HCS 2200 UCB Plant Structure Discussion

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CFAES HCS 2200 Plant Structure, Growth & Development Pamela J Sherratt CFAES The Carbon Cycle & Energy Transfer Radiant energy converted to chemical energy, then released to support the metabolism of all living organisms. Carbon is the molecule that is cycled and recycled through these processes. CFAES Autotrophs (plants & bacteria) • Process – Captured solar energy is used to synthesize carbon-based molecules called carbohydrates from CO2 & water. • Oxygen is released in the process • Some of the energy used to make the carbohydrates is now stored in the carbohydrate molecules. • Respiration breaks those carbohydrate bonds, releasing the energy, along with CO2 and water … Photosynthesis CO2 + H2O Heterotrophs Light C(H2O) + O2 CFAES Respiration C6H12O6 + 6O2 + 36 ADP + 36 PO43- 6CO2 + 6H2O + 36 ATP • Process – the transfer of carbohydrate energy to energy-rich ATP energy. • The transfer of energy to ATP requires carbohydrates, oxygen, and ADP (low-energy molecule • This then provides the energy for biological processes. • In essence, respiration is the reverse of photosynthesis • The CO2 released by respiration is then used again in photosynthesis, thus completing the carbon cycle! This Photo by Unknown Author is licensed under CC BY-SA CFAES Carbon Cycle Review • Photosynthesis & respiration are generally in balance, with the amount of carbon being reduced and oxidized being nearly equal, resulting in little change to atmospheric CO2. • The current rise in atmospheric CO2 is, in part, the result of oxidization of carbohydrates produced long ago by the plants that make up fossil fuels when those fuels are burned. CFAES Plant Growth and Development are NOT the same thing! These poinsettias are the same age. Which has most growth? Which is furthest along in development? CFAES Growth is defined as an irreversible increase in size (biomass). Definition: Size increase by cell division and enlargement, including synthesis of new cellular material and organization of subcellular organelles. CFAES Development is the changes that occur during ontogeny (the maturation process). Stages of development: seed germination, growth of vegetative organs and tissues, initiation & maturation of reproductive organs and tissues, fertilization, seed development and maturation, scenescence and death. CFAES Senescence/death Vegetative growth Reproduction CFAES CFAES Life cycle of a coffee bean https://www.reddit.com/r/Damnthatsinteresting/comments/b5kbiz/the_life_cycle_of_coffee/ CFAES Plant Shoot Growth • Determinate growth pattern – after a certain period of vegetative growth, flower buds form at the shoot terminal and shoot elongation stops • Indeterminate growth pattern – Flowers form along the shoot, which continues to grow until senescence or an environmental influence CFAES Determinate or Indeterminate? CFAES Accumulation of Biomass (growth) Plants can increase in size by • taking up water • accumulation of organic compounds created by photosynthesis. Plant scientists often measure growth in terms of increase in dry matter (photosynthates) rather than increase in size. Dry matter is often referred to as biomass. Question: Why is biomass measured in dry weight, not fresh weight? CFAES Most producers of agricultural products are interested in biomass more than water content of their crops. For example: •Farmers don’t want corn high in water and low in starch content •Catsup producers don’t want watery tomatoes. •Golf course superintendents don’t want weak, watery grass blades. •Ornamentalists don’t want weak plants with little color or stamina. CFAES Question: What is/are the part/s of interest in the following? Chrysanthemums Soybeans Lawn Forages CFAES Biomass Partitioning by which plants divide their energy amongst their parts CFAES Annual Plant Herbaceous Perennial CFAES In the later stages of the life of an annual plant most of the photosynthetic product may be directed to seed production. Plant breeders of seed crops try to maximize the proportion allocated to seeds relative to what’s allocated to leaves, roots, and particularly stems. CFAES In herbaceous perennials, resources produced in the latter half of the growing season are diverted to the over-wintering structure, whether it is a bulb, root, or rhizome. CFAES The direction of resource allocation is an important factor in controlling perennial weeds. Herbicide is applied in the late summer to prevent the plant from allocating resources to the structures it needs to survive the winter. CFAES Ontogeny (Life Cycles) is the developmental change an individual goes through in its lifetime - the socalled stages of life or maturation. In a plant those stages can be germination, vegetative growth, flowering, fruit development, seed production, senescence (aging) and death. CFAES Plant Lifecycles: Annual CFAES Annual Plants CFAES In Ohio Winter cold kills geraniums, Summer heat kills pansies, a warm climate plant. a cool climate plant. CFAES Summer Annuals Mid-May Summer Question: What are the traits of a true “annual” plant? Name 3! Mid-October CFAES Plant Lifecycles: Biennial Year 2 Year 1 CFAES Examples of biennials: • Beets • Brussel sprouts • Cabbage • Carrots • Hollyhock • Lettuce • Onions • Parsley • Swiss Chard • Sweet William CFAES Perennials live longer than 3 years. The development of a perennial plant includes long term and annual phenological events, such as: CFAES Plant Lifecycles: Perennial Woody perennial Nonwoody or herbaceous perennial CFAES Specialised Stems & Roots: (biennials & perennials) Stems: Bulbs, corms, tubers, rhizomes & stolons (what’s the difference?) Roots:Taproots and Tuberous roots. What purpose do they serve? CFAES Question: What plant part makes you believe this dandelion weed is a perennial, & why? CFAES Define the following: 1. Woody plants 2. Non woody (herbaceous) plants CFAES Plant Growth Regulators: Plant Hormones • Auxin - cell enlargement, tropism, apical dominance, abscission of plants parts, flower initiation and development, root initiation, fruit set and growth, cambial activity, tuber and bulb