Agricultural and Horticultural Science 2.2

1. Agricultural and Horticultural Science 2.2 Describe physical factors of the environment and techniques used to modify them for plant production

2. Lessons • Introduction • Plant Parts • Stems & Leaves • Flowers & Seeds • Photosynthesis & Respiration • Plant Reproduction • Stratification • Plant Responses to Light • Weather • Water • Temperature • Growing Degree Days (GDD’s) • Wind • Site Evaluation • Changing the Amount of Light • Windbreaks • Frost & hail damage prevention • Pollination & Fruit Set • Carbon dioxide enrichment Websites http://www.teara.govt.nz http://www.teara.govt.nz/TheSettledLandscape?utm_campaign=feature-entry&utm_medium=feature&utm_content=9july&utm_source=homepage-feature-0 http://www.maf.govt.nz/mafnet/schools/kits/ourland/timeline/ http://www.maf.govt.nz/mafnet/schools/

3. Explanatory Notes 1 This achievement standard is derived from The New Zealand Curriculum, Learning Media, Ministry of Education, 2007, and is related to the material in the Teaching and Learning Guide for Agricultural and Horticultural Science, Ministry of Education, 2010 at http://seniorsecondary.tki.org.nz. 2Demonstrate understanding involves describing how techniques modify physical factors of the environment for commercial plant production in New Zealand. Demonstrate in-depth understanding involves explaining how the use of techniques influences commercial plant production in New Zealand. Number AS91290 Version 1 Page 2 of 2 Demonstrate comprehensive understandinginvolves evaluating techniques used to modify physical factors in terms of economic and/or environmental and/or social impact of commercial plant production in New Zealand. This may involve comparing and contrasting or justifying the use of the techniques. 3Physical factors are selected from frost, wind, light, temperature, water, humidity, air, and soil. 4Plant production relates to crop yield, quality, and timing.

4. Parts of the Plant • Plants are made up of – • Roots • Stems • Leaves • Flowers • Seeds

5. Roots- • Roots & stems are the main transport system for the plant. • Roots support the following processes- • Growth • Photosynthesis • Reproduction-this happens in the upper part of the plant • Anchor plants • Absorb & dissolve water • Store food • Oxygen diffuses into Carbon Dioxide out of the root hairs

7. Root hairs from a radish

8. Stems • Continues to transport nutrients from the roots up the plant & support the upper part (leaves) of the plant • Functions of stems • Provide support & hold plants to the light • Transport water, sugar & nutrients around the plant • Carry out a small part of photosynthesis

9. Internal Stem Structure The stem is made up of several layers-

10. Cross section of stemStructure of stem

11. Stems have 2 types – • Herbaceous –(non woody) have no woody tissue & rely on water to keep their shape. Lack of water will cause collapse of the stem • Woody Stems- start as Herbaceous but develop cambium tissue every year forming rings

13. Leaves • Have many shapes & sizes but have 3 main functions- • Photosynthesis-takes place in the chlorophyll (green pigment) in the chloroplasts of the leaf. Leaf shapes are designed to capture the most light to enable photosynthesis • Transpiration- loss of water from the underside of the leaf • Gas exchange-gas & water vapour move through the stomata cells. These cells open & shut so photosynthesis can take place

15. Flowers • The main function is to reproduce. Pollination can be done by either wind or insects. • Wind Pollination- flowers are small & scentless. Male flowers produce pollen which is blown to another plant’s stigma. • Insect Pollination- Insects complete the fertilisation by transferring the pollen to the stigma

16. Parts of the flower

17. Seeds • Come in many shapes & sizes • Plants use the wind, water, insects & birds to disperse the seeds. • Seeds functions are to- • Create a new generation of plants • Dispersal mechanism • Seed structure • Seed are made up of – • An embryo --new plant • Food store--endosperm & cotyledon • A protective seed coat—testa

18. Dicotyledon -A flowering plant with two embryonic seed leaves or cotyledons that usually appear at germination. Monocotyledon- Any of various flowering plants, such as grasses, orchids, and lilies, having a single cotyledon in the seed.

