Lectures 1-4 Flashcards
Three cereals that provide over 50% of our calories
wheat, rice and maize
Give examples of cereal grains
wheat, rice, maize, barley, sorghum, millet
Give examples of Root crops
potato, sweet potato, yam, cassava
Give examples of Pulse crops
bean, pea, chickpea, cowpea, lentil, mung
Give examples of Sugar crops
sugarcane, sugar beet
Give examples of Fruit crops
banana, plantain, citrus, apple, berries
Give examples of Vegetables
tomato, cabbage, onion, carrot, cucumber
2014 World Production by Crop Type Ranking
- Cereals
- Vegetables
- Roots
- Fruits
- Oilcrops
- Citrus
- Pulse Crops
- Fibre Crops
Where do most of the prairie crops originate? Why would they be grown here?
Fertile crescent. Dryland adaptation? Similar geography? Cultural and culinary characteristics of the European settlers.
Why do acreages of different crops differ in the different provinces?
Available land, summer fallow; adaptability of crop; climate, geography; frost free units (days to maturity); heat units (length of growing season); soil type, irrigation; land use competition, value of crop.
Why do yields vary in the different provinces?
All relate to moisture availability, soil type, irrigation; land use competition, varieties (winter vs. spring). In general yields also vary because of the value of the crop.
Yields are in bushels - What do they mean?
Density of grain (Hulless vs. Hulled); Seed size, shape (packing); Indication of quality.
What is a bushel weight?
A bushel weight is a set size/volume.
What is the fertile crescent?
A region in the middle east where agriculture was first settled and people begun to domesticate crops.
Define the plant domestication process and given examples.
The act of bringing wild species into cultivation and selecting for desirable traits.
- Select against shattering
- Select against husks (hulls)
- Select against lodging (strong straw)
- Select against dormancy
- Select for size (yield), taste & use
Name the Precursor of maize, how it was known, and when it happened.
Teosinte 5,000 years ago: “Food of the Gods” or “Food of Humanity”
Which technology gave rise to plant domestication?
Genetic mutation.
What are the main differences between Harlan’s and Vavilov’s theories of the origins of crop species?
Vavilov identified eight primary areas of diversity and origin of cultivated plants: Mexico / Central America;
South America; Mediterranean; Middle East; Ethiopia;
Central Asia; India / Indochina; and China. Whereas Harlan amended Vavilov’s work and theorized three regions in which domestication of plants originated, and that for each, there is a definable center of origin and a more disperse non-centre, each of which interacts with the other. He preferred the term “centre of diversity” over “centre of origin”
Define Chromosome
Highly organized bodies carrying genes in the nucleus of the cell
Define Genome
One set of chromosomes
Define Polyploidy
Extra sets of chromosomes may be found in plants (> 1 genome)
Define Level of ploidy
Greatly increases the amount of genetic variability
Describe the two aspects of Vavilov’s Law of Homologous Series.
Variation found in one plant will also be found in plants of other species and genera, and Definite cycles of variability occur among whole families and common traits develop
Draw the Polyploidy scheme.
Embryo Gamete Haploid (x) 2n n Diploid (2x) 2n n Tetraploid (4x) 2n n Hexaploid (6x) 2n n Octoploid (8x) 2n n
What is the genetic difference between common wheat and durum wheat?
Triticum aestivum (common wheat) is a hexaploid (6x), and consists of three sub-genomes (A, B, and D)
Triticum durum (durum wheat) is a tetraploid (4x), and consists of only the A and B genomes
Theory of wheat evolution.
A genome: T. urartu
B genome: Related to Ae. speltoides
D genome: Ae. Tauschii
Evolution of oats (Avena sativa L.)