formation, seed germination • Gibberelin – Cell division and cell elongation, flower initiation & sex expression, fruit set, senescence of plant parts, overcoming dormancy • Cytokinin – Cell division, cell enlargement, tissue differentiation, dormancy, phases of flowering and fruiting, retardation of leaf senescence • Ethylene (gaseous) -Fruit ripening, flower initiation, abscission • Abscisic acid – Seed dormancy, abscission, closes stomata CFAES Tropisms in Plants - Touch, light, water, gravity Thigmotropism Ref: http://www.untamedscience.com/science/wp-content/uploads/2013/10/how-phototropism-works.jpg CFAES Watch: Plant Hormones: Auxin https://youtu.be/HR9KHW-e0pY Watch: Tropisms in Plants https://youtu.be/pCFstSMvAMI CFAES Synthetic Plant Growth Regulators & Their Uses Epinasty in dandelion • Auxin : Rooting powder, weed control (2,4-D), inhibition of stem sprouting, tissue culture/micro-propagation • Gibberellin: Increasing size of seedless grapes, stimulation seed germination & seedling growth, promoting male flowers in cucumbers, overcoming cold requirement, promoting cell elongation (sugar cane) • Cytokinin: Tissue culture • Ethylene: Fruit ripening, flower initiation, changing sex expression, degreening oranges, lemons and grapefruit, harvest aids (walnuts, cotton), growth regulation, low O2 during transportation CFAES Tobacco stem. L-R: No trtm, Cytokinin = buds, auxin = roots & prevention of buds, C+A = callus, no organ dev. CFAES Gibberellin Overcoming dwarfness in corn by spraying gibberellin. (L-R: dwarf, nondwarf + G, dwarf + G) Effect of gibberellin on grape seeds. (L-R: no trtm, low, med, high rate ) CFAES Synthetic Growth Retardants • Slow cell division & elongation. Most block gibberellin synthesis Growth reduction in chrysanthemum plants. (L-R: control, medium rate, high rate) CFAES Common Name Plant Growth Regulators used on Turf Trade Name Absorption Mode of Action Comments Mefluidide Embark Foliar Inhibits cell division (mitosis) and differentiation in meristematic tissue Primarily used to inhibit Poa annua seedhead formation. App. made in spring prior to seedhead inflorescence emergence Ethephon Proxy Foliar Enhances release of ethylene into the plant, regulating growth through its influence on cell size Used alone or in combination with trinexapacethyl for Poa annua seedhead control Paclobutrazol Trimmit Root Early gibberellic acid (GA) inhibitor GA inhibitors were and are still used in the gradual reduction of poa annua in creeping bentgrass turf due to the greater inhibitory effect on Poa. Flurprimidol Cutless Root Early gibberellic acid (GA) inhibitor Originally used in the same fashion as paclobutrazol. With both paclobutrazol and flurprimodol conversion to more bentgrass in fairways is accomplished with spring and fall applications at the higher end of the recommended rate Trinexapac-ethyl Primo MAXX (liquid) Foliar Late gibberellic acid (GA) inhibitor Most widely used plant growth regulator on high quality turf. Implicated in enhancing summer stress tolerance of turf, reduced disease severity (in some cases) and improved turf quality Governor (granular) CFAES Knowledge Check: • Have a basic understanding of photosynthesis & respiration (the carbon cycle) • What is the difference between an autotroph & heterotroph? Indicate what each of the following would be: orchid, polar bear, fungus, maple tree, rabbit • Why is it not likely that the respiration of all living creatures on earth is a cause of increased atmospheric CO2? • What is the difference between plant growth and development? • What is the difference between determinate and indeterminate growth? • Biomass partitioning – the difference between annual and perennial plants • Describe the life cycle of annual, biennial and perennial plant • Hormones - give a natural function or production use for auxin, GAs, ABA, cytokinin and ethylene • Tropisms - Geo, photo, thigmo Why most plants are green? It is mainly due to the influence of the photovoltaic conversion rate of operating temperature and light conditions.When I was a child, I often thought about why most of the plants in life are green. It must be wonderful if red plants or blue plants can also occupy most of them. After I learned about plants, I understood the principle. The chloroplast photosystem is a living system that can adjust the ratio of pigments according to the light intensity and wavelength of light concentration. For example, most chloroplasts in cyanobacteria and eukaryotes are dark green to blue green, while in deep sea cyanobacteria and eukaryotes The color of the chloroplast is close to brown because of the higher proportion of lutein, and the chloroplast in the place with strong sunlight has a higher proportion of carotene, resulting in a light green color, which improves the conversion efficiency and avoids excessive temperature. Source: https://www.jic.ac.uk/blog/why-are-plants-green/ 0 What factors allow seeds to remain viable? I worked at a place that sold seed, mostly grass and cover crop seed. Each year, depending on the seed, an emergence test was done to determine the emergence rate of that bag of seed. As you might expect usually it decreased year after year. I would predict that most of the seed in the bag would be no good after 5-10 years. However, during our greenhouse tours we were told that seeds can last hundreds of years. How can this be? Do different seeds stay viable for different lengths of time? How important are the storage environments of the seeds? Source: Greenhouse Tours 11:09 AM, 3/5/2022 Options Add Response
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Answer #1; what factors allow seeds to remain viable?

While in the past, it was impossible to store seeds for long because of rotting, things have
changed significantly in the modern world. Currently, individuals have gained a lot of
knowledge and insights on managing and storing seeds effectively to enhance their durability
and not interfere with their quality. There are technologies, tools, and equipment that can help
condition seeds In a way that it is difficult to lose t...

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