4. Citrus is considered to be native of Southeast Asia, especially eastern India.
Phylogenic relationships extends through East Indies, Australia, central
China, Japan and even Africa.
Many present day citrus cultivars have been cultivated since ancient times
and their wild progenitors are not definitely known.

5. Citrus is grown in tropical and subtropical southeast regions of the world, in a
belt of approximately;
35° N and S of the equator.

6. There is a great diversity in citrus;
size
shape
fruit colour
juice contents
The most well known examples are the orange, the lemon, the grapefruit, the lime
and tangerines.

8. First organized programme was started by USDA in Florida in 1893 by W.T.
Swingle and H.J. Webber.
Disease management
(This programme was destroyed due to severe freeze in winter in 1894-95)

9. In 1908, USDA group produced large number of hybrids from many combinations
of cultivars and species.
‘Troyer’, among these, is an important rootstock
In University of California citrus breeding started in 1914, by H. B. Frost.
University of Florida started two citrus breeding programmes in 1924 and 1956.

11. Kingdom Plantae
Division Magnoliophyta
Class Magnoliopsida
Sub-class Rosidae
Order Sapindales
Family Rutaceae
Sub-family Aurantioideae
Tribe Citreae

12. W. T. Swingle classified sub family Aurantioideae into a very comprehensive
treatment.
Citrus (16 species)
Fortunella (4 specie)
Poncirus (1 specie)
Eremocitrus
Microcitrus
Citrus, Fortunella and Poncirus can be crossed with one another, and various
proven hybrids exist.

13. Citrus aurantifolia Key Lime
Citrus maxima Pomelo
Citrus medica Citron
Citrus reticulata Mandrin
Microcitrus

14. Some hybrids are;
Tangelo Tangerine X Grapefruit
Tangor Tangerine X Orange
Orangelo Orange X Grapefruit
Citrange Poncirus X Sweet orange
Citradia Poncirus X Sour orange
Citrangequat Citrange X Kumquat

16. Type Shrub or small tree
Height 5-15 m
Growth habit Ever green
Spines On twigs attachment
Leaves arrangement Alternate
Leaf characters Shiny, leathery, dotted Citrus tree facts and info. www.citrustreesnola.com
with oil glands

17. Type Solitary
Diameter 2-4 cm
Ovary 6-14 carpel
Stamens 4 X of petals
Petals 4-8 (Thick, Linear) citrus sinensis. www theflowerexpert.com
Flowers are very strongly scented. The vegetative apical meristem transforms into
a terminal flower bud. Axillary flower bud develops later than the terminal bud.

18. Technical terms Usual terms
Type Hesperidium berry Rind
Pulp
Shape Globose to elongated
Zest
Juice Sac
Size Length= 4-30 cm Segment
Diameter= 4-20 cm Mesocarp
Exocarp
Citrus. www.botany.com
A leathery rind surrounding segments or "liths" filled with pulp vesicles.

20. The plant or plant part (One of the components of budding or grating) which
provides root system after successful union of bud or graft with it.
Citrus plants grown in the "normal" way from seedlings have several problems.
Due to the complicated and in part fascinating reproductive life of citrus plants;
A tree grown from a zygotic seed seldom grows true to type.
Seedlings grown tree take up to 7-12 years before they grow a trunk and a
root system strong enough to bear fruit.

21. For getting superior true to type plants and reducing the bearing period, asexual
means of reproduction are implemented.

22. Different qualities can determine the choice of rootstock;
Tree vigor
Rooting depth
Time to reach fruit maturity
Tolerance to cold and water logging
Resistance to nematodes, foot rot (phytophthora), citrus blight
Susceptibility to citrus tristezza, exocortis and xyloporosis viruses

24. Rough Lemon Kinnow mandarins Punjab
Sour Orange Orange NWFP
However, there are a range of different rootstocks
growing at research stations and germplasm units but
they have not been commercialized.

