Plant and Soil Science Midterm Review PDF

**[Plant and Soil Science Midterm Review]** - Plants - Characteristics include - The ability to photosynthesize and use light to make organic compounds from inorganic compounds - Cell walls are made of cellulose (also most common organic compou...

**[Plant and Soil Science Midterm Review]** - Plants - Characteristics include - The ability to photosynthesize and use light to make organic compounds from inorganic compounds - Cell walls are made of cellulose (also most common organic compounds on earth) - Sedentary (unable to move) - Dependent on water, therefore developed an elaborate system for obtaining and moving water around - Famous Plants - Giant Sequoia - Live on the western slope of the Nevada in California - Largest life form on earth by volume - Bristlecone Pine - Oldest tree (we thought) - White mountains of California - Pando (clonal colony of male quaking aspen) - Determined as a single living organism as they all share the same root system - Plant dependency - Plants are the basis of the food chain, and supply oxygen - Modify, stabilize climates, and create and hold down soil - Uses of plants - 25% of modern medicines were first made from plants - Aspirin is naturally occurring in willow tree\'s bark and leaves - Biofuels- fuel derived from recently dead biological material - One strategy is to grow high sugar or starch crops and then use yeast fermentation to produce ethanol - Second strategy is to grow plants that are high in oils that can be chemically processed to produce fuels such as biodiesel - Other uses include fiber, building material, animal feed, horticulture, and remediation - Food - Approx. 7,000 plants are used for human consumption - 30 crops provide 95% of human food energy needs - Wheat, corn, and rice make up around 75% of the worlds grain production and supply 50% calories - Potatoes - Domesticated in southern Peru, and northwestern Chile Bolivia - Taken to Europe when the Spanish invaded - Grow very well in the cool moist climate of Ireland - 1845, blight (Phytophthora infestans) struck Ireland, where oomycetes break apart cells and causes secondary infection. This was caused by monogenetic. - Crop origin - Important to locate related species, and new genes for disease, genetic diversity, and insect resistance - Agriculture began 10,000 years ago and was vital to building a more complex society - Jack Harlan studied crop origin that concluded crops came from three large independent centers - Near East & Africa - China & South-East Asia - Southern Mexico & Southern America - Domestication is to train or adapt a plant to live in a human environment and be used for humans - This is achieved through propagation started by harvesting a wild crop to use the seeds to sow the next crop, as a result characteristics change over time - Fertile crescent was the early center of domestication, known as present day Iraq, Syria, and Nile River valley. Responsible for domesticating wheat, barley, lentils, chickpeas, pea, and flax - Guns, germs, and Steel - - Classification - Taxonomy is classification according to similarities and differences - Linnaeus developed the basis of the naming system called the binomial naming system which is based on evolutionary relationships of organisms and is formally known as international code of botanical nomenclature - Binomial naming system or scientific name is called a Latin name - First part of the name is the Genus, second part is the called the specific epithet (in plants) - Other forms - Agronomic use - Cereal - Pulses - Forage - Oilseed - Vegetable - Fuel - Fiber - Medicinal - Specialty uses - Leaf Retention - Coniferous (evergreen) - Deciduous - Life cycles - Annual- germinate produce seeds and die within a year - Biennial- complete life cycle in 13-24 months with vegetative growth first year and second season produces seeds - Perennial- live for several years and can produce seeds each year - Climate Adaptation - Temperature- plants that go through 4 seasons - Tropical- plants that go through 2 seasons - Photorespiration Type - C4 which are more water efficient such as corn and sorghum, make an intermediary 4 carbon molecule, more efficient - C3 gather carbon and use it for photorespiration such as wheat and barley, make an intermediary 3 carbon molecule, they use photorespiration - Day-Length requirement - Long Day- require lengthy periods of daylight - Short Day- must have shorter light periods - Day Neutral- unaffected - Main Plant types - Monocots - Parallel venation, one cotyledon below soil surface, fibrous roots, plumule is protected by coleoptile - Dicots - Network of veins, two cotyledons raised above soil surface, tap root, lacking coleoptile - Photosynthesis is a synthesis reaction while respiration uses the products of photosynthesis - Autotrophs, meaning that plants with the input of light, carbon dioxide and water, they\'re self sufficient - Photosynthesis is the manufacture of carbohydrates from carbon dioxide and water in the presence of light and chlorophyll in living green plant tissue - Only cells with chloroplasts carry out photosynthesis - Photosynthesis is an endothermic reaction - Chlorophyll passes the trapped energy on to other molecules to form high-energy bonds - Visible wavelengths: our eyes detect visible light, and plants use certain wavelengths in the visible spectrum in photosynthesis - Chlorophyll is efficient at trapping red and blue colors - 6CO2+12H2O+sunlight (carbon dioxide, water) \-\-\-\--\>C6H1206+H2O+6O2 (glucose, water, and oxygen) - Photosynthesis takes part in the leaves where sunlight is captured by the chloroplasts and that light energy is used to break