Increasing Plant ProductionAS 91290

Demonstrate understanding of techniques used to modify physical factors of the environment for NZ plant production

Contents • THE BASICS

• Photosynthesis, respiration, transpiration, nutrient uptake, water uptake.

• Liebig’s Law of the Minimum• PLANT GROWTH

• Bud formation, flowering, pollination, fertilisation, fruit set, germination, maturation, ripening.

• ENVIRONMENTAL FACTORS• light, sunlight hours, temperature (Growing Degree Days (GDDs) or

heat units (HUs)), frost, chill requirements (as expressed by chill units), rainfall, humidity, wind, soil type, topography.

• TECHNIQUES (see PPT number 2)• CO2 enrichment, artificial shelter, sprinkler irrigation, tile

drainage, hail cannon, wind machines, reflective mulch, training systems.

Plant ProcessesThere are 6 key processes that happen inside a plant

• Photosynthesis• Respiration• Transpiration • Nutrient Uptake • Water Uptake• Fertilisation/pollination Plants having sex to produce viable seeds and fruit

Learn how to spell these!

Converting light energy to chemical energy

Using chemical energy to grow and function

Getting water from the roots to the leaves

Getting macro and micro nutrients into the plant

Getting water from the growing media into the roots

Photosynthesis

Water + Carbon Dioxide Glucose + Oxygen

Carbohydrates (eg starch)

Converted to

H2O + CO2 C6H12O6 + O2

Photosynthesis

• Photosynthesis (echalk)

Photosynthesis

Is a chemical reaction occurring in the chloroplasts found inside plant cells•One purpose of the photosynthesis is to convert light energy to chemical energy to be used by the plant.•The other purpose is to create the molecule glucose that can then be used to build cell components

Capturing Energy

• The chemical energy is initially in glucose but the plant converts some of the glucose into starch for long term storage.

• The energy is released in respiration to ‘power’ other cell processes such as the formation of proteins and lipids.

Photosynthesis - Chlorophyll• Chlorophyll is a green pigment inside the chloroplasts found in

plant cells.• Chlorophyll is essential for photosynthesis• What are the essential nutrients needed for chorophyll?

You do not need to learn the structure of chlorophyll

Photosynthesis – light absorptionSo why are plants green?Chlorophyll does not absorb green light – instead it reflects green light and it bounces back off the plant into your eye and the plant (leaf) looks green.

So what colour light should plants be exposed to?

Respiration

Oxygen + Glucose Water + Carbon Dioxide

Energy released

This energy is the useful output of respirationThe energy is released in respiration to ‘power’ other cell processes such as the formation of proteins and lipids

O2 + C6H12O6 H2O + CO2

Respiration• The purpose of respiration is to release the energy from

glucose. • The water and carbon dioxide are waste products and most of

the water and carbon dioxide exit the plants through the stomata.

• Respiration occurs in all living cells in the plant. Consequently oxygen is needed in all parts of the plants including the roots

• Summary diagram showing the relation- ship between photosynthesis and respiration

Transpiration

• Transpiration is the process of water movement into the roots. Up the stem and out of the stomata in the leaves.

Transpiration• Plant transpiration is pretty much an invisible process—since

the water is evaporating from the leaf surfaces, you don't just go out and see the leaves "sweating". Just because you can't see the water doesn't mean it is not being put into the air, though. During a growing season, a leaf will transpire many times more water than its own weight. A hectare of corn gives off about 30,000-45,000 liters of water each day, and a large oak tree can transpire 151,000 liters per year.

Respiration• Glucose + Oxygen Carbon Dioxide + Water

Carbon dioxide (CO2) is an essential component of photosynthesis (also called carbon assimilation). Photosynthesis is a chemical process that uses light energy to convert CO2 and water into sugars in green plants. These sugars are then used for growth within the plant, through respiration. The difference between the rate of photosynthesis and the rate of respiration is the basis for dry-matter accumulation (growth) in the plant.

Dry matter accumulation

• Carbon dioxide (CO2) is an essential component of photosynthesis (also called carbon assimilation). Photosynthesis is a chemical process that uses light energy to convert CO2 and water into sugars in green plants. These sugars are then used for growth within the plant, through respiration. The difference between the rate of photosynthesis and the rate of respiration is the basis for dry-matter accumulation (growth) in the plant.

Nutrient Uptake• Nutrients are up taken via the roots of the plant.

• What is the optimum soil pH range?

