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Describe physical factors of the environment and

techniques used to modify them for plant production

Agricultural and Horticultural Science 2.2

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Lessons

1. Introduction

2. Plant Parts

3. Stems & Leaves

4. Flowers & Seeds

5. Photosynthesis & Respiration

6. Plant Reproduction

7. Stratification

8. Plant Responses to Light

9. Weather

10. Water

11. Temperature

12. Growing Degree Days (GDD’s)

13. Wind

14. Site Evaluation

15. Changing the Amount of Light

16. Windbreaks

17. Frost & hail damage prevention

18. Pollination & Fruit Set

19. Carbon dioxide enrichment

Websiteshttp://www.teara.govt.nzhttp://www.teara.govt.nz/TheSettledLandscape?utm_campaign=feature-entry&utm_medium=feature&utm_content=9july&utm_source=homepage-feature-0http://www.maf.govt.nz/mafnet/schools/kits/ourland/timeline/http://www.maf.govt.nz/mafnet/schools/

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Explanatory Notes1 This achievement standard is derived from The New Zealand Curriculum, LearningMedia, Ministry of Education, 2007, and is related to the material in the Teaching andLearning Guide for Agricultural and Horticultural Science, Ministry of Education,

2010at http://seniorsecondary.tki.org.nz.2 Demonstrate understanding involves describing how techniques modify physicalfactors of the environment for commercial plant production in New Zealand.Demonstrate in-depth understanding involves explaining how the use of techniquesinfluences commercial plant production in New Zealand.Number AS91290 Version 1 Page 2 of 2Demonstrate comprehensive understanding involves evaluating techniques used tomodify physical factors in terms of economic and/or environmental and/or socialimpact of commercial plant production in New Zealand. This may involve comparingand contrasting or justifying the use of the techniques.3 Physical factors are selected from frost, wind, light, temperature, water, humidity,

air,and soil.4 Plant production relates to crop yield, quality, and timing.

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Parts of the PlantPlants are made up of – Roots Stems Leaves Flowers Seeds

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Roots-Roots & stems are the main transport system for the plant. Roots support the following processes-GrowthPhotosynthesisReproduction-this happens in the upper part of the plantAnchor plantsAbsorb & dissolve waterStore foodOxygen diffuses into Carbon Dioxide out of the root hairs

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Root hairs Very small & short life span

Growing tip Cells are actively divided & the root pushes downwards

Root cap Tough cells that protect the growing tip

Xylem Tissue Transports water & dissolves nutrients from the roots up to the cells & leaves

Phloem Tissue

Transports sugar to the leaves for growth or storage

The phloem & xylem group together and are called the Vascular bundle-- is found in the roots and the stem

Woody cells are produced to support the plant as it grows

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Root hairs from a radish

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StemsContinues to transport nutrients from the roots up the plant & support the upper part (leaves) of the plant

Functions of stemsProvide support & hold plants to the lightTransport water, sugar & nutrients around the plantCarry out a small part of photosynthesis

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Internal Stem StructureThe stem is made up of several layers-

Epidermis Thin outer layer of cells protecting & preventing water loss

Cortex & Pith

Has several cell types & air spaces. Gives plant shape & stores food

Vascular Bundles-

(3 cell types )

Made up of the Phloem & Xylem cells. The Cambium cells produce new Phloem & Xylem cells

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Cross section of stem Structure of stem

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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

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LeavesHave 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

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FlowersThe 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

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Parts of the flower

Petals Protect plant parts, attract pollination animals with scent & colour

Sepals Protect the flower bud, carry out photosynthesis

Anther Contains pollen & the male sex cells (gametes)

Stigma Catches the pollen grains

Style Tube connecting stigma to the ovaries

Ovary Contains ovules & develops into the flesh of the fruit

Ovules Contains the female sex cells (gametes) & develops into seed after fertilisation

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SeedsCome in many shapes & sizesPlants use the wind, water, insects & birds to disperse the seeds. Seeds functions are to-Create a new generation of plantsDispersal mechanism

Seed structureSeed are made up of –An embryo --new plantFood store--endosperm & cotyledonA protective seed coat—testa

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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.