apart water and carbon, oxygen is given off by the stomata, hydrogen from the water molecule is combined with carbon to make glucose which is the food created by photosynthesis and water is released - Respiration is an exothermic reaction, all cells respire - NAR (Net Assimilation Rate) - Photosynthetic gains-respiration losses = NAR - In order for plant growth, the NAR must be positive - If the NAR is negative, then respiration exceeded photosynthetic gains - LAI (Leaf Area Index) - The average energy conversion rate is 2% and the rest is not used so there is a great potential to capture more energy - LAI is the ratio of leaf area to land area - Only the leaf area that is exposed to the sun is counted, not the underside - Plant cell - Cells are the building block of plant tissues - Cells are mainly made up of water - Cell wall is there for support and protection - Made up of cellulose, hemicellulose, pectin and occasionally lignin - Cytoplasm - Contains carbohydrates, proteins, and salts - Psychological activity occurs here - Vacuole - Serve as collection and storage - Contains a lot of water and account for majority of the volume - Plastid - Manufactures and stores important chemical compound - Amyloplasts are specialized for long term starch storage - Chromoplasts - Increased production of color pigments - Carotenoids are hidden in summer by chlorophyll - Anthocyanin accumulates with a combination of warm and cool nights - Tannins hidden in summer by chlorophyll - Mitochondria - Breaks down the products of photosynthesis into useable energy, this is the process of respiration - Different species have different number of chromosomes - Plant Breeding - Changing the genetics of the plant to benefit humankind - 2 types - Classic - Deliberate crossing to produce new crop varieties with desirable traits - Through sexual means resulting in a new genetic combination - Most common is triticale (wheat and rye) - Molecular - Based on the genotype - Application of molecular biology tools in plant breeding - Examples include genetic engineering, and marker assisted selection - Marker assisted selection is a category of molecular breeding and is a tool of plant breeder - Starts with a molecular marker - Molecular marker is a fragment of DNA that is associated with a certain location within the genome - Therefore, molecular markers can map the genes of the plant - Genomics - The genome of an organism is the genetic material of that organism which is contained in its DNA - Genomics is the study of plants genome to better understand the workings of the plant and what happens when certain genes interact with each other and the environment - GMO, GE (genetically engineered), and Transgenic - GMO's is used to designate GE crops - The term transgenic also refers to GE crops - A major capability of GE crops is to introduce genes from sexually incompatible backgrounds - Potential advantage of GE crops over classical breeding is the knowledge of actual genes being inserted - Genes are introduced into a genome by means other than by the usual sexual means which includes a gene transfer by agrobacterium tumefaciens, a pathogenic bacterium that naturally transfer DNA - Molecular Pharming - Refers to the use of the genetic engineering to insert genes that code for useful pharmaceutical into host animals or plants that would otherwise not express those genes - Biofortification is the idea of breeding crops to increase their nutritional value - Plant Tissues - All plants begin from a single cell that divides and eventually differentiates - Continuous organized masses of similar cells are called Tissue - 2 important types - Meristematic are responsible for growth - Apical - Tissues at the tip of roots and shoots, known as growth points - Make dicots taller - Make monocot and dicot roots deeper - Lateral or vascular cambium - Not found in monocots - Makes trees wider in the form of growth rings - Dendrochronology is the study of trees through time - Intercalary - Found in monocots - Located near nodes - Determine plant response to grazing and lawnmowers etc. - Vascular tissue is responsible for the movement of water, nutrients, and food - Xylem - Water and dissolved nutrients are transported from root to the rest of the plant - Xylem has thick cell walls with lignin for structural support - Larger xylem vessels can be seen as veins - Phloem - Food conducting tissue from the leaves and green tissues to other parts such as the roots and seeds - Useful fiber from flax is derived from phloem - Pumpkins receive 0.5 g of food through the phloem - Vascular Bundles - Xylem and Phloem are organized together in bundles, phloem is on the outside and Xylem is on the inside - In monocots they are scattered throughout the stem - In dicots they are organized in a ring - Soil - Defined as the finite natural and unconsolidated mineral and organic material on earth\'s surface that has been influenced by parent material, climate, macro & micro-organisms, and landscape, all acting over a period to produce a material different from which it was derived in many physical, chemical, biological, and morphological properties - Composed of - Soil solids 50% - 45% Mineral and 5% organic material - Pore Space 50% - 20-30% water and 20-30% air - Soil as 3-D - Soil profile is the vertical section of soil - Soil horizons make up a soil profile and they extend into the parent material - Soil Dynamic includes formation which is a slow and complex process that breaks down components while creating new ones - Destructive process - Weathering of rock and minerals - Decomposition of organic material - Synthetic processes - Clay mineral and organic material formation - Soil