Lecture 21 - Rubber

Question 1

rubber scientific name

Answer 1

Hevea brasiliensis

Question 2

origin of rubber

Answer 2

amazon basin, upper, orinoco, guyana’s

Question 3

what did the mesoamericans use rubber for

Answer 3

footwear, bottles, torches, balls

Question 4

how did rubber get its name

Answer 4

joseph Priestly discovered that it would rub out paper marks

Question 5

who first suggests plantation growing of rubber

Answer 5

Hancock

Question 6

who and when discovered vulcanization of rubber

Answer 6

Goodyear and Hancock in 1839

Question 7

what is vulcanization

Answer 7

when rubber is heated with sulpher, it retains physical properties from 0-100C

Question 8

who was responsible for sending rubber plants to brazil’s Kew garden

Answer 8

Sir Clements Markham of India Office

Question 9

who developed the method for extracting latex

Answer 9

H.N. Ridley

Question 10

what did Dunlop do for rubber

Answer 10

rediscovered pneumatic tires

Question 11

where is most rubber produced

Answer 11

southeast asia, specfically Thailand

Question 12

why is there little rubber production in south america

Answer 12

due to the South America Leaf Blight

Question 13

what determines the Plasticity Retention Index

Answer 13

the amount of natural rubber. High in natural rubber means more stretchy because of cis configuration

Question 14

ideal climate for rubber

Answer 14

slightly acidic and well draining soil
22-30C
1500-3000mm/year

Question 15

reasons for defoliation in rubber trees

Answer 15

wintering at least once a year
drought
cold and short days

Question 16

type of flowers in rubber plants

Answer 16

monoecious with female flowers on tips of branches and male flowers more numerous
cross pollinated

Question 17

how many seeds does a rubber seed capsule have

Answer 17

3

Question 18

how is rubber propagated

Answer 18

through seeds as rootstock. Plant is then budded. They sit in a nursery for 10-15 months until at 3 whorl stage and then are transplanted

Question 19

how are rubber trees produced where South American Leaf Blight is a problem

Answer 19

use a 3 part tree with a seedling rootstock, a high yielding trunk, and a leaf blight resistant top

Question 20

planting density of rubber trees

Answer 20

360-416plants/ha

Question 21

when are rubber plants ready to be tapped

Answer 21

5-8 years. Need to be 50cm in circumference at 1m height. Trunk diameter of 7-8 inches

Question 22

how long are rubber tree productive

Answer 22

production increases until 15 years old. Normally tap for 20-25 years and replace at 30yrs

Question 23

what direction are rubber trees planted

Answer 23

N-S

Question 24

t/f: legume cover crops are used in between rubber trees as N source and weed control

Answer 24

t

Question 25

maintenance of rubber trees

Answer 25

remove all branches up to 2.5 m early on for smooth trunk for latex collection

Question 26

what are latex vessels in rubber trees

Answer 26

modified sieve tubes of phloem that run counterclockwise 2.5 degrees to the vertical

Question 27

laticiferous vessels

Answer 27

latex synthesis and transport

Question 28

what direction are rubber trees tapped in

Answer 28

clockwise direction

Question 29

excision method of tapping rubber trees

Answer 29

cut grove 30 degree angle mark 1-1.25m point, go 180 around tree, not too deep (dont reach cambium)

Question 30

how many times is cutting repeated for rubber tapping

Answer 30

1-3 days

Question 31

how much bark is consumed per year when rubber tapping

Answer 31

25 cm per year

Question 32

latex composition

Answer 32

water, terpenes, sugars, enzymes, etc

Question 33

rubber tapping intensity formula

Answer 33

S/2 d/2 = 100% s=size of spiral (s2=half spiral) d=frequency/day (d/2=every 2 days

Question 34

rubber trees are usually tapped for __ months and rested for ___ months

Answer 34

6, 3

Question 35

when does rubber cutting start in the day

Answer 35

early morning (6am) because latex flow is highest due to transpiration

Question 36

how many rubber trees can one person cut in a morning

Answer 36

500

Question 37

tapping schedule of rubber trees

Answer 37

first side tapped for 4-5 yrs second tapped for 4-5 years repeat cycle on original sides

Question 38

3 types of latex

Answer 38

Liquid (highest quality) Cup rubber (cut lump that sticks to cup) Scrap rubber - strip of rubber from cut surface

Question 39

how to coagulate rubber

Answer 39

10-25% ammonia (anticoagulent), 30-35% rubber, diluted with water

Question 40

how is rubber processed

Answer 40

latex poured into moulds and then formic or acetic acid is added to coagulate the liquid latex rollers make rubber sheets with curd

Question 41

how much rubber does wild and modern clones yield

Answer 41

wild 300-450kg/ha modern - 700-2000kg/ha

Question 42

what is done with the rubber wood after cut down

Answer 42

high quality paper and hardwood floor

Question 43

Major disease of rubber plants

Answer 43

South American Leaf Blight, Leaf Burning, Fusarium wilt, white root rot fungal disease, and bark disease