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FruitAre the ripened ovaries of the flowerProtect the seedProvide nutrients for the seedHelp with seed dispersal

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Equation 6CO2 + H2O + energy === C6 H12 O6 + 6 O2

Carbon Water Glucose OxygenDioxide

Photosynthesis Is the process plants use to make food Photosynthesis is used by the plant forFood for growthMaintenance and developmentPhotosynthesis takes place in the chloroplasts of the leaf

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Rate Of Photosynthesis This can be fast or slow depending on Amount of light Amount of chemicals availableTemperature 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

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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

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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.

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TemperaturePhotosynthesis 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

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NutrientsIron & magnesium are needed by the leaf to produce chlorophyll, the pigment which absorbs most of the light energy for photosynthesis.

Age of PlantYoung 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

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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 dioxideWaterEnergy- used for growth shown by cell division and chemical reactions

Respiration can take place at day or night unlike photosynthesis

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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)

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Plant ReproductionPollination Is the transfer of pollen from the Anther to the stigmaSelf-pollination—when this happens in the same flowerCross-pollination---when it lands in a different flower —How does this happenBirds 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

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Fruit SetIs 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

GerminationSeeds 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 seedIf available light maybe needed. Most seeds do not need light to germinate, but some do i.e. lettuce

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Plant Growth & LightMany factors limit light for plant growth—The physical environment related to water (irrigation), climate, soil and topography of the areaPhysiological factors—the processes of life i.e. photosynthesisManagement decisions of the grower i.e. what crop, where, when, how far seeds/plants are planted apartGenetic potentialBiological factors i.e. diseasesPollution and the greenhouse affect, and local microclimates.

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Environmental (climatic) factors that can affect plant growth—LightStormsCyclonesFloodsUnusual weather patternsSnow frosts droughtsWindExcessive rain.

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LIGHTLight is needed for photosynthesis & different plants require different amounts

Grasses and clover require a lot of light as they grow in open placesForest floor plants require less as they have adapted to their environment.

HABITAT—is where a plant livesADAPTATION —an inherited feature that helps a plant to survive in a particular environment i.e. forest floor plants have large leaves.

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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.

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LIGHT INTENSITY (BRIGHTNESS)Measured in LUX—Full LUX is 100,000 at midsummer sunlightIt affects the amount of photosynthesis that takes place in plants. Plants such as corn, potatoes, grass and many fruit trees require high amounts of LUXFerns 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)

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NZ Light LevelsNZ 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

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SunshineIs 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 countryWinter sunshine varies dramatically—Auckland receives almost twice the hours of Invercargill. Cloud cover affects sunshine hours i.e. cold wet springs & summers

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Light energySun 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 lossThe 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 daySeasonLatitude (north or south)Topography

Higher areas get more light but also lose more heat—mountains are colder.

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Light QualityPhotosynthesis need both red and blue wavelengths to take place

Light containing the correct wavelengths is important –especially under artificial conditions

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Plant Responses to LightDay-lengthPlants know the season by the length of the day and the temperature changes.

Plant responses to day lengthChange from leaf to flower developmentChange in leaf colourGrass 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 treesSeed germinationStart of winter dormancyTuber and bulb formationLeaf drop of deciduous trees

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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

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Day length neutral plantsPlants 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 treesGladioli need 12.5 hrs of day-length to flower well.

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Growth patterns and lightPlants respond to light direction—Positive phototropism —when a plant grows towards its light source ---bush exampleNegative 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

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WeatherWeather has a major effect on both agricultural & horticultural production in NZThe main factors affecting weather areMovement of air from high to low pressure systems—known as windLong 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.

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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.

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Air PressureIs 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

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Weather MapsAre drawn to show what is happening with the weather systems at a particular point in time.