26. Citrus jambhiri
Origin:
Rough lemon originated in the Himalayan foothills in
India.

27. Vigor Very vigorous
Growth habit Spreading
Density of branches Dense
Rough lemon. Sweating Canning Growing. 2009
www. chilechews.blogspot.com

28. Leaf division Simple
Leaf colour intensity Light Green
Petiole Not winged
Rough lemon. www.bugsforbugs.com.au

29. Advantages:
Tolerant to tristeza
Drought tolerant
Moderate tolerance to salinity
Disadvantage:
Less cold hardy
Intolerant to blight
Susceptible to phytophthora foot rot and burrowing nematodes

30. Uses:
Fully compatible with compatibility with oranges, grapefruit, tangelos
and most mandarin varieties.

32. Citrus aurantium
Origin:
The sour orange is native to southeastern Asia. Arabs are
thought to have carried it to Arabia in the 9th Century.

33. Vigor Vigorous
Growth habit Spreading
Density of branches Dense
Alexandris, G. Sour orange tree. www.fotolia.com
Versatile sour orange. www.fincalasbrisas.org

34. Leaf division Simple
Leaf colour intensity Dark
Petiole Winged
Sour orange tree. www.bayflora.com

35. Advantages:
Tolerant to cold
Drought tolerant
Resistance against gummosis
Tolerate salinity and alkalinity
Disadvantage:
Intolerant to tristeza
Susceptible to nematodes

36. Uses:
Grapefruit and orange yields on sour orange are moderate, with average fruit
size and good quality.

39. Citrus sinensis
Origin:
Sweet orange are native to southeastern Asia,
northeastern India or, more likely, southern China and
Indo-China.

40. Vigor Medium
Tree shape Spheroid
Growth habit Spreading
Citrus sinensis. Plante E Animali Italiani. www.digilander.libero.it

41. Leaf division Simple
Leaf shape Elliptical
Petiole Narrowly winged
Citrus sinensis-Sweet orange. www.plantoftheweek.org

42. Advantages:
Quite hardy
Resistance against cold
Tolerant to quick decline
Disadvantage:
Sensitive to soil salinity
Susceptible to gummosis

43. Uses:
Sweet orange is a good rootstock for all the citrus cultivars, producing large,
vigorous trees. Yields and fruit quality produced on sweet orange stock are
good and unions are compatible.

45. Citrus aurantium var. khatta
Origin:
Karna is an old Indian fruit of unknown origin, most
probably native to Tropical Asia, Indo-China.
Almost certainly a natural hybrid. While the tree and
fruit are distinctive, they exhibit characters of both
rough lemon and sour or bitter orange.

46. Vigor Medium
Growth habit Spreading
Tree habit Upright
Tree shape Spheroid
Kharna sour orange hybrid. www.citrusvariety.ucr.edu

47. Leaf division Simple
Leaf colour intensity Dark
Petiole Winged
Jaskani, M. J. et al. 2006. Pak. J. Bot., 38(2): 311-317

48. Advantages:
Tolerant to cold
Drought tolerant
Tolerate salinity and alkalinity
Disadvantage:
Susceptible to tristeza
Susceptible to gummosis

49. Uses:
Grapefruit and mandarins can be grown successfully on Kharna khatta.

51. Citrus limonia
Origin:
Rangpur lime has Indian origin. It is hybrid involving
either the rough lemon or sour orange in the parentage.

52. Vigor High
Tree shape Spheroid
Growth habit Spreading
Baishaishu Rangpur lime. www.citrusvariety.ucr.edu

53. Leaf division Simple
Leaf shape Elliptic
Petiole Obovate
Rangpur. Citrus limonia
www.steffenreichel.homepage.t-online.de

54. Advantages:
Drought tolerant
Tolerate salinity
Highly resistant to tristeza
Disadvantage:
Sensitive to cold
Susceptible to phytophthora
Susceptible to burrowing nematodes

55. Uses:
It makes a good union with number of citrus spp. Like sweet orange,
mandarins and pummelo.

57. Poncirus trifoliata or Citrus trifoliata
Origin:
Trifoliate oranges are native to central or northern
China. It is widely cultivated in temperate regions.

