FACTORS THAT AFFECT PLANT GROWTH PLANTS DAY 5 FACTORS THAT AFFECT PLANT GROWTH

SUNLIGHT _________________ of light influence a plant’s ability to perform photosynthesis Quantity limited by natural environmental factors like _________ and competition from taller plants Quality of light is influenced by shading by other plants, cloud cover, time of day, and angles of incidence during different seasons – duration of natural light is dictated by the seasons TROPICAL RAIN FOREST – LOTS OF SUNLIGHT YEAR ROUND TEMPERATE RAIN FOREST (B.C.) LOTS OF SUNLIGHT FROM MAY - SEPTEMBER

Each m2 of ground absorbs only ____% of solar energy Each m2 of ground absorbs _____% solar energy

SUNLIGHT _________________ number of daylight hours in a 24 h period, is variable the further away from the equator plants are Northern hemisphere = longer daylight hours in spring and shorter daylight hours in fall and this affects productivity and reproductive life cycle of plants Different plants ___________________ to photoperiod length

SUNLIGHT Latitudinal variation in the intensity of sunlight results from the Earth's spherical shape; seasonal variation in solar radiation in the Northern and Southern Hemispheres are due to the Earth's tilt of 23.5º relative to its plane of orbit. Only the ___________ receive sunlight from directly overhead year round The tropics receive the _________ annual input of solar radiation and show the _______ seasonal variation; only small variations in day length and temperature occur. Seasonal variation in light and temperature increases steadily _____________________

PHOTOPERIOD Photoperiod changes dramatically during the year in temperate regions of the world. ___________________ plants are those that flower, or flower more rapidly, when the photoperiod is shorter ____________________ plants are those that flower, or flower more rapidly, when the photoperiod is longer For example, poinsettias and chrysanthemums develop vegetative growth when the photoperiod is long and flowers when the photoperiod is shorter. Growers use _____________________ to provide short days to induce flowering of poinsettias By knowing how daylength affects plant development in photoperiodic species, we can ____________________ the natural photoperiod to promote vegetative growth (such as to bulk up plant size or for cutting production) or flowering, whichever is desired.

WATER Water is a part of photosynthesis; maintains turgor pressure/____________________ and transports ______________ throughout the plant Amount of water regulates opening and closing of stomata = regulates __________________ Is a solvent for minerals moving into the plant (osmosis) and for glucose to move to their site of use/storage (translocation)

HUMIDITY Warm air holds ______ water vapour than cold air Relative = water in air Humidity water air could hold at a given temp. Warm air holds ______ water vapour than cold air Similar to process of diffusion, water vapour will move from areas of _____ humidity to areas of ___ humidity Humidity in air space between cells in plants is almost ____%, so when stomata are open, water vapour rushed out into ______ that is less humid As water vapour rushed out, cloud of high humidity forms around stomata and this slows down transpiration and helps to cool the leaf = stomata ______ tighter so as not to let as much water out

NUTRITION _________________: The nutrients that are required by plants in larger quantities __________________: The nutrients that are required in smaller quantities by the plants The eight micronutrients include iron, zinc, molybdenum, manganese, boron, copper, cobalt, and chlorine

Macronutrient Functions Makes up amino acids and thus all proteins and nucleic acids and chlorophyll Leaf growth Involved in water balance to control operation of stomata and water intake in roots; needed to help make proteins Component of DNA, RNA; needed for mitosis and cell division Important in developing and functioning of cell walls Component of chlorophyll Component of most proteins

ACIDITY Acidity is measured in pH level, a chemical property that governs how substances interact with each other A wide range of natural acidic properties are present in soils, but some soils may become too _______ for plants to grow healthily They can be treated with alkaline (basic) substances to make them more acid-neutral.

ACIDITY The acidity inhibits the growth of ________ and the _______________ of necessary minerals through the root cell walls = weaken plants, causing them to grow very slowly or turn ______________ in color = if acid remains high, plants may wither and die Areas with heavy _______________ tend to have more acidic soil, simply because the rain water leeches away alkaline minerals in the soil Soil with high levels of ______________will be more alkaline, while soils with high levels of granite, biomaterial (compost), peat moss or man made acidic fertilizers tend to be more acidic

PLANTS AND ACIDITY Plants that thrive in _____ soil: blueberry, gardenia, azalea Plants that thrive in _____________ soil: broccoli, muskmelon, onions

TROPHISM Plants grow in response to external stimuli; growth responses are called ____________ and are controlled by plant ______________________ _____________ tropisms are growths towards stimulus ______________ tropisms are growths away from the stimulus _______________: bending and growth of a stem towards a light source – capture more sunlight energy _______________: growth response to gravity. Stems show negative gravitropism and roots show positive gravitropism _______________: growth in response to touch – vines gain support by growing around a stem or tree trunk