uq.edu.au/agriculture/sunflower-competition

SUNFLOWER COMPETITION

2017

School of Agriculture and Food Sciences

Experiment Booklet

With sunflower seeds, some simple steps and expert information, the UQ Sunflower Competition is a fun and interactive way for Australian high school students to get into the science behind growing our food. The activities in the competition can be tied into key areas of the curriculum, giving students an opportunity for hands-on learning about how plants interact with the environment to give us the food on our table.

As part of the competition, your class could investigate:

• Water and plant nutrition: using potting mixes and soils;

• Plant nutrition using fertilizers (organic and inorganic); or

• Impact of light on photosynthesis and growth using light regimes.

The following booklet provides six detailed experiments that have been prepared by academic and technical staff from the UQ School of Agriculture and Food Sciences.

Key dates for your class diary: • Planting Day: Tuesday 28 February 2017

• Weigh–in Day: Tuesday 16 May 2017

Enquiries:UQ Sunflower Competition Team

telephone 07 3346 1467 email science.events@uq.edu.au

The 2016 Overall Grand Champions from Glasshouse Christian College with a

sunflower weighing 2.023kg.

Dear Teachers

The following series of experiments aim to demonstrate how the environment and other variables can affect plant growth and development in the context of food production. The experiments are designed to be aligned with both curriculum topics in your subjects and development of knowledge around scientific investigation.

The experiments vary in complexity and explore different themes including: photosynthesis and growth, importance of soils, nutrients, water and climate change on crop production. The experiments are designed for a range of levels across the high school science curriculum, enabling you to tailor the experiments to a level appropriate to your class.

The experiments should provide a platform for students to develop questions and hypotheses that can be investigated scientifically, with replicated treatments enabling analysis of data to identify explanations for findings. The design of the experiments should provide an opportunity to develop the concepts of replication and randomisation for advanced students. Having multiple pots for each treatment is also useful in the case of accidental damage or attack from pests.

The main aim of the competition is to have fun and to help your students increase their understanding of the science and the principles of scientific investigation.

Happy growing and I wish you all the best throughout the competition.

DR MARISA COLLINS Senior Lecturer UQ School of Agriculture and Food Sciences

MS KARLI KOLLEGGER First Year Coordinator UQ School of Agriculture and Food Sciences

Introduction Agronomy is the science behind growing plants to produce food, fuel and fibre. The main aim in growing crops is to maximize yield and profit whilst minimizing environmental impacts. To maximize yield many variables contribute to successful growth of plants including:

1. Genetics / breeding

2. Soil or growing substrate

3. Water availability

4. Nutrients

5. Light

6. Presence of pests and diseases.

The experiments described in this booklet investigate one (or more) of these variables using sunflowers as our crop.

The following are suggested experiments you can run without any experimental design. They can be easily modified using some of the variables discussed above.

Why not design your own experiment! Visit the UQ sunflower website for suggestions on designing your own experiment:

uq.edu.au/agriculture/sunflower-competition

Experimental NotesSome general notes on running an experiment with sunflowers:

• To initiate sunflowers: Plant four seeds towards the centre of each pot at a depth of 3–4 cm and water well to initiate germination. Depending upon soil temperature, seedlings should emerge in 5–7 days. Pots should be thinned to one plant per pot 7 days after emergence.

• Depending upon temperature and variety, your plants should flower in about 7–8 weeks. Prior to that, you will notice a star shape structure in the apex which swells and eventually becomes the flower bud.

• Plants should be grown in full sun and are best protected from wind if possible. You will need to water your pots regularly. Standard procedure is to water until “replete” (water flows freely from the bottom of the pot). If water is one of your experimental variables, you may need to measure the amount you add, e.g. 100ml per pot per day.

• When handling potting mixes, ensure that you and your students wear protective masks and gloves to minimise the risk of disease (the risk is low).

• Observe the plants for any pests or disease and take control measures as necessary. This will not invalidate your experiment! Take note in the results and discussion.

Seed Germination ExperimentAim To compare the effect of two seed treatments on successful germination rates of sunflower seeds.

Level and ContextBASIC

Seeds need to break “dormancy” before they will germinate. This can sometimes be a problem for agronomists and plant breeders who need to ensure stored seed will germinate.

