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Plant Physiology General the Main Light Sensitive Pigment Able to Absorb Solar Energy in Both Plants and Algae Is

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Plant Physiology General the Main Light Sensitive Pigment Able to Absorb Solar Energy in Both Plants and Algae Is Plant Physiology General the main light sensitive pigment able to absorb solar energy in both plants and algae is chlorophyll Photosynthesis this chlorophyll is contained with the chloroplasts probably the most characteristic “thing” that plants plants also have other “accessory pigments”: “do” is photosynthesis carotenoids – mainly yellow, orange almost all plants are autotrophs but usually their colors are masked by an abundance of !use energy from the sun to make sugar and chlorophyll other organic molecules out of simple fall colors are seen as a deciduous plant shuts down nutrients and chlorophyll is broken down and recycled leaving the colors of the other pigments photosynthesis requires carbon dioxide & water reds come from anthocyanins made to protect leaves as they recycle nutrients from the breakdown of chlorophyll CO2 enters through stomata or pores [Application] water is absorbed through roots researchers are studying the structure of the chloroplasts to light improve efficiency in the design of solar collectors CO2 + H2O sugar + O2 chlorophyll (glucose) today (2006) the most efficient solar cells capture only ~17% of solar energy that lands on them, while plant [photosynthesis converts water and carbon dioxide cell capture 30-40% to sugar and oxygen] !these sugars can then be broken down as needed for energy photosynthesis uses several chemical pigment to absorb the energy from sunlight Plants: Plant Physiology - General, Ziser, Lecture Notes, 2012.10 1 Plants: Plant Physiology - General, Ziser, Lecture Notes, 2012.10 2 Plant Nutrition heterotrophs must eat a variety of organic compounds to build cells and to break down for energy since plants produce their own organics they require in most cases; Nitrogen & Phosphorus are most relatively few simple inorganic nutrients likely to limit plant growth (hardest to get nutrients), like most living organisms plants need some form all fertilizers contain: N, P and K, in various concentrations of Carbon, Hydrogen, Oxygen & Nitrogen [Application] carbon, hydrogen and oxygen come from the air in the form of CO2 H2O & O2 agriculture & gardening plants, mostly nonnative species, are nitrogen & most other nutrients such as Phosphorus and selected for fast, lush growth Potassium comes from the soil: need many more nutrients (and water) than native plants van Helmont (1600’s) took tub with 200 lbs of must supplement with fertilizers soil and planted a 5 lb willow tree in it after 5 years: eg. Nitrogen the willow weighed 164 lbs the soil weighed 2 oz in most plants, Nitrogen is absorbed as inorganic minerals from the soil much of global climate change is being caused by increasing amounts of CO2 in the atmosphere however some plants are able to get their nitrogen in other ways: many oil and coal companies have touted the beneficial effects of CO2 on plant growth some plants can grow in N-poor soil using a eg. bristlecone pines and other native species have symbiosis with N-fixing bacteria that can shown enhanced growth over the past 50 extract N from the atmospshere and convert it years to a more useable form what they ignore is that many other native species do not benefit from increasing CO2 Plants: Plant Physiology - General, Ziser, Lecture Notes, 2012.10 3 Plants: Plant Physiology - General, Ziser, Lecture Notes, 2012.10 4 and in general weedy plants grow much better than do native plants with enhanced carbon dioxide levels some plants are carnivorous and get their they are therefore (at least partially) nitrogen from digesting insects and other heterotrophic animals a few of these have completely given up ! tend to grow nitrogen poor soil photosynthesis over 500 species have been described eg. parasitic plants ! N America has the most diverse 3000 species of parasitic plants carnivorous plant fauna largest group are the mistletoes (~800 sp) most prefer damp boggy soils mostly tropical and subtropics but also includes: attract insects through color, smell, nectar indian paintbrush (a hemiparasite) a few plants not considered to be sandalwoods “carnivorous” may still be able to get at dodders (eg. Cuscuta sp.) of the morning glory family broomrapes and figworts least some nutrition from them: rafflesia eg. petunias - covered with sticky hairs roots grow into host plant eg. potato, tobacco, rhododendron and teasel produce poisons that kill insects and may extract water, minerals and nutrients from absorb some nutrition from them vascular system of host eg. a rare Brazilian plant produces underground leaves that trap, kill and absorb roundworms some have given up photosynthesis altogether and get all their organics from Heterotrophic