Learn more about Botany
This course is all about "applying botany". It is
practical and applicable to anyone working or wanting to use botanical
knowledge for commercial or workplace solutions.
Despite the significance of botany to our economy
and quality of life, it is neglected all too often in our education
system. In one respect this is a tragedy; but in another respect, it
presents a career and commercial advantage to those who do study botany.
Plants have the potential to solve major problems - they can be used
to create petrol for our cars, to reduce global warming, to purify
polluted soil and air, to overcome food shortages. To achieve these and
other things with plants though, we need to keep growing our knowledge
of botany, and how to apply that knowledge to the problems of our modern
and rapidly changing world.
Lessons include: Flower physiology; phytoperiodism; control of flower
bud initiation and development; dormancy; effects of plant associations
and competition; respiration and post harvest physiology; post harvest
storage, transport, retailing and shelf life; endogenous and synthetic
growth regulators; risks involved with plant growth manipulation.
ACS Student comment: "I find the course quite interesting! At first glance, the reading material and questions look so simple, but they
actually require quite a bit of thinking and probing. The course is
very well designed!" - Joanne McLeod, Australia - Botany II course.
This course is divided into ten lessons as follows:
1. Flower physiology
- The flowering response
- Genes control flowering
- Physiological age
- Minimum leaf number
- Light sensing systems
- Blue light responses
- Red light responses
- Other light responses
- Photoreceptor forms: Pr, Pfr
- How molecules change
- Relevance to commercial horticulture
- Controlling light
- Measuring light
- What wavelengths do plants need
- Typical photoperiod responses
- Photoperiodic responses in seasonal flowering plants
- Photoperiodic classification of plants: short day plants, long day plants, day neutral plants
- Detection of photoperiod
- Critical photoperiod and flowering
- Research facts
- Other photoperiodic effects
4. Control of flower bud initiation and development
- Stages in flower bud growth
- What can affect flower bud initiation
- Effect of temperature on growth and flowering
- Research reports or reviews of specific plants
- Dormancy in plants
- Abscisic acid and dormancy
- Breaking dormancy
- Dormancy in seeds
- Factors affecting seed dormancy
- Breaking seed dormancy
6. Effects of plant associations and competition
- Plant herbivore and pathogen interactions
- Crop spacing and crop yields
- Crop canopy and plant density
- Impact of weeds
- Protected environments
7. Respiration and post harvest physiology
- Aerobic respiration
- Anaerobic respiration
- Bioluminescence and Fluorescence
- Post harvest respiration
8. Post harvest storage, transport, retailing and shelf life
- Effect of growing conditions on post harvest life
Controlled storage conditions: temperature, atmosphere, humidity
- Normal atmospheric conditions
- Controlled and modified atmospheres
- Effect of oxygen levels Effect of carbon dioxide levels
- Controlling ethylene levels
- Modified Atmosphere Packaging
- Commodity transport
- Retailing and shelf life
9. Endogenous and synthetic growth regulators
- Nature of plant hormones
- Auxins: IAA, IBA, NAA
- Gibberellins: natural and synthetic
- Cytokinins: over 130 different types
- Abscisic acid
- Other hormones: anti auxins, growth inhibitors, growth retardants, defoliants, growth Stimulators, non standard hormones
- Controlled ripening and degreening
10. Risks involved with plant growth manipulation
- Commercial risks
- Human health and safety risks
- Plant pathology risks
- Ecological risks
- Genetic modification
- Environmental hazards
- Human hazards
Course Duration - 100 hours
Plants are Chemical Factories
To grow plants well, you need to understand how they grow.
In simple terms, a plant is a sort of chemical factory. Inside it's tissues, at a microscopic level, all sorts of chemicals are being captured, disposed of processed and changed; and as those chemical processes happen, the plant changes in both size and nature.