Materials and MethodsYou will need at least 12 sunflower seeds. The more seeds you use, the more robust the experiment. Treatments include:

• Control (no treatment)

• Scarification (cut the tip of the seed open with a sharp knife, or nail clippers)

• Freeze-thaw (place the seeds in a freezer for 30 mins then allow to return to room temperature. This may be repeated several times)

Seeds can then be germinated on moistened paper towels or on the surface of moist potting mix. Emergence should occur within a week. Take daily observations.

Observations and Data CollectionGet your class to observe the type of germination (epigeal) and draw a diagram. Count the days until the hypocotyl (the plant) and the first root emerges.

Students can write a report on the experiment comparing the three germination rates and time to emergence. Did any treatments cause them to emerge faster? What was the seed germination rate?

UQ Experiment

1

Comparison of Potting MixesAimTo compare the effect of three potting mixes on the growth and development of sunflower plants.

Level and contextBASIC

The soil or substrate in which plants grow is one of the most important determinants in overall health and yield of crops. Soils supply essential macro- and micro-nutrients and soils have differing capacities to store moisture, influencing the water available for growth.

Materials and MethodsYou will need three potting mixes (treatments):

• Organic

• High quality mix (added fertilizer, trace elements, pH adjusted and perhaps water crystals) (Nursery Association – red ticks)

• Lower quality mix (Nursery Association – black ticks)

• 12 plastic pots of 14 litres capacity

• Fill four pots with each of the potting mixes ensuring you use the same volume of potting mix in each.

Observations and Data CollectionGet your class to observe the type of germination (epigeal) and draw a diagram.

Each week get your class to measure the following for each of the treatments (best if all measurements were done on the same day each week):

• Plant height (from soil surface to growing apex)

• Stem diameter at the height of the first true leaf

• Number of leaves (exclude the cotyledons)

Observe the colour and size of leaves and note the differences among treatments. Observe biological variability even within the same treatment.

Students can write a report on the experiment and draw three graphs (height, stem diameter and leaf number against time). They can explore and discuss how plant nutrition and water availability (or water stress) can influence crop growth.

UQ Experiment

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Comparison of Potting Mixes and FertilizersAimTo compare the effect of three potting mixes and a fertilizer on the growth and development of sunflower plants.

Level and contextINTERMEDIATE

In most Australian farming systems native soil fertility levels are decreasing in response to intensive cropping, leading farmers to increasingly rely on fertilizers to provide crops with the nutrients they require for good growth. Maximising the efficiency of fertilizer use is very important as using too little limits crop growth and lowers yield, while using too much reduces profits and has negative consequences for the environment.

Materials and Methods• Three potting mixes (treatments) as for Experiment 2

• 24 plastic pots of 14 litres capacity

• Fill eight pots by volume with each of the potting mixes.

Fertilizer

• None

• A general fertilizer such as Q5 (5.3%N, 5.8%P, 5.0%K, 13.3%S)

Add the recommended rate of Q5 to four pots for each of the potting mixes. The other four pots will be the controls (no added fertilizer). Remember there are nutrients in the potting mix. (This experiment can be varied by adding fertilizer at different times during plant growth, for example, four weeks after planting or at flowering, etc).

Observations and Data CollectionObserve the colour and size of leaves and note differences among treatments. Fresh weight (and dry weight if drying facilities are available: 60ºC for two days or until fully dry) may be measured once plants are mature (back of the head turns brown).

Students can write a report on the experiment and draw three graphs (height, stem diameter and leaf number against time) for each of the six treatments. Are there any interactions between the treatments? What might be causing these interactions?

Students can also weigh a set volume of each soil substrate dry and wet (ie. a pot full), and analyse the differences in soil water holding capacity between the soil types. You should water the soils till water runs freely out the bottom of the pot and then wait 30 mins before weighing the wet soil. Class results for the trial can be collated and the importance of soil water holding capacities can be discussed.

UQ Experiment

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Interaction of Potting Mixes and FertilizersAimTo compare the effect of three potting mixes and two fertilizers on the growth and development of sunflower plants.

Level and contextADVANCED

In addition to increasing dependence on fertilizers to provide crops with the necessary nutrients, the properties of the soil can have a significant influence on the availability of nutrients from fertilizers after they are applied. Chemical and physical properties of soil such as organic matter, pH, texture and water-holding capacity can significantly change the effectiveness of applied fertilizers.

Materials and Methods• Three potting mixes (treatments) as for Experiment 2

• 36 plastic pots of 14 litres capacity

• Fill eight pots by volume with each of the potting mixes.