• The plant, through photosynthesis, fixes carbon dioxide and water in the form of sugars. The sugars are used in respiration to provide energy - breaking down again to carbon dioxide and water. Some sugars are synthesize into amino acids and finally proteins, the building blocks of living tissue.

Liebig’s Law of the minimum• States that growth is controlled not by the

total of resources available, but by the scarcest resource (limiting factor).

• This concept was originally applied to plant or crop growth, where it was found that increasing the amount of plentiful nutrients did not increase plant growth. Only by increasing the amount of the limiting nutrient (the one most scarce in relation to "need") was the growth of a plant or crop improved.

Liebig’s Law of the minimum - explained

The water level in the barrel represents plant growth.By adding more light, Phosphorus, warmth etc there will be no further increase in growth.What is the limiting factor?

Nitrogen

Effect of Light and Water on Plant Production

Click here for explanation

Kiwifruit Data Exercise

Kiwifruit DataCanopy Crop Load Fruit / m2 Fruit weight (g)

lighterlow crop load 26 113high crop load 36 107

denserlow crop load 35 91high crop load 48 84

Overall, canopy density had a greater effect on fruit weight than crop load.

Exercise 1Graph the above data to show the relationship between canopy density and crop loading

Exercise 2 Explain the effect of canopy density on fruit size.Exercise 3 Explain the effect of crop load on fruit size.

Exercise 4Justify the manipulation in terms of quantity and quality of kiwifruit.

Inside a leaf

Stomata

Site Establishment

Pests and Diseases• Pests and diseases can influence the crop that can be

grown in a certain region, ie apples aren’t grown in the Waikato and grapes are no longer commercially grown in West Auckland due to dampness of the climates (botrytis).

• New growth of all plants are very susceptible to pests and diseases.• Pests chew the tender tasty tips of plants restricting

the development of the plants and their ability to carry out plant processes.

• Fungi such as mildew destroy apical buds.• Pests chew the plants providing an entry point for

diseases which restricts the ability of the plant to grow at an optimum rate.

Aphids sucking sap from cabbages

Grass grubs under turf

Aphids sucking the growing

shoot of a rose

Mildew on growing tip

InfectedClean

• CO2 EnrichmentPlate 1. Carbon dioxide generator.

Carbon dioxide generator for a large greenhouse (burns fossil fuels to generate CO2

Plates 6b. Liquid CO2 tanks.

Liquid Carbon dioxide tank supplying a greenhouse.

CO2 Enrichment• Normal CO2 level in outside air is about 340

ppm (0.3%). All plants grow well at this level but as CO2 levels are raised by 1,000 ppm photosynthesis increases proportionately resulting in more sugars and carbohydrates available for plant growth.

• Any actively growing crop in a tightly clad greenhouse with little or no ventilation can readily reduce the CO2 level during the day to as low as 200 ppm. The decrease in photosynthesis when CO2 level drops from 340 ppm to 200 ppm is similar to the increase when the CO2 levels are raised from 340 to about 1,300 ppm

Fruit Development• Which of the following Horticultural products do not develop

from a flower.

• Strawberries• Bannanas• Carrots• Beans• Peas• Pumpkin• Corgetts• Tomatos

Fruit Development• 5 stages of fruit development

• Bud set• Bud burst• Pollination/ fertilisation• Fruit development• Fruit ripening

Link the five stages of fruit development with an image

1.Bud set2.Bud burst3.Pollination/ fertilisation4.Fruit development5.Fruit ripening

Then give each a definition

Step Environmental factors affecting step

Bud set The bud develops at the node. On some plants this occurs on new growth and on some it occurs on old growth. Most fruit trees require this bud tissue to undergo a cold period before it will burst.

Bud burst The basic sturucture of the flower has developed inside the bud and then bursts out (blossums).

Pollination/ fertilisation

Most horticultural crops are insect pollinated. The exception is cerrals and maize.Fertilisation is the process of the pollen grain growing into the flower tissue

Fruit development The fruit swells

Fruit ripening Starch is converted to sugar in the fruit to make it attaractive to animals/ birds.

Environmental factors affecting fruit development

Step Environmental factors affecting step

Bud set Temperature,

Bud burst Frost – young flower suseptable to frost damageWind - young flower suseptable to wind damage

Pollination/ fertilisation Anything that reduces insect activity reduces pollination (wind, temp, rain)Fertilisation is the growth of the pollen tube. So temp and availiability of sugars in the flower tissue affect fertilisation

Fruit development Hail, sun, temp, water availibility

Fruit ripening Sun. temp