High pressureKnown 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 PressureKnown 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

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IsobarsFine 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

TroughsAre long bands of low pressure coming out of an area of low pressure

FrontsIs a boundary between two air masses—usually one warm air mass and one cold air mass—

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

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WATERWater affects the growth of plants as it is essential in all biological reaction in the plant from germination to seed production

Water is needed for-Biochemical reactions –photosynthesisWashes out growth inhibitors in seedsNeeded to dissolve chemicalsUsed in seed productionHelps control plant temperatureUsed during fertilisationHelps plant cells maintain their shape

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Too little waterPlant growth slows down or stops & plant processes are affected-Enzyme activity decreasesNutrient transport is slowedSynthesis of biological substances decreasesRespiration of plant cells slows downPhotosynthesis decreases

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Too much waterDecreases the amount of oxygen available to the plant roots causing respiration to decrease leading to less energy so the plant absorbs less water and begins to wilt and the plant may die

Other factors affectedLeaching & loss of nutrientsErosion on sloping soils Bees & other beneficial insects won’t operate in wet weatherMany plant (mainly fungal) grow well in humid conditions

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Drainage –is usually used in wet soilsThere are 3 types of drainage –Open drains –these are a drain dug and not filled in. these are cheap to build but maintenance costs are high and usually need to be fenced off.

Tile drains- a plastic pipe or clay tile pipes are laid in a trench which is back filled the pipes are laid in pea metal for about 100 mm’s around the pipe. The pea metal acts as a filter preventing soil from clogging the pipes. These are very effective but are expensive to put in but have minimal maintenance costs

Mole drains- A plug of 100mm is dragged through the soil to an open drain or creek. This drains the water away. Mole drains only have a life expectancy of 4-5 years

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HumidityThe amount of water vapour in the air at a particular timeRelative humidity-Amount of water in the air at a point in time compared to the maximum amount of water the air could hold at that time100% humidity is when the air is completely saturated0% humidity is when the air is completely dry

A range of about 60-90% relative humidity is common in most of NZ

The amount of humidity determines the amount of cloud, rain, hail, frost or snow that forms.

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When humidity is high plants & soil lose less water via transpiration because the air is already saturated with water

Fungal diseases grow well in humid conditions & more animal health problems—very few sheep in Northland

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HailHailstones grow in clouds when water drop below 0 degrees C. Hail forms around dust and seed and build up layers like an onion. More layers = bigger hailstones

Can cause lots of damage to fruit trees & crops stripping & bruising them and makes it easier for diseases to enter the plant causing further damage

Western areas get more hail but most damage is done in the East usually.

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SnowMost snow in NZ falls on the Southern Alps and the volcanic plateau Rarely in NZ does it snow below 500 metres or at least settle for an extended period. Lower lying areas may get an occasional snowfall especially in the South Island.

Heavy snow causes plant damage

Snow occurs when warm air from the north meets cold air from the south. Snow is produced when the water vapour in the cloud condenses at temperatures below freezing and forms ice crystals

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Frost

Is when ice crystals form on the ground in cold conditions. If the ground temp is below freezing before dew forms ice crystals grow forming frost

Frost occurs almost everywhere in NZ

Radiation frosts are the most common frosts. These form when there is clear still night. If there was high humidity, high cloud or a fog forms.

Dew Is formed when heat is lost from the ground at night and a layer of cold air forms at this level. As the air cools it becomes saturated with water and some of the water condenses forming dew.

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Frost severity depends on- The amount of heat the local soils store—soils with high

organic content store more heat Local topography—cold air travels down to lakes and

ponds, north sloping faces get least frost as do coastal areas

Type & height of shelter. Shelter belts can reduce the flow of air causing frosts to form

Cultivated land loses heat faster than pasture or forest land Frosts occur in winter as more heat is lost from the ground

& longer nights lower levels of sunlight.

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Frost on branches

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Frost severity Slight -1 to -3Moderate -3 to -6Severe -6 to -9Very severe -9 and below

Frosts are measured horizontally 25mm above the ground

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Temperature

Temperature affects the chemical reactions & physical responses of the plant which control growth & development

All plants have optimum temperature ranges for maximum growth & flowering

Optimum temperature = productivity or growth is greatest. All plants have a temp where growth starts or stops!

The temp range governs what plants grow successfully in any area.