19. Fruit • Are the ripened ovaries of the flower • Protect the seed • Provide nutrients for the seed • Help with seed dispersal

20. Photosynthesis • Is the process plants use to make food • Photosynthesis is used by the plant for • Food for growth • Maintenance and development • Photosynthesis takes place in the chloroplasts of the leaf Equation 6CO2 + H2O + energy === C6 H12 O6 + 6 O2 Carbon Water Glucose Oxygen Dioxide

21. Rate Of Photosynthesis • This can be fast or slow depending on • Amount of light • Amount of chemicals available • Temperature • The speed of the process is dependant on the slowest variable • Factors limiting photosynthesis • Carbon Dioxide— Is in the air & moves into the plant via the stomata cells. Higher levels of CO2 can increase the rate but only to a certain point

22. Light Provides energy for photosynthesis to take place. The greater the light (brightness) the more photosynthesis can take place up to where CO2 becomes the limiting factor as the plant cannot absorb anymore

23. High sunshine hours will increase photosynthetic rate. This will build up carbohydrates / sugar (photosynthates), which will be pumped into the fruit and increase Brix levels, thereby improving quality of fruit ready for harvest.

24. Temperature • Photosynthesis is affected by the air and the growing medium. Temperature affects- • How fast chemical reactions take place • If temperature’s get to high it causes other problems--wilting

25. Nutrients Iron & magnesium are needed by the leaf to produce chlorophyll, the pigment which absorbs most of the light energy for photosynthesis. Age of Plant Young and older plants are usually slower due to poorer leaf cover or being shaded by a forest canopy i.e. pine trees. This is known as Stratification Leaf Type Size & shape of leaves, forest floor larger leaves Plant Health Pest & diseases can prevent plants from photosynthesising adequately

26. Respiration • Process by which plants use energy for maintenance & growth • Oxygen is needed for respiration. • In the respiration process glucose modules are broken down to produce: • Carbon dioxide • Water • Energy- used for growth shown by cell division and chemical reactions • Respiration can take place at day or night unlike photosynthesis

27. Transpiration Loss of water vapour from the surface of plant leaves . This occurs when there is more water in the leaf than the air Transpiration pulls water from the roots to the plant into the air Depends on heat, humidity?????(what else)

28. Plant Reproduction Pollination Is the transfer of pollen from the Anther to the stigma Self-pollination—when this happens in the same flower Cross-pollination---when it lands in a different flower — How does this happen Birds bees wind insects small animals can transport pollen Fertilisation Occurs when the pollen gland lands on the stigma & grows a pollen tube down the style---- Then male gamete travels down the pollen tube and fuses (joins) with the female gamete and the embryo of the seed is formed

30. Fruit Set Is the immature fruit left on the tree after full bloom. These are the blossoms that survived pollination & fertilisation and can develop into fruit. They can be affected by poor nutrition i.e. lack of Nitrogen • Germination • Seeds will only germinate (sprout) under the following conditions— • Seed is viable (alive) • Water is present so chemical reactions can start to take place • The temperature range is correct for the particular species of seed • If available light maybe needed. Most seeds do not need light to germinate, but some do i.e. lettuce

31. Plant Growth & Light • Many factors limit light for plant growth— • The physical environment related to water (irrigation), climate, soil and topography of the area • Physiological factors—the processes of life i.e. photosynthesis • Management decisions of the grower i.e. what crop, where, when, how far seeds/plants are planted apart • Genetic potential • Biological factors i.e. diseases • Pollution and the greenhouse affect, and local microclimates.

32. Environmental (climatic) factors that can affect plant growth— • Light • Storms • Cyclones • Floods • Unusual weather patterns • Snow frosts droughts • Wind • Excessive rain.

33. LIGHT Light is needed for photosynthesis & different plants require different amounts Grasses and clover require a lot of light as they grow in open places Forest floor plants require less as they have adapted to their environment. HABITAT—is where a plant lives ADAPTATION —an inherited feature that helps a plant to survive in a particular environment i.e. forest floor plants have large leaves.

34. STRATIFACTION- Is the layering of plants that occurs in both managed and unmanaged environments. Plants that are lower receive less light than the taller plants. Orchards may have canopies on fruit trees then underneath some shade with herbs to attract bees to aid pollination. Under the herbs grasses for ground cover. Stratification occurs in pasture as well.