Plants their host a few plants get at least some of their organic eg. dodder, coral root orchid, broom rape, molecules in other ways than photosynthesis eg. pants parasitic on fungi Plants: Plant Physiology - General, Ziser, Lecture Notes, 2012.10 5 Plants: Plant Physiology - General, Ziser, Lecture Notes, 2012.10 6 some plant roots parasitize the abundant eg. aspens tend to grow in large interconnected colonies fungi that grow in and on the forest floor and typically all members of the colony begin to show fall colors at the same time some of these have also completely lost the ability to do photosynthesis but some diseases can also spread directly from tree to tree through these root grafts eg. snow plant also produces its own heat that can actually eg. oak wilt often spread this way melt snow a common method to control oak wilt is to trench Root Grafts around an infected tree one other way that perennial plants might get access ! breaks any root grafts with other trees to both organic and inorganic foods are through Halophytes root grafts so far we’ve talked about how plants get nutrients and as roots grow they encounter roots of other plants minerals when they are in short supply can be same or different species under some situations plants have to deal with the may grow together to form graft opposite problem root grafts are known for over 160 species of trees ! too many minerals and salts in the soil eg. birch, maple, oaks, aspen if soil contains too many minerals; ie. is too salty the nutrients can pass between them plant may be unable to absorb water effectively may be of advantage for a plant growing in poor soil that is connected to a plant nearby growing in good soil or near a ! salty soil can actually suck the water out of the creek or pond plant by osmosis (“water follows salts”) hormones can also be exchanged most plants are fairly sensitive to high concentrations of salts in soil sometimes events like flowering or autumn colors in deciduous plants are coordinated eg. too much fertilizer can kill a plant Plants: Plant Physiology - General, Ziser, Lecture Notes, 2012.10 7 Plants: Plant Physiology - General, Ziser, Lecture Notes, 2012.10 8 ! aerobic respiration eg. farmland that is continually irrigated becomes less fertile as salts and minerals build up from evaporation since plants are much less active than animals they =soil salinization have a very low O2 requirement; millions of acres of farmland have been removed from 1-2% is sufficient to maintain aerobic respiration cultivation because of salinization !some O2 diffuses across cuticle and closed especially in dry climates stomata of leaves and herbaceous stems but a few plants can grow in high salt concentrations !in roots, well drained soil usually has enough air equivalent to the saltiness of sea water ~3% salt spaces to provide oxygen for roots these plants are called halophytes !when soil is saturated with water cells can use anaerobic respiration temporarily eg. many plants of the sea shore and salt marshes but cant grow and do normal metabolism halophytes have special cellular adaptations that until the soil drains prevent them from taking up salt if soil remains flooded too long they will die or !cypress & mangrove trees have adapted to living in continuously saturated soil by producing allow them to secrete excess salt pneumatophores (“cypress knees”) which eg. trichomes (leaf hairs) act like snorkels to bring O2 to the roots Oxygen for Respiration in addition to needing oxygen atoms to build organic molecules plants also need oxygen molecules (O2) to break down organic molecules for energy Plants: Plant Physiology - General, Ziser, Lecture Notes, 2012.10 9 Plants: Plant Physiology - General, Ziser, Lecture Notes, 2012.10 10 Transport in Plants ! in one direction only most plants are large enough that they need some way to be able to move materials around the driving force of water movement in the xylem only the smallest plants lack a transport is the “pull” of transpiration system the key to transpiration is the stomata of the leaves transport in plants is not like fluid transport in animals as water is evaporated from the stomata In most animals fluids are circulated in the body, usually using a muscular pump to push them along !tension is produced Plants have no “muscle” cells – they have no pumps to resembling the “sucking” on a straw push fluids around !cohesion of water molecules “pulls” more water plants mainly use passive physical processes such up the plant to replace it as diffusion and osmosis to move things around water must form an unbroken column of water There are two major transport systems found in most molecules for process to work plants: a single bubble destroys the flow and stops xylem transpiration phloem eg. cut flowers, cut christmas trees A. Xylem Transport dissolved minerals are carried passively by the xylem is generally made of larger thicker-walled
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