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High Temps (above optimum) Low temps (below optimum)

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High Temps (above optimum) Low temps (below optimum)

Increase rate of PS & respiration Lower rates of PS & respiration

Can kill plant Can kill plant

Reduce yields Reduce yields

Sunscald & windburn of leaves & fruit

Reduce germination rates

Increase transpiration & evaporation

Cause dormancy

Damage flowers Damage flowers

Wilting

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Air temperature in NZ Coldest month usually July Warmest month usually February Mean temperature’s range from 10c to 15c. There is little

variation in mean temps---on the West Coast around 8 degrees Central Otago 13 degrees. It is unusual in NZ to have large temp

ranges---Tree ferns can be found 6kms from glaciers

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Growing Degree Days

Plants need a certain amount of heat to survive---called the BASE (min) temp for a particular plant.

No growth takes place below the base temp for a particular crop Growth only takes place once the AIR temp is past the BASE temp

Each degree above the base temp can be counted each day & added up over a period of time to give the number of growing days available----growing days are the accumulated heat for an area above a base temp

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GDD’s take into account seasonal variations where calendar days don’t. GDD is a heat sum of daily mean temps above a minimum temp. Base temp of 10C--warm season crops: maize, fruitBase temp of 5C--cold season crops: peas

GDD’s are calculated by—GDD = sum of daily mean temp – base tempGDD = Σ (T-base temp)Adding up the monthly figures (mean temp above the base temp) gives a yearly total.

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Using GDD’sThe number of GDDS a crop needs to mature depends on the species & variety. I.e. sweet corn (base temp 10) needs 800-1000 GDD A different variety will be used in Southland to the Waikato

Other factors affect GDDEarly maturing grapes need a heat accumulation of 850 GDD’s therefore they could be grown in Wellington based on heat units—but there wouldn’t be enough sunshine during flower initiation so harvest cannot be guaranteed on heat units aloneAir temperature is measured with a thermometer Often a min/max thermometer is used.

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Winter Chilling Requirements Some plants have winter chilling requirements – Pip & stone fruit to encourage bud growth in springSome plants need particular temperature’s to ensure flowering.

Soil TemperatureSoil temperature directly affects--Plant root activities-- water uptake & growthSeed germinationActivity of biological organisms—worms

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Soil temp is determined by many factors- Climate Season Air temp Aspect Soil colour Soil texture Plant cover Water status Soil depth.

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VERNALISATION=The effect of temperature on flower initiation & bud break This starts at low temperature’s which encourage the plant to flower during warmer weather following winter (spring) Perennial ryegrass is an example

BOLTING= winter chilling of the wrong length can cause premature flowering—can happen with vegetables & the crop is uselessThis happens easily with Chinese cabbage. They need temperatures of 16-20 but if temperatures fall below 10 for 10-14 days bolting will occur

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  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Daily Max Temp (oC) 26 27 24 20 18 16 15 17 19 22 22 24

Daily Min Temp (oC) 17 17 15 14 11 9 9 10 13 14 14 15

Rainfall (mm) 110 100 105 80 90 85 90 120 100 110 100 105

Frost days 0 0 0 0 1 2 2 3 1 0 0 0

GDDs 357 336 295 210 140 75 62 109 180 248 240 295

Average humidity (%) 58 60 69 70 74 77 70 78 80 84 80 70

The farmer wishes to plant tomatoes. These are very frost prone and need 950 GDD’s from planting to harvest To gain the best prices the tomatoes need to be harvested by January 31. When should he plant and why

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GDD’s in the USA July

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Effect of frost on root hairs

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Wind

Prevailing windIs the direction the wind most commonly blows FROM in aparticular area. NZ has a westerly wind pattern due to the earth’s spin. This changes in many areas because of the NZ’s

topography i.e. Wind gets funnelled through Cook Straight by the mountains in the North & South Island

Wind direction can be shown using a windsock ---Think of airstrips.

