promotes branching because it removed the apical meristem source of auxin Cambium yellow cells cells divide and produce new cells for phloem or xylem essential for radial expansion of stem primary vascular tissue found in annual plants and perennials during first year of growth secondary vasc tissue found in woody perennials after first year of growth HORT 101 Growth and Development Part 2 What environmental factors affect plant growth light is there sufficient light for photosynthesis plants are able to sense and adapt to many different aspects of light environment presence or absence of light quantity of light quality of light germination is inhibited in the dark photomorphogenesis light changing growth phototropism light turn plants grow towards the light 100 years after Charles Darwin did an experiment to find out where the plants sensed light we find out that the protein that sensed this blue light is called phototropin temp water nutrients atmosphere gravity gravitropism roots are positively gravitropic they grow down root cap contains gravity sensor If the root cap is removed the root does not respond to gravity Shoots exhibit negative gravitropism grow in opposite direction of gravity force they grow up Plants are sensitive to touch many plant organs respond to touch venus fly trap mimosa tendrils on vines How do plants controls responses they must become aware of the environmental conditions signal to responsive tissue execute the responseaction plant hormones play a big part in responses Plant hormone meet the following criteria active at very low concentrations produced in one tissue endogenous organic compound transported from the site of synthesis to the tissue where it acts affects growth development and physiological responses not nutrient or vitamin Hormones Auxin controls cel elongations and expansion in phototropism and gravitropism growth of shoots towards light auxin concentrated to side of stem away from light auxin stimulates elongations of cells on that side of stem stem bends towards the light downward growth of roots due to gravity suppresses growth of axillary buds stimulates root initiation and growth fruit growth Abscisic Acid ABA stimulates closure of stomata promotes maturation and dormancy of seeds inhibits seed germination regulates many responses to adverse environmental conditions GibberellinsGA stimulates stem elongation dwarf varieties are deficient controls metabolism of stored reserves during seed germination manipulating GA height control keeping plants small increasing size of grapes by making looser bunches promotes desired elongated shape of red delicious apples Cytokinins stimulates cell division promotes shoot differentiation delays senescence of leaves Ethylene regualtes ripening of some fruits controls senescence of many flowers triggers abscission of leaves and fruits regualte shoot growth during germination manipulating ethylene application of ethrel a compund that stimulates production of ethylene flowering ripening promotes fruit drop inhibiting the production of ethylene to delay normal pysiological processes delay ripening delay flower senscence Plant growth regulators synthetic hormones hormone analogs and inhibitors control fruit set the number of fruit that develop after pollination HORT 101 Flowers Flowers Floral Induction functions of flowers for the plant reproduction allows for maintenence of genetic diversity adapt to change for hulticulturists ornamental value pleasure sales profit fruitseed production Functions of floral parts Penduncle receptacle support Calyxlsepals protection in the bud Corolla petals attract pollinators Stamens produce and distribute male gametes Pistil produce and contain ovules screen male gametes place for seed development variations on the quotidealquot a flower lacking one or more parts a flower lacking one sex or the other flower with all partsoomplete flower lacking some partinoomplete flower with both sexedperfect may not have sepals or petals but still has both sexes flower lacking one seximperfeot all imperfect flowers are incomplete if flower lacks one sex it must lack one part not all incomplete flowers are imperfect if flower lacks one part it still may have both sexes plants with imperfect flowers may have both sexes on the same plant monoecious 1quothousequot only have one sec on any single plant dioecious2quothousequot inflorescences structures that bear flowers may be determinate elongation growth stops then flowering occurs indeterminate elongation growth continues so flowers continue to grow flowering requires the change in meristemgrowing point of a stem from vegetativestemsleaves to floral flowers this change does not occur by accident it is triggered by internal or external cues why control flowering allow all members of species to flower at the same time time seed maturity before winter comes to insure plant is large enough to support flowers fruits important factors photoperiod ight intensity affects energy availability low light low carbsow energy noreduced flowering carb accumulation phloem interruption horticultural application trunck girdling 39 temp vernalization need exposure to cold temps iuvenility two stages iuvenility cannot flower even in right environment mature can flower in proper conditions can last weeks years involves plant size hormones carbs photoperiodism plants have evolved mechanisms to make use of fluctuation in daylength in the temperate regions of earth as an environmental cue for flowering not photoperiodicday neutral photoperiodic plant will only flower when the length of the say is more or less than a critical length quotShort dayquotSD plants flower when the day length is less and critical length quotLong DayquotLD is just the opposite more photoperiodic plant will only flower when length of the nightdark period is more or less than critical length quotShort dayquot plants flower when night length is more than critical length really long nights Long day is the opposite night interruption short perioud of light in the middle of the night can change a short day or long night into a long day or short night How do plants sense length of the dark period phytochrome pollination and fertilization step one flowering step two pollination 1anthesis a lot of pollen produced 2 pollination pollin transfer to a stigma within same flowerplant self pollination between differing plantscross pollination due to wind insects 3 pollen germination on stigma pollen grain hydrated on stigmatic surface pollen grain included one quottubequot nucleus that directs tube growth and one quotgenerativequot nucleus 4 growth of germ tube in ovary tube grows between and through style ces style tissue secretes compounds that influnece tube growth nuclear division quotgenerative nucleus divided as tuve grows and becomes two sperm nuclei that will fuse with diff parts of the ovule 5 fertilization step three fertilization germ tube enters embryo sack seed development triggers fruit development what can go wrong get poication but no fertilization selfincompatibility not get pollination failure of pollincationfertilization temp wind rain low population of pollinators competitions for insects from other flowers pollenizers pollen providers
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