Plant Stresses PDF

Plant Stresses www.usask.ca Plant Stresses § What is plant stress? _____________________________________________ anything that prevents plant from growing to its full a potential Plant stress responses describe the characteristic...

Plant Stresses www.usask.ca Plant Stresses § What is plant stress? _____________________________________________ anything that prevents plant from growing to its full a potential Plant stress responses describe the characteristics that. § are observed when the plant detects some form of stress. Not all plants respond to all stresses in the same manner. Understanding a plant’s response to stress is an important and challenging topic in plant research. ABIOTIC PLANT STRESS Abiotic Plant Stress § Abiotic plant stress is caused by ______________________________ non-living thing/factor § Examples include: cold neat > - nutrient NPK S selt content Stress Caused by Salts § Salts in soils deprive plants of water and dissolved nutrients. § Plant roots have a _________ IOW water concentration which attracts water into the plant through osmosis. § Dissolved salts in the soil increase the osmotic pressure of the soil solution and less water from the soil will enter the roots. If the soil solution becomes too concentrated the plants will die, even though the supply of water and dissolved nutrients in the soil may be adequate. Salt Stress lots of salt ↓ Low Temperature § Lower temperatures will result in slow plant growth and development. However, every plant has an optimum temperature range at which it grows. § When temperatures go below 0 oC, then ____________ freezing damage can occur. The water within the cell will form into ice crystals and when the temperatures rise and the ice melts, the cell contents leak out, killing the cell. § Plant tissues that freeze generally appear dark green and water soaked at first, later becoming blackened and necrotic. In dry conditions, the tissue may appear white as the water from the broken cells evaporates. Frost Damage Frost Damaged Canola no water left - L don't want seed to stay green. stays when frost damage happens. Low Temperature § Perennial species will undergo change to become ________________ d or mant for the winter. § However, these perennial species can still be damaged by low temperature. Winter Burn § Is particularly noticeable in ______________ evergreen species. § Winter burn (also called winter desiccation) injury occurs when the absorption of water by the roots cannot keep up with the amount of moisture lost by the foliage (transpiration). § This occurs mostly on sunny days, especially when it is windy and when the soil water is frozen and the plant cannot absorb it, or if water is in short supply. § Injury appears as brown leaf margins or needle tips at the onset of the first period of warm weather. Winter Burn > - SPRUCE gets this in drought years. High Temperature § High temperatures can also damage plant tissue. However, every plant has an optimum temperature range at which it grows. § If the temperature becomes very high, the cell proteins _______________ coagulate and the plant cell dies. Wilting § During warm weather, if the plants are unable to take up moisture, they will wilt and eventually die because the __________________________ Net Assimilation Rate is negative. The respiration exceeds photosynthesis. § To cope with the loss of moisture from the leaves, the stomata will close. This results in the plant not being able to perform photosynthesis. INTERNAL LEAF STRUCTURE Stomata § Are openings in plant that allow for movement of __________________. gases - CO2 O2 H2 , , § Vaporized water leaves through stomata and carbon dioxide enters. § Stomata (of most plants) are open during the _____________(to & DX get carbon dioxide used for photosynthesis) and closed at _______________. night Guard Cells § Guard cells are: present in ___________ pairs in the _____________________ epidermis (skin) of a plant. Most are on the underside of the leaves. Can also be present in stems, petals, etc. but not the roots. the cells that surround the ___________________ Stomata and open and close them. Guard Cells chioroplast - STOMATA GARD CELLS Cuticle of leaf under microscope Turgor Pressure § If conditions are hot/windy the plant will be water stressed and wilted. § If the plant is wilted, water pressure is low and the guard cells will then be _______________________ closed § The guard cells respond to _____________________ turgor pressure (water pressure) to regulate the opening. § This is good, because the plant doesn’t want to lose the little water it has. Wilting Internal Leaf Structure not cells § ____________________ cuticle - just material is the outer surface of the leaf. There may be a _______________ waXX cuticle to reduce moisture loss. Thickness of cuticle varies among plants and can be effected by the environment. Hotter it is, the thicker the cuticle the plant will develop. This can change the activity of some herbicides. Leaf Anatomy Trichomes § Trichomes are _________________ hairs § Trichomes may be either unicellular or multicellular. § Trichomes function to: reduce water loss by evaporation by trapping water vapor and increasing humidity by limiting air movement around the leaf. reflect solar radiation to keep the plant cooler. Some trichomes are glandular and release compounds that prevent herbivory. Some species have modified trichomes that secret salt (called salt glands) that allow the plant to survive in saline conditions.  