Wind Speed Measured by a anemometer Wind is recorded in Knots or kilometers per hour (km/h)

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Negative effects of wind

What are these? Erosion Increased evaporation Increased transpiration Spreading of air-borne

diseases Lodging (collapsing) of

crops making harvest difficult

Wind chill reducing the heat available for plants---Lower PS rates

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Uneven plant growth—trees Wairarapa

Reduced or damaged plant growth—smaller leaves reduced PS

Wind-damaged fruit Upsetting insect and

small bird—affects pollination

Spreading of some weeds –thistles etc

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Positive affects of wind

Reduced frost Dries the outer leaves of plants preventing fungal growth Drying of grain crops and hay Assisting pollination

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Topography & Microclimates

Topography

Is the physical shape or landform of an area. NZ’s landform is varied as we have 3 islands divided by

ranges and mountains The effect of this is that in NZ intensive farming takes

place on the flats (usually found near the coast) The hill country is used for pastoral semi/extensive

farming and/or forestry.

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Te Mata Peak

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Effect of topography on soil typesTopography helps determine the soil types that form.Different soils can form from the same parent material but be different because of topography

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Soils at the top of a slope Soils at bottom of a slope

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Soils at the top of a slope Soils at bottom of a slope

Shallow & stony-Infertile Fertile

Acidic Deep

Low in beneficial soil animals High in beneficial soil animals

Low moisture levels Waterlogged -- poor drainage

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Effect of topography on climate

The mountain chain running down NZ forms a barrier in the path of the warm wet westerly winds and causes big differences in the west/east coast weather patterns.

MicroclimatesNZ is full of these –created by topography, slope, aspect, soil types prevailing winds, closeness to the sea---1250mm of rain on the Cooks Tooth 750mm in Porangahau.

Microclimates generally favour valleys & northerly faces will be warmer

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Factors creating microclimates-SlopeAspectWaterPlant coverPrevailing windsExposure to windShelter belts and buildings

Sometimes a microclimate will enable a crop to be grown where otherwise it may be marginal---Maize, tomatoes, peas.

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Site EvaluationThe climate, topography & soil type should match the crops requirement. The economic success of the crop will depend on this.

If the site is not compatible it may need to be modified using –

ShelterbeltsDrainage systemsIrrigation.

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ClimateLength of growing seasonThis needs to match the crops requirement i.e. radishes need 30 days, rock melons 140 days so you have to be aware of frosts. You should take harvest date and work backwards to see if the crop is feasible.Seasonal fluctuations of air and soil temperatures

Air temperature can be altered by-ShelterbeltsArtificial structures Choosing a suitable microclimate

Soil temperature’s can be changed by -Drainage-helps avoid soil temperature fluctuationsAdding organic matter-make the soil darker warms it up.

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Soil Temperature

Soil temperature directly affects-- Plant root activities-- water uptake &

growth Seed germination Activity of biological organisms—worms

Soil temp is determined by many factors- Climate Season Air temp Aspect Soil colour Soil texture Plant cover Water status Soil depth.

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Seasonal wind Wind direction, strength, frequency can be altered with shelterbelts &/or artificial structures

Correct use of cultivar will help i.e. short thick stemmed barley will not break as easily in the wind.

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Rain amounts & seasonal distributionConsider both these when selecting a crop to grow especially if irrigation maybe needed.

Rainfall historyToo little water can be overcome by using irrigation—has to be good quality water probably should be analysed to determine the quality Excessive water-poor pollination, harvesting problems i.e. sprouting of wheat—good drainage & soil structureContour/terrace ploughing-avoids erosion and traps any moistureMulching-layer of organic material (pea straw)Pasture, tussock and stubble can capture moistureSunshine hours-choose a good site or sheltered if needed

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Pollution of a siteSoil pollution can be caused by chemical, rubbish or oil-based products careless or indiscriminate disposal of these products.

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Soil Structure, texture & pH of the siteThese can be changed to suit a crop but can be very expensive. Use a soil map to determine the crops suitability.

