Lecture 15 - Citrus

Question 1

family of citrus

Answer 1

Rutaceae

Question 2

citrus classification 3 main progenitor species

Answer 2

C. medica (citron)
c. maxima (pomelo)
c. reticulata (mandarin)

Question 3

origin of citrus

Answer 3

southeast asia

Question 4

best growing conditions of citrus

Answer 4

24-27 C (best at lower temp)

Question 5

what is peel colour of citrus related to

Answer 5

temp - low temp brings out orange color

Question 6

leaf morphology of citrus

Answer 6

petiole (winged or not) and leaflets
distinct scent of crushed young leaves

Question 7

citrus flower parts are in sets of ___

Answer 7

five

Question 8

citrus fruit is a berry called ______

Answer 8

hesperidum

Question 9

how many citrus flowers actually set fruit

Answer 9

1-5%

Question 10

how are citrus able to produce seedless fruit

Answer 10

parthenocarpy

Question 11

weakly parthenocarpic

Answer 11

only a few fruit is produced without pollination

Question 12

moderately parthenocarpic

Answer 12

fair crop is produced without pollin

Question 13

strongly parthenocarpic

Answer 13

sets good crop without pollination

Question 14

nuclear embryony

Answer 14

embryos form from nuclear tissue. Means most embryos are vegetative, not zygotic (clones)

Question 15

does citrus have nuclear embryos

Answer 15

yes

Question 16

implications of nucellar embryony

Answer 16

essential trait in rootstock (enable true -to-type propagation from seeds)
impedes progress in breeding

Question 17

propagation of citrus

Answer 17

done through scion and rootstock (got from seed or cuttings. seed works better)

Question 18

why use rootstock for citrus propagation

Answer 18

avoids juvenility (produces fruit faster)
necessary for plants without seeds
optimizes tree and root health

Question 19

important rootstock attributes

Answer 19

anchorage, abiotic and biotic stress tolerance
compatibility with scions

Question 20

what are the progenitors of sweet orange

Answer 20

pomelo and mandarin

Question 21

t/f: sweet orange is not poly embryonic

Answer 21

f

Question 22

scientific name of sweet orange

Answer 22

citrus sinensis

Question 23

4 types of sweet orange

Answer 23

sugar/acidless orange
pigmented/blood orange
navel orange
common orange

Question 24

current classification of mandarin

Answer 24

type 1, type 2a, type 2b, type 3

Question 25

type 1 mandarin

Answer 25

pure with no interspecific admixture

Question 26

type 2a mandarin

Answer 26

early-admixture containing small amount of pomelo alleles

Question 27

type 2b mandarin

Answer 27

early-admixture containing additional pomelo alleles

Question 28

type 3 mandarin

Answer 28

late-admixture with additional pomelo introgressions in type 2, and further crossed with sweet orange

Question 29

what are the progenitors of grapefruit

Answer 29

pomelo and sweet orange

Question 30

scientific name of grapefruit

Answer 30

citrus paradisi

Question 31

2 groups of grapefruit

Answer 31

white fleshed pigmented

Question 32

T/F: pomelo is monoembryonic

Answer 32

t

Question 33

2 groups of pomelo

Answer 33

white-fleshed pigmented

Question 34

what are the progenitors of lemon

Answer 34

citron and sour orange

Question 35

what is lemon highly sensitive to

Answer 35

cold

Question 36

are lemon seeds mono or polyembryonic

Answer 36

polyembryonic

Question 37

what are the progenitors of limes

Answer 37

citron and c. micrantha

Question 38

type of limes

Answer 38

small-fruited lime large-fruited lime

Question 39

what is kumquat (citrus japonica)

Answer 39

small oranges that are eaten whole. Peel is sweet, flesh is sour/tart

Question 40

what determines fruit flavor in citrus

Answer 40

sugar:acid ratio determines flavor

Question 41

acid and sugar in balance =

Answer 41

good flavor

Question 42

high acid/low sugar =

Answer 42

sour flavor

Question 43

high sugar/no acid =

Answer 43

no flavor

Question 44

factors affecting sugar:acid ratio in citrus

Answer 44

genetic climate agronomic

Question 45

macronutrient deficiencies in citrus

Answer 45

excess nitrogen = excess vigor, promote vegetative growth instead of flowering low nitrogen = yellow leaves, promotes extensive flowering low phosphorus = hollow core, thicker rind low potassium = smaller fruit

Question 46

grapefruits and pomelo will develop ____ rinds in cooler temps or under phosphorus deficiency

Answer 46

thicker

Question 47

grapefruits and pomelo will take ____ months to sweeten up

Answer 47

14-16

Question 48

Major challenges of growing citrus

Answer 48

freezing citrus canker citrus greening/yellow dragon disease

Question 49

cultural practices to protect citrus from freezing

Answer 49

sprinkler irrigation through microsprinklers clean, hard-packed soil surface covered trunks

Question 50

biggest problem disease in citrus

Answer 50

HLB/citrus greening