Rootstocks

        The following tables show the principal commercial rootstocks and their most important characteristics. A larger number of plus signs indicate better performances.

Rootstock

Growth rates

Productivity until 10 years of age

Productivity after 10 years of age

Fruit Quality

Rangpur lime

+++++

++++

+++

+++

Volkameriana

+++++

++++

+++

++

Swingle

+++

+++

++++

+++++

Trifoliata

++

+++

++++

+++++

Cleopatra

++++

++

++++

++++

Sunki

++++

+++

++++

++++

Rootstock

Drought resistance

Resistance to Foot Rot

Resistance to Nematodes

Resistance to Blight

Resistance to Sudden Death

Rangpur lime

+++++

++

++

+

-

Volkameriana

+++

+++

++

++

?

Swingle

+++

++++

+++++

+++++

+++++

Trifoliata

++

++++

+++++

+++

+++++

Cleopatra

++

+++

+++

++++

+++++

Sunki

+++

+

+++

+++++

+++++

         Rangpur lime. It is the most utilized rootstock in São Paulo due to its heavy and early bearing, and drought resistance. Resistant to Tristeza but susceptible do Blight and Sudden Death. In areas of high disease incidence, Rangpur lime has been replaced or used in conjunction with a second rootstock on the same plants. Trees on Rangpur lime are very vigorous and adapt well to a great variety of soils, even the weakest sandy ones, always with supplemental fertilization. Fruit are large but internal quality is only average. Sugar production per area is excellent. Rangpur lime induces early maturity to the fruit, when prices are higher.

     The special conditions in which growers become interested in other rootstocks to replace Rangpur lime are the following: (the change usually requires the installation of irrigation in the orchards)

- High incidence and severity of Citrus Blight

- Incidence of Citrus Sudden Death

- Soils with high humidity but without free water on the surface like low lands adjacent to springs, rivers and prairies.

- Need for high quality fruit, usually for export

- Need for late maturing fruit for better prices

- High incidence of foot rot or nematodes

- For reset in areas with high incidence of Blight or soil diseases

- Need to control tree vigor in order to reduce operational costs

         The multiple-rootstock technique is a good alternative to just changing the rootstock. It is expected that plants with 2 rootstocks maintain all qualities of Rangpur lime in addition to the higher longevity of the second rootstock, typically resistant to most diseases.

         Volkameriana. Initial vigor and precocity similar to Rangpur lime. It is less drought resistant, trees are smaller as well as the fruit. It is more resistant to foot rot, but it is susceptible to Blight. Its behavior in relation to citrus sudden death is controversial.

         Swingle. It is a hybrid between grapefruit and trifoliata. Resistant to foot rot, nematodes, tristeza and sudden death. Excellent tolerance to citrus blight. High sugar levels in the fruit, excellent flavor and high sugar levels per box of fruit. Tree growth is less vigorous than that of Rangpur lime. However, due to its disease resistance and longevity, trees on swingle become very large. In spite of that, trees on swingle are usually planted in higher densities, yielding high crops per unit area although still smaller that those on Rangpur lime in the first 10 years of the orchard. It has been the rootstock more commonly utilized in the multiple rootstock technique, together with Rangpur lime, with excellent results.

           Trees budded on Swingle are drought susceptible. However, under Sao Paulo conditions, they have recovered well after the dry season in the field, flushing and blooming profusely, with good fruit set.  Irrigation, nevertheless, can be very beneficial to trees on Swingle. The use of 2 rootstocks - Rangpur lime and Swingle - has reduced drought susceptibility of budded citrus trees in the first years of observation.

            Swingle is not compatible with Pera and Seleta oranges, Murcott tangerine, and some true lemon varieties. The use of a compatible interstock is required for propagating these varieties on Swingle.

       Trifoliata. Similar to Swingle except for being susceptible to citrus blight and growing more slowly.

       Cleopatra. Trees budded on Cleopatra grow uniformly to reach large sizes. As they are more demanding on nutrients and less tolerant to drought, crops and fruits are smaller than for Rangpur lime in the first 10 years of the orchard. However, due to their resistance to diseases, longevity is greater and productivity is better after the first 10 years.

          Internal quality of the fruit is superior to that of trees on Rangpur lime, with more sugars. Fruit are smaller and mature later. t is a rootstock utilized for tangerines and for late maturing varieties.

          Cleopatra is resistant to sudden death, tristeza, and less susceptible to citrus blight than Rangpur lime. It is susceptible to foot and root rot, and nematodes.

       Sunki. Trees on sunki have intermediary resistance to drought, fruit size and maturity, and productivity between Cleopatra and Rangpur lime. They are resistant to citrus blight, tristeza, citrus sudden death, but very susceptible to foot and root rot. Sunki has been a rootstock choice for Pera orange in areas with high incidence of sudden death or citrus blight, or used as a second rootstock on Pera trees budded on Rangpur lime.

CITROLIMA rootstocks

       Mudas Cítricas Citrolima has been developing new rootstocks for more than 20 years. New rootstocks are created through free or controlled hybridization among the known commercial varieties. The most promising ones are listed below. As the plants have less than 15 years observation time, information on citrus blight and foot rot resistance is still preliminary.

       Sunki Voadora (Flying Sunki).A cross between Sunki and  Flying Dragon trifoliata. Fruit quality and tree vigor, productivity and drought resistance are very good.

       Citrange Voador (Flying citrange). A cross between sweet orange and Flying Dragon trifoliata. Fruit quality and productivity are very good.

       SSW 1. A cross between Sunki and Swingle citrumelo. Good vigor and productivity. Drought resistance better than that of Swingle.

       SCZ 1 e SCZ6. Crosses between Sunki and Carrizo citrange . Good vigor and productivity.

       SAZ 2. Cross between Sunki and Sour Orange. Good vigor and productivity.

       528, 530, 539 e 541. Crosses between Sunki and Flying Dragon trifoliata. Good vigor and productivity.

       RV 14, 18. Crosses between Valencia orange and Rangpur lime. Good vigor and productivity.

       Rangpur lime A. Free pollination Rangpur lime hybrid very similar to Rangpur lime but with smaller trees.

       Rangpur lime J. Free pollination Rangpur lime hybrid with smaller trees, less drought resistance but high productivity.

       390, 391, 392, 393, 394 e 396. Free pollination Sunki hybrids with excellent vigor and productivity.

       SO 4 e SO 10. Crosses between Sunki and Orlando tangelo. Excellent vgor, good productivity and less drought intolerance than Orlando.

       SV 10. Cross between Sunki and Volkameriana. Good vigor and productivity.

       SC 2 e SC 7. Crosses between Sunki and Cleopatra. Good vigor and productivity.

       Volkameriana Citrolima. Free pollination hybrid with smaller trees and better foot rot resistance.

 

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