Lecture 5: Starchy Staple, root design and function

Question 1

What are the characteristics of the root?

Answer 1

lower part of axis
subterranean
lack of chlorophyll
indeterminate apical meristem
highly branched

Question 2

How many axes and laterals does winter rye have?

Answer 2

13 million (about 1 million per day)

Question 3

What is the total length on average occupied by the roots of winter rye?

Answer 3

greater than 500 km

Question 4

What is the average surface area covered by the roots of winter rye?

Answer 4

greater than 200 m^2

Question 5

What are the functions of roots?

Answer 5

anchorage
absorption (water and minerals)
storage (has parenchyma)
rhizosphere
synthesis ( roots can make particular compounds)

Question 6

What does it mean by rhizosphere?

Answer 6

the bacteria and fungi extend the plants’ reach into the soil

Question 7

Describe dicot roots

Answer 7

branch acropetally
the tap root penetrate deeper than monocots
due to acropetal structure; binds less tightly to soil
suberized (make wood)
secondary growth ( the formation of vascular cambium and cork cambium)

Question 8

Describe monocot roots

Answer 8

wide branch angle (enables it to bind more tightly to soil)
sclerenchyma cells conger rigidity
shallow roots

Question 9

Describe the penetration process of a dicot?

Answer 9

radicle to
tap root to
lateral roots

Question 10

Describe the penetration of monocot roots

Answer 10

tap root to

fibrous adventitious

Question 11

Define contractile roots

Answer 11

eg. carrots, hyacinth, sugar beet
- contracts up to 70%
- swells outwards
- draws apex down the soil
- contracted part may be a storage organ

Question 12

What is the benefit of contracting these organs?

Answer 12

So that it won’t get eaten; keep the energy

Question 13

true or false; soil structure affects growth

Answer 13

true

Question 14

How does compact soil affect root growth?

Answer 14

resistance to root growth

Question 15

How does lots of water in the soil affect root growth?

Answer 15

slows down root growth

Question 16

How does less water in the soil affect root growth?

Answer 16

speeds up root growth; extensive branching

Question 17

Why does less water speed up root growth?

Answer 17

because there is less amount of nutrients available

Question 18

What is the flood response of roots?

Answer 18

formation of aerenchyma

Question 19

What are hard pans?

Answer 19

iron rich soils
rigid pore structure
roots only grow in cracks

Question 20

What happens when a root meets a pore smaller than itself (in hard pan soil)

Answer 20

the root forces the crack to open

Question 21

How does the root force the small pore to open?

Answer 21

diameter of the root increases
tissue distortion
small extension zone
many root hairs grow in the zone of maturation thus increasing anchorage for pushing

Question 22

What do you call roots that extract O2 from the atmosphere?

Answer 22

pneumatophores (mangroves)

Question 23

What is the purpose of pneumatophores?

Answer 23

so that the starch (energy) stored in the roots can be released via respiration

Question 24

What are epiphytes

Answer 24

• don’t grow on soil

- can absorb atmospheric moisture and nutrients via VELAMEN

Question 25

What are flower pot plants characteristics

Answer 25

- leaf forms FLATTENED succulent structures (pot) | this collects - debris and rainwater

Question 26

What is the purpose of ants living in flower pot plants?

Answer 26

ants deposit nitrogen

Question 27

What is the purpose of adventitious roots of flower pot plants?

Answer 27

adventitious roots from node above grows down into 'pot' to absorb water and minerals

Question 28

What are examples of root crops?

Answer 28

carrots sugar beet kumara cassave

Question 29

Where were carrots first domesticated?

Answer 29

Afghanistan

Question 30

What was the color of the first domesticated carrot?

Answer 30

purple

Question 31

How did the orange strain of carrot species come about?

Answer 31

16th century pale yellow variety was cultivated in Europe

Question 32

Who cultivated the orange species?

Answer 32

Dutch breeders

Question 33

What is the advantage of the orange colored carrots to its consumers

Answer 33

had more carbohydrate content - has beta carotene which breaks down to vitamin A - Vitamin A is a precursor for retinol - retinol is light absorbing pigment in rod cells in the eye

Question 34

Are carrots biennial or perennial?

Answer 34

biennial

Question 35

What happens during these 2 years of carrot growth

Answer 35

1st year: stores reserves in swollen taproot | 2nd year: reserves used to form flowers (release seeds)

Question 36

Why does the storage tap root shrink during the second year of growth?

Answer 36

This is because energy is being used to produce leaves and flowers

Question 37

How much % of parenchyma in cortex (starch and sucrose) are carrots composed of (dry weight)

Answer 37

20% sucrose | 6% starch

Question 38

Where did kumara originate?

Answer 38

South America

Question 39

Where were Kumara first domesticated?

Answer 39

Peru

Question 40

Who introduced Kumara to Europe and when?

Answer 40

Columbus (1492)

Question 41

Where is the most Kumara grown nowadays?

Answer 41

China

Question 42

Where is kumara an important staple food?

Answer 42

warm temperate countries | livestock feed in tropics

Question 43

How much in % does the parenchyma of kumara contain (starch and succrose and protein)

Answer 43

30% starch + sugars | 2% protein

Question 44

How is kumara likely to be propagated nowadays?

Answer 44

from cuttings

Question 45

true or false; 40% of the table sugar in the world today is from sugar beet?

Answer 45

true

Question 46

Where is sugar beet native to?

Answer 46

the Mediterranean

Question 47

How has selective breeding increased the sucrose content of sugar beet?

Answer 47

from 2% to 20%

Question 48

What in its structure does sugar beet have a lot of ?

Answer 48

cambia

Question 49

What does supernumerary cambia mean?

Answer 49

phloem cambia xylem

Question 50

Where did cassava originate?

Answer 50

South America | - domesticated more than 3000 years

Question 51

How much weight of the cassava in % is in the central pith of root

Answer 51

35%

Question 52

How many people consider cassava as their staple food

Answer 52

800 million people; including 250 million in the sub- Saharan desert

Question 53

how much in % is the calorie intake of cassava in Africa?

Answer 53

37%

Question 54

true of false; cassava grows well in relatively dry regions?

Answer 54

true

Question 55

How many years can cassava be stored?

Answer 55

3 years

Question 56

true or false; cassava produces more starch per hectare under relatively dry conditions than any other known crop

Answer 56

true

Question 57

Why is cassava poisonous if it wasn't boiled?

Answer 57

contains cyanogenic compounds cyanide is released when cells rupture thus roots must be boiled or soaked & dried

Question 58

How much is the estimated population growth of humans in the year 2050

Answer 58

9 billion

Question 59

How many people in the world are under nourished?

Answer 59

1/7 of the world population 1.02 billion

Question 60

What are the staple crops?

Answer 60

cassava, sweet potato, sugar beet, yams (rice, potato, maize, wheat, soybeans)

Question 61

What is BioCassava plus

Answer 61

research - international integrated team of scientists - reduce malnutrition through improved cassava - provide complete and balanced nutrition - readily marketable higher yielding food crop - aim for field testing in two african nations in 2010 - greater than 12.1 million dollars grant by Bill and Melinda Gates foundation

Question 62

What are the aims of BioCassavaPlus

Answer 62

- increase the content of zinc and iron content in cassava tubers - increase protein content of cassava - increase vitamin A and E content of cassava tubers - decrease cyanogen content - delay post harvest deterioration of cassava tubers - develop virus resistant cassava varieties