Crops like-Good well drained soil, good soil textureWell balanced nutrients & appropriate pH levelNo pan Water holding ability

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Topography & AspectDesirable sites tend to be-North facingSlightly sloping for drainageGood access for machinery—forestry sitesSuit the crop grown

Water table that suits the cropPlanting on the leeward side of a large lake can provide a better microclimate as the lake water provides less temperature fluctuations over the year.Appropriate frost levels

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Contour cultivation Ponding

Irrigation Mulching

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Changing the Amount of LightIncreasing/maximising light levelsLight is essential for photosynthesis and is an essential factor in achieving this

Plant spacingSpacing should be to achieve maximum leaf exposure to the plant without sacrificing valuable ground area or so the crop doesn’t compete with itself—a careful balancing act

WeedsWeeds compete for light so they need to be removed.

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GrazingGood grazing will keep the pasture at the correct level to enable all the plants to get the correct amount of light—i.e. clover and stratification.

Crop row orientationTry to grow crops from north to south to ensure maximum sunlight—more important with long term crops like grapes.

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Matching a plant species to the sites light levels Plants should be planted in an area that is compatible with their light needs. Full sun plants (6-8 hrs per day) plant north/south Partially sun plants (4-6 hrs) plant east/west. These plants can also be grown in shade houses or

well shaded microclimates

Day lengthAs the day length changes throughout the year it cannot beeasily controlled outdoors so plant crops that- Suit the day length Suit the season’s day length With no day length requirements

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PruningPruning techniques affect the amount of light different crops can get. Different techniques can-- Open the canopy so more light gets into the trees Shade can reduce the temperature of fruit which can slow

maturity and reduce fruit size Thin young fruit—common with apples

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TrainingSome plants can be trained. Usually wires are used. – grapesapples kiwifruit etc Is done to prevent leaf canopy blocking the sunlight out

ensuring good photosynthesis. Called espaliering—training trees to grow vertically or

horizontally along wires

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Artificial lightThis can be supplementary or used entirely. Different species require different light levels.

This depends on--Wavelength must be suitable for photosynthesis and use the correct red or blue light wavelengthDistance from the plant must be correct –intensityLength of time lights are on/off must match the crops requirement

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Decreasing Light levelsSome crops don’t require high light levels at certain times and shading maybe necessary. The type of shade will depend on the crop and what structures are available. Cost is an important factor.

Shading Shade fabrics can be used –protect crops by 30-70% depending on the fabric. Most fabrics are now UV tolerant & last up to 10 years

Shade HousesIn NZ these are multipurpose and are used throughout the year-Provide shelter from wind & frost as well. Used for hardening offGlasshouses may need shading as well to prevent leaf burn and too much light. Use solar paint or shade cloth

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WINDBREAKSServe several purposesReduce wind speed and moisture lossIncrease soil & air tempReduce wind damage to plantsCan provide shadeCan provide a habitat for beneficial insects & animals

DisadvantagesFrosts can be more severeGive pests & diseases somewhere to shelter over winterTake up space of other plantsCompete with other plants for light & nutrientsCost of setting up & maintaining

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Windbreak designPermeable (open) windbreak is more effective---create gaps that reduce the force without creating turbulence--shelter 10-20 times the height Solid barrier-- shelter 1-2 times the height 50% solid –10 times the height shelterShould have wings at each end to prevent swirlingWindbreak spacing should be 20 times the height to make effective use of them

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Most windbreaks are only 2-3 trees wide—in snow prone areas should be wider spacing and thicker width-snow gets blown into the wind breakLarge areas can be planted with tall trees on the outside and smaller on the insideCan be planted across a valley to prevent funnelling and make best use of light

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Living windbreaks

Advantages of live shelter

1. Cheap to set up

2. Last for many years

3. Attract wildlife & aesthetic

4. Multipurpose

5. Can smother weeds

6. Costs can be shared with neighbours or subsidised

Disadvantages

1. Weed or irrigation control during establishment

2. May need pruning

3. Pests & diseases

4. Death gaps will need replacing

5. Stock fencing

6. Subsoiling next to crops may be needed

7. Roots may block drains

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Live shelter Live shelter is multipurpose & offers-ShadeErosion controlStock & bee fodderTimberStock over-winter grazing

Trees that are good for shelter-CedarTaupataGumsPoplarWattlesPinesMacrocarpa

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Preventable shelterbelts problems-Drains—don’t plant closePublic structures—power lines, main road

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Artificial windbreaksExpensive to set up but advantages are--Instant shelterLow maintenance usuallyTake up little spaceDoesn’t use soil water or nutrients

Often used when living shelter is establishing.