Every part of the plant can have different chemical processes at play; and those processes can change at different points in time. Consider something as simple as a seed:
The onset of seed development dormancy is marked by a lowering of metabolic rate of the embryo. Dormant seeds are dry, about 10% water content. The seed coat is impervious to water and/or oxygen and mechanically resistant to embryo enlargement. In some seeds, germination is prevented for some time by chemical inhibitors. Dormancy ensures that the seeds do not germinate while conditions are unsuitable for early plant development. Seeds of many tropical plants do not show any dormancy, as conditions are usually suitable for germination throughout most of the year because of the absence of a distinctive seasonal variation. A dormant bud or embryo can be ‘activated’ only by certain environmental cues.
Dormancy in seeds takes a number of forms:
- Physical inhibitors to germination such as hard or waxy seed coatings, prevent the entry of water or oxygen which stimulates the development of the embryo. These seed coatings need to be abraded before germination can occur. This wears the seed coat, permitting water or oxygen to enter the seed. This is also referred to as seed coat dormancy.
- Chemical inhibitors that directly prevent the development of the embryo until the chemicals have worn off or leached out. Both phytochrome and abscisic acid have been linked to dormancy and germination in seeds. This is also known as embryo dormancy.
- Environmental inhibitors such as the requirement for particular temperatures over particular time periods, particular volumes of water, or particular light conditions.
- Note that it is also possible for a seed to have what is called Double Dormancy. This means that it has seed coat dormancy and embryo dormancy. Theses would obviously require double treatment to initiate germination.
Factors Affecting Seed Dormancy
- Pollination -If pollination of the flower is incomplete, a high percentage of infertile seed is likely to be produced. Some plants need up to twenty visits to a flower by a pollinating insect before the pollination is completed.
- Ripening – Seed needs to fully mature before it is viable. If it is collected from a plant too early, it will not germinate. If something happens to interfere with the ripening process (e.g. being dislodged from the plant by storm or animal damage; stress caused by adverse conditions such as flood and water-logging); seed may appear to have matured, but in fact may not have matured properly.
- Storage Conditions – Most plants produce much larger quantities of seeds than what would be required to reproduce and sustain the population of that species, if all of the seeds were to germinate. In nature, seeds are distributed randomly, falling onto the ground below the plant, carried away by water (floods, streams, rivers), blown in the wind, carried by birds or other animals, etc. Some will be deposited in a friendly environment and others in a hostile environment. Though every species has its own preferred storage conditions, there are certain conditions which can be a problem for most types of seed, including excessive moisture, high humidity, high temperatures and the presence of pest or disease organisms.
- Chemical Locks – Chemicals within seeds inhibit germination. In nature, these locks are removed with time. The rate at which chemical locks are removed can vary from one seed to the next, even among seeds from the same fruit.
- Temperature - seeds will only germinate when temperature conditions are within a range needed for that species. If temperature is too hot, or cold, seed will remain dormant. At high temperatures, seed can be more susceptible to attack by disease; and at higher than required temperatures, pest (e.g. Insect) activity can increase (e.g. seed may be eaten). For some species, the temperature code required for germination is very complex and not properly understood. While many seeds simply require temperatures to be inside a certain range; others may require a sequence of differing temperature conditions to trigger germination.
- Moisture Levels - Seeds will only germinate if temperature conditions are within a range appropriate to the species. Under excessively moist conditions, most seeds are extra sensitive fungal disease (rotting). We know that deterioration of seed is affected by not only the % of water, but also the way in which that water is attached to the molecules that make up the seed tissue.
- Percentage of Viable Seed – Some species can produce large quantities of seed that are not viable (e.g. seed does not contain an embryo at all; hence cannot germinate). Genera that can be like this include: Aster, Eryngium, Solidago, and Vernonica. This characteristic may be an adaptation to help survival in the wild. If the seeds are prone to pests being eaten by animals), the plant may be producing larger quantities of seed in order to increase the chances of at least some surviving to produce new plants. Because it may take considerable energy to grow a viable embryo, the majority of seeds produced are made without embryos.
This course helps you to understand such conditions and processes in a plant; and by building that capacity to understand plants, you will build your capacity to work with plants.