WIND Trichomes ↑ sont white to reflect tiny little sunlight hairs BIOTIC PLANT STRESS What is a biotic stress? caused by living organisms. Weeds § A weed is defined as any plant that is growing in a place that it is not _____________________. wanted § Include the weedy species (plants with no use to humans), volunteer crops and ornamentals that have escaped. What plant is this? purple loose strife I's Wetlands > - Why are weeds a problem in an agricultural system? 1. Compete for light, water, nutrients 2. Contaminate crop 3. Cause quality downgrading 4. Can kill you or your animals. 5. 1, 2 and 3 6. All of the above Yield Loss § This loss is due to weeds competing for the essential of plant growth. compete for __________________________________ water , sun and nutrients , Canada Thistle (Cirsium arvense) Wild Oats (Avena fatua) Yield Loss Yield Loss of Canola due to Canada Thistle Which is the worse weed in canola Yield Loss of Canola due to Wild Oats based on plants per square metre? Contamination § When weed seeds are __________________ inseparable from the crop seed, they lower the grade and value of the grain. make the grain unsuitable for certain uses. For example, wild mustard seed is similar in size and shape to canola seed and is impossible to separate by conventional methods. As low as 20 plants per square metre in canola may result in wild mustard accounting for up to 5% of the harvested seed (the maximum tolerance of wild mustard in any grade of canola). http://www.gov.mb.ca/agriculture/crop s/weeds/images/fab18s00g.jpg Contamination: wild mustard (Sinapis arvensis) Harvest Losses § This may occur if the weeds are so thick that harvesting is difficult. Slower operation. Cost of control. _____________________ Earth + ap is exasperated by green weeds and reduces quality. Ear + h + ag > birt stuck to seed -. Harvest Losses: kochia (Bassia scoparia) Toxic Weeds § Some weeds are toxic to animals and people. _____________________________________ Death cam as All parts of this plant contain the poisonous alkaloid zygadenine, which some claim to be more potent than strychnine. One bulb, raw or cooked, can be fatal. The lethal dose is estimated at between 2.0-6.0% of animal body weight. Flowers have been reported as poisonous. _____________________________________ water hemlock The toxins are concentrated in the chambered rootstock but also occur in the leaves and stems as well. A consumption of 0.1% of body weight of the green material (leaves and stems) is lethal. The oil in a single bulb is enough to kill a 1600 pound cow (or horse) in 15 minutes. poison in Europe (even Socrates died by drinking poison of this plant). Toxic Weeds Water hemlock (Cicuta douglasii) Death camas (Toxicoscordion venenosum) Toxic Plants: rhubarb (Rheum rhabarbarum) leaves Rhubarb Leaves § Rhubarb leaves contain poisonous substances including oxalic acid and glycosides. § Consuming too much oxalic acid can be fatal, although death from it is incredibly rare as you would have to eat a very large amount of rhubarb leaves for death to become a threat. Why are weeds a problem? § Weeds are hard to control because they are very suited to their environment: vigorous growth habits, competitive adapted to wide range of environments quick life cycle and ________________________ tons of seeds special dispersal mechanisms effective________________ dormancy mechanisms Specialized Stems § Modified stems are common. § These structures are often involved in _________________________________________ Vegetative reproduction § Allows weeds to be very __________________ persistent § Can also be a good food source for humans. pOtatO's · Rhizomes Rhizomes § Rhizomes are horizontal _____________________________________ underground stems. § Serve as over-wintering organs and a method of vegetative propagation. § These stems produce shoots and roots at nodes that grow into a new plant. And while establishing itself it gets nutrients from the parent plant. § For example · Canada Thistle · purple 100se strife Seed Distribution § Many weedy species are effective at dispersing their seed. § Dandelion Has a pappus that is adapted for __________________________ wind dispersal Adaptations for Distribution PAPPUS Adaptations for Distribution § Seeds and fruits