58. Vigor Medium
Tree shape Ellipsoid
Growth habit Spreading
Trifoliate orange. www. users.kymp.net

59. Leaf division Trifoliate
Leaf shape Ovate
Petiole Obovate
Poncirus trifoliata. www.plantsystematics.org

60. Advantages:
Resistant to tristeza
Tolerant to cold and water logging
Resistant to phytophthora and nematodes
Disadvantage:
Sensitive to drought
Intolerant to salinity
Slow growing rootstock

61. Uses:
It is used in high density planting as it is a dwarf rootstock. It is a good
rootstock for sweet oranges, tangerines and grape fruit.

63. Citrus reshni
Origin:
Cleopatra mandarin are native to tropical Asia, Indian
subcontinent.

64. Vigor Medium
Tree shape Spheroid
Growth habit Spreading
Cleopatra mandarin. www.users.kymp.net

65. Leaf division Simple
Leaf shape Elliptic
Petiole Obovate
Citrus reshni. www.flora-toskana.de

66. Advantages:
Cold hardy
Tolerate salinity and alkalinity
Resistant to tristeza, gummosis and quick decline.
Disadvantage:
Sensitive to nematodes
Sensitive to water logging
Susceptible to phytophthora

67. Uses:
Blood red and Valencia oranges perform well when budded on Cleopatra
mandarin.

69. Hybrid of;
Washington navel orange X Poncirus trifoliata
Purpose was to combine cold hardiness of trifoliate
orange with good traits of sweet orange.
Origin:
The original crosses were made in the early 1900s by the
United States Department of Agriculture with the
intention of producing cold tolerant scion cultivars.

70. Vigor Moderate
Tree shape Ellipsoid
Growth habit Spreading
Density of branches Dense
Oklahoma Cold Hardy Citrus Hybrid Project.
www.okcitrus.com

71. Leaf division Simple
Leaf colour intensity Dark
Petiole Winged
About1418 citrus. www.citrus.forumup.org

72. Advantages:
Cold tolerant
Tolerant to tristeza
Tolerant to Phytophthora and nematode
Disadvantage:
Adversely affected by high pH
Sensitive to soil salinity and water logging

73. Uses:
Fully compatible with navel and Valencia orange varieties.

75. Hybrid of;
Washington navel orange X Poncirus trifoliata
Origin:
It was originated as a hybrid of the Washington navel
orange crossed with trifoliate orange pollen that was
made at Riverside, California in 1909. In 1934, Swingle
named it for A. M. Troyer, on whose place at Fairhope,
Alabama, it first fruited.

76. Vigor Moderate
Growth habit Spreading
Density of branches Moderate
Citrange, 'Troyer‘. www.woodlanders.net

77. Leaf size Medium
Leaf division Trifoliate
Leaf colour intensity Dark
Citranges. www.homecitrusgrowers.co.uk

78. Advantages:
Cold tolerant
Tolerant to tristeza
Tolerant to Phytophthora and nematode
Disadvantage:
Adversely affected by high pH
Sensitive to soil salinity and water logging

79. Uses:
Troyer citrange is the major rootstock used for mandarins.

81. Hybrid of;
Poncirus trifoliata X Citrus sinensis
Origin:
The cross was made by J.W. Cameron & R.C. Baines in
the Citrus Research Center, Riverside, CA, in 1951.

82. Vigor Medium
Growth habit Spreading
Tree shape Spheroid
Citranges‘. www.woodlanders.net

83. Leaf shape Elliptic
Leaf division Trifoliate
Petiole shape Obovate
Citranges‘. www.woodlanders.net

84. Advantages:
Cold tolerant
Drought tolerant
Tolerant to tristeza
Tolerant to Phytophthora and nematode
Disadvantage:
Sensitive to soil salinity
Adversely affected by high pH

85. Uses:
Citrange 35 is used as rootstock for navel oranges, grapefruit and valencia
oranges.

87. W. T. Swingle classified sub family Aurantioideae into a very comprehensive
treatment.
Citrus (16 species)
Fortunella (4 specie)
Poncirus (1 specie)
Eremocitrus
Microcitrus
Citrus, Fortunella and Poncirus can be crossed with one another, and various
proven hybrids exist.