Diploids - Evolution 2N = 14 to Tetraploids - Evolution 2N = 28 to Hexaploids - Evolution 2N = 42
Diploid Oats (2N = 14)
Little commercial value, all wild species
Avena brevis – “Short oat”
Wild in SW Europe
Avena wiestil – “Desert oat”
Wild in Africa, Egypt, Ethiopia
Avena strigosa – “Sand oat”
Wild around the Mediterranean
Avena nudibrevis - Small seeded, naked
China
Tetraploid Oats (2N = 28)
Little Commercial value
Avena barbata – ”Slender oat”
Wild in Mediterranean
major range forage in California
Avena abyssinica – “Abyssinian oat”
Cultivated in Ethiopia
Hexaploid Oats (2N = 42)
Important species for cultivation
Avena nuda - Naked oat
China
Avena sterilis - Wild red oat
Algeria, N. Africa
Avena fatua - Common wild oat
Avena sativa - Common white oat
spp. diffusa (tree oat)
spp. orientalis (slide oat)
Avena byzantina - Cultivated red oat
Warm climate oat
Parent in many Canadian A. sativa species
Major difference between covered oat and naked oat.
Covered oat has a thick hull, whereas naked oat has a thin hull.
Triticale – Origin and Breeding
Triticale (X Triticosecale Wittmack)
Wheat X Rye hybrid
First found growing in Scotland in 1875
Potential for new, useful crop for humans
1890 - Partially fertile octoploid triticale was discovered
- Spontaneous doubling of chromosomes
- Colchicine discovered in 1937
- Facilitated the development of triticale
- Octoploids had poor performance and only partial fertility
Hexaploid Triticale.
2n = 42 = AABBRR
Developed from a cross between tetraploid durum wheat (2n=4x=28) and rye
Found to be superior to octoploids
Focus shifted to development of hexaploid triticale
Genetics of Triticale.
- Hexaploid wheat x Rye
ABD (2n = 42) R ( 2n = 14)Triticosecale octoploid ABDR (2n = 56) - Tetraploid wheat x Rye
AB (2n = 28) R ( 2n = 14)Triticosecale hexaploid ** ABR (2n = 42)
When does the growth stage of plants start?
Starts at germination.
What are gibberelins?
Plant hormones and act as Growth regulators.
Gibberellins have a number of effects on plant development, including:
1) stimulate rapid stem growth (stimulates cell division and elongation)
2) induce mitotic division in the leaves of some plants
3) increase seed germination rate (breaks dormancy)
Explain the two types of germination and give an example of each.
Epigeal: food reserves pushed above soil surface
e.g. canola, bean.
Hypogeal: food reserves remain below the soil surface
e.g. cereals, peas.
Requirement for Fertility, weed, disease, insect, and lodging management decisions.
It requires agronomic planning based on the stage of plant growth, rather than calendar dates.
Explain the process of cereal germination as discussed in lecture.
- Imbibition: water fills the seed and embryo produces gibberelin.
- The water activates secretion of hydrolic and proteolic enzymes from the aleurona layer.
- Mobilization of starch and protein in the endosperm, and growth of the embryo.
What are Seminal roots, Adventitious roots, and Coleoptile?
Seminal roots: First roots out of the radicle
Adventitious roots: Form from the seminal
Coleoptile: First structure to reach the surface
Discuss the different types of meristems and their significance.
Cells in the meristem can develop into all the other tissues and organs that occur in plants. Differentiated plant cells generally cannot divide or produce cells of a different type. … There are three types of meristematic tissues: apical (at the tips), intercalary (in the middle), and lateral (at the sides).
Longitudinal Section of Base at 3-leaf stage.
Tissue differentiates to become different leaves.
Types of meristems
Apical meristems Elongation Leaves, nodes internodes Roots Inflorescence Intercalary meristems Elongation
Describe the beginning of Tillering and how it relates to the development of other plant parts.
- Begins at 3-leaf stage
- Sequential
- Coleoptilar tillers
- Prophyll
- Direct relationship between tiller development and - crown root development
- More roots means more tillers
- Phyllocrons
Describe the Single ridge stage.
Primordia give rise to axillary buds, the lower half of each future spikelet. Starts floret formation.
Describe the Double the ridge stage.
2nd series of primoria; maximum number of spikelets is fixed.
Describe the Terminal spikelet formation.
No further florets can be initiated; maximum kernel potential; occurs by late jointing.
Stem Extension features.
- Pseudostem to true stem
- Begins once head formation is complete
(5-6 leaf stage) - Elevates developing head above ground
- Triggered by accumulated temperature and increase in day length
Describe the Boot stage characteristics.