are the plants way to propagate themselves. § They can be distributed in several ways: __________________________ wind winged fruits (maple) parachute fruit (dandelion), or entire plant (Russian thistle) are designed to move with the wind. ___________________________ water designed to be carried in water (coconut). ___________________________ animals attach to animals and move to new site by the use of barbs (bluebur). Adaptations for Distribution SEEDS little hooks · to a ++ ach Infectious Plant Diseases www.usask.ca Infectious Plant Disease § Another biotic stress is plant disease that is spread from plant to plant and caused by a living agent (pathogen). § The majority are extremely infectious and difficult to control. Infectious Plant Diseases § The disease cycle is broken in to a number of stages: ________________________________ inoculation period when pathogen is transferred from a source to a host plant. ___________________________ incubation time period from when the pathogen reaches the plant until it begins to effect the plant s function. _________________________________ infection multiplication of the pathogen and the appearance of the characteristics of the disease. Infectious Plant Diseases § Control methods are most effective (usually) when implemented during ___________________________ in oculation § Diseases are responsible for huge yield and quality losses in crops. § If conditions are favorable, disease can be a big problem. § The best disease management is to prevent or limit infection. If disease is already present, it may be difficult or not economically viable to control. Prevention is the best management. Causes of Infectious Disease § Caused by microorganisms which attack susceptible plants. § Environment or agronomic conditions can favor disease including __________ wet weather, injured or stressed plants (herbicide injury, lack of nutrients, hail damage, deep seeding, poor quality seed, etc.). § These conditions can make plants more susceptible to disease or increase the incidence or severity of the disease. What is the most common (and important) plant disease causing organism in Western Canada? § Fungi § Bacteria § Virus § Other Fungi § Fungi reproduce by spores. § Spores can spread by wind, water, machinery, animals, insects, contaminated seed, etc. § When moisture is present, spores on the plant tissue germinate and grow along the plant surface, and penetrate the plant through the stomata or ____________________________ a wound in the plant § Spores can survive in plant residue in the soil or form overwintering bodies. How Plants React to Disease § Plant disease will cause ______________________________ Y eild loss § Symptoms of disease can include: 9 vali + y death of part or all of the plant lesions on stem will cause a loss of photosynthetic area changes in coloration reduced growth, stunting, dwarfing, wilting galls, tumors Sometimes you can identify the disease by symptoms but often lab culture is needed because symptoms can be very similar. Sclerotinia (white mold) Sclerotinia § Sclerotinia stem rot, commonly known as white mould, is caused I· by the fungus Sclerotinia sclerotiorum. § It is found in most parts of the world and has a large host range that includes __________ over 400 different plant species. § The major field crops that are susceptible include canola, mustard, flax, sunflower, borage, potato, pea, bean, lentil, chickpea and forage legumes. § Yield losses due to sclerotinia stem rot vary from year to year as the disease is greatly influenced by weather. Disease incidences are highest in the northern agricultural region of Saskatchewan, where _____________________ moisture tends to be greater and a larger percentage of susceptible crops are grown in the crop rotation. Sclerotinia Ergot § Ergot, Claviceps purpurea, is another fungal pathogen that creates _______________ Sclerotia as overwintering bodies. § Infects a floret of flowering grass or cereal and produces a sugar honeydew (filled with spores) and then finally replaces the seed with a black mass of spores. Ergot SCLEROTIUM Ergot is Toxic § Convulsive ergotism is characterized by nervous dysfunction, where the victim is twisting and contorting their body in pain, trembling and shaking, delusions and hallucinations, as well as a number of other symptoms. § In gangrenous ergotism, the victim may lose parts of their extremities, such as toes, fingers, ear lobes or in more serious cases, arms and legs may be lost. This type of ergotism causes gangrene to occur by constricting the blood vessels leading to the extremities. Because of the decrease in blood flow, infections occur in the extremities, accompanied by burning pain. Once gangrene has occurred, the extremity become mummified and will eventually fall off as a result of infection. Aster Yellows § Is a disease caused by a phytoplasma that results in ______________________ Phyllody and is transmitted by leaf hoppers. § Can cause stunting, deformation, virescence (greening of flowers), phyllody (development of leaf-like flower petals), reddening of foliage, reduced root system, and sterility.