Citrus Rootstocks

1. Of CITRUS ROOTSTOCKS Description Identification Multiplication

2. WAQAS AHMED M. Sc ( Hons .) Agriculture (Horticulture)

3. Origin and History

4. Origin and History 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. Origin and History 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. Origin and History 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.

7. History of improvement

8. History of improvement 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. History of improvement 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.

10. Classification of Citrus

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

12. Classification of Citrus 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. Classification of Citrus Citrus aurantifolia Key Lime Citrus maxima Pomelo Citrus medica Citron Citrus reticulata Mandrin Microcitrus

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

15. Botany

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

17. Citrus Flower Solitary Type 2 - 4 cm Diameter 6 - 14 carpel Ovary 4 X of petals Stamens 4 - 8 (Thick, Linear) Petals 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. Citrus Fruit Citrus. www.botany.com A leathery rind surrounding segments or " liths " filled with pulp vesicles. Hesperidium berry Type Globose to elongated Shape Length = 4 - 30 cm Diameter= 4 - 20 cm Size Technical terms Usual terms Juice Sac Mesocarp Segment Zest Pulp Rind Exocarp

19. Citrus Rootstocks

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

22. Citrus rootstocks 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

23. Commercially used Citrus rootstocks in Pakistan

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

25. Rough Lemon

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

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

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

29. Rough lemon 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. Rough lemon Uses: Fully compatible with compatibility with oranges, grapefruit, tangelos and most mandarin varieties.

31. Sour orange

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

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

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

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

37. Other rootstocks

38. Sweet orange

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

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

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

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

43. Sweet orange 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.

44. Kharna Khatta

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

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

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

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

50. Rangpur lime

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

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

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

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

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

56. Trifoliate orange

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

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

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

60. Trifoliate orange 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. Trifoliate orange 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.

62. Cleopatra mandarin

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

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

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

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

68. Carrizo citrange

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

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

72. Carrizo citrange 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. Carrizo citrange Uses: Fully compatible with navel and Valencia orange varieties.

74. Troyer citrange

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

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

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

80. Citrange - 35

81. Citrange - 35 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. Citrange - 35 Medium Vigor Spreading Growth habit Spheroid Tree shape Citranges‘. www.woodlanders.net

83. Citrange - 35 Elliptic Leaf shape Trifoliate Leaf division Obovate Petiole shape Citranges‘. www.woodlanders.net

84. Citrange - 35 Advantages: Cold tolerant Drought tolerant Tolerant to tristeza Tolerant to Phytophthora and nematode Disadvantage: Sensitive to soil salinity Adversely affected by high pH

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

86. Breeding in Citrus

87. Breeding in Citrus 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.