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Frost & hail damage preventionFrostMost damage is usually done when a late frost strikes—grapes in HB

Pre planting frost controlCrop losses can be prevented or minimised byFrost free sitesPlant crops after frosts have finishedFrost tolerant cropsLimiting water to the minimum—hardening offUse cover on tender cropsRow orientationPrune lower branches of shelterbeltsPlace crops near heat sources i.e. lakes

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Protection methods usedOverhead sprinklers—go off automatically when temp gets to -1Helicopters- by creating an inverted layer of heat Wind machines– by moving the air to prevent the frost from settling Frost pots—not used much now as very pollution prone

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Hail PreventionHail netting—expensive but getting cheaperHail guns-work by releasing a sonic boom which breaks up the hailstones Hail cannon—work ok on small hailstones onlyInsurance—expensive 6-15% of crops final value. With limits on the payout.Hail rockets-not used much in NZ as very expensive-fires silver iodide into the air causing rain to fall instead of hail.

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Pollination & Fruit SetPollinationMain methods of pollination in NZ are InsectsBirdsAir movement

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Improving Wind PollinationWind pollination occurs in-Wind pollination is best in light winds as large amounts of pollen are producedWet weather is bad for wind pollination & crop levels may decreaseOverhead irrigation should be kept to minimum during pollinationGrasses including grainsSome nuts—walnutsCrops like grapes & tomatoes

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Encouraging Insect PollinationWith insect pollination the pollen does fall from the open anthers as with wind pollination but sticks to outside of the anthers until it is transferred by insects.

Plants that need insects for pollination-Clovers & some pasture plantsFruit trees, flaxes

Bee-hives can be used to help insect pollination—Avoid the use of insecticides when bees are pollinating as they may kill the beesSupply food for the bees etc at other times of the year

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Causes of poor pollination & how to avoid this

No suitable insects. Some insects have been introduced to NZ for pollination purposes i.e. bumblebees for red clover. Plants in glasshouses & other environmentally controlled structures may need artificial pollination i.e. hand or introduce insects.Insects may be attracted to other plants in the crop rather than the crop itself.Hives should be close or in the same paddock as the crophttp://queenbeejan.com/kindsbee.htm

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Pollen or Stigma InjuryCaused by 1. Frosts, rain or hail—Temps

below zero can kill the pistil and/or slow the growth of the pollen tube. Bees do not operate well in cold temps

2. Wind—can dry out stigmas & prevent pollination. Bees cannot operate in high winds. Some plants need light winds to pollinate though

3. High Humidity—prevents insect & wind pollination. Overhead irrigation should be used carefully during pollination to prevent humidity in the crop

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4. No Pollen Bearing Flowers—crops like apples, pears, plums need to have a plant growing close to the crop—Pollinator—The pollinator will be a cultivator that releases its pollen when the stigma is receptive

Cross pollinated apples produce heavier crops than self-pollinated cropsMonoecious--Walnuts are wind pollinated but also need a Pollinator. They produce separate male & female flowers on the same tree.

Dioecoius—male flower on one tree-female on another. Kiwifruit is an example of this. The female stamens does not produce pollen so both male & female plants need to grown for pollination

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5. Low air movement—usually in an enclosed environment Plant hormones can be sprayed onto the plant

6. Light levels—good light levels are needed for fruit set Plants like grapes produce leaves before they flower. These crops need to be pruned & trained to ensure good light levels to get as many flowers as possible.

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Controlled EnvironmentsAre used to protect plants from the natural environment & to provide ideal growing conditions

A controlled environment is dependant on- Water availabilityLight intensity & durationAir exchange including oxygen Carbon-dioxide levelsHumidityTemperatureNutrient levelsGrowing mediaAir movement

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Structures UsedCan be simple row covers to shade houses, plastic houses & glasshouses that are fully automated and controlled.