horizon development - Global Functions of soil - Plant growth medium - Anchorage for roots - Source of water and nutrients - Indirectly provides human uses - Regulates water supply - Absorbs, stores and re-releases precipitation - Regulates flow for rivers and streams - Purifies water by filtration, absorption, and decomposition of toxic substances in water - Habitat for soil organisms - Organisms carry out nutrient recycling - Global energy cycle - Moderates influence of solar radiation on earth's surface temp - Absorbs and reradiates a large amount of solar energy back into space - Influence atmospheric conditions - Affects air quality by contributing dust, water evaporates into the air, etc. - Engineering medium - Roads, dams, and foundations - Soils and Ecosystem Services - Ecosystem is a dynamic complex of plant, animal, and microbial communities, interacting within the non-living environment and may include human beings - Provisioning services- products obtained from an ecosystem - Regulating services- benefits obtained from regulation of ecosystem processes. E.g. Climate, disease, flood, erosion - Cultural services- non-material benefits obtained from ecosystems - Supporting service - Human change on ecosystems have increased economic prosperity to meet demands, but have degraded ecosystems and biodiversity - Soil degradation - Erosion- loss of topsoil from water, wind, tillage, and overgrazing - Compaction- Traffic or grazing squishes soil particles together reducing pore space - Nutrient mining- removal of nutrients in harvest plant material without replenishment - Loss of organic matter- caused by accelerated decomposition of organic matter - Salinization- increase in salinity - Contamination- pollutants spilled or leached into soil - Core Soil properties - Texture - Hard to change over time and inherited form parent material - Minerology - Mineral is a solid crystalline material with defined chemical and physical characteristics and a rock is a naturally occurring mixture of two or more minerals - Soil organic matter - Management of SOM is important to sustainable management due to its rapid response to manipulation - Weathering- living organisms are catalysts in both forms - Mechanical - Breaks down a rock into smaller pieces without altering chemical composition, eventually into particles of individual minerals - Frost wedging, roots fracturing rock, water, wind, gravity - Biogeochemical - Process that changes the chemical composition of rock minerals - Hydrolysis- clay mineral formation - Dissolution- limestone dissolution - Oxidation- rust formation - Soil particles - Particle size influences soil function, each size is called a soil separate - Sand- 0.05-2 mm (about 0.08 in) - Silt- 0.002-0.05 mm (about 0 in) - Clay- \ ammonia in air - Ammonia volatilization is higher in alkaline soils due to more OH ions present - Leaching - Nitrate us susceptible to leaching down the soil profile into ground water - Nitrate is more mobile in soils than ammonia because nitrate doesn't bind to clay particles - Phosphorus - Soil P originates from weathering of primary minerals - It does not cycle through the atmosphere - 0.1% of soil is P, but not more than 0.01% total P is available for plant uptake - Plants take up P as inorganic phosphate ions - Fixation refers to the chemical process that render P unavailable to plants, processes leading to fixation: - Precipitation - Adsorption - Mineralization- organic forms of P can be mineralized to inorganic forms by soil microorganisms - Net immobilization occurs if the organic residues have a CP ratio greater than 250:1 - Net mineralization occurs if organic residues have a CP ration less than 250:1 - Erosion and Runoff - Leaching of P to groundwater is not a significant loss - P lost to erosion and runoff can lead to eutrophication of surface water bodies - Potassium - Organic K: - Plant residues - Animal manures - Soil organic Matter - Inorganic K: - Weathering - Desorption - Inputs: - Weathering of primary minerals - Fertilizers - Internal Transformations - Nonexchangeable K \~slow~ Exchangeable K \ ~fast~ Soil Solution K - Mineralization/Immobilization - Losses: - Leaching, runoff, soil erosion - Exports of K important in Hay crops - K does not cause off site environmental problems - Nutrient Supplies - Plants take up nutrients in ionic form from the soil solution, so soil solutions must be replenished with nutrients - Replenished in two ways: - Soil reserves (internal source) - Fertilizers (external source) - If nutrient supplies are adequate, crop will remove characteristic amounts of nutrients and removal of nutrients cannot continue without depleting productivity of the soil - Fertilizer is a natural or artificial substance that contains nutrients that improve plant growth and productivity by enhancing natural fertility. They can be broadly classified as - Organic (ex. Compost, manure, sludge) - Inorganic (ex. Synthetic or mined processed elements) - Fertilizers are defined by the Fertilizer Act of the Govn't of Canada and sale regulated by Canadian Food Inspection Agency - First number is nitrogen, second is phosphorus, third is potassium, and fourth is sulfite - Fertilizers are subject to nutrient cycling - 4R Nutrient Management involves the implementation of best management practices that optimize efficient use of fertilizers - Right source- balanced supply of nutrients for the plant growth - Right time- avoid application on frozen soils and fall fertilization, one pass is efficient - Right rate- preform annual soil tests, calibrate equipment - Right place- respect recommended setback distances for nutrient application, place nutrient below the soil