1. Citrus belongs to the family:
A. Rosaceae
B. Rutaceae
C. Sapindaceae
D. Myrtaceae
Answer: B
Rationale: Citrus is classified under Rutaceae.
2. The center of origin of cultivated citrus is:
A. Mediterranean region
B. Central America
C. Southeast Asia–China region
D. Africa
Answer: C
Rationale: Citrus originated in Southeast Asia and southern China.
3. Citrus fruit is botanically a:
A. Berry
B. Drupe
C. Hesperidium
D. Pome
Answer: C
Rationale: Citrus fruits are specialized berries called hesperidia.
4. The edible portion of citrus fruit is:
A. Mesocarp
B. Endocarp juice vesicles
C. Epicarp
D. Seed coat
Answer: B
Rationale: Juice sacs (vesicles) are modified endocarp tissues.
5. The aromatic oil glands in citrus are present in:
A. Endocarp
B. Mesocarp
C. Epicarp (flavedo)
D. Albedo
Answer: C
Rationale: Oil glands occur in the flavedo.
6. Polyembryony in citrus is due to:
A. Sexual embryos
B. Zygotic embryos only
C. Adventive (nucellar) embryos
D. Endosperm embryos
Answer: C
Rationale: Nucellar embryony causes multiple seedlings.
7. A commonly polyembryonic citrus species is:
A. Sweet orange
B. Pummelo
C. Mandarin
D. Lime
Answer: C
Rationale: Many mandarins exhibit polyembryony.
8. The most common method of commercial citrus propagation is:
A. Seed sowing
B. Cutting
C. Budding
D. Air layering
Answer: C
Rationale: Budding ensures true-to-type plants.
9. T-budding in citrus is usually done during:
A. Peak summer
B. Active sap flow period
C. Winter dormancy
D. Flowering stage
Answer: B
Rationale: Active cambial activity ensures bud take.
10. Rough lemon (Jatti Khatti) is mainly used as:
A. Scion
B. Interstock
C. Rootstock
D. Pollinizer
Answer: C
Rationale: It is a vigorous and compatible rootstock.
11. Trifoliate orange (Poncirus trifoliata) is valued for:
A. Salt tolerance
B. Drought tolerance
C. Cold tolerance
D. High vigor
Answer: C
Rationale: It imparts cold hardiness.
12. Citrus prefers soil pH in the range:
A. 4.0–5.0
B. 5.5–7.5
C. 7.5–8.5
D. Above 8.5
Answer: B
Rationale: Slightly acidic to neutral soils are ideal.
13. The most critical micronutrient for citrus is:
A. Copper
B. Zinc
C. Iron
D. Manganese
Answer: B
Rationale: Zinc deficiency is widespread in citrus.
14. Zinc deficiency in citrus causes:
A. Leaf scorch
B. Little leaf and rosetting
C. Interveinal chlorosis of young leaves
D. Fruit cracking
Answer: B
Rationale: Zn deficiency leads to small, clustered leaves.
15. Iron deficiency in citrus is common in:
A. Acid soils
B. Sandy soils
C. Calcareous soils
D. Peaty soils
Answer: C
Rationale: High lime reduces iron availability.
16. Citrus flowering in tropical regions is mainly influenced by:
A. Photoperiod
B. Low temperature
C. Moisture stress followed by rains
D. Wind speed
Answer: C
Rationale: Stress–rainfall cycle induces flowering.
17. The phenomenon of heavy fruit drop soon after fruit set is called:
A. June drop
B. Pre-harvest drop
C. Physiological drop
D. Post-harvest drop
Answer: C
Rationale: Hormonal imbalance causes early drop.
18. Application of which PGR reduces fruit drop in citrus?
A. GA₃
B. NAA
C. CCC
D. Ethrel
Answer: B
Rationale: NAA improves fruit retention.
19. Citrus greening (HLB) is caused by:
A. Virus
B. Fungus
C. Bacterium
D. Nematode
Answer: C
Rationale: Caused by Candidatus Liberibacter spp.
20. The vector of citrus greening is:
A. Aphid
B. Psylla
C. Whitefly
D. Thrips
Answer: B
Rationale: Transmitted by citrus psylla.
21. Tristeza disease of citrus is caused by:
A. Bacterium
B. Fungus
C. Virus
D. Phytoplasma
Answer: C
Rationale: Citrus tristeza virus (CTV).
22. The primary vector of citrus tristeza virus is:
A. Citrus psylla
B. Leaf miner
C. Aphid
D. Mealybug
Answer: C
Rationale: Mainly spread by aphids.
23. Gummosis in citrus is caused by:
A. Alternaria spp.
B. Phytophthora spp.
C. Colletotrichum spp.
D. Fusarium spp.
Answer: B
Rationale: A soil-borne oomycete causes foot rot/gummosis.
24. Citrus canker is caused by:
A. Fungus
B. Virus
C. Bacterium
D. Nematode
Answer: C
Rationale: Caused by Xanthomonas citri.
25. The most susceptible stage to citrus canker infection is:
A. Mature leaves
B. Dormant buds
C. Young flush and fruits
D. Harvested fruits
Answer: C
Rationale: Tender tissues are highly susceptible.