Fertilizer

• None

• Liquid fertilizer (e.g. Thrive or Aquasol)

• Solid fertilizer such as Q5 (5.3%N, 5.8%P, 5.0%K, 13.3%S)

Add the recommended rate of Q5 to four pots for each of the potting mixes. Another four pots will be the controls (no added fertilizer). Remember there are nutrients in the potting mix. The liquid fertilizer will be added weekly using a watering can to the final four pots at the recommended rate, starting two weeks after emergence. Try to ensure you add the same volume of water to each plant. All other pots should receive the same volume of water without fertilizer added.

Observations and Data CollectionNote when the star shaped structure first appears. Observe the colour and size of leaves and note differences among treatments. Fresh weight (and dry weight if drying facilities are available: 60ºC for two days or until fully dry) may be measured once plants are mature (back of the head turns brown).

Students can write a report on the experiment and draw three graphs (height, stem diameter and leaf number against time) for each of the nine treatments. Are there any treatment interactions? Students can also express the results of each treatment as a mean and standard deviation.

Students can weigh a set volume of each soil substrate dry and wet (ie. a pot full), and analyse the differences in soil water holding capacity between substrates. Water the soils till water runs freely out the bottom of the pot and then wait 30 mins before weighing the wet soil. Class results for the trial can be collated and the importance of soil water holding capacities discussed. Also discuss the chemical differences between soils and how this can affect nutrient availability (ie. acid soils, clay soils).

UQ Experiment

4

Comparison of Light RegimesAimTo compare the effect of two light regimes on the growth and development of sunflower plants.

Level and contextADVANCED

Plants require light for photosynthesis and via phytochrome use it as a signal for physiological changes such as when to flower (photoperiodism), germination of seeds and to set circadian rhythms. Plants will adapt physically when exposed to lower-than-optimal light conditions.

Materials and Methods• You will need a high quality mix (added fertilizer, trace elements, pH adjusted and perhaps

water crystals) (Nursery Association – red ticks)

• Eight plastic pots of 14 litres capacity

• Fill the pots by volume with potting mix.

Light Regimes

• Natural light

• 70% shade cloth (shade house or structure supporting the shade cloth, simple frames can be erected using pvc pipe and shade cloth)

Observations and Data CollectionEach week the class is to measure the following for each of the treatments (best if the measurements are done the same day each week):

• Plant height (from soil surface to growing apex)

• Stem diameter

• Number of leaves

Note when the star shaped structure first appears. Observe the colour and the size of the leaves and note the differences between the treatments. Plants that are in the shade will use less water and grow slower. Ask students to investigate and discuss why this could be the case.

Students can write a report on the experiment and draw three graphs (height, stem diameter and leaf number against time). On each graph, compare the natural and reduced light. Students can discuss why reducing light would affect growth and photosynthesis.

UQ Experiment

5

Interaction of Light Regimes and FertilizerAimTo compare the effect of two light regimes on the growth and development of sunflower plants with and without fertilizer.

Level and contextADVANCED

Both light and nutrient are essential for plant growth. Light is required for photosynthesis and provides energy for growth, while nutrients provide the building blocks for growth and all biological processes. In addition, plant nutrient and water uptake is closely linked to light exposure with water moving from the soil to the leaves in response to light-driven stomatal opening.

Materials and Methods• You will need a high quality mix (added fertilizer, trace elements, pH adjusted and perhaps

water crystals) (Nursery Association – red ticks)

• 16 plastic pots of 14 litres capacity

• Fill the pots by volume with potting mix.

Light Regimes

• Natural light

• 70% shade cloth (shade house or structure supporting the shade cloth, simple frames can be erected using pvc pipe and shade cloth)

Fertilizer

• None

• A general fertilizer such as Q5 (5.3%N, 5.8%P, 5.0%K, 13.3%S)

The Q5 will be added at the recommended rate to eight pots (four pots will be placed in natural light and four under shade). Pots without fertilizer will be equally distributed between the shade house and natural light.

Observations and Data CollectionNote when the star shaped structure first appears. Observe the colour and size of leaves and note differences among treatments. Under shade, plants will use less water and also grow slower.

Students can write a report on the experiment and draw three graphs (height, stem diameter and leaf number against time). On each graph, compare natural and reduced light with and without fertilizer. Are there any interactions between treatments? Students can investigate and discuss how and why photosynthesis and plant nutrition are linked.

UQ Experiment

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CRICOS Provider No. 00025B

Enquiries:UQ Sunflower Competition Team

telephone 07 3346 1467 email science.events@uq.edu.au