[ Aster Yellows ↑ carries disease Insects www.usask.ca Insects § There are more species of insects in the world than all animals combined. § Diverse areas and diverse insects (some are specialized). § There are two groups: ____________________ beneficial ____________________ harmful Beneficial Insects § Perform duties advantageous to humans. § Example: Pollinating insects. Parasitic insects (wasps - lay eggs in aphids and other larva). Flies recycle nutrients Beneficial Insects Harmful Insects § Damage to crops, food, buildings, etc. § Ongoing battle to control insects can become resistant to insecticides. Insect Injury to Plants § Pass on _____________________________ diseases § Direct injury - insect feeds directly on the plant tissue. § For example: sucking plant juices from leaves girdling the stem - damages vascular tissue chewing the leaves, flowering parts, developing seed Insect Damage § Extent of damage depends and how well the plant recovers is dependent on: insect population> - pheromone traps plant growth stage growing conditions weather Insect Population § The greater the population size, the more and faster the damage will be done. Plant Growth Stage § Smaller plants suffer more than _________________ larger plants. Older plants often recover better (if they can recover). § Seeding date can be altered to avoid damage. Growing Conditions § Good growing conditions lessen the effects on the insect injury. § Plants are able to attempt recovery if conditions are good for growth. nutrients · water · · herbicide injury Weather § Some insects function better at different temperatures grasshoppers · some like hot conditions best. § Often cool or cold temperatures result in insect ___________________ inactive The Cyclical Nature § Damage occurs in a cycle related to life cycle of insect. It may be the larva that does the damage or the adult or in some cases, both stages. § Some insects have several generations per year, others only one. § Some insects remain in a stage for many years. The Cyclical Nature § Insect populations are cyclical as well. § Population build up over time, become a major problem and then are reduced by natural parasites or disease. § Environmental conditions play a major role in the build up and decline of insect populations.  Copyright Sourcing Slide 1: Permission: Saskatoon, SK: University of Saskatchewan. Slide 3: Permission: Saskatoon, SK: University of Saskatchewan. Slide 6: Source: https://commons.wikimedia.org/wiki/File:Wheat_selection_k10183-1.jpg Permission: Public Domain. Slide 8: Source: https://commons.wikimedia.org/wiki/File:Zmrzl%C3%A1_rostlina.jpg Permission: CC BY 3.0 Slide 9: Source: https://www.canolacouncil.org/media/image-gallery/symptoms-of-frost-damaged-canola/ Permission: Courtesy of Canola Council of Canada. Slide 12: Source: https://www.flickr.com/photos/50697352@N00/14143789051 Permission: CC BY-SA 2.0 Courtesy of F.D. Richards. Slide 15: Permission: Saskatoon, SK: University of Saskatchewan. Slide 18: Source: https://commons.wikimedia.org/wiki/File:Cuticle_of_leaf_under_microscope.JPG Permission: CC BY-SA 4.0 Slide 20: Source: https://commons.wikimedia.org/wiki/File:Figure_30_05_03.jpg Permission: CC BY 4.0 Courtesy of author CNX OpenStax. Slide 22: Source: https://commons.wikimedia.org/wiki/File:Leaf_anatomy.jpg Permission: Public Domain. Slide 24: Source: https://en.wikipedia.org/wiki/Capsicum_pubescens - /media/File:Cap1033-botao1.jpg Permission: CC BY-SA 2.5  Copyright Sourcing Slide 25: Permission: Saskatoon, SK: University of Saskatchewan. Slide 27: Source: https://www.flickr.com/photos/calliope/27566217 Permission: CC BY 2.0 Courtesy of liz west. Slide 30: Source: https://www.flickr.com/photos/nature80020/14709171102 Permission: CC BY 2.0 Courtesy of nature80020. 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Slide 61: source: https://commons.wikimedia.org/wiki/File:Ergot_sur_bl%C3%A9.jpg Permission: This material is licensed under the terms of the GNU Free Documentation License. Courtesy of Dominique Jacquin. Slide 64: Source: https://en.wikipedia.org/wiki/Phyllody#/media/File:Phyllody_1.jpg Permission: CC BY-SA 3.0 Courtesy of Obsidian Soul. Source: https://en.wikipedia.org/wiki/Macrosteles_quadrilineatus#/media/File:Aster_leafhopper.jpg Permission: CC BY 3.0 Courtesy of Whitney Cranshaw. Slide 65: Permission: Saskatoon, SK: University of Saskatchewan. Slide 68: Source: https://www.flickr.com/photos/99758165@N06/14559576835 Permission: CC BY 2.0 Courtesy of Aphid Mummy. Source: https://en.wikipedia.org/wiki/Acyrthosiphon_pisum#/media/File:Acyrthosiphon_pisum_(pea_aphid)-PLoS.jpg Permission: CC BY 2.5 Courtesy of Shipher Wu.