35. LIGHT INTENSITY (BRIGHTNESS) • Measured in LUX— • Full LUX is 100,000 at midsummer sunlight • It affects the amount of photosynthesis that takes place in plants. • Plants such as corn, potatoes, grass and many fruit trees require high amounts of LUX • Ferns and orchids require less as they have adapted and only use 50% LUX (LUX--a unit of illumination equal to 1 lumen per square meter; 0.0929 foot candle)

36. NZ Light Levels NZ has higher light levels than most other areas of similar latitude, as we are closer to the sun in our summers than northern latitude countries. The higher light intensity increases yields as more photosynthesis takes place. More light = More photosynthesis

37. Sunshine Is important at different stages for development of some crops, i.e. onions need long sunshine hours. NZ sunshine hours can vary dramatically within a short distance/area. i.e. northerly & southerly faces (aspect) Shelterbelts running north/south can cause shading of up to 20% Summer in NZ sunshine hours are much the same across the country Winter sunshine varies dramatically—Auckland receives almost twice the hours of Invercargill. Cloud cover affects sunshine hours i.e. cold wet springs & summers

38. Light energy • Sun light hits the ground and is transformed into heat, which is then radiated out. • Most heat is lost but some is absorbed by the soil. • Cloud cover can reduce the heat loss • The spread of sunlight (heat) depends on the angle the sun hits the earth’s surface • The angle the sun hits the ground depends on- • Time of day • Season • Latitude (north or south) • Topography • Higher areas get more light but also lose more heat—mountains are colder.

39. Light Quality Photosynthesis need both red and blue wavelengths to take place Light containing the correct wavelengths is important –especially under artificial conditions

40. Plant Responses to Light • Day-length • Plants know the season by the length of the day and the temperature changes. • Plant responses to day length • Change from leaf to flower development • Change in leaf colour • Grass tillering (A shoot that • sprouts from the base of a grass. To send forth shoots from the base of a grass.) • Bud break on fruit trees • Seed germination • Start of winter dormancy • Tuber and bulb formation • Leaf drop of deciduous trees

41. Photoperiodism. Is when plants respond to the season changes---day length Plants actually respond to the length of the night but this is a relatively new discovery. Temperature also has an affect Short day plants— Plants that flower with longer nights i.e chrysanthemums as these are autumn flowers, clovers & onions Long day plants— Plants that flower with shorter nights-- Petunias

42. Day length neutral plants • Plants that do not fit into either category. i.e Barley, carnations • Day-length determines flowering which then determines crop maturity • Different cultivators will flower at different times - • Early flowering cultivars have a low photoperiodic requirement • Later flowering cultivars have a higher photoperiodic requirement • Longer days versus shorter days • Different areas grow different crops and varieties. • —Wines & fruit trees • Gladioli need 12.5 hrs of day-length to flower well.

43. Growth patterns and light • Plants respond to light direction— • Positive phototropism —when a plant grows towards its light source ---bush example • Negative phototropism—when a plant grows away from the light source • Roots grow away from a light source & this helps the roots grow into the soil

44. Weather • Weather has a major effect on both agricultural & horticultural production in NZ • The main factors affecting weather are • Movement of air from high to low pressure systems—known as wind • Long narrow shape of NZ, small land mass, and the main ridge of mountains running down the centre of NZ (main divide) • Vast areas of water around NZ giving us a temperate climate • NZ in the path of the massive westerly air stream.

45. Land and sea absorb different amounts of heat from the sun and this factor also contributes to NZ’s coastal weather patterns. As the land heats up air above it rises & is replaced by cooler air from above the sea. This air movement creates wind. Hot air rises as air particles are further apart, moving faster and the total air mass is lighter.

46. Air Pressure Is the weight of ALL the air directly above an area The air pressure decreases with increasing height above sea level. Air pressure is measured using a barometer

47. Weather Maps Are drawn to show what is happening with the weather systems at a particular point in time. High pressure Known as an anticyclone or a high –H is used on weather maps to mark it. In the southern hemisphere the air circulates in an anticlockwise direction around the H Low Pressure Known as a depression or low –L is used on weather maps to mark it. In the southern hemisphere the air circulates in a clockwise direction around the L

48. Isobars Fine lines on weather maps, usually somewhat circular that connect places of equal atmospheric pressure. Also show wind direction and indicate the winds strength by the closeness of the lines--- close or far apart Troughs Are long bands of low pressure coming out of an area of low pressure Fronts Is a boundary between two air masses—usually one warm air mass and one cold air mass—

49. Cold air is heavier & denser than warm air! Warm front—warm meets cold air and produces a long period of light rain Cold front—produces short heavy rain that clears up quickly