A well sited glasshouse should—East/west orientation for less roof shading of the cropGet full sun Protected from the windNo overhanging treesLevel, well drained site

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Materials used Many materials can be used but should beGood protection from environmental extremesMany types of cladding are available.Good light penetrationLow maintenanceLow heat lossUV stabilised

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Carbon dioxide enrichment

Reduced heating deficit at night

Warmer soils & improved root growth as higher temp’s can be maintained

Higher yields Better fruit set Earlier yields

Lower heating cost as soil is warmer

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The Importance of Carbon Dioxide (Co2)for Healthy Plant Growth

Most of the applied research on greenhouse crops has dealt with effects of environmental conditions on plant growth. Factors such as water, light, temperature and nutrients are more easily controlled for optimum growth. It is now possible to also control and accurately measure Carbon Dioxide concentrations in greenhouse and Controlled Environment Garden (CEG) atmospheres.

Carbon Dioxide (CO2) contributes to plant growth as part of the miracle of nature known as photosynthesis. Some of these sugars are converted into complex compounds that increase dry solid plant substances for continued growth to final maturity. However, when the supply of carbon dioxide is cut off, or reduced, the complex plant cell structure cannot utilize the sun's energy fully and growth or development is curtailed.

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Although carbon dioxide is one of three main components which combine to produce the products necessary for plant growth, the amount of carbon dioxide in the air is only 0.03% (250 to 330 parts per million).

Make up of the atmosphere

CO2-0.03%

nitrogen 78%,

oxygen 21%

trace gases 0.97%

Tests have proven that during the winter months CO2 concentrations inside greenhouses is invariably much lower than in outside air. This same phenomenon has been shown in controlled environment gardens.

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CARBON DIOXIDE (CO2)IMPROVES PLANT GROWTH AND QUALITYResearch has shown that in most cases rate of plant growth under otherwise identical growing conditions is directly related to carbon dioxide concentration.

The amount of carbon dioxide a plant requires to grow may vary from plant to plant, but tests show that most plants will stop growing when the CO2 level decreases below 150 ppm. Even at 220 ppm, a slow-down in plant growth is significantly noticeable.

Colorado State University conducted tests with carnations and other flowers in controlled CO2 atmospheres ranging from 200 to 550 ppm. The higher CO2 concentrations significantly increased the rate of formation of dry plant matter, total flower yield and market value.

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CARBON DIOXIDE (CO2)CUT OPERATING COSTSWHILE INCREASING PRODUCTIONDuring the winter months, plants near the middle of greenhouse beds generally do not grow as rapidly as plants at the edge. Tests have shown CO2 concentration lower in the center of greenhouses than near the outer walls. Outside air leaking in through small openings around windows carries enough carbon dioxide to satisfy requirements of plants at the edge of beds. The lack of adequate CO2 lowers the average plant yield quality and market value.

Costly methods of stimulating plant growth, in order to market them at optimum profit, are presently being used. One of these is extra heat (with open vents). This, however, increases operating costs and decreases profit. On the other hand, growers using CO2 are cutting their heating costs as much as 50% while realizing extra profit from increased crop production.

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SAMPLE RESULTS FROM CO2 ENRICHMENT STUDIESBIBB LETTUCEBy adding CO2 to the atmosphere around the plant, a 40% crop increase was achieved. Whereas previous crops averaged 22 heads per basket, lettuce grown in the increased CO2 atmosphere (550 ppm) averaged 16 heads of better quality per basket.

CARNATIONSCO2 levels to 550 ppm produced an obvious increase in yield (over 30%), but the greatest benefits were earlier flowering (up to 2 weeks) with an increased percentage of dry matter.

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ROSESThe addition of controlled carbon dioxide provided a remarkable improvement in blossom quality, number and yield. Plants consistently produced many more flowers with 24 to 30 inch stems. Average yield was increased by 39.7%.

TOMATOESWork in experimental stations has shown that crop increases of as much as 29% have been obtained by increasing the CO2 concentration. More desirable firmness and more uniform ripening are also observed.

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