26. Which citrus species is most cold tolerant?
A. Sweet orange
B. Lemon
C. Mandarin
D. Trifoliate orange
Answer: D
Rationale: Trifoliate orange tolerates low temperatures.
27. The common spacing for citrus orchards is:
A. 3 × 3 m
B. 4 × 4 m
C. 6 × 6 m
D. 10 × 10 m
Answer: C
Rationale: Standard spacing allows canopy development.
28. Citrus trees bear flowers mainly on:
A. Old wood
B. Current season’s shoots
C. Roots
D. Trunk
Answer: B
Rationale: Flowers form on new growth.
29. Citrus fruit cracking is mainly associated with:
A. Boron deficiency
B. Calcium deficiency
C. Irregular irrigation
D. Excess nitrogen
Answer: C
Rationale: Fluctuating moisture causes cracking.
30. The practice of removing excessive fruits to improve size is called:
A. Pruning
B. Training
C. Thinning
D. Ringing
Answer: C
Rationale: Thinning balances crop load.
31. Citrus leaf miner damage mainly affects:
A. Roots
B. Flowers
C. Young leaves
D. Fruits
Answer: C
Rationale: Larvae mine tender leaves.
32. The major harvested product of citrus peel oil industry is:
A. Limonene
B. Citral
C. Eugenol
D. Menthol
Answer: A
Rationale: d-Limonene dominates citrus oils.
33. Which citrus is mainly used for marmalade?
A. Sweet orange
B. Lemon
C. Bitter orange
D. Mandarin
Answer: C
Rationale: Bitter orange has suitable pectin and flavor.
34. The maturity index of citrus fruits is commonly judged by:
A. Fruit weight
B. Peel thickness
C. TSS:acid ratio
D. Seed number
Answer: C
Rationale: Sugar–acid balance indicates maturity.
35. Citrus trees respond best to pruning when done:
A. During peak flowering
B. Immediately after harvest
C. During monsoon
D. In winter dormancy
Answer: B
Rationale: Post-harvest pruning encourages healthy flush.
36. The physiological disorder “granulation” is common in:
A. Lemon
B. Mandarin
C. Sweet orange
D. Lime
Answer: C
Rationale: Granulation affects juice quality in sweet orange.
37. Which nutrient deficiency increases granulation?
A. Nitrogen
B. Potassium
C. Calcium
D. Magnesium
Answer: B
Rationale: Low K is linked to granulation.
38. Citrus is mainly pollinated by:
A. Wind
B. Bees
C. Flies
D. Birds
Answer: B
Rationale: Bees are important pollinators.
39. Which citrus type is most tolerant to salinity?
A. Sweet orange
B. Lemon
C. Mandarin
D. Lime
Answer: B
Rationale: Lemon shows relatively higher salt tolerance.
40. The economic life of a well-managed citrus orchard is about:
A. 10–15 years
B. 15–20 years
C. 25–30 years
D. 40–50 years
Answer: C
Rationale: Citrus orchards remain productive for decades.
41. The practice of covering soil to conserve moisture in citrus is:
A. Propping
B. Mulching
C. Earthing up
D. Training
Answer: B
Rationale: Mulching reduces evaporation and weeds.
42. Which citrus species has the highest vitamin C content?
A. Sweet orange
B. Lemon
C. Mandarin
D. Grapefruit
Answer: B
Rationale: Lemon is particularly rich in vitamin C.
43. The main carbohydrate stored in citrus trees is:
A. Sucrose
B. Starch
C. Glucose
D. Fructose
Answer: B
Rationale: Starch reserves support flowering and fruiting.
44. Citrus root system is generally:
A. Deep tap root
B. Shallow and fibrous
C. Adventitious only
D. Rhizomatous
Answer: B
Rationale: Shallow roots necessitate frequent irrigation.
45. The best irrigation method for citrus is:
A. Flood
B. Basin
C. Sprinkler
D. Drip
Answer: D
Rationale: Drip improves water and nutrient efficiency.
46. Which citrus species is commonly used for pickling in India?
A. Sweet orange
B. Lime
C. Grapefruit
D. Pummelo
Answer: B
Rationale: Lime is preferred for pickles.
47. Citrus fruits are considered:
A. Climacteric
B. Non-climacteric
C. Both
D. Pre-climacteric
Answer: B
Rationale: Citrus does not show a climacteric rise.
48. Post-harvest wax coating in citrus helps to:
A. Increase acidity
B. Reduce respiration and moisture loss
C. Enhance seed germination
D. Increase oil content
Answer: B
Rationale: Waxing extends shelf life.
49. Which citrus variety is widely grown in India for juice?
A. Kinnow
B. Mosambi
C. Nagpur mandarin
D. Malta
Answer: B
Rationale: Mosambi is popular for fresh juice.
50. Citrus yield is most reduced by:
A. Excess phosphorus
B. Severe pruning
C. Virus and greening diseases
D. High rainfall
Answer: C
Rationale: Systemic diseases cause major yield losses.
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