- Leaf sheath swells
- Continues until emergence of flag leaf
- Flowering may take place inside or outside the boot
Boot Stage Cleistogamy.
- Flowering occurs before emergence
- Act of pollination in the boot
E.g. Barley
Boot Stage Protandry.
“Maturing the anthers before the stigma”
Male parts develop before the female parts
Ensures quick pollination
E.g. Rye
Describe the Types of Flowering and give examples.
Open flowering: occurs shortly after head emergence (e.g. wheat)
Closed flowering: occurs prior to head emergence (e.g. spring barley)
What can Trigger flowering?
- Vernalization: a) reproductive response to cold temperatures
b) switch from vegetative to reproductive phase
c) examples winter annuals, winter seeded cereals - Photoperiod: a) reproductive response to day length
b) long-day (short-night)
c) short-day (long-night)
Reproductive Structures
Two floret bracts= outer lemma + inner palea
What is Anthesis?
A developmental stage in flowering:
- Transition between heading and grain fill
- Occurs shortly after heading
- Lasts 3 to 5 days
- Anthers with pollen are extruding from floret
- Depends on open or closed flowering
Define: Polination, Cross-polination, and self-polination
Pollination is the transfer of pollens from anthers (stamens) to stigma of the flower.
Self pollinated:
Transfer of pollen within same flower
Transfer of pollen from one flower to another on the same plant
Anthers are extruded after pollination
Cross pollinated:
Transfer of pollen from one individual to another
Anthers are extruded before pollination
How does grain fill begin, what are its phases and how does it end?
Begins with fertilization
Three phases
Lag phase
Constant rate phase
Maximum weight phase
Ends with physiological maturity
Plant Structure: Kernel
Endosperm + embryo
Physiological Maturity:
No further accumulation of dry weight
Black layer stage in corn
Now waiting for loss of seed moisture for harvest
Varies among crops (25-40%)
4 facets of phasic development.
- All the growth and development responses of a plant are influenced by the environment.
- There are minimum, optimum, and maximum temperatures for different processes in the plant, and these temperature limits may be (and usually are) different for each of the stages of the life cycle.
- Temperature is one of many environmental factors influencing plant growth.
- The relationship between the plant and its environment is very complex.
Elaborate on the Barrel Theory:
Justus Von Liebig Law of the Minimum. The nutrient with minimum rates will limit the developmennt of the plant to the rate to which that nutrient is at.
What determines grain potential and what are its limitations?
Determined by initiation of spike formation (DR)
Influenced by: variety, management, stress, environment, partitioning.
Limited by:
a) Capacity of source (leaves)
b) Capacity of sink (grain)
Partitioning: Contributions to wheat grain yield from plant parts.
Plant parts closest to ear, contribute most to the ear’s development
Percent Ear 30 Flag leaf 30 Flag sheath 15 Flag internode 15 Remainder of plant 10
Source (leaves) capacity:
Anything that impacts upon photosynthesis
- Management
- Crop canopy
- Water availability
- Inputs (fertility)
- Competition (weeds, etc.)
Sink (grain) capacity:
- No. heads / unit area
- No. grains / head
- Kernel weight
And depends on:
Tillering pattern
Primordia production
(rate and duration)
Genetic limits to each of the above
Environmental effects on each
What are the yield components?
Yield is the product of sink(grain) capacity and the availability of assimilate (source) to fill these sinks.
Yield / unit area = (heads/area) x (kernels/head) x (wt/kernel)
Yield = X x Y x Z
Average yield of wheat.
Average yield of wheat - 35 - 37 bu/acre
Parkland area - 75 - 100 bu/acre
Model predicted yield potential - 337.5 bu/acre
Guinness World Records:
- 2003 wheat yield of 223 bu/ac
Surpassed in 2010 by 232.64 bu/ac
Both in New Zealand
Principles for agronomic management.
If you know the main constraint to yield at your site, the site or crop may be managed to reduce the constraint.
Agronomic management=
- seeding dates
- rates of seeding
- planting depth
- row spacing
- fertility management
- choice of crop species
- choice of species variety
- soil management
